Unusual Symptoms???

[67 B-body]

Ok,, the new engine isn't doing so well!
I noticed when checking timing that it was reading 30deg advance at idle. I tried bringing it down to something closer to normal, but it doesn't run with anything less!?
I thought the cam timing might be off, so I tore the front apart and it looked like it might in fact have been one tooth off,,,, I don't know how, I was sure that I got things set correctly during assembly, but hey,,, maybee I had a case of crooked eyes going on. So I removed the timing set, lined it all back up and installed.... I checked, double checked and tripple checked the alignment,,, it looks good now! I put everything back together and still the same damn thing???!!!
OK, out comes the can of carb cleaner chasing down any Vac leaks that might be messing things up. I found a slight leak around the base of the carb, so a new gasket was in order. New gasket, no leak, same damn thing! I spray carb cleaner down the throat of the carb and the RPM's sky rocket! No other leaks around the intake or carb can be found at this point.
I know that advancing ign timing causes a higher vac reading, and wonder if the timing being so high is compensation for the extra lean condition? Maybe the extra vac being generated is allowing the carb to provide a richer fuel mixture? One thing unusual is that typicaly you can advance the Ign timing to a point where an engine will begin cranking hard. Mine has to up to 50+deg or so before this starts happening. I ran it up to this point once, and backed it back down a bit and ran it for a while.... Seemed to run about the same as before. I ran through the valves setting lash at 27int and 31exh. Didn't realy find any out of spec, but set each one just incase. I lost my comp tester a while back and haven't replaced it yet, but I dont think this is an issue anyhow. My heads are the Victor 440 knock offs, and forged domed pistons, so compression should be plenty high. Also I have found in the past that burnt/leaky valves typicaly results in backfiring out the exhaust or intake.
The exhaust has no restriction,,, large tube TTI headers 3 1/2 collectors and stainless pipes all the way back to dual chamber mufflers dumping in front of the rear axle. BTW, I took the #1 plug out, ran it up to TDC and the timing mark was at the 0 indicator on the timing tab. I thought maybe my aftermarket SFI rated balancer might have been miss marked,,, doesn't look like it though! I have around 7psi or so of fuel pressure, 140gph electric pump 10AN fittings with steel braided line, this goes to 1/2" aluminum line then up to the regulator on the inner fenderwell. From there it goes back to the steel braided line up to the carb. All nice stuff!!!
Could the carb be that F'd up to cause all this? I remeber one time having a large vac leak beneeth the carb on a Chevy Super Suck, and it acted similar.
Oh,,, when I have the idle mixture screws set around 2 turns out, it will run on the prime from the acc pump squirt, then die when the fuel is used up! I turned them out to about 6 full turns and it still runs lean!!!
I'm thinking that it might all be carb related, and if I were to get the lean condition taken care of, I would have a ton of idle RPM where things are currently set, and I could back the timing down from that point...
Any thoughts or comments?

Thanks!
:spam dragon:

 

[daredevil]

Need some engine info,cam,heads, carb size,what dizzy?

 

[67 B-body]

Need some engine info,cam,heads, carb size,what dizzy?

OK,,,, LOL!!!!!!!!

440 .030" bored
.612" @ 1.6:1 lift both intake and exh solid flat tappet cam.
Victor 440 72cc aluminum heads 2.25 intake valve raised exh ports etc, etc
Forged .140" domed pistons
Forged steel crank "standard stroke"
Scat 4130 H beam rods
Hughes main stud girdle
Balanced rotating assy
Hughes oil through Solid lifters
1.6:1 ratio roller rockers
Victor 440 intake
Holley 4150 850cfm carb with jet extensions in the rear and still retains the front power valve "used carb"
Mopar points dist vac advance removed lighter springs on mech weights.

 

[SUPERSTOCKRACER]

what distrib. do you have, is it locked out or with springs/
lets start their 1st.
when you rev it up to 3000+ rpms what is your timing?
check that 1st if your distributor is not locked out.

 

[67 B-body]

what distrib. do you have, is it locked out or with springs/
lets start their 1st.
when you rev it up to 3000+ rpms what is your timing?
check that 1st if your distributor is not locked out.

not locked....
mechanical adv comes in and climbs to the highest point... This changes as I adjust the base timing of course, but is as stock would have been... I have seen it going up to around 50 btdc when rev up. I can tell you how much mechanical advance it has available tomorrow after measuring the slot in the mech adv mechanism. this is a list of mech adv based on slot size in the T.

dist. degrees / slot size
6.............. .340
7............... .355
8............... .375
9............... .390
10.............. .405
11.5 ........... .420
12.............. .435
13.............. .445
14.............. .460
15.............. .475
16.............. .490
17.............. .505
18.............. .520

The trouble I have is at base timing at idle. It wont run at anything less than 30 deg initial and revs as if it was super lean when I spray carb cleaner in the carb throat, or just hit the acc pump arm.
I think maybe something is wrong before taking into account any dizzy mech or vac adv. I could be wrong tho,,,, just wondered if anyone has seen this before?

 

[70Hemi]

my 2 cents worth ... if it revs up when you are hitting the acelerator pump by hand you a definatly lean. have you checked float levels in both float bowls? you said used carb.. was it working on another motor recently or was it laying around the shop? possible someone took it apart and used wrong metering plate gaskets. when you were looking for vacuum leaks did you block off power brake booster hose if you have power brakes?

 

[67 B-body]

No power brakes, Vac lines on carb all pluged with rubber vac caps. I agree with the lean condition, and I THINK it's carb related "not leaking vac somewhere". I am certain if I get this figured out I will be able to reduce the initial timing adv "some". I just dont know how much though... I think it will have to remain higher than I typicaly seen in my other builds. I can say that it hasn't been un-common to see timing up towards the 20deg BTDC with high duration cams, but never 30+ just to be able to run! The carb was a used purchase, and said to be in perfect working order, also just removed from a drag car at the end of last season. The original owner said his engine was due for a larger carb "950" I think because of recent upgrades.
I'm tearing it down today to inspect it,,,, and I'll spray the crap out of all the passages!
Thanks

 

[67 B-body]

my 2 cents worth ... if it revs up when you are hitting the acelerator pump by hand you a definatly lean. have you checked float levels in both float bowls? you said used carb.. was it working on another motor recently or was it laying around the shop? possible someone took it apart and used wrong metering plate gaskets. when you were looking for vacuum leaks did you block off power brake booster hose if you have power brakes?

Forgot to reply to the float level...... They are fine,,,,, clear float level plugs...:icon_cyclops_ani:

 

[fugly]

Very lean Jetting will do just what you describe and also cause very hot exhaust temps- try 4 jet sizes up from where you are (ex has 84s-go to 88) once it's running check your vacuum at idle and adjust your power valve from there.

 

[Al K]

I can't offer any advice different from what's been offered,but...

Be EXTREMELY cautious with the carb cleaner when checking for leaks. I knew a guy who lost his car,and almost his garage because of that-the carb cleaner caught fire. Please be careful!

 

[67 B-body]

Very lean Jetting will do just what you describe and also cause very hot exhaust temps- try 4 jet sizes up from where you are (ex has 84s-go to 88) once it's running check your vacuum at idle and adjust your power valve from there.

I wondered about jetting too, but I wasn't sure that idle mixture was affected by jet size.
I was trying to dig back through the archives in my mind "getting harder to do every day!" I thought the idle bleed passage was only restricted "adjustable" by the restrictor srew and the size of the bleed hole in the little brass plugs on top of the throttle body. It's been a long time since I had one completely tore down to know for sure though.....
Thanks for the reply, after studying this for a while now I believe your right about the lean condition causing the symptoms. However, I'm not sure why it wouldn't fatten up yet with the mixture screw adjustments. Or perhaps there is some other type of air leak, like maybe between the intake runners were they meet the heads? What would happen if one intake port sucked air from the port next to it? I haven't had the brain power to set down and figure that one out yet, but I'm guessing it wouldn't have the correct valve positioning to get anything from the adjacent cyl intake port.... :happy11:

 

[67 B-body]

I can't offer any advice different from what's been offered,but...

Be EXTREMELY cautious with the carb cleaner when checking for leaks. I knew a guy who lost his car,and almost his garage because of that-the carb cleaner caught fire. Please be careful!

Yep, cautious it is,,,,, doing it all out in the back yard too!!!
Thanks

 

[67 B-body]

Well, after the carb was torn down cleaned and placed back on, it seems to respond the mixture screw adjustments, but the timng is still pretty high at 25deg adv..?? I didnt re check for vac leaks at the carb base "reused the new gasket" but I doubt it leaks. I had a week batt at this point so I have it charging, then I'll fire it back up and check things out some more. Also the plugs might be wet due to try to get the timing down before the carb work was done and flooding the engine a bit. I'll pull the plug clean them up and re-install them too.
If this doesn't take care of things, I'll be back to square one!
ARGG!!!!!!

 

[SUPERSTOCKRACER]

who's distributor do you have?
if your carb. worked before why is it not working now???
if you have a msd distrib. black cam, one blue spring one silver spring so all advance comes in early.

 

[moparpoor]

It sounds like you are building something fairly healthy.Victor heads,high compression @what?,Fairly large cam 612 lift @ what duration?Couple of things to do.Find TDC and check your timing marks on the balancer.Second take the mopar ditributor out and give that piece of **** to somebody you hate the most.I will repeat myself get rid of that piece of ****.If your cam duration is large enough it will require more initial timing for a decent idle.Don't sweat it so much,The only reason you set initial timing is for startup and idle.In saying this I assume you are running a larger convertor 3500 plus.What is most important is total advance.I don't even look at initial timing.Turn the distributor to get the cleanest idle and adjust the msd bushing to bring total advance to 38.I run black bushing with two silver springs.The black bushing only allows 12 degrees advancement wich puts my initial timing at 26 degrees.Don't meant to pick on your distributor,I just hate them.

 

[SUPERSTOCKRACER]

It sounds like you are building something fairly healthy.Victor heads,high compression @what?,Fairly large cam 612 lift @ what duration?Couple of things to do.Find TDC and check your timing marks on the balancer.Second take the mopar ditributor out and give that piece of **** to somebody you hate the most.I will repeat myself get rid of that piece of ****.If your cam duration is large enough it will require more initial timing for a decent idle.Don't sweat it so much,The only reason you set initial timing is for startup and idle.In saying this I assume you are running a larger convertor 3500 plus.What is most important is total advance.I don't even look at initial timing.Turn the distributor to get the cleanest idle and adjust the msd bushing to bring total advance to 38.I run black bushing with two silver springs.The black bushing only allows 12 degrees advancement wich puts my initial timing at 26 degrees.Don't meant to pick on your distributor,I just hate them.

yep, what he said. toss it and get a msd pro billet distributor. lock it out and have fun.

 

[67 B-body]

Actualy, I have a Mallory Unilite dist, but the module is bad. I only put this thing in to get it running and check things out. The Mallory is mech adv only and is adjustable for tottal adv. I agree that for actual performance and good driveability, the stock dist has to go! I just havent seen timing need to be this high at base, and also it sounds like it's hunting for a good idle,,,, I mean it kind of surges down,,, runs rougher and slower,, then picks up rpm and smooths out a bit on its own.... Just weird stuff! Also, it now has poor throttle responce with a definate pulse studder lazzy rev... I wish I could make sound affects come through... LOL! Have you ever heard an old 305 chevy with the bad cam rev? Kind of like that only not quite as bad... Also the RPM drops slower than it should after a good rev "high adv sound"... real lazy coming back down..
I dont know,,, maybe I need to wait till I return from my trip after next week and swap out the dist, then try again...
I just can't stop from thinking something else is going on that I'm trying to compensate with extra fine tuning in carb and dist. I know there are folks out there throwing alot junkier stuff together and having better results!!!!! Frustrating to say the least!!!
Ok, well I can say that all header tubes seem to have the same heat, no popping out intake with adv timing and no backfire through the exhaust. This "SHOULD" indicate that I dont have valve issues, and the rockers dont seem to be getting loose each time I've checked them. Nothing funny looking in the oil,,, Not loosing any coolant,,, no steam from the exhaust haven't noticed any bubbles or excess pressure in the radiator.
I just wonder if it would run at all if I didnt have such high comp?? LOL!
One other thing I will do is buy a new comp tester and get a good base line of whats going on for sure in the engine mechanicaly. I guess if it reads good and high, I can certainly rule out anything bad mechanicaly! This is about the only test I can think of that doesnt care about fuel ratios or ign timing! If I find a low reading then I'll go from their... I dont know what to expect for an actual reading at this point, because I haven't been able to load the engine to seat the rings...
So that's where I'm at for now.... maybee I'll mess with it a bit tomorrow, but it wont be much... Fathers day stuff to do..

L8R

 

[67 B-body]

BTW I do have a 3500rpm COAN convertor

 

[70Hemi]

im still banking on a lean condition. i had a intake gasket leak between intake runner and lifter valley. i have seen heads and or blocks surfaced so much that the intake doesnt set low enough for the passages to line up right. everything you talk about just sounds like a vacuum leak somewere to me. leaks at the intake manifold gasket are hard to locate with carb cleaner method. only takes a few minutes to pull the intake and look at gasket to see if its been fitting together ok.

 

[moparpoor]

It sounds like a fuel issue.Surging idle and lazy throttle responce sounds like a fuel problem.What fuel are you running and octane.