392 V8 Dies under 1000RPM

[AkioOhtori]

Originally Posted by IH64Scout

Before you do anything get the timing set. I run it usually around 5 degrees. I've had luck around 10 too but I wouldn't take it that high until all the problems are fixed. If its still high after id look for a vacuum leak. Now by not touching the carb out of the box, you did at least adjust the idle screw right?

I don't have a timing light and couldn't borrow one for about a week. That said, If I was looking at buying one should I do adjustable or basic. ~$30 difference but I don't know what will actually be useful.

Yes, I have played with both idle screws.

[AkioOhtori]

Originally Posted by fredsterra

Where do you have your dist. advance ported to? I have a 1406 on my 345 / 392 non EGR intake. And I found it better to hose to manifold vac. vs. carb.

I have the vacuum advance on the left but may try moving it to the right. No inspections in Oklahoma. The EGR is on the manifold. Thats the only vacuum hose that hasn't been replaced so I'll have to check it.

[fredsterra]

[QUOTE=AkioOhtori;776496]I have the vacuum advance on the left but may try moving it to the right. No inspections in Oklahoma. The EGR is on the manifold. Thats the only vacuum hose that hasn't been replaced so I'll have to check it.[/QUOTE

At the rear of the intake. I have a 1/2" pipe port and a 1/4 or 3/8" since I have hydra boost brakes I pluged the 1/2" port and use the other for Cruise Control and Dist. advance. I didn't have much luck with the front ports for Dist. advance.

Also I found it better to go one step leaner on my primary jets and rods. And one step richer on the secondries. This helped the drivability quite a bit.

Also I had a wistle problem under aceleration that souned like a belt slipping. After several attempts to fix I called the Edelbrock tech line. And he said right off the bat. "Your using an open spacer" And gave me a number for a 4 hole spacer to use. (Sorry I don't have the number in front of me) But it fixed the whistle problem!

[TBAKPhi22]

This sounds like an Impala I had years ago with a 350. I put an edelbrock manifold on I got from my friend that he took off his camaro. Could never get it to run well under 1000 rpm. Finally figured out the intake was warped. Tried putting it on twice with new gaskets each time, but still had a vacuum leak between the heads and the intake runners. Ended up putting the old cast iron 2bbl manifold on and it ran like a top.
Like someone else said, take some wd-40 or carb cleaner and spray around the whole intake to see if it will speed up the engine. If so, definitely a vacuum leak.
Also, I have a 600cfm Edelbrock on my '73 with a cam, and didnt even touch the carb except for the idle jets. They are pretty damn good right out of the box. Same thing with my camaro years ago... messed with the jets and rods, but came back to the ones it came with. Ran the best that way.

[Will Marsh]

The EGR could be your vacuum leak, in the valve if not in the hose. All the TVS's should either have ALL the hoses hooked up or NONE of them.

In starting an engine with a new carb, I disconnect and plug EVERY vacuum connection with the exception of the vac choke pulloff if it has one. The Edelbrock doesn't. Set the timing and idle speed, then hook up the hoses one by one. It eliminates any unnecessary problems in the initial setup, and identifies any problems as I hook them back up.

The vacuum advance on the distributor needs to be hooked to the right side port on the Edelbrock. If you hook it to the other side you're just masking a problem you should fix.

Every 392 I've had pings at more than 5 degrees initial advance at 5000 ft of altitude on regular gas if everything else is right. Set the initial at 0 and make the rest of your adjustments. Then if you want to play with timing advance it a couple degrees at a time until it pings under load then back it off to the last setting.

HTH,

Will Marsh

[AkioOhtori]

Thank you everyone for the responses! I went out last night and tried checking for vacuum and adjusting the timing. Here is what I came up with:

Timing: It was set to ~25 degrees advance best I can tell. Yikes! Now that was at 1000RPM, so the vacuum advance was probably in play to some extent. I need to play with it more, but I can get it to run ~600 (but no lower) at about 10 degrees. Any lower and it dies. Thinking about it, I probably need to adjust the idle screw and it would run lower (duh!) but I didn't think of that at the time. (Again, total newb.)

Vacuum leak: There may have been a small vacuum leak on the carb. Spraying carb cleaner around the gasket the RPM did surge a bit when I hit the front. I tightened down the top bolts and that seemed to help. I'll need to double check this.

I took it out for a drive after all of this and it actually ran pretty well (aside from the steering is still all messed up). That said, I made a "small" mistake in my wire routing and sort of let some magic smoke out.

After I get that junk sorted I'll double check my vacuum leak and see if I can get my timing to 5 or 7 degrees.

[scoutboy74]

Timing was off by a country mile! That'll do it. Good thing you didn't attempt a severe load with it set there. That's a great way to blow a hole in the top of a piston. If you can get it to hit on all eight and keep on hitting fairly smoothly at 600 revs, you're pretty dang close. Be careful about tightening your carb bolts. If they are noticeably loose, that's one thing. If they're already snug, they can be over-snugged and you don't want to go there. The thing about spraying vapors near your carb, is its easy for them to be sucked through the top of the carb making you think you found a vacuum leak. You need to be precise with the direction of your spray and be sure the top of the carb is shielded so this can't happen.

[AkioOhtori]

Originally Posted by scoutboy74

The thing about spraying vapors near your carb, is its easy for them to be sucked through the top of the carb making you think you found a vacuum leak. You need to be precise with the direction of your spray and be sure the top of the carb is shielded so this can't happen.

Goooooooood point. I'll try that once I fix my screw up...