john gill

Hello All
With regards to the oil valve in the head for the lifter oil control, I propose changing to the 944 type has anyone any information on the seat for the existing ball & valve , How is the seat removed ?

I notice that some of you have made this modification ,

How did you remove this seat in each head ?

Did you have to machine it out ?

as I notice it is not a serviceable area from the manual

TIA

heinrich

John why the change?

john gill

This is my experimental GT engine , it has been heavily track modified ,(heads high compression etc) & I am following the spec of the porsche race engines which is available in a pdf , format again mentioned in a thread in the last few days (I figured the factory new something )

heinrich

Will you please share the PDF?

GregBBRD

The 944 valve allow less oil to the cams and lifters. Since the 944 engines did not make as much torque, they figured that they would always be turning more rpm's, thus generating more oil pressure and flow. The reduction of oil flow to the overhead reduces the amount of oil running back to the crankcase, thus reducing potential windage. Also, at any given moment, there will be more oil in the oil pan, to feed the oil pick-up.

Almost all "race engines" reduce the amount of oil that gets to the overhead, since race engines very seldom idle for long periods of time.

Fabio421

So are you saying that it may cause problems in a street 928?

john gill

copy of link re 928 cup cars

Thanks to bill Ball who recently posted it

http://www.norcal928.org/928cup/

Cheburator

Do you need them if you are running a dry sump engine?

john gill

I am as I do not have a dry sump , but my thoughts are to stick to Porsche was doing without going the route of the dry sump ,

I wish someone would cough up some ideas on the ball seat & how to remove in the cylinder heads .

Cheburator

I hear you, but one of the cars built to the same specification as in the article by TTP suffered a catastrophic 2/6 failure two years ago. Thus I don't really think that these valves are a cure on their own... Get the engine dry sumped - it really does cure oil ingestion, consumption and 2/6 failure...

john gill

No not on their own , but in combination with , baffle , oil catch tank , windage plates , should all help , although this car will be part track , part road , every little bit helps , & wont have slicks .

Maybach_Man

hi John;
I am in the process of rebuilding my engine (and car!!!)and purchased the whole oil valve, ball spring and seat etc from dave R, i assumed that as he just supplied them and it was a readily available part it was an easy change...WRONG!!! i have tried several 'pullers' to no avail, so im now stripping the engine to see if i can press them out from under the head. it might be an idea to ring him and ask the question???

Geoff

john gill

yes the seat looks to be brass , I am glad that someone has had a go at removal , as I would think they look to be pressed in there to begin with , drilling out may be the only answer.
Looks that we both sourced from the same place ,I did send an email to them after purchase , but havent had a reply as yet , must follow up , was hoping that someone has been down this road before on the list , as it has been discussed before.

Maybach_Man

the seat i got was ally!!!!! if you want ill talk to jeannie or dave on monday about it???

Geoff

Mrmerlin

the only thing I can add is that we had a condition where the ball seat on a 89 GT had been forced up by the oil pressure as it was loose in the head this effectivly cut off the oil supply to the cams/ lifters and the cams seized in the head and thus the belt snapped.
If you remove the old seats then make sure they are loctited and staked into place, you might have to drill the top portion of the old seat to get it to be removable as it should be staked into place. Goodluck