engine meltdown

[Satty71]

Well it went down like this. Pretty stock 318 (for the moment) started missing, turned out the choke wans't opening all the way. Then when driving and coming to an idle it was rough and pinged while under acceleration. Car just hit 90K on a pretty stock 71 318. Ignition is in great shape, vacum is good while running, charge is good and so is oil pressure. Now this thing won't idle all of a sudden and cuts off after warming up. It started stalling and wouldn't start a while back but would kick right over after sitting for a bit. This thing has a massive exhaust leak and the carb (2bl for now) is about 3 years old and has had no problems so far. Right now my new headers, fuel pump and timing chain are on the way. Any thoughts on what this might be? Should these new parts most likely take care of this? Comments please!!

[Tarrbabe]

Carb. Can't hear it run so it is hard to say. Next I would guess timing or timing chain...........

Just thinking out loud..

[Satty71]

Pretty much my thoughts also. Thanks for the reply!!

[pcrmike]

If the exhaust leak is near the heads, you may have a burned ex valve or three. :-) PCRMike

[Dick]

Massive exhaust leak.............choke not opening..........heat riser rusted through? If the exhaust leak is near the top, could be cooking fuel and getting vapor locked.

[jd-indy]

Check to see if the exhaust valve is open on the passenger side manifold. That shuts off when the motor is cold forcing the exhaust through the intake manifold. This valve often gets stuck on old engines. Another common problem is that the intake manifold exhaust cross over gets plugged. If this happens at the same time the exhaust has nowhere to go and can cause many of the problems you have. Headers will fix this.

[Satty71]

Thats aweosme, the first time I saw that valve I was like what the???? Its acting like the engine is choking out and dying. I forgot about that valve. The other day it died on me and I tried to start it. It choked out again and spit a lot of black smoke out from under the hood. What does a burnt valve do? I have seen some where the engine went lean and the spring started to pull the valve up creating a warped valve and preventing a good seal. Can I identify a burnt valve with a compession gauge? I am trying to prevent pulling the heads off until I get some new ones and new carb.

[dart662dp]

burnt exh valve will pop on decel. prolly timing set.

[Dick]

Originally Posted by Satty71

Thats aweosme, the first time I saw that valve I was like what the???? Its acting like the engine is choking out and dying. I forgot about that valve. The other day it died on me and I tried to start it. It choked out again and spit a lot of black smoke out from under the hood. What does a burnt valve do? I have seen some where the engine went lean and the spring started to pull the valve up creating a warped valve and preventing a good seal. Can I identify a burnt valve with a compession gauge? I am trying to prevent pulling the heads off until I get some new ones and new carb.

It sounds like there is some confusion between the heat riser valve and the exhaust valves. Heads do not require removal to service the heat riser. A compression check on each cylinder would pinpoint valve problems.

[30desoto]

Another thing you want to check is the coil and the wires, sometimes when a coil go's bad they will open when warm and start missfiring bad and then when you shut it off will cool down and start right up, I don't know how long it's been since you replaced the coil or wires, but I would check them out.

30dee

[TK]

I have seen the heat crossover get so full of carbon it splits the manifold under the carb................................

[Satty71]

Coil is pretty new accell mabye a couple of years old, I will check the heat riser when I pull the fuel lines to replace the pump. This is a 2bl manifold. However next question. I have a 71 340 intake which is in great shape but needs cleaned up. What is the best process. There is a machine shop on base that has a hot tank, would this be the best route to go. It has some gunk from sitting and is a little rusty nothing to aweful. I would like to get it back to premo condition prior to instalation.

[TK]

This is a 2bl manifold.

Single plane?

[pcrmike]

That one would be dual, but the pickup in the dist is known for stuff like this too. Had it happen. Replaced coil, dist cap, wires, timing set, everything. Replaced pickup in dist, problem solved! :-) PCRMike