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I hate to add a "this or "that" but I had a similar problem with a Corvette a number of years ago. Same issue on one cylinder. All the symptoms of what you had and I checked all the things you that you have looked at.
Within the valve spring retainer--which is not visible to the naked eye--the top two lands of the spring were broken. The valve opened fine when doing a remote starter crank. I diagnosed it by a wire pull with a tach. The car didn't miss that bad until under a load and at higher RPMs. Compression was there, wires and plugs checked out, just about drove me nuts. Filled the cylinder with air and removed the retainer to examine the valve spring (thought it might be a soft spring) and found it. Good luck |
After a QUICKIE midnight tune up on the boat, I had a fight that sounded just like yours, Turned out to be the FIRING ORDER!
Good Luck! |
Frustrated in Florida
Thanks for all the suggestions....base on your ideas I applied cylinder pressure, removed and inspected the valve springs and the pushrods for the intake and exhaust for No 1. They couldn't be in better shape....there perfect. The engine has been running for almost 4 years and running great...This all started when I had to put new advance springs in the distributer....Thinking that I had not done it correctly...I replace the distributer with another from a working car....same symptoms. I have checked and rechecked the firing order and its the same as its always been with that cam....no difference from the book for a 302 or 289. I even moved the No1 wire to the cap slot before and after the No1 position to see if there was any indication of fire...None. The exhaust manifold is cooler on No. 1 and even a different color at the No1 port....than the rest of the manifold. I have checked for an obstruction in the manifold with some wire...and have found none but I am heading out to remove the carb and go in with a "claw pick-up....if this don't work....Hmmmm! maybe its time for a bowtie!
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I still think you should replace the intake manifold gasket. The 289/302 is know for the gaskets going bad on the ends.
Poorboy |
Don't go over to the dark side man, a bow tie is NOT the answer, LOL.
Keep the faith! Ernie |
When you did the distributor work did you replace the rotor cap at the same time?
If so maybe there is a fault in the new cap? You should really look at what things you did that have changed the engine set up, even the smallest things. The cap may have been moulded poorly and the pickup has moved or was set wrong, causeing the timing on that one cylinder to be out by afew degrees? I really cant see a carb fault causeing concerns only in cyl#1 If it specific to only one cylinder it is most likely something that works on cylinders sepperately , ie: cylinder specific. Did you check the plug gaps? Please keep us informed, this is allways good stuff to learn from. |
Try blowing some air in the air corrector jets in the top of the carb. If a piece of foriegn material has lodged itself in one it will act very strange. Then look inside the carb. There may be a passage blocked.
Rick |
What was the anwer to the fault?
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Is there any reason to think you may have a bent valve stem or a broken valve spring (that is if you have dual or triple springs)? Maybe a bad roller rocker? Your compression test is done at cranking speed. At running sppeds you may have a valve that is not closing fast enough to build proper combustion pressure.
This is not too long of a shot. I've seen it happen. |
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