BSB67
Well-Known Member
Last edited:
Degree an installed/unknown camshaft
- Thread starter Wietse
- Start date
Wietse
Well-Known Member
Short and sweet
I must apologize for being so stubborn to you BSB67, you were very right in the fact of the need to use a lifter to get readings instead of just a dial gauge.
It was several days later i had a thought about what you said, then realized what you were on about on went to look for a solid lifter.
I will check and see if the crank sprocket has multiple keyways and if there is something to do with it.
Otherwise i will need to speak with my local machine shop to bring the engine and get some new camshaft bearings installed and search for a new camshaft.
If this is for sure not going to improve i need to bite the bullet and change it while the engine is out.
BSB67
Well-Known Member
Short and sweet
I must apologize for being so stubborn to you BSB67, you were very right in the fact of the need to use a lifter to get readings instead of just a dial gauge.
It was several days later i had a thought about what you said, then realized what you were on about on went to look for a solid lifter.
I will check and see if the crank sprocket has multiple keyways and if there is something to do with it.
Otherwise i will need to speak with my local machine shop to bring the engine and get some new camshaft bearings installed and search for a new camshaft.
If this is for sure not going to improve i need to bite the bullet and change it while the engine is out.
I would not presume that you need new cam bearings. It is very unlikely that you do.
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wyrmrider
Well-Known Member
agree with bsb on the lifter
that and checking up off the base circle can throw off your numbers
however
you have a high compression motor and a big hyd cam so making it work is possible
that and checking up off the base circle can throw off your numbers
however
you have a high compression motor and a big hyd cam so making it work is possible
Wietse
Well-Known Member
I can only assume the camshaft bearings were replaced when the engine was rebuild, no idea how much miles it has done since...i guess not that much when looking at the condition of the cylinder liner crosshatch marks. If so i can just do a check anyway with a micrometer, max allowable is 0.005".
I am hoping to avoid going for a new camshaft, then a lot more will come in to play like push rods, springs etc.
But how would i be able to make this work then?
The guys you mentioned who can do some math are only on FABO forums? Did not find the names on here.
I am hoping to avoid going for a new camshaft, then a lot more will come in to play like push rods, springs etc.
But how would i be able to make this work then?
The guys you mentioned who can do some math are only on FABO forums? Did not find the names on here.
wyrmrider
Well-Known Member
PM on FABO
both great helpers
most likely no new cam bearings necessary
but we still do not know where the ICL is given lifter and checking on the base circle
you could be advanced
both great helpers
most likely no new cam bearings necessary
but we still do not know where the ICL is given lifter and checking on the base circle
you could be advanced
Wietse
Well-Known Member
ICL is at 89deg BTDC right?
I mean, that is where i found it.
And when going for the middle of both readings at 0.050" lift (27deg BTDC & 29deg ABDC) you also end up at 89deg ICL.
I will double check as you mentioned and start at the tip of the lobe and work 0.050" down on both sides and see where i end up.
I mean, that is where i found it.
And when going for the middle of both readings at 0.050" lift (27deg BTDC & 29deg ABDC) you also end up at 89deg ICL.
I will double check as you mentioned and start at the tip of the lobe and work 0.050" down on both sides and see where i end up.
wyrmrider
Well-Known Member
using a lifter?
let's see what happens
when you pm
note which posts have the timing with a lifter and to ignore earlier posts done with the dial indicator directly on the lobe
you are not going to have much vacuum but you can use a resoviour or a pump
let's see what happens
when you pm
note which posts have the timing with a lifter and to ignore earlier posts done with the dial indicator directly on the lobe
you are not going to have much vacuum but you can use a resoviour or a pump
Wietse
Well-Known Member
Yes, i am using a solid flat tappet lifter.
Just checked this, when starting on the tip and working both ways i end up at 49deg ATDC and 48deg BBDC. Both times in normal rotation direction, not in reverse...chain slack
Edit: i wrote rubish.
As per these readings the ICL should be at 90,5deg
This gives an LSA of 106,75 ==>107deg
I send a PM to both gentlemen, i hope they might chime in.
Just checked this, when starting on the tip and working both ways i end up at 49deg ATDC and 48deg BBDC. Both times in normal rotation direction, not in reverse...chain slack
Edit: i wrote rubish.
As per these readings the ICL should be at 90,5deg
This gives an LSA of 106,75 ==>107deg
I send a PM to both gentlemen, i hope they might chime in.
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PRHeads
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Using your .050 numbers I get 236/245-107.25 in at 91.
27+180+29 = 236
66+180-1= 245
236/2=118.... 118-27=91
245/2= 122.5.... 122.5+1 =123.5
123.5+91= 214.5 ...... 214.5/2= 107.25
The cam is advanced approximately one tooth, provided the degree wheel and pointer were zeroed out correctly at the beginning.
It’s more than likely one of the Hughes cams from the Engle days.
27+180+29 = 236
66+180-1= 245
236/2=118.... 118-27=91
245/2= 122.5.... 122.5+1 =123.5
123.5+91= 214.5 ...... 214.5/2= 107.25
The cam is advanced approximately one tooth, provided the degree wheel and pointer were zeroed out correctly at the beginning.
It’s more than likely one of the Hughes cams from the Engle days.
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AJ/FormS
Well-Known Member
You might be in trouble;
You cannot run 200psi on your gas with iron heads without detonating the pistons to pieces.
With aluminum heads it may be possible.
Do you have aluminum heads?
WietseR/T said: ↑
just the fact it idles poor and only pulls 10Hg vacuum at idle in Park (900-950 rpm)
Define "runs rough"
Your combo should not need to idle that high. Ima thinking your tune is off. You may just need to set the Transfer Slot exposure, provide some idle air, and fiddle with the idle timing. The 10" vacuum @900/950 sounds about right for this cam. Big-cam engines idle "poor" and "rough" as a result of the pistons pushing just-inducted A/F charge back up into the intake, on the compression stroke. This is a fact of life with them. The next smaller cam will do the same thing, just less violently. And the next smaller also, and so on until about a 268 advertised, and a pressure reduction to about 150. Then it will be reasonably smooth.
You seem to have figured out by now, what size cam you have installed. But IMO, that cam is just about too big for a street driven, automatic-equipped car. Yeah you can make it work with a hi-stall and big rear gears, but if you can't afford to drive it because it's so hard on gas, what's the sense in owning it.
The problem is that with this combo,is that you cannot install a smaller cam without the swap creating even more cylinder pressure, leading to even worse detonation. So that means the cylinder pressure will have to be reduced. Which means the Compression ratio will have to be reduced.Which means either heads with larger chambers, or the pistons need to be lowered.
But
I'm not a fan of the way you set your equipment up to measure the lobes. Anytime you use the pushrod cup to cradle the dial indicator, you can practically guarantee a measuring error as the indicator tip wallows around in the cup. I just had the machine shop make me a slug with both ends milled flat and parallel, problem solved.
But
Since your results seem to have been repeatable, I bow to your expertise. And, in any case, the error would not be very great. I'm just a perfectionist some times.
So please elaborate on runs rough, and head material. Ok page one shows iron heads, got it. In that case I would borrow another gauge and retest the cylinder pressure, to verify the 200psi..
You cannot run 200psi on your gas with iron heads without detonating the pistons to pieces.
With aluminum heads it may be possible.
Do you have aluminum heads?
WietseR/T said: ↑
just the fact it idles poor and only pulls 10Hg vacuum at idle in Park (900-950 rpm)
Define "runs rough"
Your combo should not need to idle that high. Ima thinking your tune is off. You may just need to set the Transfer Slot exposure, provide some idle air, and fiddle with the idle timing. The 10" vacuum @900/950 sounds about right for this cam. Big-cam engines idle "poor" and "rough" as a result of the pistons pushing just-inducted A/F charge back up into the intake, on the compression stroke. This is a fact of life with them. The next smaller cam will do the same thing, just less violently. And the next smaller also, and so on until about a 268 advertised, and a pressure reduction to about 150. Then it will be reasonably smooth.
You seem to have figured out by now, what size cam you have installed. But IMO, that cam is just about too big for a street driven, automatic-equipped car. Yeah you can make it work with a hi-stall and big rear gears, but if you can't afford to drive it because it's so hard on gas, what's the sense in owning it.
The problem is that with this combo,is that you cannot install a smaller cam without the swap creating even more cylinder pressure, leading to even worse detonation. So that means the cylinder pressure will have to be reduced. Which means the Compression ratio will have to be reduced.Which means either heads with larger chambers, or the pistons need to be lowered.
But
I'm not a fan of the way you set your equipment up to measure the lobes. Anytime you use the pushrod cup to cradle the dial indicator, you can practically guarantee a measuring error as the indicator tip wallows around in the cup. I just had the machine shop make me a slug with both ends milled flat and parallel, problem solved.
But
Since your results seem to have been repeatable, I bow to your expertise. And, in any case, the error would not be very great. I'm just a perfectionist some times.
So please elaborate on runs rough, and head material. Ok page one shows iron heads, got it. In that case I would borrow another gauge and retest the cylinder pressure, to verify the 200psi..
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Wietse
Well-Known Member
Thank you for commenting Aj/FormS,
OK, here goes..i own this car for 3 years and have been driving it since.
Actually now is the first time i focused that deep on the engine, this is because i will pull the engine soon to do various jobs.
I still wanted to do a paint job in the engine bay, get the engine painted as well and do some repairs on the bolt holes for the exhaust.
But since i found 1 header is cracked i realized i better do it now because of a potential fire hazard it would not be smart to keep driving it in this state.
Therefore, with the engine out it would be easy to change camshaft if i have to to reach my type of driving style i am looking for and with in the back of the head to change the 4.10 ratio rear to a 3.55.
Define "runs rough"
Since i own the car the engine "stumbles" at idle and actually shakes quite excessive.
It is not able to run a smooth set rpm, sounds like every now and then there is a random cylinder not firing. Let it idle at 1000+ rpm and it will be better.
It has been like that no matter what, different timing settings tested from 10 deg initial to 25+deg, with and without vacuum, ported and manifold but no difference.
Having the vacuum can attached causes detonation at some point, being under load or when at very light throttle so i left the vacuum advance off.
When i installed an AFR meter i found it was cruising with an AFR of 10-10.5, plugs were black and greasy.
It is not the excessive fuel consumption that i worry, it is just the fact it simply does not run as it should for on the street.
I can do pulls all day long, mid, high throttle or WOT and it will burn my tires clean off, but idling normal or have a good AFR during cruising is not happening.
There is no such thing as hesitation or any other carb/fuel related issue, if you hit it just make sure you have a clear road and have 2 hands at the steering wheel.
This thing must have been raced at the strip, which is not my idea to drive the car and i am aiming for a street style performance car with a decent idle.
I know, i want a different car than i currently own, but finding a medium would do me already, just to get the nervous edge off.
I had replaced the old Holley 750 4bbl with mech secondary's for a street avenger 770 with choke and vacuum secondary.
Took some time playing with jetting but the last times i drove it i am having nice AFR readings all over.
The street avenger has only 2 corner idling but i can manage, i get the same vacuum readings as with the old carb.
I am quite new in this Mopar stuff and i will probably have some settings not 100%, but i cannot believe there is something i did so wrong causing this poor idle as i have tried so many things in different ways that at some point i must have found the right combination already if there was one.
The converter stall speed is unknown, i do have a 4.10 ratio rear axle with SG and part of my plan was to change this to a 3.55 run a little lower on rpm at cruise (50mph).
Here all settings and specifics for the engine:
906 head (no idea on valve size)
Adjustable rockers with 1.6 ratio
Edelbrock performer RPM dual plane intake
Holley 770 Street avenger, vac secondary's
1-7/8" headers (to be replaced with new ones, same size)
MSD RTR distributor with an MSD Blaster SS coil, Timing set at 18deg intial and 18deg mech advance, 36deg all-in @ 2500rpm. (checked all spark plug cable for resistance and are good)
Fuel i am using is octane 94-95 i guess, advertised as 98 but probably lower.
Camshaft i found the initials CWC, which is the cast manufacturer, they don't do the grind.
Compression test results:
#1: 200 #2: 200
#3: 195 #4: 205
#5: 200 #6: 198
#7: 197 #8: 203
I might have overdone it with 5-8 cranking strokes, warm engine, carb at WOT.
The gauge is a new kit i purchased for that purpose...for sure not a calibrated gauge but i guess it should not be far of the truth.
Regarding the way i set up my dial gauge, the tip of the dial gauge was centered by the oil hole in the center of the cup and could not move around.
I just made sure it lined up straight without forcing it in position.
The readings were consistent, just eye balling the degree wheel could have caused the slight error.
2x correcting for 0.5deg is already 1 degree
My timing curve, with black advance bushing @ 18deg.
OK, here goes..i own this car for 3 years and have been driving it since.
Actually now is the first time i focused that deep on the engine, this is because i will pull the engine soon to do various jobs.
I still wanted to do a paint job in the engine bay, get the engine painted as well and do some repairs on the bolt holes for the exhaust.
But since i found 1 header is cracked i realized i better do it now because of a potential fire hazard it would not be smart to keep driving it in this state.
Therefore, with the engine out it would be easy to change camshaft if i have to to reach my type of driving style i am looking for and with in the back of the head to change the 4.10 ratio rear to a 3.55.
Define "runs rough"
Since i own the car the engine "stumbles" at idle and actually shakes quite excessive.
It is not able to run a smooth set rpm, sounds like every now and then there is a random cylinder not firing. Let it idle at 1000+ rpm and it will be better.
It has been like that no matter what, different timing settings tested from 10 deg initial to 25+deg, with and without vacuum, ported and manifold but no difference.
Having the vacuum can attached causes detonation at some point, being under load or when at very light throttle so i left the vacuum advance off.
When i installed an AFR meter i found it was cruising with an AFR of 10-10.5, plugs were black and greasy.
It is not the excessive fuel consumption that i worry, it is just the fact it simply does not run as it should for on the street.
I can do pulls all day long, mid, high throttle or WOT and it will burn my tires clean off, but idling normal or have a good AFR during cruising is not happening.
There is no such thing as hesitation or any other carb/fuel related issue, if you hit it just make sure you have a clear road and have 2 hands at the steering wheel.
This thing must have been raced at the strip, which is not my idea to drive the car and i am aiming for a street style performance car with a decent idle.
I know, i want a different car than i currently own, but finding a medium would do me already, just to get the nervous edge off.
I had replaced the old Holley 750 4bbl with mech secondary's for a street avenger 770 with choke and vacuum secondary.
Took some time playing with jetting but the last times i drove it i am having nice AFR readings all over.
The street avenger has only 2 corner idling but i can manage, i get the same vacuum readings as with the old carb.
I am quite new in this Mopar stuff and i will probably have some settings not 100%, but i cannot believe there is something i did so wrong causing this poor idle as i have tried so many things in different ways that at some point i must have found the right combination already if there was one.
The converter stall speed is unknown, i do have a 4.10 ratio rear axle with SG and part of my plan was to change this to a 3.55 run a little lower on rpm at cruise (50mph).
Here all settings and specifics for the engine:
906 head (no idea on valve size)
Adjustable rockers with 1.6 ratio
Edelbrock performer RPM dual plane intake
Holley 770 Street avenger, vac secondary's
1-7/8" headers (to be replaced with new ones, same size)
MSD RTR distributor with an MSD Blaster SS coil, Timing set at 18deg intial and 18deg mech advance, 36deg all-in @ 2500rpm. (checked all spark plug cable for resistance and are good)
Fuel i am using is octane 94-95 i guess, advertised as 98 but probably lower.
Camshaft i found the initials CWC, which is the cast manufacturer, they don't do the grind.
Compression test results:
#1: 200 #2: 200
#3: 195 #4: 205
#5: 200 #6: 198
#7: 197 #8: 203
I might have overdone it with 5-8 cranking strokes, warm engine, carb at WOT.
The gauge is a new kit i purchased for that purpose...for sure not a calibrated gauge but i guess it should not be far of the truth.
Regarding the way i set up my dial gauge, the tip of the dial gauge was centered by the oil hole in the center of the cup and could not move around.
I just made sure it lined up straight without forcing it in position.
The readings were consistent, just eye balling the degree wheel could have caused the slight error.
2x correcting for 0.5deg is already 1 degree
My timing curve, with black advance bushing @ 18deg.
BSB67
Well-Known Member
My position comes from a few high level observations:
1) as mentioned, the cam appears to be adjusted one tooth advanced. Therefore, there is no need to get too wound up about the cylinder pressure. It'll come down with proper installation of this cam, or any reasonable replacement cam.
2) if you believe the numbers from the OP's last set if measurements, the cam actually seems to be slow off the seat (even understanding that the 0.006" numbers will be probably 2° - 3° different than 0.005" numbers). So the cam has at least 80° overlap.
3) the OP does not like the 10" hg at idle now with + 80° overlap with the cam over advanced. There is no way he'll like this cam after we talk this cam to death.
Honestly, call Dwayne and get a new cam.
I don't know crap, but considering you have adjustable rockers already, get a Comp Cam XS solid, maybe XS274S and open the lsa a little, maybe. Simple, easy on parts, great idle, increased performance......
1) as mentioned, the cam appears to be adjusted one tooth advanced. Therefore, there is no need to get too wound up about the cylinder pressure. It'll come down with proper installation of this cam, or any reasonable replacement cam.
2) if you believe the numbers from the OP's last set if measurements, the cam actually seems to be slow off the seat (even understanding that the 0.006" numbers will be probably 2° - 3° different than 0.005" numbers). So the cam has at least 80° overlap.
3) the OP does not like the 10" hg at idle now with + 80° overlap with the cam over advanced. There is no way he'll like this cam after we talk this cam to death.
Honestly, call Dwayne and get a new cam.
I don't know crap, but considering you have adjustable rockers already, get a Comp Cam XS solid, maybe XS274S and open the lsa a little, maybe. Simple, easy on parts, great idle, increased performance......
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Wietse
Well-Known Member
I will not get to it today, but tomorrow i will check the distribution chain setup and see if it is advanced or not.
What would be the main reason for going with a solid cam?
I mean, for the reasonable small price increase to stick with a hydraulic cam i would not bother.
Unless there are some good benefits over a solid one in this case?
I did read up on them and found that they are better for high rpm's, cheaper and obviously less mechanical parts are involved so more bullet proof.
Doing a valve lash adjustment every now and then would not bother me.
Would there be anything important to know on valve springs when swapping?
I have no idea how much force is required for spring compression on these.
Edit: just read this article, looks like a similar setup and a good comparison between solid and hydraulic.
https://www.hotrod.com/articles/mopp-0312-solid-vs-hydraulic-lifters/
What would be the main reason for going with a solid cam?
I mean, for the reasonable small price increase to stick with a hydraulic cam i would not bother.
Unless there are some good benefits over a solid one in this case?
I did read up on them and found that they are better for high rpm's, cheaper and obviously less mechanical parts are involved so more bullet proof.
Doing a valve lash adjustment every now and then would not bother me.
Would there be anything important to know on valve springs when swapping?
I have no idea how much force is required for spring compression on these.
Edit: just read this article, looks like a similar setup and a good comparison between solid and hydraulic.
https://www.hotrod.com/articles/mopp-0312-solid-vs-hydraulic-lifters/
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Wietse
Well-Known Member
Came home earlier then expected, so jumped straight in the garage to get this chain cover off.
It is advanced 1 tooth, strange thing is that the camshaft gear is 180 deg out.
If i line up the indicator dot on the cam gear to the bottom the intake valve would already be lifted as in attached pictures.
First and second picture are from gears and camshaft in same position (at TDC and both inlet and exhaust valve lifter would be on the baseline of the camshaft), 3rd and 4th picture are when rotated 180 deg.
It is advanced 1 tooth, strange thing is that the camshaft gear is 180 deg out.
If i line up the indicator dot on the cam gear to the bottom the intake valve would already be lifted as in attached pictures.
First and second picture are from gears and camshaft in same position (at TDC and both inlet and exhaust valve lifter would be on the baseline of the camshaft), 3rd and 4th picture are when rotated 180 deg.
wyrmrider
Well-Known Member
let's get this one degreed in and looks like a new timing chain
then get the compression and ask AJ to rerun the numbers
you were so correct in your hunch that you were advanced
Thanks Aj PRH and all
motor is in the car- right- so not so easy to pull the cam and check the numbers?
still too early to start picking cams
Hughes does not supply seat timing but you could ask if you get the number or give them the final info
lotsa luck
you will have better luck with Engle
however the current cam is what it is and knowing more really will not help much
let's see where we're at before jumping
and think about where you want to end up
shorter cam would depend on your compression and a good tune
YR as evidently made HC motors work
put it at TDC on the ignition stroke and look where your dist rotor is pointed- # 1 wire you want to go back together same way but moved some due to one tooth
you will have to retime
cam looks good to me
then get the compression and ask AJ to rerun the numbers
you were so correct in your hunch that you were advanced
Thanks Aj PRH and all
motor is in the car- right- so not so easy to pull the cam and check the numbers?
still too early to start picking cams
Hughes does not supply seat timing but you could ask if you get the number or give them the final info
lotsa luck
you will have better luck with Engle
however the current cam is what it is and knowing more really will not help much
let's see where we're at before jumping
and think about where you want to end up
shorter cam would depend on your compression and a good tune
YR as evidently made HC motors work
put it at TDC on the ignition stroke and look where your dist rotor is pointed- # 1 wire you want to go back together same way but moved some due to one tooth
you will have to retime
cam looks good to me
AJ/FormS
Well-Known Member
Ok I get it, I'll give you my opinions and the reasons for them.
But first ;
As for the cam-timing being out a tooth; I doubt it. Your valves would be all bent up. To run open-chamber heads, at 200psi would require pop-up pistons with deep eyebrows. One tooth out would plow the valves into the crowns.
The opinions
Firstly, the cylinder pressure is waaaay too high, and will only get higher with a smaller cam. You would have to lower the Scr, to run a smaller cam.
Secondly, as it stands, that cam will not ever be happy with 3.55s,ever; unless you put a monster hi-stall in it.
Thirdly; the idle tune is way off.
The reasons
Your cam is similar to the old DC292/292/108/.509lift cam.Wyrmrider can tell you that this 292 is about a 249*.050 and something like [email protected], I forget how big, suffice it to say BIG!
I was able to make that cam idle just fine at 750rpm in my 367, and it would pull down to 550 rpm, in gear with a 4-speed and 3.55gears.. At 500 it wanted to stall and I had to slip the clutch. I got rid of that cam, cuz even with a clutch, it did not play nice with the 3.55s, that I wanted to keep. It was awesome tho with 4.30s!
You have to work within the confines of your gasoline. Your 200psi and your best gasoline conspire with your waaay too early all-in timing, to limit your throttle opening to slow and easy does it and wait for 3000 to 3500 before slamming the pedal down. The only reason the skirts haven't fallen into the pan yet is those 4.10s which reduce the load on the engine, by semi-instantly spinning up the tires.
As it stands; you cannot swap out those 4.10s. cuz they are the only thing keeping your engine alive.
Now 200psi is an awesome pressure, but the general consensus is that you can only run that at WOT, with aluminum heads. I have run 190 with our Canadian 87E10 (Ron+Mon)/2. So you should be able to run with your 98 gas at WOT with the alloys. And on the hiway, at Part Throttle, you can run a grade or two less.
You were right to swap out the 750DP on this combo, for a VacuumSecondary carb, because you can slow the rate of the secondary opening so as not to detonate your engine to death.
Now the tune.
The first thing I wanna know is; at what rpm does your TC flash-stall? Cuz if it's a factory TC yur in trouble. And the second thing is this; with the 950 rpm Neutral idle rpm, what is the in-gear idle rpm? In other words how much does it drop?
Cuz if it drops 250 rpm, yur in deep trouble.
more coming
But first ;
As for the cam-timing being out a tooth; I doubt it. Your valves would be all bent up. To run open-chamber heads, at 200psi would require pop-up pistons with deep eyebrows. One tooth out would plow the valves into the crowns.
The opinions
Firstly, the cylinder pressure is waaaay too high, and will only get higher with a smaller cam. You would have to lower the Scr, to run a smaller cam.
Secondly, as it stands, that cam will not ever be happy with 3.55s,ever; unless you put a monster hi-stall in it.
Thirdly; the idle tune is way off.
The reasons
Your cam is similar to the old DC292/292/108/.509lift cam.Wyrmrider can tell you that this 292 is about a 249*.050 and something like [email protected], I forget how big, suffice it to say BIG!
I was able to make that cam idle just fine at 750rpm in my 367, and it would pull down to 550 rpm, in gear with a 4-speed and 3.55gears.. At 500 it wanted to stall and I had to slip the clutch. I got rid of that cam, cuz even with a clutch, it did not play nice with the 3.55s, that I wanted to keep. It was awesome tho with 4.30s!
You have to work within the confines of your gasoline. Your 200psi and your best gasoline conspire with your waaay too early all-in timing, to limit your throttle opening to slow and easy does it and wait for 3000 to 3500 before slamming the pedal down. The only reason the skirts haven't fallen into the pan yet is those 4.10s which reduce the load on the engine, by semi-instantly spinning up the tires.
As it stands; you cannot swap out those 4.10s. cuz they are the only thing keeping your engine alive.
Now 200psi is an awesome pressure, but the general consensus is that you can only run that at WOT, with aluminum heads. I have run 190 with our Canadian 87E10 (Ron+Mon)/2. So you should be able to run with your 98 gas at WOT with the alloys. And on the hiway, at Part Throttle, you can run a grade or two less.
You were right to swap out the 750DP on this combo, for a VacuumSecondary carb, because you can slow the rate of the secondary opening so as not to detonate your engine to death.
Now the tune.
The first thing I wanna know is; at what rpm does your TC flash-stall? Cuz if it's a factory TC yur in trouble. And the second thing is this; with the 950 rpm Neutral idle rpm, what is the in-gear idle rpm? In other words how much does it drop?
Cuz if it drops 250 rpm, yur in deep trouble.
more coming
Last edited:
PRHeads
Well-Known Member
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- Location
- So. Burlington Vt
Just so everyone is on the same page....... there is no such thing as the cam is “180* out”.
It’s the cam that creates the 4 stroke cycle, and the difference between an intake stroke and a power stroke.
Without the camshaft, the pistons are just going up or down.
With the cam dot to dot, on a Mopar v8 you’re at #6 firing.
One other observation...... the rockers.
They’re likely either early Hughes, or Indy, or Proform.
The early Hughes were Dove, same as the Indy’s..... and the blue is likely 1.6 ratio(blue Indy’s are 1.6).
If they’re Proform, they’re all blue(and I don’t know if they even offer 1.6’s).
If you’re thinking of a different cam, you’ll want to know for sure what the ratio is.
If the cam comes out, I’ll be surprised if it’s not a Hughes HE3844BL, or the Engle equivalent.
The “advertised” duration numbers for those profiles are taken at .008” tappet lift........so, 283/291 for the 3844.
“If it were me”, I’d install the cam correctly and see how it runs.
Opening the intake valve 14* early allows for a lot of intake back flow, which will have a negative impact on drivability.
Sure, the early closing point bumps up the cranking pressure, but I don’t think that ends being a “wash”.
Likewise, the 14deg early ex opening point hurts torque....... with no real upside.
I’d install it at 104-105 and see how it runs.
As for the grind itself, from a street manners perspective, the lsa is as much of an issue as anything.
That same cam on a 110 or 112 would “behave” noticeably better with closed exhaust.
Also...... if in fact the rockers are 1.6 ratio, that also has an impact on drivability, since it increases the effective area of the overlap triangle.
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Wietse
Well-Known Member
I did never check the converter flash stall, but from the back of my head i would say 2800-3000.
I have seen it ramp up when pushing it and it would be somewhere near these figures.
The torque converter has a dark blue colour, that's all i know so far. probably not OEM Chrysler.
What the rpm drop is i could not tell you to be honest, i do remember the vacuum drops off from 10Hg to 5-5.5Hg. Would not surprise me if it does fall 200-250 rpm when throwing it in Drive.
I do have the feeling that when increasing idle rpm the rpm-drop also becomes less when putting it in Drive.
Thing is that due to a rpm signal converter from the MSD to the original tach it does show a bit odd at low figures. It drops down quite far and sometimes seen it show near zero rpm so that is not really something to rely on. (i could check on my strobe light as that also indicates rpm)
Noob talk here so excuse me because i will be probably wrong, but the intake valve closing at 29* ABDC does increase the cylinder pressure also? So compared to closing the intake valve at say 35* ABDC the cranking pressure should drop right?
As i mentioned that the cam gear seems like 180* out, when cylinder #1 is at TDC at the compression stroke these dots normally line up right?
That's why i said it is 180* out because when the crankshaft is in cyl #1 TDC position, at the compression stroke, both valves are not operated, the dot on the cam gear is on top.
This cam gear sits on a locator pin or key right? How can it end up the other way then...so confusing this thing..
Or are these dots that supposed to line up not located on the #1 TDC position?
In the end my question becomes, can i stay with this cam if retarding it or am i looking in getting another camshaft?
And with saying another camshaft i mean that it will probably be a similar type camshaft.
Due to work i have not much time at home now, somewhere next weekend i will leave home again for 3-4 weeks and i do not have space, time and manpower to assist me with removing the engine.
This will be done next time at home, then i have around 4 weeks off to play with the engine removal, painting and repairs.
I have seen it ramp up when pushing it and it would be somewhere near these figures.
The torque converter has a dark blue colour, that's all i know so far. probably not OEM Chrysler.
What the rpm drop is i could not tell you to be honest, i do remember the vacuum drops off from 10Hg to 5-5.5Hg. Would not surprise me if it does fall 200-250 rpm when throwing it in Drive.
I do have the feeling that when increasing idle rpm the rpm-drop also becomes less when putting it in Drive.
Thing is that due to a rpm signal converter from the MSD to the original tach it does show a bit odd at low figures. It drops down quite far and sometimes seen it show near zero rpm so that is not really something to rely on. (i could check on my strobe light as that also indicates rpm)
Noob talk here so excuse me because i will be probably wrong, but the intake valve closing at 29* ABDC does increase the cylinder pressure also? So compared to closing the intake valve at say 35* ABDC the cranking pressure should drop right?
As i mentioned that the cam gear seems like 180* out, when cylinder #1 is at TDC at the compression stroke these dots normally line up right?
That's why i said it is 180* out because when the crankshaft is in cyl #1 TDC position, at the compression stroke, both valves are not operated, the dot on the cam gear is on top.
This cam gear sits on a locator pin or key right? How can it end up the other way then...so confusing this thing..
Or are these dots that supposed to line up not located on the #1 TDC position?
In the end my question becomes, can i stay with this cam if retarding it or am i looking in getting another camshaft?
And with saying another camshaft i mean that it will probably be a similar type camshaft.
Due to work i have not much time at home now, somewhere next weekend i will leave home again for 3-4 weeks and i do not have space, time and manpower to assist me with removing the engine.
This will be done next time at home, then i have around 4 weeks off to play with the engine removal, painting and repairs.
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AJ/FormS
Well-Known Member
That's a problem, and shows the torque is rapidly falling, and I think, is pointing to the transfer Slot exposure being off.
That cam wants lots of air at idle, and the usual cure is too just crank up the idle speed. But this moves the throttle up the transfer slot. which causes the AF to go way rich, and the engine complains about it by greasy and sooty plugs, which tend to misfire, causing a poor and unstable idle.
So the first thing to do is to set the transfer slot exposure under the blades to something known to be pretty close, and then giving the engine the air it craves,somewhere else, while simultaneously adjusting the idle speed with idle timing. Now the torque curve will not drop so fast, and the manifold vacuum will not drop so low, and the AFR will remain more stable, which will stabilize the idle quality.
The PCV is your primary source of idle air bypass, so make sure you have one installed and working. Next, if that is not enough, you will have to bring in more air from somewhere else.
There are two methods out there; The first is to crack the secondaries, and the second is to drill small holes in the primary throttle valves. Every time I try cracking secondaries, I run into issues. Others report success, just not me; so I prefer the second method. More on this later.
Now, if the idle speed gets to be excessive, you will change it with idle-timing.
Ok so now, I will tell you what worked on my 292/108 cammed 367.
Start the car, warm it up, and reset the idle-timing to 14*. While it's warming up, check/adjust the running fuel level per the Holley spec. Take your time and get it right, this is critical.
Take the carb off, secure the primary throttle so it stays on the curb-idle screw, then flip it upside down. Go find the transfer slots. Using the curb-idle screw,adjust the exposure to a little longer than it is wide, say about 20 to 30% longer, no more.Now go find the idle discharge ports, just to identify them. Later, you will need to know where they are. Then flip it right side up, and adjust the mixture screws to 3/4 turn out from lightly seated.
Now remove the front bowl and swap out the PV for a plug. Then put it back together and re-install it. Again, make sure you have a working V8 PCV installed.
Finally start the engine and warm it up. The first thing you should notice is that the idle speed is very low, and it may not even stay running; that would be normal; the engine wants more air. And we are gonna give her some;just NOT at the curb-idle screw.
The question is how much?
Well in my case I installed a Tee in the PCV line and experimented with introducing air there. The more you give the higher the idle will go, until the fuel becomes too little to support the increase, then the exhaust will start to stink real bad.Water-your-eyes bad. So that would be too much. Ok so adjust the idle air bypass until you get a good quality idle, and at least 650 rpm. Finally increase the idle-speed to 750 using idle-timing.
Next, figure out the area of the introduced leak and convert it to the equivalent of two round holes, and that is the size of the holes we are gonna drill thru the primary blades. I'll guess the holes will need be 2 of 3/32, or so, one hole in each valve.. I started with 1/16 holes because this was my first time, and just kept drilling bigger. When I hit 1/8 the idlespeed became excessive, and I knew I had gone too far.
Next is where to put them. I drilled on the side where the transfer slots are; about half way between the shaft and the outter edge and at about 90* to said shaft, somewhere between the transfer slots and the idle-discharge ports.
If you go too big on the holes, don't panic. I chamfered the holes and dropped a gob of solder in there, and let it cool. I verified that it was well attached and then filed it flatish. Then moved over and drilled new SMALLER holes. On the 292 cam I think I ended at 3/32 or 7/64. That was year 2000, and the solder is still in there.
If drilling holes in your brand new carb scares you, just go get that 750DP. You'll just have to learn to control your right foot,lol. After you see how nice this works, you'll be dying to try it on the 770.
Final finally, twiddle the mixture screws for best quality, but they should come in between 1/2 and 1 turn.
But if they don't; we can talk about that later.
Ok so now it is ballparked!
You still have some fine-tuning to do. and we can talk about that later.
If your idle timing ends up different from what it is now, then you will have to change your power-timing. In your case I would start the tune by limiting it to 32/34 and not all-in until 3400 or higher. This will be 3.55-ready
And we can talk about the Vcan later.
If you noticed, there are three or four talk-about-it-laters. hhat's because I have been accused of having loooong rambling posts. So we can talk about that later.You're going away anyway so won't need to know until, well, later,lol.
Happy HotRodding
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