Hey guys, seems like I only get on here when my ass is on fire lol My 67 Skylark has recently developed some bad issues with the engine. It's missing like hell but, only after it warms up, and only when the engine is under load, ie cruising or accelerating. Does just fine at idle or when coasting downhill. I just rebuilt the carb last year, and have already made sure the fuel filter is unclogged. I have yet to check the points or condenser, but, I know it needs a valve job and it's making a loud, heavy, knocking sound when I hit the gas more than just a little. My dad seems to think that's the crankshaft bearings going bad too. Just curious as to what you guys thought these issues might be. Given that they could be pretty major I'm thinking of just replacing the whole engine at this point. The car is nearly undriveable and I really need to get her road worthy again. Any help is appreciated
It runs fine when cold? That's odd. If it's pinging under load, it either has too much timing or is very lean. Could be a huge vacuum leak when hot but it wouldn't idle either. The wrong carb base gasket will burn thru and it won't run worth a damn. But you say it runs ok at times. hmmmmm. You can try tying the choke partway closed after it's warmed up and take it for a test drive. If it improves it's lean for some reason. Check your timing at idle and at 3000 rpm. A vacuum gauge is a great diagnostic tool too. Got one? Larry should be up in a couple hours, he's a wiz at this sort of problem....
I'd be more concerned about the knocking sound. Whats your oil pressure cold and hot? Can you post a video of it running warmed up and missing?
Sort out the knock like mentioned, and if it's needing a valve job , that could be a lot of power loss issues. Get a vacuum gauge on it .
Take a look at your plug wires. I always like to look at the easy stuff first. I've had bad plug wires that have exhibited several of the symptoms you're describing.
Sounds like you will be needing to run through the basics and do some verification. Number one, compression test - maybe your timing jumped a bit on the nylon roller, Next is vacuum test, timing verification and making sure the weights in the distributor aren't stuck or something goofy. I would still verify fuel delivery, you could have a clogged sock in the fuel tank. Pull spark plugs off one by one, or stick a tester in each one and make sure you don't have bad wires. How old is you coil and points? A bad coil will work okay when cold and then run crappy and misfire when hot.
First thing I would do is check vacuum. Sounds like you have a vacuum leak somewhere. The choke covers the problem up when the engine is cold.
Can you elaborate on the knocking noise.... is it only when warmed up? only when driving? Is it 'pinging' during acceleration, or is it a knocking sound from the bottom of the engine even at idle?
