1940 V8 lost compression

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Apr 28, 2005 | 05:40 PM

CaptivaRay

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1940 V8 lost compression

I have a 1940 fire truck with a flat head V8. I had it in the shop for almost a year doing some restoration work. Now it has 2 cylinder, exactly opposite of each other, with zero compression. I'm thinking frozen rings, could it be anything else? I have put plenty of PB Blaster and still not free it up. I find it odd that the 2 cylinders are opposite of each other.
All other cylinders have 100 lbs, (+or-).
Ray

Apr 28, 2005 | 09:30 PM

51ford fan

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Joined: Apr 2004

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From: Seattle WA.

Ray, it sounds like the valve seats may have come out of the block holding the valve open. If so, the block might be cracked from the cylinder to the valve pocket. I was doing some reasearch, and an article I was reading said the use of unleaded fuel without lead additive causes the valves to weld themselves to the seat. I Don't know if there is any truth to that statment. The internet is full of articles that say straight unleaded in a street Flathead won't cause any problems. I was thinking of building a Flathead for my 51 but I'm so confused I'm not sure if it's the most cost effective way to go or not. Good luck, there sure seems to be a lot of guys with similar problems asking questions right now.

Hope this helps
Rod

Apr 29, 2005 | 10:28 AM

JCPSME

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Joined: Feb 2003

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From: S.K.C. MO

If you've put lube in the cylinders with no change in compression then it's a valve problem. They are stuck open maybe a little corrosion on the stems or seat problems like 51 said.
Jeff