blown 944

I have found a company that will do a regrind up to 244 degrees @ .050 and .460 lift and may have a few less aggressive profiles available. This service is available at only $99. However this requires the base circle diameter to be reduced in order to add lift and duration. I am considering the best way to compensate for the differential.

At this point I'm considering; lash caps, sinking the valves (including stronger springs) potentially having the cam ground advanced and shaving some material off the cam tower.

I am waiting on info regarding how much material is removed off the base circle. I'm also awaiting info regarding modifying the lobe center slightly during the regrind.


Any input/experience is appreciated.

Tom M'Guinn

Sid, In an effort to redeem myself...if you reduce the base circle you need to be very careful not to starve the lifter by having the oil feed hole blocked by the side of the lifter bore. Shaving the mating surface might help address that...

blown 944

Tom, no worries.

I had thought of that initially regarding using lash caps hence the tower idea. I am not aware of the distance the lifter would be moved yet so that obviously would be part of the equation. I am going to take a look at the tower and see if the oil passage could be massaged. If it can, that opens up the possibility of using lash caps or possibly different retainers and longer springs or longer valves etc..

I'm sure this has been done many times over in some regard. I just havnt seen a lengthy writup

Tom M'Guinn

Yeah I have never done it but have heard of folks running small base circles and starving their lifters. Probably is some way around that, but you also have to think about cam timing if you shorten the tower. Seems like a lot of effort when well-ground cams are plentiful for this motor, no?

Scott H

Doesn't WebCam sell unground blanks for our cars for a reasonable price? I want to say <$200 for a core, would that extra material make it so you wouldn't have to grind down the base circles?

Van

How about solid lifters and longer valves. Then you don't care if the oil holes line up.

blown 944

Tom, im just trying to come up with an inexpensive option and to be able to do a custom grind.

Scott, that may be an option. (a great one)

Van, yeah that is certainly a consideration for some, but I'll have to pass on the solid lifter idea for a DD. The longer valve idea is still very viable though, but I'm still trying to see if it can be done with only modifications done via the cam and tower so the average guy could do it.

If the tower is easily manipulated and lash caps are readily available then this could be a great upgrade for less than $250 unless I'm missing something.

TurboTommy

Sid;
you mentioned a 460 lift. Is that intake or exhaust or both?
I think stock lift on the intake is already 474; so maybe it's the exhaust?
In any event, I bought a cam from Milledge; also with a slight decreasing of the base circle> fairly aggressive with the 2.7l head> intake 503, Exhaust 480
I had a conversation with him about exactly this topic. He said even with this increase in lift that the decreased diameter of the base circle is so little that this "slack" is made up by the hydraulic lifters, and there's no problem with oil holes lining up with the channel.

BC

99 dollars? Each cam?

blown 944

thank you Tommy for that information. I thought the lift was .434 on both but I was incorrect it is .470 on the exhaust. They are 223 degrees @ .050 from my research. My thought is that they (they machine shop) use this (.460) as a std baseline for hydralic camshafts. I imagine it could be higher lift . I will call him tomorrow.

If I can get one done for 99 bucks with a decent spec sheet then that would be nice....and if the follower will take up the slack then we are in business.

elargentino

All correct.

For the sake of ease of conversation, all these "475", "503" are simply SAE - the real numbers are 11 and 12MM, respectively.
Example - .503 x 25.4.....etc.

67King

Do not sink the valves. It will hurt flow, especially on teh exhaust.

blown 944

Thanks, I'd love to pick your brain regarding cam profiles for this engine. I'll pm you sometime if you don't mind?

67King

Sure, don't mind at all. May take a while to answer but I'll try to quickly.

67King

Sid I forgot to mention that i have used tips on valves before. RFF valvetrain but i assume it would work on bucket applications. Ill see if I can find them and post up a picture.