Pre load

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aspira
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Pre load

Post by aspira »

Hi Guys,

I've just installed a Viper Hurricane cam in my Rover 3.5 with new std lifters. I also put in a Cloyes timing chain and used the standard keyway - not either of the 4º options.

When I checked the lifter pre-loads, the gap was pretty massive on all of the valves - probably around 150 thou' or more I think.

The thickest shims I have are 47 thou' so won't get with the pre load tolerances. Do you think it's okay to stack more than one shim under each pedestal if I have to to get the pre load into the right range, or could I just use the 47 thou' shim and live with a higher than recommended pre load?

I believe the cause of the problem is because I had the heads skimmed by 20' and I'm using a composite gasket. Apart from that it's a bogg standard Rover 3.5.

Any help much appreciated...
- Stephen


1978 MGB Roadster
Converting to V8

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ChrisJC
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Re: Pre load

Post by ChrisJC »

Skimming the head and fitting a composite gasket sort of compensate for each other depending on dimensions. You've had 0.5mm taken off the head, which isn't far off the ballpark for the thickness difference between a tin and composite gasket.

I suspect your valves have been reseated too far into the head...

Nevertheless, I have used multiple shims in the past without any issue.

Note there is a 1.6:1 rocker ratio, so you won't need as many shims as you think you do.

Chris.
--
Series IIA 4.6 V8
R/R P38 4.6 V8
R/R L405 4.4 SDV8

aspira
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Joined: Sun Jan 25, 2015 9:05 pm
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Re: Pre load

Post by aspira »

Many thanks Chris, much appreciated
- Stephen
1978 MGB Roadster
Converting to V8

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