Author Topic: Twin Cam valve guide longevity  (Read 245 times)

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Offline TurboFource

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Twin Cam valve guide longevity
« on: Monday,November 02, 2020, 04:21:06 AM »
I have read that valve guide life on Twin Cams is rather short, the guides on my head been upgraded and seals fitted on the intake side. Has anyone tried dry film lubricant on the valve stems or something similar to increase the longevity?
The more I do the more I find I need to do....

Offline jbcollier

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Re: Twin Cam valve guide longevity
« Reply #1 on: Monday,November 02, 2020, 07:16:56 AM »
The guides are fairly short so they won't last as long as longer guides would if it were possible to first them.  So that's one factor.  The other is how often you use high rpm.  If you spend a lot of time near the red-line, that will also shorten valve guide life.

Also, the goal posts have moved significantly since the early 60s.  At the time, redoing a cylinder head at 20K to 40K due to excess carbon deposits was the norm.  Changing the guides as well seemed like a reasonable compromise for the increase in performance.  Now spark plugs last 100K and we feel hard done by if the engine requires any major work at all.

To your specific question, your guides should have a significant amount of self lubrication (bronze or cast-iron).  I would lightly oil the valve stems on assembly and that's it.

Next time also fit seals to the exhaust side.  There are large vacuum pulses in the exhaust side that can pull oil in and make smoke.

Offline TurboFource

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Re: Twin Cam valve guide longevity
« Reply #2 on: Monday,November 02, 2020, 09:05:17 AM »
Thanks JB
The more I do the more I find I need to do....