comp check
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From: Iggesund SWEDEN
comp check
Hi I wonder what a normal reading would be when You do a Comp check on a stock -74 460 ? I think that my readings are very low, they are fairly the same but very low 105-110 psi
If some one have mont the camshaft wrong (one cog)
would that lower the reading ? the car don´t work very well either.
ps. where did the spellcheck go? ds
Mask Sweden
If some one have mont the camshaft wrong (one cog)
would that lower the reading ? the car don´t work very well either.
ps. where did the spellcheck go? ds
Mask Sweden
Elder User
Joined: Apr 2001
Posts: 997
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From: texarkana, tx
comp check
Hi Mask,
My freshly built 460 has 150 pounds across the board and runs like a scalded dog....if the camshaft were off a cog, that should not interfere with the sealing of the compression chamber....if a valve was BENT keeping the valve from closing all the way; that would make the compression low!! Squirt some oil into the cylinders then run your check again....let us know if your compression then increases...
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
My freshly built 460 has 150 pounds across the board and runs like a scalded dog....if the camshaft were off a cog, that should not interfere with the sealing of the compression chamber....if a valve was BENT keeping the valve from closing all the way; that would make the compression low!! Squirt some oil into the cylinders then run your check again....let us know if your compression then increases...
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
Thread Starter
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New User
Joined: Feb 2001
Posts: 24
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From: Iggesund SWEDEN
comp check
The oil in the hole din´t improve the reading and I don´t think that all valves are bent,because its no real diffrens between
them. Maybe all my valve seats are bad. I dont know
Mask
them. Maybe all my valve seats are bad. I dont know
Mask
Elder User
Joined: Apr 2001
Posts: 997
Likes: 0
From: texarkana, tx
comp check
Hi Mask,
All the oil was for was to verify a ~particular~ cylinder's compression did not improve when lubed with the added oil. I would have to say you've got valve problems..possibly seat issues. If the compression improved when squirting the oil into the cylinder that would indicate you've got a blatant ring sealing problem. To tell you the truth, depending on the mileage, the compression ring (top-most ring) might have some wear on it, allowing compression to pass it - and losing the charge into the crankcase. What's the mileage on the motor, Mask?...
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
All the oil was for was to verify a ~particular~ cylinder's compression did not improve when lubed with the added oil. I would have to say you've got valve problems..possibly seat issues. If the compression improved when squirting the oil into the cylinder that would indicate you've got a blatant ring sealing problem. To tell you the truth, depending on the mileage, the compression ring (top-most ring) might have some wear on it, allowing compression to pass it - and losing the charge into the crankcase. What's the mileage on the motor, Mask?...
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
Elder User
Joined: Apr 2001
Posts: 997
Likes: 0
From: texarkana, tx
comp check
Good luck with the renovation!! The 460 really makes my truck a screamer!!!! I barked the tires last night...I could have smoked the entire area if I had wanted to....but let off the gas.
Hey - I need to get to Windows XP training....catch you tommorrow....
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
Hey - I need to get to Windows XP training....catch you tommorrow....
The LaptopGeek -----
1974 White F100 Custom Fleetside
460 bored .040 over & C-6 automatic 2WD
Lunati cam, L&L Headers / mounts
Holley Avenger 770CFM & Edlebrock RPM
Plush black leather 40-20-40 bench seat
38 gallon JC Whitney fuel tank
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