Need some valvetrain geometry help!!
First off, here is what I have:
Magnum 360 block with stroked crank.
Lunati Roller Cam with .357 / .367 lobe lift (.571 / .587 valve lift with 1.6 rockers)
Harland Sharp 1.6 Roller Rockers NON ADJUSTABLE
Mopar cast R/T heads with 2.02/1.65 valves stock length
Stock Pushrods
Hughes 1110 Springs with correct retainers.
None of this is assembled.
The rockers were mounted on these r/t heads with the stock length valves, a stock cam and stock pushrods. The contact patch on the valve stem were perfect, equal distances from center.
I am installing this cam into this engine now that I have the 408 rotating assembly. I have not mocked any of this up yet to see how it turns. Will the pistons need flycut with that .587 lift?
Now, to the big business
. I am worried about the valve train geometry. I have not measured the base circle, but a quick call to Lunati gave me an answer with: "Yes the base circle is much smaller than stock to gain that much lift". He also told me that due to the angle of the pushrod to the rocker arm, the lift at the valve would actually be somewhat less than the figure obtained from lobe lift x rocker ratio. I also gave Harland Sharp a call to see what options I had with the non adjustable rockers. They said customers have, in the past, both milled the fulcrum bases down, and shimmed them up to get the right geometry.
I have read that at exactly midlift, I should see that the valve side half of the rocker arm should be at or as close to 90 degrees to the valve stem as possible.
I am sure I can easily obtain that 90 degrees with this smaller base circle/higher lift cam by getting longer pushrods. I am afraid, however, that with this lift I will be pulling the contact patch on the valve stem much too far inside towards the rocker pedestal.
So then I feel like +0.100 stem valves need to be installed (with the correct shim kit for the correct IH). This may or may not require custom pushrods. This may or may not set the rocker correct at 90 degrees for mid lift.
I may have to shim/mill the rocker bases. In any one of the options.
With the longer valve stems, I will be able to write off the retainer to guide/seal clearance issues (however my machinist said he only charges $30 to mill down seal seats)
What have you guys done in the past with these lifts, issues? Why I ask before jumping in to tackle this my self is for these reasons: I do not mind buying what I need to do the job as long as its done right. However, I hate purchasing parts then finding out they do not work and I can not return them. Say I bought pushrods, that ultimately didn't not get my contact patch correct, so I bought longer valves, but now my pushrods are wrong. Or I milled the rocker bases, etc...
What I am thinking is to get two check/test vlave springs, two adjustable pushrods and somehow find some cheap 0.100 lash caps for the valve stems and start testing, measuring. Is there an easier way? Are there any tried and true setups that can be recommended to work?
I feel that where the contact patch is now, with the stock cam, pushrods and the Harland roller 1.6 rockers is perfect. The contact patch is perfectly centered on the stem of the valve. The midlift, furthest point of contact on the stem from the rocker pedestal, will never change on these particular valves no matter what cam I go with , due to the location of the valve and the length of the rocker arm. I want to say that no matter what I do, with what ever parts are replaced, the contact point will always be moved back towards the rocker pedestal.
Maybe I need re-schooled on the proper geometry at different lift points. Or maybe it doesn't matter what the angle is at certain lifts, as long as the contact patch is centered.
First off, here is what I have:
Magnum 360 block with stroked crank.
Lunati Roller Cam with .357 / .367 lobe lift (.571 / .587 valve lift with 1.6 rockers)
Harland Sharp 1.6 Roller Rockers NON ADJUSTABLE
Mopar cast R/T heads with 2.02/1.65 valves stock length
Stock Pushrods
Hughes 1110 Springs with correct retainers.
None of this is assembled.
The rockers were mounted on these r/t heads with the stock length valves, a stock cam and stock pushrods. The contact patch on the valve stem were perfect, equal distances from center.
I am installing this cam into this engine now that I have the 408 rotating assembly. I have not mocked any of this up yet to see how it turns. Will the pistons need flycut with that .587 lift?
Now, to the big business
. I am worried about the valve train geometry. I have not measured the base circle, but a quick call to Lunati gave me an answer with: "Yes the base circle is much smaller than stock to gain that much lift". He also told me that due to the angle of the pushrod to the rocker arm, the lift at the valve would actually be somewhat less than the figure obtained from lobe lift x rocker ratio. I also gave Harland Sharp a call to see what options I had with the non adjustable rockers. They said customers have, in the past, both milled the fulcrum bases down, and shimmed them up to get the right geometry.I have read that at exactly midlift, I should see that the valve side half of the rocker arm should be at or as close to 90 degrees to the valve stem as possible.
I am sure I can easily obtain that 90 degrees with this smaller base circle/higher lift cam by getting longer pushrods. I am afraid, however, that with this lift I will be pulling the contact patch on the valve stem much too far inside towards the rocker pedestal.
So then I feel like +0.100 stem valves need to be installed (with the correct shim kit for the correct IH). This may or may not require custom pushrods. This may or may not set the rocker correct at 90 degrees for mid lift.
I may have to shim/mill the rocker bases. In any one of the options.
With the longer valve stems, I will be able to write off the retainer to guide/seal clearance issues (however my machinist said he only charges $30 to mill down seal seats)
What have you guys done in the past with these lifts, issues? Why I ask before jumping in to tackle this my self is for these reasons: I do not mind buying what I need to do the job as long as its done right. However, I hate purchasing parts then finding out they do not work and I can not return them. Say I bought pushrods, that ultimately didn't not get my contact patch correct, so I bought longer valves, but now my pushrods are wrong. Or I milled the rocker bases, etc...
What I am thinking is to get two check/test vlave springs, two adjustable pushrods and somehow find some cheap 0.100 lash caps for the valve stems and start testing, measuring. Is there an easier way? Are there any tried and true setups that can be recommended to work?
I feel that where the contact patch is now, with the stock cam, pushrods and the Harland roller 1.6 rockers is perfect. The contact patch is perfectly centered on the stem of the valve. The midlift, furthest point of contact on the stem from the rocker pedestal, will never change on these particular valves no matter what cam I go with , due to the location of the valve and the length of the rocker arm. I want to say that no matter what I do, with what ever parts are replaced, the contact point will always be moved back towards the rocker pedestal.
Maybe I need re-schooled on the proper geometry at different lift points. Or maybe it doesn't matter what the angle is at certain lifts, as long as the contact patch is centered.