Is it valves or barrels ;(

Masdomonkey

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I cant figure if my valves are leaking or my pistons are bad, compression test dry and wet came around 60 psi in EACH cylinder... the engine runs, at idle i can remove the wires to #1 and #3 with no change in idle but #2 and #4 have about the same compression as #3 and #1. When i rev it with the wires off if #1 and #3 and its gross but with the wires on the engine runs fine past idle, the carb is in check for sure tuned it multiple times.

So my theory is that when i rev it the compression comes back high enough to run normally off idle but when at a stop it will putter. Im gonna tear into it soon and need to know if i just need head work or barrels as well


I dont always go fast, but when I do its defiantly not in bed
 

JEFFRPM

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What engine is it 4cyl 6 8 10 what ford or chev? That's a start.

60psi is pathetic I'm surprised you can't start it with a rope on the balancer kinda like a lawnmower....... wait you guys in kalifornia aren't allowed gas engines they cause cancer or something so keep plugging that electric lawnmower to that coal fired "clean" power source. Gawd I'm in a mood today.
 
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manicmechanic

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Are you doing compression checks with the engine running on the other cylinders?.
 

brad inch

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do a leak down test,it will tell you where you are losing it.look up leak test on utube.you will need a different gauge.
 

Masdomonkey

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What engine is it 4cyl 6 8 10 what ford or chev? That's a start.

60psi is pathetic I'm surprised you can't start it with a rope on the balancer kinda like a lawnmower....... wait you guys in kalifornia aren't allowed gas engines they cause cancer or something so keep plugging that electric lawnmower to that coal fired "clean" power source. Gawd I'm in a mood today.
Aircooled vw



I dont always go fast, but when I do its defiantly not in bed
 

Masdomonkey

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do a leak down test,it will tell you where you are losing it.look up leak test on utube.you will need a different gauge.
Ive heard of this ill look on it more, thank you


I dont always go fast, but when I do its defiantly not in bed
 

Masdomonkey

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What engine is it 4cyl 6 8 10 what ford or chev? That's a start.

60psi is pathetic I'm surprised you can't start it with a rope on the balancer kinda like a lawnmower....... wait you guys in kalifornia aren't allowed gas engines they cause cancer or something so keep plugging that electric lawnmower to that coal fired "clean" power source. Gawd I'm in a mood today.
Lol no fuqs given even if i am from cali i aint no tree hugger


I dont always go fast, but when I do its defiantly not in bed
 

burninfuel

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I would check the valve lash, valve doesn't close and poor compression.
That will keep you busy for about 1/2 hour.
I run them .002" looser so when your running hot at the dunes it's still running strong.
 

43mod

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a good size squirt of oil in the cylinder will increase compression if the rings are bad. It will do nothing if the valves are bad/open . Not a gallon maybe a fluid ounce or less. A flat cam can also drop compression .
 

partybarge_pilot

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Your doing the test with the throttle held WFO right? Doing the test with them closed will give you low readings. They will also vary hole to hole if you don't have your carbs synq'd well.
 

Masdomonkey

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Your doing the test with the throttle held WFO right? Doing the test with them closed will give you low readings. They will also vary hole to hole if you don't have your carbs synq'd well.
So when i turn it over to do a comp test your saying to hold it wfo and it should go up? I havent tested that yet


I dont always go fast, but when I do its defiantly not in bed
 

Turbo Dog

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Yes, keep the throttle wide open and allow the engine to turn over enough times to allow the gauge to get it's highest reading. It always seems to need about 4 or 5 pumps to get a full reading. You need a good fully charged battery because the cranking speed also determines how well the cylinder can draw in air.
 

Turbo Dog

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I should also mention that it is best to do this with the engine at operating temperature. Depending on how bad it is running that may or may not be possible.
 

Masdomonkey

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I should also mention that it is best to do this with the engine at operating temperature. Depending on how bad it is running that may or may not be possible.
It runs okay, has a bit of a misfire every once and awhile but its a vw, thank you for the details


I dont always go fast, but when I do its defiantly not in bed
 

Turbo Dog

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If the misfire is random it is probably not related to a mechanical failure problem. What are you running for ignition? And have you tried looking down the throat of the carb while it is running? Look to see if the fuel is being atomized well, meaning that you shouldn't be able to see the fuel going into the air. If it is dripping, that will cause some erratic running. Run the engine at night in the dark, power brake it and have someone what all the ignition wires to look for sparks where they might be shorting out.

Note: ALWAYS wear safety glasses when looking down the throat of a carburetor on a running engine!
 

Masdomonkey

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If the misfire is random it is probably not related to a mechanical failure problem. What are you running for ignition? And have you tried looking down the throat of the carb while it is running? Look to see if the fuel is being atomized well, meaning that you shouldn't be able to see the fuel going into the air. If it is dripping, that will cause some erratic running. Run the engine at night in the dark, power brake it and have someone what all the ignition wires to look for sparks where they might be shorting out.

Note: ALWAYS wear safety glasses when looking down the throat of a carburetor on a running engine!
The electronic points system? I dont know what to call it... plus a blue coil

Heres the results from the test, i didnt bother for a wet test because im gonna get new pistons and cylinders
ImageUploadedByrace-deZert1495238322.147678.jpg







I dont always go fast, but when I do its defiantly not in bed
 
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