Rebuild suggestions needed

dcriss · 12:00 PM

Hi Guys,

I need some input and recommendations on my current engine rebuild project. First let me give to some history and my thoughts. The engine is a 1980 911sc 3.0 that had the usual “broken exhaust head bolts” (5 of them to be exact). The engine has +90,000 mile on it, so I plan to do a complete rebuild. It is out of a very clean, good looking wide-body. Until the broken head bolt issue, it ran great, no leaks and pretty good mileage (27mpg on the e-way) ….CIS of course. The engine seems to be in pretty good shape and even has Mahle Cylinders.

Anyway, I’m not looking’ to get ridiculous, but I would like a few more ponies without breaking the bank (like you’ve never heard that before, right). I would also like to keep as much of my mileage as I can.

So anyway, here are my thoughts:

3.0SC Case (of course) 3.0L (70.4mm) Crank. Either keep the CIS Piston or perhaps use 95mm JE’s. As far as the cam goes, I was thinking of getting the Cams reground to 964 specs. Good Idea? Also, because I would like to keep as good a mileage as I can, I was thinking of keeping the CIS system (thus the 964 cam would not be too radical). Finally, I’m thinking SSI heat exchangers. (although, has anyone tried the 911 MAXFLO Header Muffler Kit with HEAT from FabSpeed? Is it worth that kinda money? http://fabspeed.com/911Carrera.html )

Please let me know your thoughts on what I am thinking and perhaps your thought on what you would do with this project instead.

Thanks

Oh ya, what about twin plugs?

kenikh · 09-18-2007, 12:57 PM

964 RS cam should be fun. I think this is about as far as you want to go with CIS.

BReyes · BReyes's Garage

Sounds like ok stuff to me (or break the bank with turbo) and worth it.

dcriss · 09-24-2007, 04:57 AM

Ya, I had thought about adding a Turbo, but not really in the budget right now.

dcriss · 09-24-2007, 05:05 AM

Here are a few photos:

cnavarro · 09-24-2007, 05:41 AM

How do your cylinders and pistons measure out? If the pistons are in good shape and the ring lands are within spec AND the bores are straight and have good cross hatch, maybe just re-ring them and reuse them. I personally think it's money better spent than buying 95mm JE Pistons, when for a little more money you could put on a set of bored and replated mahle cylinders with 98mm JE's.

964 cams would be a nice upgrade and friendly enough for the CIS.

Not too sure if twin-plugging would be all that worth it being you're in the midwest and have good pump 93 octane, which is more than sufficient for what you are doing. If you did go up to 98 or 100mm and ran more compression, then the twin plugging would definately be worth it.

I'd also consider replacing the rod bolts with ARP's while you are at it, along with the head studs which you already have to.

dcriss · 09-24-2007, 10:03 AM

Thanks Charles,

Yes, this pistons are in great shape, just the normal carbon on the domes. The cylinders are also in great shape very good cross hatch and straight bores. That all being considered, would it be that big a performance advantage to the 98mm JE's and bored cylinders over the current CIS Pistons and Cylinders (along with the 964 cam with either setup)? ... I'm all about saving the money and putting it in the right place.

As you suggested, I was planning on the ARP rod bolts and head studs.

What about the Exhaust? ....any thoughts there?

Thanks,

911 tweaks · 09-24-2007, 10:11 AM

here he goes... great questions... he is on the edge of the slippery slope... is he a lemming or does he have a clear objective... I dont know fans, sounds like the "while you are in there" bug has stung him...
my suggestion, if the p/c are fine, then , clean all up, measure the ring lands on the pistons for in spec. If all in spec, clean all up, new gasket set, new steel head studs, new arp or raceware rod bolts, forget everything else.

You can do a million things as you are suggesting, i.e. ssi for exhaust, sport muffler, 964 cams... save all of these ideas for building a spec motor or when and if yours ever blows up.

Just my 2 cents worth.
Bob

dcriss · 04:54 PM

LOL..... Ya perhaps you may be right Bob,

I do know for a fact that I'm going with the 964 cam though. I had the opportunity to drive 3.0L with this cam setup and ...WOW...what a difference.....it pulled all the way though the power band and throttle response was fantastic. Someone also recently pointed out to me that this was also one of Wayne's top picks for engine upgrades in his book. Since the motor is already apart, I may as well have at it. :P

....Then again, I could just polish the valve covers and make it look fast.....(wink)