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What Will It Run?

PRHeads said:
The way I see it....... it doesn’t have enough power(speed) to run a significantly better ET.

The 60’ times still seem a tad weak for a 500” motor in a 3400lb bracket car.

What does the current converter flash to on the hit?

Without reading back through everything..... are the cam specs and compression ratio known?

Going by the Moroso chart, to go from 121mph to 125mph will require about another 50hp.
Click to expand...
I have a 512" motor, 10.5:1 compression. Cam is a Lunati solid flat tappet. Specs are .600intake/.600exhaust. duration at .050 is 276intake/276exhaust. 108* LSA. converter is a PTC 8". I don't have the stall and flash numbers handy. Cross ram intake with dual eddy 750's. Edelbrock Victor heads, 1.5:1 rockers.
 
Tires appear to be radials.. quicker maybe? Not as consistently hooking.. possible.
Lack of seat time? Raced much before?
Different days and times of days..
 
RemCharger said:
Tires appear to be radials.. quicker maybe? Not as consistently hooking.. possible.
Lack of seat time? Raced much before?
Different days and times of days..
Click to expand...
Tires are Mickey Thompson ET Streets. Traction is not an issue. Car hooks fine. Seat time and driver competence are an issue for sure. I have only been at this on a regular basis for about a year and a half. My tune could also be waaaay out of whack! I have set up the carbs based on advise from another racer with a similar setup, timing is locked at 35*. Valve lash is set at .026.
 
PRHeads said:
Cam is 276/[email protected].
Pretty big for only 10.5cr.

Have you done a cranking compression test?

The heads are MW Victors and the intake a MW crossram?
Click to expand...
Yes, MW Victors and MW crossram.

I have not done a cranking compression test. If I have a chance this weekend, I will get those numbers.
 
ksurfer2 said:
Tires are Mickey Thompson ET Streets. Traction is not an issue. Car hooks fine. Seat time and driver competence are an issue for sure. I have only been at this on a regular basis for about a year and a half. My tune could also be waaaay out of whack! I have set up the carbs based on advise from another racer with a similar setup, timing is locked at 35*. Valve lash is set at .026.
Click to expand...
Ahh yes. The old "2 carb " trick! I have no experience in that arena.

If it were me , I'd put a good 4 bbl setup on it to dial it in, then go back..
 
Here’s the Moroso chart......
121mph lines up with a 10.92
So they’re close to the actual best of [email protected]

Typically when they’re off from each other(actual ET and speed don’t line up), the speed is better than the ET....... unless the motor is laying down on the top end.

52E7C3B4-5470-4A5B-AAE8-5160FE31D490.jpeg
 
Just doing a calc myself......
With your ET/mph and a weight of 3400 all in? if you input 509fwhp it shows a slip like this>
60 Foot E.T. : 1.52 Seconds
1/8 Mile E.T. : 6.92 Seconds
1/8 Mile Trap Speed : 98.20 MPH
1/4 Mile E.T. : 10.97 Seconds
1/4 Mile Trap Speed : 122 MPH
wallace mph is inherently on the upside.
So a 512ci with Victors and the rest of your combo = 509fwhp on track?..where's the rest hiding, intake/carbs etc.?, thats a tough combo to get right I think with minimal experience but can a tune be really 100hp+off when it seems to run ok, surely that combo should be in the 600hp range......I too would put a single 4 like a 950 on their and try.
Just as a comparison, my old 440-6 bottom end 906 headed (260cfm) less than 10:1CR motor with an 850DP and a Team G intake in 1991 made 530fwhp on track re weight/mph, cam was a Comp Cams sft, .650/.650, [email protected], around 3300lbs@line ran 10.71@125 NA and had 10.50's in it with more air in the tyres.
 
440rb said:
Just doing a calc myself......
With your ET/mph and a weight of 3400 all in? if you input 509fwhp it shows a slip like this>
60 Foot E.T. : 1.52 Seconds
1/8 Mile E.T. : 6.92 Seconds
1/8 Mile Trap Speed : 98.20 MPH
1/4 Mile E.T. : 10.97 Seconds
1/4 Mile Trap Speed : 122 MPH
wallace mph is inherently on the upside.
So a 512ci with Victors and the rest of your combo = 509fwhp on track?..where's the rest hiding, intake/carbs etc.?, thats a tough combo to get right I think with minimal experience but can a tune be really 100hp+off when it seems to run ok, surely that combo should be in the 600hp range......I too would put a single 4 like a 950 on their and try.
Just as a comparison, my old 440-6 bottom end 906 headed (260cfm) less than 10:1CR motor with an 850DP and a Team G intake in 1991 made 530fwhp on track re weight/mph, cam was a Comp Cams sft, .650/.650, [email protected], around 3300lbs@line ran 10.71@125 NA and had 10.50's in it with more air in the tyres.
Click to expand...
What did you shift that at?
 
If you mean me, around 6400, trapped around 6750, 4.88's/32" tyre, 8" 4800stall.
 
Mine cranks a pretty consistent 175. 440 +30 flat tops with open chamber heads. But a small cam.
That does seem like a large cam for only 10.5 to 1.
 
ksurfer2 said:
Cranking compression test showed a consistent 118-120 psi across all 8 cylinders.
Click to expand...

That seems very low, my 499 ci with 12.8:1 compression and 272/276 cam is 215psi. That may be the problem. Hopefully PR Heads can advise
 
How late does the intake valve close on that, do you have the card?..was it dialed in proper, a late closing intake valve will in effect reduce stroke and hence CP+ ally heads don't help.
Our mild 10:1 589ci wedge motor had 185+ with ally heads and a s/roller of just 260/[email protected].
Try advancing it 4 deg or so, so it closes earlier if you have enough vpc, that will increase CP, its gotta be something along those lines and not just intake or carb tune.
Again albeit iron headed I'd hate to think what my 440 motor had for CP with a [email protected] and less than 10:1, intake closed on that around 80deg. I think which is late but it ran real strong and made good hp. CP is not the b all and end all of hp but that is somewhat low.
 
440rb said:
How late does the intake valve close on that, do you have the card?..was it dialed in proper, a late closing intake valve will in effect reduce stroke and hence CP+ ally heads don't help.
Our mild 10:1 589ci wedge motor had 185+ with ally heads and a s/roller of just 260/[email protected].
Try advancing it 4 deg or so, so it closes earlier if you have enough vpc, that will increase CP, its gotta be something along those lines and not just intake or carb tune.
Again albeit iron headed I'd hate to think what my 440 motor had for CP with a [email protected] and less than 10:1, intake closed on that around 80deg. I think which is late but it ran real strong and made good hp. CP is not the b all and end all of hp but that is somewhat low.
Click to expand...
The specs I posted above are right off the cam card. I did not do the cam install. The engine was assembled when I bought the car. Browsing cam profiles, comp has a solid roller cam that is 660 lift and 252 intake and 263 exhaust at .050 with 108 lsa. Would that be a better profile? I will follow up with tech support, but would like opions from the racers here as well.
 
Dwayne (PRHeads) will be the guru there on that, he's on Moparts as well.....that cam does sound quite good tbh.
Ally heads generally do not require so much duration as I ran with iron heads moons ago however the bigger the motor the duration effect tends to diminish, that [email protected] s/roller in our 4.500" stroke motor makes 695 peak hp from 5500-5900 with single old 950HP carb.

As said before your ET/mph is in line, it just makes what it does but thats 100+hp less than it should with that spec as I think we all see it and that CP is probably where things lie among other things maybe. Putting a single carb on would be interesting to see the results but hassle. Victor heads ootb if thats what they are aren't that good just like Indy-1's ootb aren't, they don't even get to 300cfm. I'm peeing in the wind here really guessing at things, I think that motor needs to come apart or at least the heads off and looking at carefully but that= no track time.:(.....The car should really be at least in the 10.3's@129>130 I think.
 
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The first thing I would do is borrow another gauge to verify the results.

Test should have been done with the carbs at WOT, battery charger on.
I like to look for these 3 things......
1- psi on the first pump
2- psi after 4 pumps
3- psi after the needle stops moving(around 8 pumps)

It usually takes a few tries to get the results for all 3.

If the big number is really only 120, I’d also follow up with a leak down test on a few cylinders to verify there aren’t bent valves.
Then, assuming all seems normal, the next thing is do is verify the cams installed position.

If that’s correct, then it’s time for less duration.

Edit- plugging the numbers into the Wallace calculator shows the cranking pressure should be more like 135...... which would still be too low for a cam that size.
Changing the CR to 13.5 shows the cranking pressure to gain 50psi.

Leaving the CR at 10.5 and closing the intake valve 20deg sooner is worth about 30psi on the gauge.

The 120 seems “lower than it should be”.

One more thought....... the lash spec for that cam is pretty loose, at .026/.028.
If you’re running them tighter than that....... the cranking numbers will be a little lower.
 
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The car runs a little slower than most would think. But without knowing the actual measured compression ratio, cam C/L, or head prep, what it really should run is a guess. However the fact that it has a consistency issue is another matter to itself. Its got plenty enough steam to run 11.25 index in N/SS. I would chase the consistency issue first. Since the converter is new I'd be looking hard into a steady timing curve. Maybe borrow a known good pair of carbs.
Doug
 
For sure...... it doesn’t seem like there is a running “problem” per se........ so nothing really has to be changed.

Any items related to upgraded performance could certainly be put off until the motor is apart for normal servicing.

It’s pretty easy to get caught up in going down the “better ET” rabbit hole.
 
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