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Speedin' Ian

Cam trouble

4 posts in this topic

I was puttting my motor back together last night after rebuilding the trans and I noticed after installing the cams that the intake cam does not spin nearly as freely as the exhasut cam. How easy should it be to spin the cam after it is tightened down? Any thoughts on what would cause this? Thanks for the help

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Make sure the intake cam is seated correctly. Also, proper torque settings on the cam 'caps' are critical to ensure your cams spin freely :cry:

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I had this same thing happen on my 250F. I couldn't see anything wrong with how it was together, so I left it like that and it's fine. Had it apart later, and the bearing surfaces are still OK.

Here's what you should do to be as sure as you can be that things are OK. Check the clearances on the cam using PlastiGauge or similar as laid out in the manual. Be VERY careful when torquing down the cam caps. The manual calls for 7.2 foot pounds, which is 86.5 inch pounds. A lot of people, including myself, think that this is too much for this assembly and reduce the torque value. I use 70-75 inch pounds (6 foot pounds). Use an inch pound wrench and torque it down evenly from the center outward in 15 inch pound increments.

Also be sure you haven't left any of the dreaded "foreign material" (lint from rags, dirt, even a hair) in the bearing saddles, or on the surfaces where the caps mate to the head.

If none of this turns up anything definitely wrong, and you can rotate the cam at all by hand, you're probably all right. Warm it up gently the first time back out, and go back in to check on it later, just to be sure.

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Thanks for the advice guys, it spins freely, just not as easily as the exhaust. I will remove the cam just to make sure there is nothing in the cam seat and go from there.

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