Loss of compression on cly #1

[rafriesen]

First of all I am a die hard Chevrolet man. I bought a 1947 Coupe with body and interior restoration done. Why did I buy it -- because the price was right.

Did a brake job and then got it running. I ran great but failed on first test drive. Replaced fuel pump and it ran great again. Took it out for a 4 mile ride and it was running great. Set in the shop over night and when started the next day it was missing real bad. Compression on 2 - 6 was 75lbs. and compression on 1 was zero. Again I am new to this engine and need some advice as to where to start. Valves, lifters, adjustment or pulling head just need some Ideas.

[55 Fargo]

First of all I am a die hard Chevrolet man. I bought a 1947 Coupe with body and interior restoration done. Why did I buy it -- because the price was right.

Did a brake job and then got it running. I ran great but failed on first test drive. Replaced fuel pump and it ran great again. Took it out for a 4 mile ride and it was running great. Set in the shop over night and when started the next day it was missing real bad. Compression on 2 - 6 was 75lbs. and compression on 1 was zero. Again I am new to this engine and need some advice as to where to start. Valves, lifters, adjustment or pulling head just need some Ideas.

Valve stuck open on cyl 1, head gasket is bad.

I suggest you pull the head and have a look, see what you need, this happens, and is not that bad of fix, if just a gasket. While your in there, you can clean up the top end, and have head shaved a bit........let us know what happens

[JIPJOBXX]

Yep I just had that problem a few weeks ago and it was just a blown head gasket. Easy fix and I did have the head shaved and it did increase my power range. Edited March 17, 2010 by JIPJOBXX

[Merle Coggins]

If it was the head gasket you would have lost compression on 2 adjacent cylinders. I believe you have a stuck valve. Since it ran fine earlier I suspect that the old sludge, oil, and carbon has become gummy and is causing the valve to hang open. Start it up and let it warm up some. I have a feeling that it'll begin working again. If I am correct, and it loosens up again, you'll need to get something in there to clean up the valve guides. Maybe an oil change and a long drive would work some fresh oil in there.

Merle

[Niel Hoback]

Since its a stovebolt, take off the valve cover and see if the valve moves when its running. If the valve is stuck, you,ll hear the rocker arm clacking even with the cover on.

You could have a hole in your head gasket that leaks into the coolant or even out the side of the head without going into another cylinder.

[Niel Hoback]

Does this mean we have converted another Chevy fan?? Woohooo, all it takes is owning one.

[dezeldoc]

Does this mean we have converted another Chevy fan?? Woohooo, all it takes is owning one.

Niel, only if the bowtie is not choking them you might convert them!

I am in agreement , the valve is stuck open. Change the oil and filter and add a pint of marvel mystery oil to it, it will keep thing from sticking. if you pull the side cover under the exhaust manifold you can see if it is stuck or not and if it is you should be able to get it free from there unless it is seized in the guide.

[rafriesen]

Well I think the old Chevy man figured it out. Seafoam in the tank and get it started and spray some down the carb and walla it runs great again. Ten mile test run and it keeps on running. A Chevy man changing over I doubt if you look at my sig. Thanks for all the help.

[dezeldoc]

Hey how does that 56 run with the twins?

[rafriesen]

The 56 is not finished yet. All the chassis work is done, 25-5 NHRA certification, rearend, brakes,tranny and turbo setup with headers is all finished. I have started on the engine and will have to do the fuel system and then have fun with 1300hp on only 10lbs of boost. Should be a great street ride I hope.