ironhead help
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Joined: Jul 2010
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From: pasadena, texas
ironhead help
i replaced all the gaskets and orings in the motor along with the piston rings. i put the cams in time but didnt have the motor at tdcc, i fixed that then i did a compression test and the front is getting 15 and the rear is getting 0 they are 10 over pistons and the rings are obviously 10 over. can anyone help me as to why im not getting good compression?
Tourer
Joined: Sep 2007
Posts: 400
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From: se ohio
yes re check push rod adj, make sure your heads are sealed, did you check the valves and seats while the heads were off? did you check ring end gap? did you try to start it with the cams in wrong? if so may be a bent valve or two
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Joined: Jul 2010
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From: pasadena, texas
i rotated it over i never started up that's when i found out about the cams being wrong. i remeber checking the gap but i will check again. to assist the rings to seat should i put a bit of oil into the cylinders?
Stellar HDF Member
Joined: Feb 2006
Posts: 3,035
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From: Houston Texas
If they fail to seat, and that sometimes happens, then you remove the cylinders and hand sand in an X pattern using 400 wet/dry silicone carbide paper.
The fact that you have such low (or none existent) compression concerns me. Rings not seated would not cause such a lack of compression. Good compression should be 125 to 150 psi.
When you do a compression check be sure to open the throttle wide open and kick it through three or four times. This lets it suck in lots of air to compress.
Look first for the correct pushrod adjustment. If the valves are open then this is why you have no compression.
If the pushrods are adjusted correctly, then you may as well remove both heads because you have bent a valve when you turned over the engine with the incorrect position of the cams.
pg
Did you have the pinion gear off of the shaft? It must be aligned correctly on the shaft. Then rotate the engine until the pinion gear mark is at about the 11:00 o'clock position and install the cams, lining up all the marks.
Do not oil the cylinders - that would prevent the rings from seating.
Last edited by IronMick; Jul 2, 2010 at 09:27 PM.
Road Master
Joined: Mar 2006
Posts: 775
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From: OC California
There is no relationship between the cam timing and TDC. You completely ignore the TDC when installing the cams.
+1 Your cams are not timed correctly. With 0 and 5 lbs compression I bet your valves are staying open. DO NOT keep turning the engine over until you fix this issue!!!!!!!!!!!!
+1 Your cams are not timed correctly. With 0 and 5 lbs compression I bet your valves are staying open. DO NOT keep turning the engine over until you fix this issue!!!!!!!!!!!!
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