Have you tried another carburetor? Have you pulled that one to double check the secondaries are COMPLETELY closed?
Stumped on 318 2500-3000 rpm idling issue. Don't think its a regular vacuum leak. Swapped 2 intakes, 2 carbs ,and 6 different gaskets still no luck.
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PlymouthPontiacEnthusiast
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The other carb is a 600 Edelbrock older style pre avs2. Just the two screws on the front the carb on the car now is a brawler double pumper 650. Best photos I could get. Like I said the Edelbrock went back on my Pontiac and runs just fine
PlymouthPontiacEnthusiast
Member
Yeah I backed that out, it's like barely touching but I have tried completely backing that off until it wasn't touching at all.
Why is there a spacer plate on the intake manifold?
Back that screw out all the way.
PlymouthPontiacEnthusiast
Member
I was trying to isolate the carb better for modern gas boiling so easily now to prevent vapor lock when starting which is an issue I have on my other car with the carb bolted straight to it. I have tried removing it to no effect. I ran the Edelbrock bolted straight to the intake and it did the same thing.
What is this piece of "Wire" holding the butterfly open?
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Transfer slot. Butterfly is open considerably.
Has anyone asked what the initial timing is? I'm asking. lol
PlymouthPontiacEnthusiast
Member
Been messing with it more today, pinned the fast idle and got the carburetor completely closed. It's set to 12* initial, Totally eliminated the vacuum advance and I think I got the weights to kick off and now I'm able to get it down to 1600 but that's as low as it goes the throttle is closed all the way and runs rich as hell. I can get it closer to 1100-1000 rpm if I bring it to zero degrees or retarded but it makes no vacuum and wants to die and backfires if you hit the throttle.
That's not enough timing. That thing will need probably 18-24 initial with that cam in it. Pull in 18 initial and see if you can idle it down then.
PlymouthPontiacEnthusiast
Member
When I have it up there at 18* it runs up to 3200+ rpm and won't idle down.
If this has the possibility of being a spark issue one of the other posters recommend swapping the DUI HEI module for a stock HEI module. Which I might try thats an easy thing to do.
What ignition coil are you running?
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Thermal Paste for installing GM HEI Module to the grounded aluminum heat sink base.
Conducts the heat out of the HEI module so they don't burn up.
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Conducts the heat out of the HEI module so they don't burn up.
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Are the china wall pins still in place?
Spray carb cleaner or something along the intake manifold gasket surface.
As someone suggested, cover the carb inlet. If you have it down to a decent RPM level, I saw 1200 or so, do it at that speed. Secondaries first see if the idle profile changes. Do primary. Then cover both sides.
It's sucking unwanted air from somewhere. I doubt it's a systems problem with ignition or compression because it runs OK and not missing at multiple RPM levels.
Spray carb cleaner or something along the intake manifold gasket surface.
As someone suggested, cover the carb inlet. If you have it down to a decent RPM level, I saw 1200 or so, do it at that speed. Secondaries first see if the idle profile changes. Do primary. Then cover both sides.
It's sucking unwanted air from somewhere. I doubt it's a systems problem with ignition or compression because it runs OK and not missing at multiple RPM levels.
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An engine with a DUI (Distributor Ignition Unit) and a Dodge 318 that refuses to idle down is most commonly caused by excessive ignition timing advance or a mechanical/digital timing malfunction.
(Basically saying it's that All-In-One DUI distributor assembly and its electronics that are failing).
Time to go with the good old Mopar Electronic Distributor with the HEI conversion and the E-core coil to power the spark. Simple is Good
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An engine with a DUI (Distributor Ignition Unit) and a Dodge 318 that refuses to idle down is most commonly caused by excessive ignition timing advance or a mechanical/digital timing malfunction.
(Basically saying it's that All-In-One DUI distributor assembly and its electronics that are failing).
Time to go with the good old Mopar Electronic Distributor with the HEI conversion and the E-core coil to power the spark. Simple is Good
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TT5.9mag
Two atmospheres are better than one
Had this same problem on a small block recently. Your very next step should be a leak down test. Woulda saved me hours of time. You have a head gasket that is not sealed. Could be dowels that are too long or something stupid like that. Mine was a rivet on mls gaskets that was pinched.
1) Which is easy to determine with a timing light, hence why I suggested setting the base timing to zero for testing.
2) Both my Dart and GTX running full timing as soon as the car cranks over and starts, 38 degrees BTC in the case of the GTX and I have no problem with an idle.
A 1980 distributor from a truck is the same base unit as a 73 electronic unit, IIRC. Not a lean burn or anything crazy like an all in one.
He keeps avoiding the question of what he is running for a coil.
There is a very good chance that his coil is a mismatch to go with the DUI chip on his distributor. Probably some cheeper grade tower coil, that can cause conflict in itself.
Or that he has his leads flipped on his DUI module. Has been known to happen and the engine will run, just not run as well as it should.
Keep chasing the problem... somebody is going to stumble across the simple soultion.
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Coil isn't going to make it idle fast.
TT5.9mag
Two atmospheres are better than one
George pay attention, it has an HEI module already on it.
It will tell you how he has his system laid out, vs the All-In-One distributor.
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Felpro #1243 fiber intake manifold gaskets, made for the 318 sized ports.
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