2.0 liter 67 911 normal rebuild Suggestions

blau911 · 04-15-2003, 09:57 AM

Wayne,
I have a 1967 911 2.0 engine that has been sitting in my garage for a few months. It is in perfect working condition and despite being rebuilt back in 1981, it has only 35k miles on the rebuild and leaks no oil. I pulled it from my car only because I was looking for more power and ended up finding a freshly rebuilt 2.4E engine rebuilt to S specs for a good price. Now that the 2.0 engine has been sitting there a few months, I am considering going back to the 2.0 liter engine and rebuilding it so that the car remains matching numbers.
I am not looking for any crazy hp set-up, just something close to or slightly above the original 2.0S 160-170hp with 7,200 redline and the great feel of the high reving cams when I want to get a Sunday morning buzz on the way to brunch.
I understand that the differences between the 911 normal and 911S engines were higher piston crowns, larger valves and S cams. Therefore, my first thought was to try to buy a set of 2.0 S pistons and S cams in order to come up with the original S spec engine and then have the heads ported and polished to get a little more hp. However, I am finding out that 2.0 S pistons are impossible to find unless I went with racing pistons. These would be more than I need though and certainly much more than I want to spend.
That being said, wouldn't my cheapest and most cost effective way simply be to have my original heads removed and have them flycut to raise compression to S spec (the normal 911 CR was 9.0:1 versus the 911S 9.8:1), and have the heads ported and polished increasing the valve sizes? I am told that a good porting and polishing job would give me at least 20-25 hp across the board, and the flycut heads would raise compression at least to 9:5.1 which would be close enough. I have a guy in Ft Lauderdale (Jarvis Tech) who did the heads on the 2.4 engine I bought, and he could do the work.
Also, by focusing on the heads only, I would theoretically only be looking at top end rebuild work which would save time and $$$.
Your thought s would be greatly appreciated since it would probably save me time and money?

PS
By the way, I will be buying your book on rebuilding 911's when I get back from Easter vacation (it's too late to order it and get it by this Friday).

blau911 · 04-16-2003, 01:10 PM

Bump....
I was hoping to get some feedback...

TimT · 04-16-2003, 01:33 PM

Flycutting heads is the last resort to increase cr... if you need the mating surfaces of the heads refinished. the machinist should take off as little as possible... The reason for this is that you will be moving the center of the cams closer to the crank... this screws up the cam drive geometry, the chain tensioners could then possibly run out of travel and this could play havoc with the valve train.

JE can make you a piston to any spec you want....

Which 2.0 heads do you have? the E&T have smaller valves than the S heads.. so even if you port and polish, the valves will be the restriction.. If you have S heads then you could open the ports to 906 specs and give away some bottom end , but then get more top end power..

Polish the exhaust ports.. smooth the intakes and leave some roughness to them...the roughness supposedly keeps the fuel from attaching to the ports...

blau911 · 04-16-2003, 03:08 PM

Hi Tim,
I am pretty sure I have E heads since Porsche didn't start making the T model until 68 and my engine case numbers show 66/67.
As you mention though, the T and E both had smalled valves so having E heads doesn;t seem to help me much.
When I consider the option of having my heads machined to increase valve sizes to S spec in addition to the porting and polishing, not to mention the potential problem created by flycutting the heads, perhaps I am better off going with S spec JE pistons and trying to find a set of 2.0 S heads.
I know that the 2.2S and 2.4S heads were interchangable. However, I have to believe that 2.0 liter S heads will be as elusive as the S pistons. Any thoughts on where I could find them or if there is another alternative?

TimT · 12:14 PM

2.0S heads are hard to come by, the 2.2 and 2.4 heads are probably more desirable because of the shape of the combustion chamber... The problem is the 2.2 heads use a crush ring gasket. the 2.0 uses a flat gasket.

You could have new (larger) valves installed in the E heads. Things start to get expensive now.. You have a number of options all depending on your budget..

blau911 · 04-28-2003, 08:51 AM

Wayne,
Could you offer any advice?

Wayne 962 · Wayne 962's Garage

Hmm, off the top of my head, I don't think the 2.2 and 2.4 heads are that interchangeable. In general, the 2.4/2.7 heads are very similar.

Honestly, I doubt you would be happy going from a 2.4S to a 2.0S with it's very peaky performance. It's just not the same. The 2.0 heads are not shaped evenly, and tend to not flow the combustion across the heads as well as 2.2 and higher. I would honestly keep the original engine stock and in a corner of your garage. Matching nubmers are nice, but so is a 2.4 when you're driving. I don't think you'll be happy with the end result...

-Wayne