Were having problems with my buddies 500 indy motor. Since we installed Harland rockers we seem to have lost some oil pressure. When its hot its only making 40-50 @ 6800 rpm. Ive modified the oil feed pipes to te indy heads and fitted size 60 NOS jets but dont know how much restriction I can run to these rockers. Its got a high vol oil pump fitted and I just cant figure out where were losing the pressure! Its a fairly fresh motor and we always had good pressure until we switched to the harlands. Any ideas people?

You must be getting a TON of oil up in heads and valve gear ... have you tried viewing this as the engine is running ?

Sounds like maybe there is too much clearance between the rockers..
Were these shimmed properly, and then rechecked after torqueing down the shaft..

Just my $0.00..

Your having the typical over oiling problem when using true roller rockers like Harland Sharps, T&D and so on, not bushed rockers,on a single shaft. Try restricting it down some more, are you using two restrictor jets, one in each head or one in the T block going to both heads? One is probally better than two

I didnt fit them my buddy did so not sure if they need shimming? Tbh I wasnt aware they'd need to be shimmed I thought they would be just bolt on and go! I fitted two NOS jets one in each pipe as we had to try find a solution quickly! Pressure did increase but not as much as we need! isnt the golden rule 10psi per 1000rpm? Do I need to shim these rockers or just downsize the NOS jets more?

Bump
I would like to know the best way on this subject too. Oil restriction that is.

I have a problem with restricting the oil that much
to each head when using a single shaft... it takes so
long for the oil to fill the tube and finally make
it to the push rod cup/tip which could cause a push
rod tip issue... I would rather have some pressure in
the shaft and restrict the side play and maybe even
use a simple seal on each side of the rocker to hold
more in there.... would be a whole nother game if you
were push rod oiling.... then I could see a .015
orifice in each push rod... I have .030 in each push
rod and thats more than plenty... JMO

NOT ONLY a push rod issue .... you could also TOAST valve springs.

MOST of the cooling that VSs get is from oil. But then again ....tooo much oil up-there costs HP to drive the pump THEN there is the HP loss with the crank and rods driving-through all that excess drain-back oil.

I just put on a set of HS also I was just in the garage priming the oil I have a .069 jet in each line and that is still WAY to much oil up top and I have the side clearence set at .012 so I will have to change jets

Cheers everyone I think Ill try going a little lower on the jet sizes to see if we can get the pressure back up and maybe see if I can shim them out a bit to add restriction. Can you get a shim kit for these rockers or will I just have to find some that fit? I wont get to be with the car for a couple more weeks til we get back to the track so I'll just have to wait and see how it goes I guess. I really dont wanna toast his top end so I'll just have to keep an eye on things as we go!