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CVO Technical => Twin Cam => Topic started by: Farm boy on July 20, 2019, 02:22:07 PM

Title: Adjusting valves
Post by: Farm boy on July 20, 2019, 02:22:07 PM

I put cr575 gear drive cams in my 03 serk. I used the harley adjustable pushrods (24 tpi). It said to go 2-1/2 turns after zero lash. I have johnson hy-lift lifters in it. I have more valve "clatter" than I think it should be. 
Can I safely go to 2-3/4 turns to quiet this thing down ?
I am a mechanic, sounds like a sbc set 1/2 turn after zero lash, instead of a full turn at the moment.
Yes, rocker lockers have been done.

Title: Re: Adjusting valves
Post by: grc on July 20, 2019, 07:12:30 PM

Total lifter piston travel is supposed to be 0.200", and it's normal to set the piston centered in that 0.200".  With a 24 tpi pushrod, 2.5 turns is 0.104" which is basically centered.  Many people recommend running an extra .025" preload to reduce noise, with your 24 tpi pushrods that would be an extra half turn (3.0 turns total, which calculates to 0.125" piston travel).  It may or may not actually help the noise issue, but it shouldn't hurt anything to try it.

Jerry

Title: Re: Adjusting valves
Post by: Farm boy on July 21, 2019, 03:36:10 PM

Thank you

Title: Re: Adjusting valves
Post by: snowrider13 on July 22, 2019, 10:31:16 AM

What was your crank run-out? Gear drives tend to be a bit noiser. Cam choice is another factor.

Title: Re: Adjusting valves
Post by: Farm boy on July 22, 2019, 09:34:31 PM

.002"
Not gear noise. Sounds like excessive valve lash.
Note: this is a fresh top end. That is why I was asking about valve adjustment.

Title: Re: Adjusting valves
Post by: snowrider13 on July 23, 2019, 11:46:56 AM

Just thought maybe you could use the info. Had the same issues myself. For me the valve lash did not affect it. Good luck.

Title: Re: Adjusting valves
Post by: Farm boy on July 23, 2019, 06:21:34 PM

Thanks for the input.