Low Compression on Rebuild causing no start
Administrator
Joined: Apr 2010
Posts: 87,362
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From: Clayton MI
I think dot to dot is actually cylinder 6 in firing position. 
(or maybe I am just having flashbacks to small block chevy days....)
Should be able to rent the gauges at one of your local auto parts stores. Not like it's a tool you use a lot. (though it IS handy to have, when you find you need it. )
(or maybe I am just having flashbacks to small block chevy days....)Should be able to rent the gauges at one of your local auto parts stores. Not like it's a tool you use a lot.
(though it IS handy to have, when you find you need it. )
Thread Starter
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Registered User
Joined: Jan 2023
Posts: 16
Likes: 1
From: Thomasville, Ga
I went back through the timing I have it on tdc compression stroke with cam dot at 12 and crank dot at 12. I check compression on numbers 1,3,6,and 8 cylinders all only 30-45 psi. I have given it much thought and believe the only thing possible is the rings are either bad or undersized.
Thank You all for the help,
Thank You all for the help,
Administrator
Joined: Apr 2010
Posts: 87,362
Likes: 4,209
From: Clayton MI
And you only get 50 -60 PSI, yeah.... That's bad..... I might be tempted to yank a piston, and measure stuff out.... and make sure all the rings gaps aren't lined up.....
Grand Champion
Joined: Feb 2015
Posts: 7,435
Likes: 578
Just putting the lifters in oil is only half of it. You have to manually "pump" the lifter and you will see air come out. If you have air in the lifters it will not lift the valve(or at least not enough). This may be what's happening. Have you looked at the valves with the covers off to see if they are working? There is a way the lifters are to be installed also(#2).
INSTALLATION
1. Lubricate tappets.
2. Install tappets and push rods in their original positions. Ensure that the oil feed hole in the side of the tappet body faces up (away from the crankshaft). This is for stock lifters and if they are aftermarket they may be different. I think the air will find it's way out either way under oil pressure.
3. Install aligning yokes with ARROW toward camshaft.
4. Install yoke retainer. Tighten the bolts to 23 Nm (200 inch lbs.) torque. Install intake manifold.
5. Install push rods in original positions.
6. Install rocker arm.
7. Install cylinder head cover.
8. Start and operate engine. Warm up to normal operating temperature. CAUTION: To prevent damage to valve mechanism, engine must not be run above fast idle until all hydraulic tappets have filled with oil and have become quiet.
1. Lubricate tappets.
2. Install tappets and push rods in their original positions. Ensure that the oil feed hole in the side of the tappet body faces up (away from the crankshaft). This is for stock lifters and if they are aftermarket they may be different. I think the air will find it's way out either way under oil pressure.
3. Install aligning yokes with ARROW toward camshaft.
4. Install yoke retainer. Tighten the bolts to 23 Nm (200 inch lbs.) torque. Install intake manifold.
5. Install push rods in original positions.
6. Install rocker arm.
7. Install cylinder head cover.
8. Start and operate engine. Warm up to normal operating temperature. CAUTION: To prevent damage to valve mechanism, engine must not be run above fast idle until all hydraulic tappets have filled with oil and have become quiet.
