Fixing cold weather running problems on older 318 V8

[Wheeler]

Hey guys. I hope you can help me with a problem...

I have an 1985 Dodge truck with the 318 V8 and Holley 2bbl carb. The truck idles real rough when cold, stalls, runs way too rich and doesn't settle down until it warms up. Essentially, your traditional Chrysler cold weather running trouble.

After doing some research, it seems that carb icing is causing the problem - not enough heat getting to the base of the carb. Chrysler small block intakes have a tendency to plug up in the crossovers, not allowing any heat to get into the base of the carb.

When I bought the truck, it had stock exhaust manifolds with a heat riser valve. Later, I installed Hedman headers with dual exhausts. The truck ran rough in the morning with the iron manifolds, and ran rougher with the headers. I also tried a rebuilt Carter BBD 2bbl, but it didn't help.

1. What causes the intake to get plugged with carbon?
2. Can the carb icing problem be traced to a poorly designed factory intake? Poorly designed carb?
3. Is a heat riser valve ABSOLUTELY necessary? Several people have told me otherwise, but I'm not 100% convinced.
4. Will cleaning out the intake eliminate the problem? In the past, I had a mechanic pull off the intake and chip out the carbon in the crossovers, but it didn't help much.
5. What's the best way to clean out an intake? I've heard that putting the intake in the hot tank TOTALLY cleans out the intake.
6. Should I junk the stock intake and carb, and go with an aluminum intake and aftermarket carb?

Essentially guys, how can a Mopar man solve this traditional Chrysler drivability quirk without going to EFI?

Wheeler

[dl79]

Hey Wheeler,
I vote for #6, and hope it's right, because that's what I'm doing to my '79 pu with 318. It came with 2bbl Carter carb., and doing a complete overhaul, and installing Edel. Performer manifold, carb., and cam kit. It's on the engine stand ready to drop in this Sat., so I will know soon if this setup will work. Good luck!!

[rumblefish360]

You don't need the heat riser valve. It helps when it's coolder than hell. #6 is where my vote is cast. dl79 is going to like it when he squares everything away.
I had a '79 Dodge Magnum with the 2 bbl. Holley. I fired the Holley! With a few ignition tricks and a dual exhaust added to a 4bbl , I was netting 20 mpg's on the hwy with my 360 @ 60-65 mph.
Sure beat the 10 mpg's with the Holley and single exhaust. LOL

[72satellite]

I have a 72 Satellite with a 318 and a 2bbl carb. I could not get enough muscle with the 2bbl so went with an Edelbrock Dual plane intake manifold and an Edelbrock Performer 4bbl Carb. The swap was easy and the difference was significant.

I would recommend that you ditch the 2bbl and go with a 4bbl and new intake. You will see a big difference and in both starting and performance. It's worth the investment.

Now I can get some muscle out of the 318 and so should you.

[Jims451]

I vote for #6 also, at least you can tune/jet the 4-bbl carb for best performance. Use a carb with an electric choke too.
The aluminum intake will warm-up quicker and more evenly.
If you live in very cold climate, run a heated air tube off the header so the air going into the carb is warmed up, but this is not great for performance. With the aluminum intake and 4-bbl, you should not have carb icing problems, but a can of "Heat" gas additive will prevent most icing problems.

[Glen440]

I'm going through this same thing right now. I'm getting a stock 2 barrel 360 ready to drop into my Truck. I pulled the heads and intake to clean out those passages. The heads were plugged solid form the valve to the intake. It has to pass emissions so I'm sticking with the stock setup with single exhaust. I do have a LD340 intake and 700 holley I could put on it to see the diff.
Basically the passages are a poor design. I've been told you need to drive it hard and often to keep them clean.

[dynorad]

Your problem could also be a leaky choke pulloff.