Doing SC top end at 45k, go to euro pistons?

[fpvga]

Hi there. My relatively good-shape low-mileage 82 SC has at least two broken head studs, one appears to be very low down. So thinking that I will do a top end rebuild — compression and leak down are good but there are a few misc oil leaks from the cylinders and early broken studs. “While I am in there”, I was thinking of going to euro pistons and getting the extra power with the higher compression. I’m having a shop do it — expense is not the primary concern but obviously don’t want to throw money away. I haven’t read a lot here about the many top end rebuilds also doing this change — is there a reason not to?

Thank you for any thoughts!

W

[darrin]

you might also want to consider looking for/picking up a used set of carrera cylinders, get them bored to 98mm, matched with higher comp pistons and add some displacement while you're at it -- that would build out as a 3.2l short stroke engine (the carrera achieved its 3.2l displacement through a longer stroke crank)

[Bill Douglas]

A 964 or similar cam.

It seems a shame to get new pistons as the chances are yours will be fine.

[fpvga]

Yeah this is sort of the thing...do I just do a refurb of what’s there, considering it will be in good shape, or so I start down the slippery slope of cams, displacement, etc...can’t decide.

[Bill Douglas]

Yes, LOL tough call.

Another thing to consider. While it's out it would be a good time to get SSIs fitted up. It requires a few new oil lines too, so while it's on an engine stand would be a nice time to do this.

SSIs give it a noticeable power/liveliness increase.

[fpvga]

Amusingly, the whole reason it’s in the shop and we noticed the broken head studs was that I was getting a broken exhaust stud fixed to do an SSI install. The usual .

[Harpo]

3.2ss with 964 cams and SSI would be pretty awesome

David

[coomo]

I Have excellent used set of euro cylinders and pistons.Vapor cleaned.Which we was going to use before going 3.2.ss
SC Cylinders

[Nick Triesch]

I just had a top end at 160k. Was very expensive! You car has very low miles. Why not just have the studs replaced ? And any other little things fixed? Unless you are independently wealthy. Then it does not matter.

[darrin]

Originally Posted by Nick Triesch

I just had a top end at 160k. Was very expensive! You car has very low miles. Why not just have the studs replaced ? And any other little things fixed? Unless you are independently wealthy. Then it does not matter.

good point -- how many miles before you need to add a quart of oil? You could well have 100k + miles left on your valve guides, as SCs don't generally suffer from the premature valve guide wear that my 86 suffered (had top end redone when my oil consumption dipped below 600 miles per quart)

[AndrewCologne]

Originally Posted by Harpo

3.2ss with 964 cams and SSI would be pretty awesome

But not for a US 3.0 from '82 as it comes with small ports where these will be a bottleneck where all enhancements mentioned above will noticably suffer from. Except SSIs - these will give better sound but ... honestly not more than approx. 5 hp if the cam timings are not retarded to 0.9-1.1 mm as well.

(http://www.elfertreff.de/showthread.php?t=26670 ... see graphs further below ... its in german and I will publish an english version in the future but for now you can use an online translator)

Best invest of money for performance enhancement of a 81-83 US sc is:
- SSIs but as mentioned with timings of the cames set to the Euro SC specs 0.9-1.1
- a recurved dizzy which matches in its ignition curve with the Euro Dizzy (81-83) incl. chnanging to Euro dizzy vacuum unit from 81-83!
- If no recurving is possible, go for the 123-ignition Distributor (the one for the 6 wire CDI!!) as you can fully program it to match the Euro SC 81-83 gnition timing curve

These above wil even give a more noticable performance bump compared to just changing the pistons to Euro 9.8:1 ones

[bpu699]

I’ll be the contrarian. Replace the head studs and leave everything else alone, assuming it’s all fine. You will spend a small fortune upgrading the motor, when it sounds like it isn’t necessary. You will be into it for $20-25 k before you know it...

[Bob Kontak]

Originally Posted by bpu699

I’ll be the contrarian. Replace the head studs and leave everything else alone, assuming it’s all fine. You will spend a small fortune upgrading the motor, when it sounds like it isn’t necessary. You will be into it for $20-25 k before you know it...

+1

The later US SC engines are perfectly fine when running properly.

Our dear passed friend Grady Clay said don't do nuttin' you don't have to - or something similar.

I say get the studs fixed properly with the later steel ones which are relatively inexpensive, focus on replacing seals and boots for the CIS, set cam timing with a bias for lower end grunt which is as simple as dialing it in at one end of the overlap TDC lift tolerance or the other (I don't recall).

[fpvga]

That’s sage advice. Agree I think that’s what I’ll do — pretty easy to spend a fortune and then end up with a motor that doesn’t run well around town, doesn’t perform like a 3.6 you could have gotten for the price, and wastes a bunch of perfectly fine parts. I think I’ll just do the studs and a basic top end job, and get the thing on the road. But I’ll still dream about something crazy for the future after I get bored of the 3.0

[Trackrash]

Agreed. Unless you are wanting a huge HP increase, just do the studs. SC motors with SSIs can be a sweet running combination.

Follow Andrew's post #11 and you will be happy. That is as long as your cylinders are in good shape, which it sounds like.

[Baz]

I agree with the "keep it stock" crowd here. The 3 liter is a fantastic engine. Just make sure your CIS is tuned properly, valves adjusted, etc, and enjoy!

[LUFTKUL]

Supertec’s 3.1 kit is reasonable:

https://forums.pelicanparts.com/porsche-911-used-parts-sale-wanted/1030224-remanufactured-911sc-3-1l-pistons-cylinders.html

[Nick Triesch]

If your motor is low mileage and had good leak down and did not use a lot of oil , I would just replace studs and not send out the heads. But that is just me. Enjoy your car!!

[Flojo]

Originally Posted by Nick Triesch

I just had a top end at 160k. Was very expensive! You car has very low miles. Why not just have the studs replaced ? And any other little things fixed? Unless you are independently wealthy. Then it does not matter.

THIS

3.2 top-ends with tuning are up to 20k... if you had that money you'd just do it (and not ask)

Fix the studs and get back on the road. Spring is near.

[fpvga]

Learning a lot here, thank you. All the euro ignition timing suggestions are great. So not a stupid idea to simply replace the studs but leave the cylinders, valve seats, guides, etc all untouched?