Just starting rocker geometry checks

2056 build, new AA 2L heads with 44 36 mm valves. Webcam 086 cam .423" lift both I and E valves, using Porsche 911 OEM swivel feet. Rockers were machined relieved properly.

Following published procedures and reading many geometry searches, Initial checks with an adjustable push rod set at 27.1 cm I get on both number 1 and #2 cylinders

Intake .444" lift, and when checked at half lift, the alignment is perfect. No additional adjustment seems to be needed.

Exhaust .423 lift and at half lift again valve stem and rocker adjuster are parallel.

So QUESTION is the .444" lift is right at the 5% max tolerance. Should I adjust the push rod to lower the lift closer into the 5% range, if so how much. OR are we good as is.

Thanks

jjs3rd914

Read this thread first then get back to us with your questions.

http://www.914world.com/bbs2/index.php?sho...229571&st=0

You need to cut them down assuming you purchased the chromoloy push rods. When I did this the machinist, and I use that word lightly, cut one wrong. Ended up buying another set. Your rocker arms will end up very close to hitting your valve cover.

delete

From the post Mark Henry suggested we are to refer. Yes I have read many times and am following the instructions. But It's still unclear about how far over the 5% on the intake. So if I read this right (reproduced from the link)

[i]**NOTE It is sometimes possible to net MORE valve lift on the intake valves than the cam card calls for, if this happens take advantage of it within the 5% range, if you end up with more than this for net lift start questioning the cam card for accuracy, don’t allow the intake side of things to go over 5% more lift than the card specifies. If this happens you may actually imbalance the port flow of the heads as it is very odd to ever get the full net lift from the exhaust side of the engine due to the rocker arm ratio and rocker/head design***

Then it appears I must REDUCE the intake lift to something less than the 5% max by adjusting the push rod. But the question remains by how much? My 5% max is 0.444" the cam card says it should be 0.423" so "taking advantage" of the added lift I should target say 0.435 for example????? but not exceed say .440"

Thanks

jjs3rd914

If you are within the 5% then you are good. So .444 is within that. You should be able to take that same PR length into each intake and the other 3 cylinders should be similar, but not a guarantee.

Intake rockers have a slightly higher lift ratio. The cam card from webcam assumes the same rockers ratio.
I don't have the exact numbers handy but you should be good as long as intake lift is the same on all cylinders.
If the lift is too much then you might be measuring incorrectly and it may be the valve is not closing too

Thanks to all, I did use modeling clay and have plenty of room even with the higher intake lift. So I suppose one should be happy to get a little more than we thought.

Again thanks

jjs3rd914