pipingken1

So you mean its going to be expensive..

Can you have the standard cams reground to RS spec?

Steve Weiner-Rennsport Systems

Yes but,..........
There are two ways to do that; regrind the cams and reduce the base circle or hardweld the lobes to add material. Both methods have several drawbacks. The former affects lifter travel and the latter affects rocker arm durability.

I'm not a fan of either procedure for many reasons which is why I always install new billet cams. In the long run, you get a more reliable engine and honestly, that's really what its all about.

ReinerFink

Mike J - I think the idea is "if you have to replace it, then why not make it better". This is what I am thinking of for the heads/valves. I don't have anything totally firm there yet, but since I am not doing any crazy ITBs or Motec+MAP I don't need full custom headwork. For VRAM, I never drive under 4k rpm anyhow ;-) No real hp goal (not going to bother with dyno) just want to make it better than original and have it go for +200k before the next top end rebuild.

I'm open to suggestions for the head work given that I already have RS cams + all new rockers but will be keeping everything above in the intake stack stock.

NP993 - may yet split the case. Depends on how the project is proceeding and what the condition of cams, rockers, pistons and cylinders is. Definitely will replace the through bolt O-rings even if I don't split the case (they can be done one at a time).

Ntmatter - I shudder to think of what the whole cost is. Don't want to add it all up. If I did, then I would have to honestly think about just purchasing an entire used vehicle instead. The tranny parts alone are $6500... I have been pack-ratting stuff, I have a RS flywheel from when DM were still the coin of the realm, and the Drexler diff was acquired more than 1 year ago. Seems to soften the blow when you spread it across may years of accumulating parts for the day when you know your rebuild will arrive.

-reiner

pipingken1

Reiner, sorry I did steal your thread a bit, sounds like squirreling things away softens the cost a bit.

Steve, thanks for all the great input, and it sound like keeping Mr Porsche rich is the safe way to go with the cams.

If anybody has 'squirrelled away a set of RS cams and no longer needs them let me know.

pipingken1

Okay I was looking on PET to get the right part numbers and they list the seats as an insert. I had missed this. Do you machine the old ones out and push in the new or modify the existing standard seat?

pipingken1

Does anybody know?

ReinerFink

Im looking at valve options -- seems to be a few choices:

1. Factory RS (both have Na cooling) but are $$
2. Intervalves - lots less $ but both hollow
3. TRW - seems their quality has gone downhill, and these should be avoided

Perhaps I could split the cost and get the Factory RS intake valves and the Intervalve exhaust?

In either case I need new larger RS seats.

-reiner

ReinerFink

From my read of PET:

RS intake valve seat: 964 104 332 85
RS exhaust valve seat: 964 104 335 85

PET calls them "valve seat ring"

-reiner

Mike J

Out of curiosity, what is the Sunset price for the RS valve set? Be interesting to see what they are going for now.

Not sure about how the machining is done with the seats, but I do know there are a least two important areas on the heads where the quality of the machine shop really counts. Those are the seats/valve interface and the fit and honing of the valve guides to fit the valves.

I assume on your heads that the ceramic liner is in good shape as well? I seem to remember that that liner cannot be repaired, but not sure about the current state of the technology.

Cheers,

Mike

pipingken1

I have a VRAM which has 43.5mm exhaust valves so I was considering leaving the hollow valves and existing seats rather than replacing with the Na filled ones.

Open to opinions on this.

ReinerFink

Mike - I checked my source and they are crazy expensive compared to the intervalve options.

Also, the cost of the machine work to put the larger RS seats means that this is out of the budget.

So, I think using the intervalve VRAM intake and exhaust valves and have the existing seats ground is where I am headed.

-reiner

C4S993

Courtesy of:
http://www.pcarworkshop.com/images/e...1590geolab.pdf

pipingken1

How expensive was the head work quote? I saw the Excellence mag article and Steven had $2500 in his budget tabulation but not sure if that was just the machine work or valves included.

ReinerFink

I think its just under 2k for R&R + machining. If you need the larger RS seats, you can add ~%50 more.

However the real cost is the valves -- for factor Na cooled (which for a street/track motor is I think the right choice) the cost is well over $200 / valve for both intake and exhaust.

If you are building a pure race motor, then the intervalve RS sized vales are lighter and should allow you to rev higher, but won't dissipate heat as well.

-reiner

ReinerFink

Mike J / C4S993 :

Thanks for the TSB reminder. I own all of the books for 93-97. So I though I would go back and read them for giggles. I came across a good one:

TSB 9701 1505: Tightening Camshaft Drive Gear

Mike - Appears you are hosting it

http://www.pcarworkshop.com/images/e...0197geolab.pdf

Turns out there is a newer part starting in 1996 for the washer that goes between the cam sprocket and bolt that can help keep your timing correct. I just added two of those to my cart since I have a March '95 build car.

-reiner