Please help me figure out what I have here R/S engine ?

[pjv911]

I just bought a 1975 euro 911 which appears to be a euro carrera R/S.
Unfortunely at some time someone decided to convert it to a steel widebody car. Its been sitting outside for over a year uncovered and took on some rain water which entered cyl #6 and froze. This resulted in a cracked cylinder and head.
Today I removed the engine and tore it down. Aside from the #6 cylinder and #6 cyl head everything looks great. The previous owner said the engine has less than 500 miles used since a full rebuild. I can confirm this by the new pistons and cylinders. As well as the freshly built heads and fresh cut flywheel among many other things.
Anyways he said the engine has race cams. Well aside from saying he got them from performace products thats all the info he had. Oh yea the engine was built 4 years ago.

The heads are all part # 911.104.307.1R and dated in 1974. They have the factory cut threaded mfi injector holes on the intake ports so im guessing they are euro 2.7 r/s carrera heads. The casting # appers to be the same as the 2.4s heads but those would have earlier date codes.
The ports sizes are 36mm intake and 35mm exhaust. The valves are 45mm intake and 35mm exhaust. Can anyone confirm what heads these are ? And would a 2.4 s head make a good replacement once flycut for 90mm jugs ?

The MFI injection appears to be Carrera R/S as well. The injection pump is dated 3/73 and is part # 0408-126-019 . The stacks are part # 911.110.312.1r and the bore size is huge compared to my 72t stacks. The throttle bodys have no part #s that I can see but the bore diameter is 35.8mm or 36mm without the gasket crap and after a good cleaning.

The connecting rods are part # 911.103.105.OR . I believe these are the same rods used on all 2.4/2.7 engine but not sure.

The pistons are high dome hemi shaped and are most certainly standard replacement 90mm r/s types. Also as far as the jugs go are these the same ones used on the normal CIS engines ? Im aware of different height groups. Can I replace a bad r/s cylinder with a standard cis cylinder ? I have quite a few of these in the correct (6) height group.

The cams are a mystery to me. I have only taken down the one side of the engine so I have only 1 cam part # to offer. It is 901.105.110.1R . Of course they could be regrinds so that may not help. However the nose of the cam has 9.01 on the top and 168.0 on the bottom. The nose im reffering to is the part you see when you pull the timing chain cover off and look at the cam. The back side of the cam (front when installed) has a vaguely stamped S surrounded by a triangle that shaped kinda like a wankel rotor. Also the heel of the lobes are pretty close to flush with the camshaft casting(maybe .020") and the toe is nearly as high as the bearing surface(maybe .040" shorter). In short it doesnt appear theres much room to have more lift in the profile. To the eye the lobes are much more aggressive looking compared to a 1977 911s cam I had to compare it to.


Lastly acording to the red book the engine case appears to be a standard euro 2.7 case and not the desireable 911/83 case. It is a 911/81 and has a vin # 6361543. Is this anything special ?

I know this is a long post so I really do appreiciate anyone who will take the time to offer some help.

Im currently seeking a head and piston so I can reassemble this thing. So fast advise may aid my direction with this engine.


Kurt Williams

[real550A]

Kurt-
Your case with #6361543 and 911/81 is a ROW '76 911 engine
case.
The rest, including 019 pump might have been moved over from
a 911/83 at some point. Sorry I can't help with the cam #'s.

[YTNUKLR]

The only 2.7 MFI engine case is a 911/83 Mag. So, unfortunately that's not what yours is.

The crank and rods are the same for all 2.4/2.7 engines.

Pistons for the RS are 90mm Mahle forged, 8.5:1, sounds like that's what these are. Nikasil cylinders. If you have a Nikasil (slightly magnetic bore) cylinder in the correct height group (or all 6 cylinders are surfaced to the same height), and they are all in spec, go for it. The cylinders for the RS are the same as the CIS Nikasil 90mm Mahle cylinders.

The heads for the RS are 36/36 mm ports, corresponding date codes for the build date and a slight chamfer on the head for the larger 90mm pistons. Post a pic if you are not sure, sounds like that is what you have

That is a 911S / 2.7RS cam part number, the other one should have a "183" instead of "110". Remember these could have been reground to a different profile so you can only know if you run them on a cam tester

The MFI pump for the RS sounds correct--"019" part number.

I don't know what's wrong with the head you've got, post a pic... those heads are rather hard to find , I'd try to replace that one. If you replace it w/ a 2.4T head, you need to chamfer it for the larger cylinders, port it to 36/36mm. If you get a 2.7CIS head, you need to tap it for MFI injector and port to 36/36mm. For either head, you need to cc it, and make sure it matches the others, surface it so that the mating surface is the same height, and also you should flow test to make sure it moves the same amount of air as the rest of the heads.

best of luck
Scott

[pjv911]

Great post Scott. I found a 2.2/2.4 S head that I will have matched. Also found a piston. This board is great,

Kurt Williams

[M491Cabriolet]

Kurt,

Are these the cams you sold to me as original S (RS) cams a while back? I'm nowhere near ready to install these cams in my engine (being rebuilt) but I got curious and just opened the orange plastic wrap you sent them in today. I noted the strange (1965 Solex?) part number on the right cam. The left cam has the correct S number on it. What's up with this? If these are not the original S cams I paid you for, reground or mismatched, I'm gonna be really unhappy! Please advise.

[pjv911]

I did have those cams checked/measured and they are matched S cams. If I recall correctly that set you bought was from this above described engine. I had more than one set but I believe the set I sold you was used so those must be the ones described above. Also as far as I know the factory was using solex cams as cores for S grinds but its just something I remember and not a fact.

Kurt