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Top end rebuild - jammed! help please.

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i'm rebuilding my 270x top end.

with the cylinder and head installed, *less* the camshaft, she turns over nicely, like a kitten, using just a hex wrench from the side.

now, after i install the cam, double check the timing, and torque down the cam towers, she won't turn over...

...when the lobes for the intake valves spin forward and down to depress the intake valves - something's jamming right there....

this has got to be something simple that i'm screwing up?

any ideas? tia!

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sounds like you're not TDC on the compression stroke. Intake valves hitting the piston. Rotate the engine one complete turn and see if that helps.

Lobes facing to intake side and slightly up while on TDC on the compression stoke?

Might be wrong but thats what it sounds like to me.

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are you sure the cam chain is on the crank at the bottom? Mine slipped off and was binding up. Also check that the cam rollers are in the grooves on the caps. Maybe they slipped off. Whatever it is, I'm sure it's an easy fix.

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can your piston go in backwards? maybe the valve cutouts on the piston don't line up with the valves. :thumbsup:

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Have you tried turning it over with the plug out??? Mine did this when I put it together and it was just stuck at top dead center. Needed a prod. Try turning engine in reverse direction to find the problem

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can your piston go in backwards? maybe the valve cutouts on the piston don't line up with the valves. :thumbsup:

That's a possibility. It will turn over w/o the cam but when you put the cam in the valves will hit.

Large cutouts go on the intake side.

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can your piston go in backwards? maybe the valve cutouts on the piston don't line up with the valves. :thumbsup:

This is possible TR270 piston is marked incorrectly on the piston! I had to confirm this myself when I put mine in.

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