Holley carb help

[87gn2]

I have a 331 in my 68. It had a Carter AFB but did not run very well, or start very well. Since everything else was new I replaced the carb with a Holley 4160 600cfm carb. It started right up and I drove it a few miles. No problems with warm or cold starts. The next day I started it again, it did not start as quickly, but it started. It ran pretty rough, did not want to rev, and backfired when I tried to do so. I let it warm up, then shut it off. Immediately I tried to start it again, it would not start. It just cranks and cranks and cranks. I happened to have 2 4160s so just for the heck of it I put the other one on. Same thing.

The car is getting air. Fuel squirts in when I push the throttle by hand. Spark is not super great, but it managed to arc from a wire. Fuel pressure fluctuates between 5 and 8+ psi, which I know is a little high. Fuel pressure with the first Holley was lower, but I do not know what it was when I tried to start it. I used to have a FPR lying around but can't find it.

My dad thinks it is ignition, but voltage is fine and like I said, it sparks. It ran yesterday and the day before so I think ignition is not the problem. But I think the carb is flooding. Again . I have tried to describe the problem as best I can. It just cranks, it doesn't even get close to starting. I can post a video if necessary.

edit: fuel pressure seemed higher with the 2nd 4160 but again I had the same problem.


Any assistance would be greatly appreciated.

 

[ratio411]

You are all over the place here.
Let's see if we can get some things ruled out, and there is a lot to rule out by your post.

Your 600 vac is new, correct?
What list number?

Have you checked float levels?
Personally I don't think your fuel pressure is high enough to overwhelm the bowls.

Why do you feel the spark is "not super great"?
Is your ignition all new?
What do you have for ignition? Points? Magnetic? Unilite?

I have to brainstorm why it would run good at first, then not run the next day...
What gives you the idea that it's "flooding"?
If the carb is older, it may not have PV protection.
In that case, it would run good until the "backfire" you describe, then it will load up (flood) and could get the plugs fouled to the point it won't start.
Both carbs could have blown PVs... very common, and this is assuming they are both pre-PV protection. That started around List XXXX-4. If the number after the dash is lower than 4, it probably is not protected.

 

[87gn2]

Both 600s are new in the box vacuum secondary electric choke models.

I got the idea it was flooding from the troubleshooting portion of the manual.

The ignition is an MSD billet distributor and an MSD coil. I say it is not sparking great because it is not as strong as it was when I built the engine 2-3 years ago, the car has been sitting because I was overseas.

I have not checked the float levels...geuss I should have done that before saying it is flooding, eh?

Thanks for the response. I will pull a plug and see what it looks like.

 

[87gn2]

 

[ratio411]

Hard to tell from the pic, but it looks wet...

You could be flooding.
If it was a PV, I would expect the car to run, but crappy and the plug to be sooty.
That just looks like raw fuel.
Hard to tell from the pic though.

I would make sure the needles and floats are not stuck open or set too high.
I always put clear sight plugs on my Holleys to make checking easy as a glance.

One question:
If the car has been sitting, did you drain the fuel?
Gas does not last longer than a few months. They say 6-12 months if you use a preservative like Sta-bil.
It also gathers water from the humdity in the air when it sits for a long time.
If you have old gas in there, it will run REALLY BADLY, if at all.
Or if you concentrated a couple years worth of condensation...
That will put the stops on your spark and appear as wet on the plugs.
Also, if you gained any rust in the tank, and it got by your filter, it could lodge in a needle and keep it open.

Just brainstorming.

My brother in law lets the fuel sit in his riding mower over winter.
Usually very little, but this last winter he left a full tank.
I tell him gas goes bad, but he never believed me.
He tried for 2 weekends to get his mower to start and it ran rough for a bit but then stopped running totally. He dumped a load of dough into everything trying to fix it. Finally he called me and said to come get the piece of crap, he bought a new one and I could have the other if I wanted to try and salvage it.
I brought it home, drained the tank and carb, put new gas, and been cutting my grass with it for a month now. Runs like a top!

 

[jman340]

Not sure if it's your problem or not, but I just upgraded from a 2 barrel to a 4 and had lots of problems. Turned out that the vacuum line to the auto trans came undone. It idled poorly and popped back when I let off the gas. I flooded it trying to start it once too. If you continually pump it while cranking, you are putting raw gas from the accelerator pump into the engine.

 

[grainboy]

I recently had a bad experience with a new holley. I bought a polished 600 vaccuum secondary, with electric choke. It was tempermental from day one. It loaded up at idle, even when set lean. I took it apart to find most of the zinc flaking off and white rust under the cracked/peeling plating. It was only 3 months old, so was easily exchanged at CSK. New one has different stainless idle screws, and plastic bowl bolt gaskets. I jetted to 66 and stuck it on. Idled well with screw backed completely off. Night and day difference. I just hope it stays that way.

 

[87gn2]

Thanks to all who replied...

The car is running!

I removed the spark plugs and turned the engine over a few times. Replaced them with new NGK ones with a heat range of "6". Tried to start the car. It cranked a lot faster, but to no avail.

It was sitting at a nose-down angle, approx. 15 degrees, in my driveway. I pushed it into the street and tried again. No luck.

So I said "screw it" and pumped the throttle by hand about 30 times to see if the car was somehow out of gas. The tank (its a fuel cell actually, should have mentioned that, no rust issues) was empty (dry)...but there was still enough in the lines I guess. I gave up pumping the throttle by hand and said "Dammit, I'm going to try to start it one more time, just for kicks." Otherwise I would have had to push the car back into my driveway by myself, I am not that strong, it would have been interesting. Especially since my garage has a 2-3" step between it and the driveway...

Lo and behold, it started! Not slowly, but right away! I was amazed! It stalled when I put it in gear (low idle) but it started right up again!

So again, thanks to everyone who replied. I still am not sure what was wrong, other than the plugs.

 

[D.Hearne]

What was wrong? Sonds to me like someone forgot to fill the tank. With a Holley, two "pump shots" should be all that's needed to prime the engine to start. As for spark, if the spark is white or blue, that's normal. If its red to orange, you've got ignition problems.

 

[87gn2]

Well I haven't put any gas in it...and it still runs... Magic neverending gasoline?

I wasn't even trying to prime it...just venting my anger on the carb, that's all.

What was wrong? Sonds to me like someone forgot to fill the tank. With a Holley, two "pump shots" should be all that's needed to prime the engine to start. As for spark, if the spark is white or blue, that's normal. If its red to orange, you've got ignition problems.

 

[D.Hearne]

Well I haven't put any gas in it...and it still runs... Magic neverending gasoline?

Better keep a look out for those secret government/oil company helicopters from now on