On cold start, the engine goes to high idle like it should, but has a misfire sound from the exhaust pipe. The engine also shakes a bit. When kicked down to curb idle, it idles rough and the engine shakes as if it isn't hitting on all six. When stopped at a red light in gear, the idle is very slow and rough. Idle speed in neutral is set to 750 RPM.You mentioned that it runs like it has a dead cylinder. What does that mean? No power? Can you describe the symptoms a little more?
The car has a new tank and fuel filter, plugs, rotor and distributor cap. Valve lash is set correctly.Sounds electrical or fuel related. How's your fuel system Cruiser? I recently had to replace the Tank on my 74 Duster because sediment and rust particles were coming through. Make sure all the simple stuff is ok - Cap, Rotor, Distributer. Maybe a bad plug firing intermittently?
A recent photo of the plugs, numbers 1 to 6 from top to bottom.Compare the plugs.
Sounds and looks like a burned exhaust valve because you hear it at the tail pipe and judging from the plugs looks like 1 and 6 are your culprits. Time for a compression and a leak down test.On cold start, the engine goes to high idle like it should, but has a misfire sound from the exhaust pipe. The engine also shakes a bit. When kicked down to curb idle, it idles rough and the engine shakes as if it isn't hitting on all six. When stopped at a red light in gear, the idle is very slow and rough. Idle speed in neutral is set to 750 RPM.
Timing at 10 degrees before. Trying to figure out how to hook up a vacuum gauge.Plugs look ok, and don't show anything obvious.
What is the initial timing set at, and do you have a vacuum gauge to hook up to manifold vacuum?
Plugs look ok, and don't show anything obvious.
I thought he recently had the head off of that engine? And earlier it was said "all cylinders had the same rpm drop when plug wire pulled vs the others...
Not to me. # 1 and #6 do not look normal. Something going on in those holes. Burnt valves high on the list of suspects IMO. A leak down test would reveal that. Buy a tester, best tool I ever bought as far as diagnostic.
Good question. The answer is no, not yet. Here's what I'm thinking. The motor in my Duster was a replacement engine installed 36 years ago, and now has over 105K miles on it. I'm not sure how much life this engine has left in it. I suspect that it had poor maintenance prior to my ownership. If I can solve the problem I currently have, there's no guarantee that another problem won't pop up shortly thereafter. I plan on keeping this car forever and driving it a lot. There's one school of thought that says to cut your losses and just go with a new engine. That way you can enjoy many years of trouble free driving. Since the current engine now in my car isn't the numbers matching original, it's not that valuable. If it WAS the numbers matching motor, no question - I'd keep it and rebuild it. But this isn't the case unfortunately. Yes, I'm planning on running the test you mentioned, and I really appreciate the technical advice. I just don't want to "throw good money after bad" as the old saying goes. I definitely haven't made the decision to buy a new motor. I'm just in the "thinking about it" phase right now. There's a place called S and J Motors that will sell a rebuilt long engine, balanced and with mild head porting work for about 3K. What's your take on all this, Rusty?I see you're on another thread asking about crate engines. Have you EVEN run a compression test yet?
I think you're on the right track. Regarding the "crate engine" approach. If you plan to start with nothing, in other words, you want a "TOTALLY" complete new engine, just be advised it will not be cheap. Someone will have to come up with an entire long block. That's the easy part. Then, they have to locate all of the tin, the valve cover, timing cover and oil pan. Next is all of the various fasteners. That takes a lot of time and effort. It's not something that's going to happen for say 2500-3500 dollars. Sure, a basic long block can be had for that, but people seem to forget about all the other details. That is of course you plan on using all of that from your present engine. If you want a "plug and play" approach, just be prepared to pay someone for their time, parts and effort.Good question. The answer is no, not yet. Here's what I'm thinking. The motor in my Duster was a replacement engine installed 36 years ago, and now has over 105K miles on it. I'm not sure how much life this engine has left in it. I suspect that it had poor maintenance prior to my ownership. If I can solve the problem I currently have, there's no guarantee that another problem won't pop up shortly thereafter. I plan on keeping this car forever and driving it a lot. There's one school of thought that says to cut your losses and just go with a new engine. That way you can enjoy many years of trouble free driving. Since the current engine now in my car isn't the numbers matching original, it's not that valuable. If it WAS the numbers matching motor, no question - I'd keep it and rebuild it. But this isn't the case unfortunately. Yes, I'm planning on running the test you mentioned, and I really appreciate the technical advice. I just don't want to "throw good money after bad" as the old saying goes. I definitely haven't made the decision to buy a new motor. I'm just in the "thinking about it" phase right now. There's a place called S and J Motors that will sell a rebuilt long engine, balanced and with mild head porting work for about 3K. What's your take on all this, Rusty?