Bought the 64 Valiant 3 years ago, and it has/had run great. The previous owner had the original motor rebuilt. Last year I did a compression check just to see what it had. It had a 144psi average, so above stock. Well over the last few months the car has been driven 500 miles a week. I was riding to work with my brother, but he sitched to another shift.
So I noticed the the gas milage has been dropping. So I did a tune up, but not much help. Over the last couple weeks the power and mpg have dropped. Did a compression check this morning and had a 70psi average with #2 cylinder reading 0. Didn't have time today, but will do a leak down test tomorrow.
Never seen all cylinders drop like that at the same time. Anyone else have this happen? My first guess is valve seats had enough. I see a lot of people putting money in the block and going cheap on the head. Secon guess cheap cast rings. I've put 30,000 plus miles on it. Not sure how many the previous owner put on it. Th oil and coolant look great, so thinking head gasket may be ok.

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AGAINST THE GRAIN IS MY WAY

Try adjusting the valves first.

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Official Cookie and Mater Tormentor.

Did those about 4,000 miles ago, started to run ruff. All were set pretty close. But #2 exhuast i did have lto back off a bit. That's why I am leaning toward the seats.Seen quite a few heads with exhaust valves sucked in the head. But will double check them.

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AGAINST THE GRAIN IS MY WAY

adjust the vakves

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Yeah....Im the one who destroyed this rare, vintage automobile.....

.......or valves

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Yeah....Im the one who destroyed this rare, vintage automobile.....