chancecasey

I have to strongly second a vote for A. I don't know how I got talked into non-A.

KirkF

Anyone know if:

You can you use 993 pistons & cylinders and then machine the '89 heads with the right groove? Or would 993 heads be required as well? (would 993 heads be ok?)

There seems to be alot more 993 parts available right now than 964.

I did a few searches but I couldn't find a definite answer. PET shows the parts numbers changed.

Kirk
p.s. I am going to beat this topic to death until I figure out the right solution, but its a slow month on rennlist anyways.

JasonAndreas

If you have the cylinder head surface machined on a lathe the TSB (02081994) says to use the regular steel sealing rings (964-104-115-20). Has anyone come up with a way to fix the leak that doesn't require new cylinders and pistons?

chancecasey

Yeah, Ted at German Precision. De-chamfers the cylinder and resurfaces (no significant change) the heads. Increases the CR by an insignificant fraction of a percent. We'll see how the results are when I get them back and get back on the road. But I still vote for A. After talking to most of the shops who claim a fix for this he sounded the most knowledgeable. And, if he's good enough for Anderson/Woods, he's good enough for me.

KirkF

The TSB is interesting. I found a set of 1995 993 P/Cs. But I am not sure if I could use them, and then just bolt them up with my existing heads after this machining.

For anyone who is interested here is the TSB about the machining the heads.

Kirk

JasonAndreas

I would be pissed/heartbroken if I spent all that time rebuilding the engine only to have the heads start leaking because I didn't fix the problem when I had everything already apart. Especially if it only costs ~$500USD.


Works for me too. When you get everything back together and running please (if you don't mind) post a message with a cost breakdown for everything.

chancecasey

Yep, keeping all my receipts and will post the results.

P.S. - Mine head/cyl junctions weren't "leaking" - it was a "weep" that NEVER dripped. And they looked just like these pictures. I was going to leave well enough along, but I just HAD to drink beer at Ted's and somehow my wallet gets a lot lighter when that happens - like letting him cut me a deal on his fix. Sad thing is I brought the beer.

Indycam

Hiya JasonAndreas
In the stock early motors you have a metal to metal seal between the head and cylinder .
In the later motors you have a metal to metal to metal to metal seal ?
If one metal to metal seal is not good , why / how is two metal to metal seals better ?
Is it that the clamping pressure is on a smaller area ?

KirkF

Chance,

I see you removed your head studs? Which tool did you use? Are you replacing them with raceware studs?

Kirk

Gary C2 UK

Hi all,

I believe that a 993 conrod is thinner at 20mm than a 964 one at 22mm so no you cannot use the 993 piston without modify you existing rods or replacing with 993.

The barrels are a straight replacement and have the later gaskets but to use them with your existing pistons may case more problems than before due to the unmatched wear characteristics.

Hope this helps? It was something I had considered too!!

Gary

chancecasey

I'm undecided on head studs. I'm either going to get the 993 ones, which are relatively cheap and should do the job just fine for a stock 964 (my dilivars were fine after 100K), or I will get upgraded ones.

If I'm going to blow the extra money on "better" ones, I'll use the ones from Henry at Supertec. Call him and ask for a deal . I'm convinced they're as good or better than the ARP/Raceware, and, this is the cool part, the head side threads are finer pitch than all the others, which are all the same coarse pitch, so you can get a more accurate torque value on assembly. The appealing part about this is that by getting more even torque I may help mitigate this head/cyl issue. Or it could just be a big waste of money, who knows. The finer threads is the ONLY benefit - 993s are more than adequate for a stock setup.

I removed my head studs by using the head nut (the funny looking 12pt one) and a hex nut I pulled off from somewhere else on the engine and did the "double nut" technique. You'll need at least 3 foot of leverage whatever you do. I used a 3 foot, 3/4" square steel tube (my "bar") and put it over one of the forks of a doube-open wrench attached to the hex nut. Be sure to use this along with another wrench to really make the "double nut" tight first, otherwise you'll just turn both nuts and not turn the stud. I also almost screwed myself once by the 12point nut not being threaded on the stud enough and it pulled through (both nuts need to have equal amounts of stud thread), and again by almost snapping one of the studs after about 5 or 10 very stubborn turns.

Red rooster

There are companies around who machine the heads/cyls to flat , cut grooves for seal rings in the cyls and off you go !
Got to be the cheapest option if wear is OK.

Good luck

Geoff

Bill Verburg

The 993 piston is not compatible w/ the 964 rod

darth

Kirk

If you want another source, Jack at G-Tek 416 755-7884. I think he recommends a fly cut/gasket solution.

Hope this helps
Bill
90C2

Christer

FYI, when my engine was built 9M said that Raceware fasteners were not necessary even with the increased power. I have replaced though the whole valvetrain with titanium items as well as using Carillo rods....