Acceptable rocker arm to pushrod clearance at max lift
#1206965
03/31/12 02:45 PM
03/31/12 02:45 PM
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Joined: Apr 2009
Posts: 3,415
Toronto
mshred
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Hey guys, So I have finished measuring up the pushrods on my 360 build. Using a set of RHS Indy X heads ported by Brian at IMM with Hughes 1.6 ratio rockers (Shaft mount) and a custom juice roller ground by Brian as well. Just finished checking for length with an adjustable pushrod tool that I made and am slightly concerned. I have no idea what size my current tool is, but I measured about .026-.030" of clearance from the outside of the pushrod cup to the rocker body. I ran 5/16" pushrods before with no issues, but im worried that with the 3/8" ones im stepping up to I may have issues. What is the acceptable clearance in this area? Also, if I do encounter rubbing, do I have to go and grind these pretty rocker arms down so everything fits? I am going to get the pushrods custom made, so im wondering if there is a way I could order a reduced cup thickness to avoid this? Just looking for some suggestions and opinions on this! Thanks! 
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Re: Acceptable rocker arm to pushrod clearance
[Re: MR_P_BODY]
#1206970
03/31/12 05:06 PM
03/31/12 05:06 PM
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Joined: Apr 2009
Posts: 3,415
Toronto
mshred
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OP
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Quote:
Quote:
Hey guys, I should have been clearer sorry. DOH
This clearance that I am measuring is at max lift, so the rocker is at its maximum arc. The range of motion throughout the lift range is perfectly fine, it was at this max lift that I was concerned about since thats when it gets close.
Also, the pushrod and valvegear is that best compromise right now for max lift and best geometry. Both intakes and exhaust are set so that 2-3 threads are sticking out the top of the adjuster screw
You dont care whats sticking out the top... you need
to know how much is on the underside of the rocker...
but you might be grinding on the rockers
EDIT
also are you talking the cup of the PR is close...
if so just grind the OD of the cup down
The spec from Hughes for bottom protrusion underside the rockers is .450" which equals about 2-3 threads sticking out of the adjuster screw give or take a little
Yes, I am talking about the OD of the cup, that is all...at max lift the clearance spec is as I mentioned in my original post. So I am just wondering, based on the fact that im not sure what gauge my checking pushrod is (made it out of a junk one my dad found at work last year) if the 3/8" pushrod cup will hit since I only had 5/16" pushrods last year
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Re: Acceptable rocker arm to pushrod clearance
[Re: MR_P_BODY]
#1206972
03/31/12 06:16 PM
03/31/12 06:16 PM
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Joined: Apr 2009
Posts: 3,415
Toronto
mshred
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Quote:
The spec from Hughes for bottom protrusion underside the rockers is .450" which equals about 2-3 threads sticking out of the adjuster screw give or take a little
Yes, I am talking about the OD of the cup, that is all...at max lift the clearance spec is as I mentioned in my original post. So I am just wondering, based on the fact that im not sure what gauge my checking pushrod is (made it out of a junk one my dad found at work last year) if the 3/8" pushrod cup will hit since I only had 5/16" pushrods last year
The cup OD will be the same size so you dont have
to worry about that if you have clearance now
How do you figure that? The cups the pushrod manufacturer's use are all the same o.d. regardless of the pushrod thickness? Is it only the cup size that dictates this o.d.?
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Re: Acceptable rocker arm to pushrod clearance
[Re: mshred]
#1206973
03/31/12 06:20 PM
03/31/12 06:20 PM
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Joined: Jun 2003
Posts: 52,972
Romeo MI
MR_P_BODY
Master
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Master
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Posts: 52,972
Romeo MI
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Quote:
Quote:
The spec from Hughes for bottom protrusion underside the rockers is .450" which equals about 2-3 threads sticking out of the adjuster screw give or take a little
Yes, I am talking about the OD of the cup, that is all...at max lift the clearance spec is as I mentioned in my original post. So I am just wondering, based on the fact that im not sure what gauge my checking pushrod is (made it out of a junk one my dad found at work last year) if the 3/8" pushrod cup will hit since I only had 5/16" pushrods last year
The cup OD will be the same size so you dont have
to worry about that if you have clearance now
How do you figure that? The cups the pushrod manufacturer's use are all the same o.d. regardless of the pushrod thickness? Is it only the cup size that dictates this o.d.?
Some of the manufactures have some what different
cup OD's but not by much... the stem thats pushed
into the PR is different diameters
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Re: Acceptable rocker arm to pushrod clearance
[Re: MR_P_BODY]
#1206974
03/31/12 06:33 PM
03/31/12 06:33 PM
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Joined: Apr 2009
Posts: 3,415
Toronto
mshred
OP
master
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OP
master
Joined: Apr 2009
Posts: 3,415
Toronto
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Quote:
Quote:
Quote:
The spec from Hughes for bottom protrusion underside the rockers is .450" which equals about 2-3 threads sticking out of the adjuster screw give or take a little
Yes, I am talking about the OD of the cup, that is all...at max lift the clearance spec is as I mentioned in my original post. So I am just wondering, based on the fact that im not sure what gauge my checking pushrod is (made it out of a junk one my dad found at work last year) if the 3/8" pushrod cup will hit since I only had 5/16" pushrods last year
The cup OD will be the same size so you dont have
to worry about that if you have clearance now
How do you figure that? The cups the pushrod manufacturer's use are all the same o.d. regardless of the pushrod thickness? Is it only the cup size that dictates this o.d.?
Some of the manufactures have some what different
cup OD's but not by much... the stem thats pushed
into the PR is different diameters
Ahah! good point Mike
Hopefully I will be fine then
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Sounds like another turn out on the adjuster & a shorter pushrod... Pay attention to any oil passage but also check all clearances through a full motion of the valve..