Need help on what to do with this engine. While car is gone opened up the engine to adress some issues i had a feeling on. So far i have found leaky gaskets and a bent pushrod on cylinder 4, as well as cylinder 4 has not been firing for some time. Didnt know that until i pulled plug wire at dist. Cap. As well as i dont think the rings are sealing very well anymore. Cylinder walls have vertical scratches, not just the factory cross hatching. Below are pics of my ol tree fiddy
Rings don’t seem like your issues. Cylinder walls look normal. But get more zzdp in you oil. That one exhaust valve looks to be stuck open,possible burnt. Looks like a valve Job is first. Some look sunk. Possible need exhaust seats. Or valves at least. Might as well go with bigger valves on exhaust at least if your having to replace the valves. There’s a reason they are sunk. Springs may be junk. Cam too large for springs. Or something else. Now would be a good time to deck heads if you’re wanting more compression. Looks like possible low timing or rich carb, head carbon looks wet. Not firing well.
Like Andy said, cylinder walls look normal. Get the heads done tho, a bent pushrod usually means the valve springs lost control of a valve at some point. Check your bearings too.
Thanks guys! Okay will do. I thought it maybe rings because when i pulled spark plugs they were dark and wet. Seemed like oil/ gas but couldnt tell for sure. I just assumed the worst. I had a feeling something didnt look right when i pulled the heads. Could it be the float of the carb is set too high? I also cant remember what the timing was set at, we had messed with it to fix another issue we were having with detonation after i shut the key off. The heads will be gone through thats for sure. I will go through the bearings as well, to ensure everything is else is happy. Do you think old age, or too much cam lift killed my valve train? Cam should be close to stock as the original flattened first intake lobe
I’m gonna suggest timing/ timing chain problem.Has timing chain been replaced? Although you don’t mention mileage of engine, or any other information on engine. What is Timing set to? , did you do any compression tests. What oil you have been using. Stock carb? Maybe sticking choke? Weak 50 year old valve springs and overreving might be the bent pushrod issue . If cam going flat , you may not be using oil with zinc. And a flatter cam , will have less preload on lifter,pushrod and rocker , can contribute to valvetrain problem.
The engine is a stock 72 350 that came out of my 72 skylark. New Stock 2bbl carb, 75,000 miles on the engine. Timing chain and gears were replaced by me to get rid of the plastic gears from factory. Not sure of how much timing was in the car. Because me and my dad messed with it to fix an issue i had with the car still trying to run when i shut the key off. Never checked how much timing we had in it. Oil i ran was pennzoil 10w-30/40. Spark plugs were E3 sparkplugs. The cam has been replaced with another stock cam. The original one had a stuck lifter that wiped a lobe on the first intake. The replacement cam has no indication of going flat. Everyso often i throw tge zinc additive in the oil for the cam, because most of the oil today doesnt have zinc
I would take the block down to bare, hot tank it, mill 20 thou off the deck, and use a flex hone (part number GB33424 3 75), and be sure to replace the cam bearings with TA grooved versions. I would avoid the E-3 plugs. I would also hot tank the heads and machine as needed, I would also take 20 thou off the deck of the heads for a new sealing surface.
Okay, i would probably leave the pistons and crank alone then. And work on cleaning the block and heads, to freshen up the top end of the motor. Would you guys recommend NGK plugs, AC delco whats the preference? And what about switching from 2 to 4bbl? Not going for a race setup. Just a reliable motor that i can cruise and show for a little while, until i build a new engine for the car
