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1957 - 1960 F100 & Larger F-Series Trucks Discuss the Box Style Ford Trucks

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Old 07-09-2012, 09:41 AM
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cbass139 cbass139 is offline
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compression and leakdown results

Already posted this in the engine section and on the Yblock site but thought I would try to get a few more heads thinking about this.

So the truck ('58 292, Mallory dizzy) has been running like a dream thanks to everybody here but lately I have noticed a lot more fumes coming out the down draft tube so I decided to do a compression and leak down test to see what was going on, kind of wish I hadn't. The compression was right around 100-110 across the board but I was thinking that my gauge might not be working right because it would jump up to that number and right back down to 0, I never had to release the pressure. Then I did the leakdown test with 80 psi it would drop to around 20 on the cylinder side and my little compressor had a hard time keeping up with the amount of air that was rushing by. Had it at tdc, with the choke closed and accelerator plate wide open, no air cleaner on. It sounds like the air is going passed the rings and or the valves (I know "really narrowing it down") because I can hear it coming out the dipstick I think. My question is, with the numbers could I really have the truck running so nice, it sounds like clockwork? Thanks to all in advance.
Cbass (Sebastian)
"Nothing is particularly hard if you divide it into small jobs."
"Chop your own wood, and it will warm you twice."
-Henry Ford
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Old 07-09-2012, 10:45 AM
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theodore/teddy theodore/teddy is offline
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The good news is that the leak in your compression gauge will be easy to fix.
The bad news you already know, and will be a little more spendy to deal with.
With all the blow by it's hopefully just worn rings and you could hone the cylinders and replace the rings if you are on a tight budget, do you still have good oil pressure.
Although you know a complete rebuild would get you down the road for many years.
Good luck in your quest.

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1959 F250 4x4
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Old 07-09-2012, 11:25 AM
willowbilly3 willowbilly3 is offline
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In 1980 I bought a 59 Belair with a 283. It had 100 psi across the board, ran like a dream after a good tune up and never used much oil or smoked, always popped right off, even in 30 below weather. I drove the stink out of it for years and then gave it to my sis for a wedding present. Her oldest son drove it all through high school and also didn't baby it. The car is garaged now but still starts and runs good. Long story short, don't mess with what ain't broke. If it runs good, just drive it and have fun.
Oh, and this is just me but I never bother with leak down tests. The compression test and a vacuum gauge will tell me everything my lazy butt needs to know about engine condition.
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Old 07-09-2012, 11:25 AM

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