rocker arms keep failing

mk-Zero · **Posted:** Wed May 11, 2011 11:40 am

supaninja wrote:

Here's how I did mine, btw no shims were harmed in the making of my motor

actual 911 adjusters(i'm type 4 so I had to find some 1.7l rockers and then machine .060" off the bottom face for clearance). There are a lot of crap swivel adjusters out there.
chromoly cut to length pushrods
adjustable PR(the exact same kind as the ones I'm running, PR's can have shapped ends then it would comprimise all my measurements).
Started in a ballpark with the adjustable PR, for type 4's thats 26.1cm
Started on the intakes and found the warm fuzz PR length that got me within +/- 5% of the cam's spec'd lift(tried to get as much as I could) while having a perfectly inline swivel adjuster/valve stem alignment at exactly half lift.
I did that for all the intakes, and did an average then determined my ideal intake PR length
Then did the same for the ex valves, turns out my exhaust valse are 1mm shorter then my intakes and the PR's need to be 1mm shorter as well.

Also I think its fitting to mention with chromoly PR's you want zero valve lash. the stock PR's are Al and need .006" lash for expansion. Chromoly PR's expand at the same rate as the cylinders/head studs so it all jives nicely.

Jake wrote that because type 4's last over 100,000 miles and you don't want to wear your guides out before your next rebuild. Valve geometery is a very critical step of engine building, and thats why I spent 2 full days on that to quadruple check everything and make sure it is as close to perfect as I can get. Lots of math and measuring involved.

Brian- I'm kinda surprised your not super anal about valve train geometery, your super anal about every other part in the motor.

There's a difference between being anal and wasting time.

There's only basicsally two things you can change, the PR length and shims, you change those two things till you get the geometry I described as close as possible and then presto, you're done. People blow it waaay out of porportion as far as I'm concerned, it really is quite simple...

fartfignewtons · **Posted:** Wed May 11, 2011 12:12 pm

mk-Zero wrote:

supaninja wrote:

Here's how I did mine, btw no shims were harmed in the making of my motor

actual 911 adjusters(i'm type 4 so I had to find some 1.7l rockers and then machine .060" off the bottom face for clearance). There are a lot of crap swivel adjusters out there.
chromoly cut to length pushrods
adjustable PR(the exact same kind as the ones I'm running, PR's can have shapped ends then it would comprimise all my measurements).
Started in a ballpark with the adjustable PR, for type 4's thats 26.1cm
Started on the intakes and found the warm fuzz PR length that got me within +/- 5% of the cam's spec'd lift(tried to get as much as I could) while having a perfectly inline swivel adjuster/valve stem alignment at exactly half lift.
I did that for all the intakes, and did an average then determined my ideal intake PR length
Then did the same for the ex valves, turns out my exhaust valse are 1mm shorter then my intakes and the PR's need to be 1mm shorter as well.

Also I think its fitting to mention with chromoly PR's you want zero valve lash. the stock PR's are Al and need .006" lash for expansion. Chromoly PR's expand at the same rate as the cylinders/head studs so it all jives nicely.

Jake wrote that because type 4's last over 100,000 miles and you don't want to wear your guides out before your next rebuild. Valve geometery is a very critical step of engine building, and thats why I spent 2 full days on that to quadruple check everything and make sure it is as close to perfect as I can get. Lots of math and measuring involved.

Brian- I'm kinda surprised your not super anal about valve train geometery, your super anal about every other part in the motor.

There's a difference between being anal and wasting time.

There's only basicsally two things you can change, the PR length and shims, you change those two things till you get the geometry I described as close as possible and then presto, you're done. People blow it waaay out of porportion as far as I'm concerned, it really is quite simple...

Amen on setting geometery! :hillbilly:

Can I buy it in spiral bound form for my office?

supaninja · **Posted:** Wed May 11, 2011 12:23 pm

To me it's not a waste of time at all, but reassurance since its not going to change unless there is a failure somewhere in the valvetrain.

Donnie/doug- if you guys want, I got some time off school next week(or the weekend after this weekend), if you get some uncut PR's and 911 adjusters I can swing by and help set your geometry.

PawpawsBug · **Posted:** Wed May 11, 2011 12:57 pm

supaninja wrote:

To me it's not a waste of time at all, but reassurance since its not going to change unless there is a failure somewhere in the valvetrain.

Donnie/doug- if you guys want, I got some time off school next week(or the weekend after this weekend), if you get some uncut PR's and 911 adjusters I can swing by and help set your geometry.

holy shit......those 911 adjusters are $20 each

beetleluvr · **Posted:** Wed May 11, 2011 1:01 pm

Deez67VW wrote:

supaninja wrote:

To me it's not a waste of time at all, but reassurance since its not going to change unless there is a failure somewhere in the valvetrain.

Donnie/doug- if you guys want, I got some time off school next week(or the weekend after this weekend), if you get some uncut PR's and 911 adjusters I can swing by and help set your geometry.

holy shit......those 911 adjusters are $20 each

When you play with the big boys (BIG engine), you have to pay the big bucks :help:

PawpawsBug · **Posted:** Wed May 11, 2011 1:06 pm

beetleluvr wrote:

Deez67VW wrote:

supaninja wrote:

To me it's not a waste of time at all, but reassurance since its not going to change unless there is a failure somewhere in the valvetrain.

Donnie/doug- if you guys want, I got some time off school next week(or the weekend after this weekend), if you get some uncut PR's and 911 adjusters I can swing by and help set your geometry.

holy shit......those 911 adjusters are $20 each

When you play with the big boys (BIG engine), you have to pay the big bucks :help:

i hear ya.

supaninja · **Posted:** Wed May 11, 2011 1:14 pm

Deez67VW wrote:

supaninja wrote:

To me it's not a waste of time at all, but reassurance since its not going to change unless there is a failure somewhere in the valvetrain.

Donnie/doug- if you guys want, I got some time off school next week(or the weekend after this weekend), if you get some uncut PR's and 911 adjusters I can swing by and help set your geometry.

holy shit......those 911 adjusters are $20 each

they are the best plus the p-word is never cheap http://www.aircooledtechnology.com/stor ... 287&page=1

Boom · **Posted:** Wed May 11, 2011 1:31 pm

Buy the ones Meredith has for sale it's cheaper.

mk-Zero · **Posted:** Wed May 11, 2011 1:36 pm

Another option is to get rid of those things all together and get some performance rockers that have a "foot" on the valve side and the adjuster on the PR side. I'm running over .55" of lift at the valve with those in my daily driver and mine *never* need adjusting. They are rock solid.

tommiebsmith · **Posted:** Wed May 11, 2011 2:34 pm

don't forget the lash caps with that style..

as of now with cam and engine width 1.1's and 1.25's should fine with stock length PR's
with possibly pedistal shims.

OH and don't forget that Meridiths will net you 585 Lift..

rocker arms keep failing

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