Poor Compression 221 2 cyl's

dean333 said:
Seth, my 85hp 37 has about 70lbs compression across the board and runs like a raped ape, no loss of oil.
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That's what I'm experiencing with my '35, testing lo on all cyl, one at 40, one up to 90 on the high side. Two at 80, two at 60 and two at 70. She starts up right away and I've driven her on a 100 mile trip a week ago, no problems. I just did the comp test today and now i'm concerned! Should I be? Doesn't use any amount of oil and no smoke! I'm guessing valve job in order.
 
So, I'm wondering if a cold compression test is more accurate or a hot one or does it make a difference? I know I have issues but it runs fine. Any ideas?
Thanks
 
I was always told to do a compressin test on a fully warmed up engine. And as stated the gas pedal needs to be to the floor. I usually cut a stick that fits between the floored pedal and the seat. You said it was rebuilt but not when. 25 years setting in a garage? Either was things stick. Rings, valves etc. I always introduce some marvel mystery oil to the gas and the oil and run it hard. Has worked wonders for me. As far as you 'having issues', don't worry we all do or we wouldn't be owning and working on these old cars.
 
Thanks GB for your much appreciated info, I did the test cold and I'll do another one warm and also with the throttle open.
The car was redone in the early 90's and I've had her about 3 yrs now and put roughly 1400 miles on her. I love driving the old car to shows or just around town, gets a ton of attention!
Thanks again and I'll let you know the results when I re- test.
 
BobR35 said:
That's what I'm experiencing with my '35, testing lo on all cyl, one at 40, one up to 90 on the high side. Two at 80, two at 60 and two at 70. She starts up right away and I've driven her on a 100 mile trip a week ago, no problems. I just did the comp test today and now i'm concerned! Should I be? Doesn't use any amount of oil and no smoke! I'm guessing valve job in order.
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Drive it for as long as you can stand it. I finally got tired of adding oil, the blow by out of the breather and clutch chatter from a wet clutch disk. If your engine is giving you satisfactory proformance, enjoy it as is.
 
Seth Swoboda said:
Drive it for as long as you can stand it. I finally got tired of adding oil, the blow by out of the breather and clutch chatter from a wet clutch disk. If your engine is giving you satisfactory proformance, enjoy it as is.
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Yes, I think that's exactly what I'm going to do Seth. I drove it 60 miles today to a friend's hanger and we did a warm compression test and results were a little different/better but still on the low side. She runs great, uses no oil and no smoke so I'm gonna keep driving her and enjoy the ride!
 

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BobR35 said:
Yes, I think that's exactly what I'm going to do Seth. I drove it 60 miles today to a friend's hanger and we did a warm compression test and results were a little different/better but still on the low side. She runs great, uses no oil and no smoke so I'm gonna keep driving her and enjoy the ride!
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526808
 
every engine is different what you are looking for is the difference between cylinders. Any difference above 10% is a concern make sure engine is at operating temp, all plugs removed and throttle is held wide open then cranks till it doesn't increase usually about 3 times .Record readings and then repeat after dropping about 5 drops of eng oil into each cylinder in turn record readings and compare should be a slight rise in compression but not dramatic
 
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