Acceptable rocker arm to pushrod clearance at max lift

Posted By: mshred

Acceptable rocker arm to pushrod clearance at max lift - 03/31/12 06:45 PM

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!

Posted By: HPMike

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 06:54 PM

Is it possible to post a pic?? I might be misreading the post, but it almost sounds like you have the adjsuter too far backed out of the rocker arm..

MB

Posted By: 1_WILD_RT

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 07:01 PM

Quote:

Is it possible to post a pic?? I might be misreading the post, but it almost sounds like you have the adjsuter too far backed out of the rocker arm..

MB

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..

Posted By: mshred

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 07:19 PM

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

Posted By: MR_P_BODY

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 08:54 PM

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

Posted By: mshred

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 09:06 PM

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

Posted By: MR_P_BODY

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 09:28 PM

The cup OD will be the same size so you dont have
to worry about that if you have clearance now

Posted By: mshred

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 10:16 PM

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.?

Posted By: MR_P_BODY

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 10:20 PM

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

Posted By: mshred

Re: Acceptable rocker arm to pushrod clearance - 03/31/12 10:33 PM

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