StealthElephant

So it took 4 distributors to get the car to run.

Well we set the idle to around 650 and it drove, went into gear without stalling etc. The problem is it keeps stalling when I sit at a dead stop for more then 30 seconds. I've had it die on me at lights, and I've sat in front of my house, with the car in drive and my foot on the brakes, around 30-45 seconds and it just starts stuttering and eventually stalls. Why is this?

The carb is a 670 Holley Street Avenger and we have the electric choke open all the time. We never hooked it up, is that the problem? Should the choke be closed while I'm stopped to keep it from stalling (got knows w/o the choke I'm having really hellish morning 1st starts)? Is it a carb issue?

It drives fine, has good response, good braking power, an dif you just sit at a light for like 10 seconds its fine, but if you have to sit at a long light it will just start getting rougher and rougher and then start stalling. I tried to jack the idle up, and I put the idle up another 200RPM and it's still stalling out. What gives?

This car gave us nothing but trouble...the 4th distributor got it running, but everyone who helped me said that while the distributor might have fixed the immediate problem, that it seemed like there was something just not right about my engine. I mean, we did it all, took out spark plugs and hooked an air compressor up to see if I had valves hung open, compression tests (200PSI). The engine sounds perfect mechanically, and all tests show that the valvetrain/heads are fine. What gives?

Could it just be more carb tuning? I'm running an MSD HEI distributor brand new. What adjustments could I make? It idles so perfectly at a stop for like 15-25 seconds, but then out of nowhere the idle quality starts to get rougher and rougher.

It just isn't streetable, and not safe to be stalling out in the middle of major roads. I mean....I haven't heard problems like this from XE274 cams, the 268 should be a tame kitten. Am I having problems holding vacuum? We had vacuum problems in the past, (which is why we resealed the intake, and checked for hung open valves). The intake isn't leaking, we know that....just can't figure it out.

Thanks

FishPig

how is your fuel pressure at low RPMs, Do you have a mechanical fuel pump, have you checked your fuel filter, This problem sounds to me(PLEASE READ) IMO that it is a fuel problem not a elect. NOW that could be that you don't have enuf vaccuum to suck it out of the tank or a clogged fuel line, of a bad fuel pump.....I would lean more toward the vaccuum not being high enuf at the low RPMs. You say it runs great until you sit at low RPMs for a minute or more. That would lead me to believe that you are burning off the fuel between either the pump and the carb or the filter and the carb.....and not sucking any more to replenish.
Sorry, if that isn't good enuf. But that is what it sounds like IMO. IF that is what it is you might look at how you have your vaccuum ran and see if there is a way to improve it. Maybe take some stress off the one boosting your fuel delivery??? Also don't know what shape your vaccuum hoses are in you might test them to see that it isn't just worn out hoses??? Hope that helps.

StealthElephant

Thanks for the idea, I def want to check out my fuel system.

Heres my setup:

Mallory 3 Port adjustable Fuel pressure Reg
Stock 305 TPI inline fuel pump

All the fuel lines in the engine are new, we simply took the original lines for the TPI and hooked them up to the regulator. We adjusted the pressure to about 7PSI, the fuel gauge we were using was bobbing between 6-8PSI.....

When we had the 3rd distributor we had the problem that we could not get the engine to idle under 1000RPM with the vacuum advance hooked up. Like, we would base time the engine at about 8 degrees advanced, at around 700RPM, then hook the vacuum advance up, and it would rev to like 1000. If we tried to lower the base to aroung 500 then hook the vacuum advance up it would never kick in, the vacuum advanced would simply never happen, and at 500RPM you couldn't shift into gear or drive w/o stalling. It was also very choppy and inconsistent from a vacuum stand point. We can't get 12inches of vacuum until 700RPM. There seems to be a "void" from 500-700RPM where I had only 7 inches of vacuum. We don't understand why since the cam isn't that wild. The engine doesn't have valves hung open, the intake is sealed perfectly. The entire top end is brand spanking new.

The 4th distributor let us get the car idle at 650RPM with vacuum advance hooked up. Something the previous 3 couldn't do. We got about 10 inches....

With the 3rd distrib, we could rev the engine, it would get vacuum, hold the vacuum advance, but then it would slowly fade away. It seems like the car has that same symptom, just much milder. Meaning, as soon as I stop driving. I sit at a light, the vacuum is almost slowly fading to the point where the advance goes away.

We just have no idea, carb, ignition, fuel.....guy who helped me build the engine is in disbelief. 100 engines and hes never had the trouble we're having with thing before.

Any insight would be appreciated....

Rice Killer87

what kind of exhaust do u have? not having enough backpressure can cause a loss of vacuum i believe.

StealthElephant

Stock exhaust with flowtech ypipe/headers

onefastgta

Hook up the choke.

What type of distributor do you have, the stocker or a mechanical advance one from an older HEI car?

The stock electronic distributor only controls inital advance. You need an older distributor to get full advance.

I think you have a timing and carb tuning problem.

StealthElephant

I'm running an MSD HEI Vacuum Advance distrib. The choke is hurting my morning start, but it shouldn't affect my engine when it's fully warmed up on a 70 degree day at a red light.

It seems like I still have a vacuum problem. I don't know why it will sit there and idle perfectly for like 30 seconds then just fall apart.

FishPig

Like I said before, I think it is your vacuum also. Something that you might want to look into is a vacuum booster. A lot of people that have big cam engines have to use them because of the lobing problem and no vacuum. Just a thought. Keep us informed as to what you find.

grygst76

Did you just bolt that carb on and run it?? checked your float level recently or put a 8" power valve in it? checked timing at idle and at 2500 RPM's? I do not believe you are losing vacuum when you are idling, as far as the car slowly dying that's a fuel delivery issue what is your psi at idle? if it is more then 7.5 your killing the car to have that much vacuum with the XE274 is kind of weird, my 284 only had 3" at idle you need to put the car in gear and then check the vacuum, then choose a power valve rated 1.5" less then that figure, tell us what's up..

StealthElephant

Whats a power valve? That part of the carb? I've got the XE268H cam....how much PSi should I have, I thought 6-8 was acceptable....is there a relation to PSI and vacuum I should have at idle?

I don't think I need a vacuum reserve because my brakes work fine....

grygst76

Please reread my post! If you are not sure of what a power valve is you are going to continue to beat yourself up!! Go to Holley's website and under technical information better yet here is the link, I think you need to tune that carb of yours

http://www.holley.com/HiOctn/TechSer...o/Trblsht.html

after that one try this one

http://www.holley.com/HiOctn/TechSer...o/FMCTech.html

this link above I think you should pay attention to and print some of the exploded views. you need to check those thing's I asked in my post above BEFORE you can properly troubleshoot anything IMO