2.5ss in swb
 

I have a 1966 911 with a 901/01 2.0 engine, the engine leaks a fair amount of oil and i am getting ready to pull it to do a reseal/rebuild. The car is a decent car and i plan on having the body put back to stock as it has been flared, and it will be painted an original color. Here is my question I want to make it a faster car and i thought of building a 2.5 short stroke while I have it out, I dont want to hurt the value of the car but the car is not a complete original car anyways. It has webbers and after market seats etc. Should i leave it stock or should i build the motor?

I plan to build a 2.5ss for my 67 as well, although I don't have the original 2.0l to start with. In my case I figure I can't hurt the value because I don't have a matching numbers car. Your situation is a bit different because it sounds like you have the correct engine. If I were you, I would keep the 2.0 stock and build a 2.5 from another engine. If you ever decide to sell the car, simply pull out the 2.5 and stick the original 2.0 back in and you have a nice original car again.

I want to put something together to one get rid of my multiple oil leaks and two a little more power, I got a price today from a very reliable porsche engine builder of about 10000 to 15000 to build a bullet proof 2.5, I guess there is a fair amount of machining involved to change the rod bearings to better quality ones and use custom rods. It will take me a yr to save that kind of cash so im not sure what i am going to do.

First you need to decide how fast you want to spin it, then go from there. Stay under 7.2k rpm and the stock bottom end with uprated bolts is just fine. There is nothing wrong with a mod S cam.

You said 2.5, long stroke or short? Do a LS and you won't have to touch your case spiggots (ie bore them) but it will be a few bucks for P&Cs. Bore the spigots and you can use (reuse) 2.7 cylinders which are pretty common. Maybe $1250 for a replate if you get real cheap crap :D and hone to size, $900 for JEs.

Rebuild a set of 36 mm heads is $900 for the machine work from Anchor. Toss in Ti retainers for a mod S cam.

Bottom line... It's expensive. Stay under 7.5k rpm and the really nice 36 mm stock ports will feed a 2.8/2.9 on an S cam.

Now, if you want nutty...:D:D...A stock 36 mm head 2.5 on a 906 grind is a 'tiny hair bit' soft compared to 38 mm ports, on top cause its getting tight breathing at 8.5k but you wont notice :D. BTW, most poo poo the 'old' 906 grind but it has really, really gentle ramps and will control 46/40 valves 8.5k on stock rate springs. Saves wear and friction both of which add longevity for a street killer! Toss in R&P rods, like $1400 iirc, and $600 for Ti wrist pins (saves 30g where it does the most good) along with x-drill the 66 mm crank, bigger oil pump, case mods and yee har!

Find someone who has an engine you think you want and grab a ride. That will decide real quick. Make sure you hit traffic!

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2.5 ss, I was under the impression that 2.7 heads and cyl, and pistons on the 2.0 bottom will give me this? I was told this was a cheap way to go.

Thanks for this thread .........

Assumed your engine is the original one and with that aluminum it would be stable enough to overbore the spigots to accept 90mm P/Cs.

But with respect to originality i would rather go for a set of 86mm Biral/JE P/Cs which would be slip fit so overboring would not be necessary and the case remained unmodded, capable of being backdated again. It would make sense also to use a set of 2,2 / 2,4L heads because of better combustion chamber shape and valve sizes. This would give you some 2.3L. Bottom end remains original. Original heads, PCs cleaned, conserved and shelfed.
Small reasonable mod to the case IMHO would be the insertion of piston squirters and oil bypass while being in there.

Still slip fit would be additionally going for a 70,4mm crank (and rods) adding up to a 2,45L, a really nice combo.

If original, your engine should have 06 cams, so "E" spec., these are reasonable or might be upgraded to a mod Solex and the port sizes i would keep conservative.

If you are aiming just for "a little more power" the 2.3L would more than satisfy.