overheating??

[inprogress]

I've got a 74 challenger with a 360 in it. When I bought the car I was given a set of 340 x heads with bigger valves and some port work done. I put them on the car last winter and ever since, if sitting at a light, my temp will keep increasing. up to 240 degrees and will start to boil the fuel in my carb. I end up shutting it off come this point.I never had any problems like this before I put the heads on. if I drive it the temp is around 195-210. I matched the head gaskets up when I first did the swap.. im a licensed mechanic and definatly know what I am doing but I am stumped and any ideas would be greatly appreciated. thanks in advance

 

[Daves69]

Check that the water pump intake hose is not collapsing on you.

 

[inprogress]

The hose is fine.. Builds pressure and holds just fine.

 

[moparleo]

Sounds like an intake leak. Remove the intake and check the intake surfaces on the heads and manifold for tell tale heat evidence from port mismatch. Does the car idle smoothly at an idle? 700 rpms or so ? Alsp pull the spark plugs and check them. Make sure you don't mix them up as you remove them. This can identify the cylinder/s with the problem.

 

[Adam]

Do you have a clutch fan? I suspect a problem there because it is ok when you are driving.

 

[Chryco Psycho]

Timing , lean mixture , loose clutch fan , not enough rad capacity , all can cause heat issues ,block the heat crossover if you pull the intake .

 

[inprogress]

I'm beginning to think it may just be an intake issue. Does anyone know if the fel-pro intake set would require the use of those tin coolant passage blockers? I know I never used them when I swapped the heads but cant remember if the set even came with them or not!!

 

[Chryco Psycho]

no passage restrictors in the 360 intake kits , you have to make your own , I usually cut a piece from the old gasket & fit it to block the crossover port , no reason to restrict the coolant passages at all . the rear passages go nowhere

 

[rapid transit cuda]

Could it be that the 340 heads raised the compression enough to bring out the overheating issue?

 

[moparleo]

No. The problem would get worse . To quickly identify a vacuum leak, with the engine at idle, remove the air filter first. We are looking for the idle speed to go up. Second, with your hands slowly cover the top of the carb. If then idle speeds up, you have a vacuum leak. If it just dies with no change, you have a different problem.

Have you pulled the plugs yet? They will tell you if it is just one or more cylinders are overheating.

To properly diagnose a problem, you have to check everything one at a time. Do the obvious first. Is the initial timing set correctly? Are all vacuum lines correctly hooked up ? Is PCV valve working ? Proper idle speed is set ? With a vacuum gauge, adjust mixture screws to highest steady vacuum reading. About 18" with standard cam. Spark plugs are the proper ones, Champions were OE. Here is a link with the proper tune-up specs for a 1970 to 1975 Dodges :
http://www.tpocr.com/dodge2.html:icon_study: