964 heads on 911 3,2?

[Nürburgring]

Is it possible to use std/modified 964 cyl. heads and camhouses on an older 3,2 litre engine? Whats different on those engines?

[Bill Verburg]

no, the thru bolt spacing was enlarged, each bolt was moved radially outward from it's bore ctr.

[Walt Fricke]

Bill

What about 964 (or 993) cam carriers? Will they bolt onto earlier heads?

What about post 3.2 chain housings? Can you retrofit the "tensionerless" system?

Walt Fricke

[Bill Verburg]

What about 964 (or 993) cam carriers? Will they bolt onto earlier heads?

Dunno, never heard of any one doing it, bore centers are the same, some of the other external pieces are swapable?????

What about post 3.2 chain housings? Can you retrofit the "tensionerless" system?

Dunno here either. the 964/993 have hyd. tensioners of a diffrent design, WAG is probably?????

[ChrisBennet]

I've seen a 964 cam housing casting number on an '88 or '89 Carrera. The hardware on a 964 cam housing is different than an earlier cam housing. The most obvious difference is that the 964 valve covers are held on with 6mm studs and the earlier housings use 8mm studs. The oil feed fitting is different as well.
-Chris

[Walt Fricke]

Well, the 964 valve covers have holes in them in the same places the earlier covers do, just smaller diameter. Not much of a problem, and I've seen earlier motors with these covers (and their nice rubber O-ring type gaskets). (Me: whadayuhdoin with a 964 engine in this class? Huh? The valve covers! Oh, we just put those on - the engine is based on a sandcast case and is a 2.8. And it was.)

My suspicion is that since Porsche doesn't change things like stud spacing often (and then only to accomodate things like larger spigots), and the cylinder center to center distance holds constant, the studs holding the cam carrier to the heads are in the same place and are the same size because there would be no particular reason to move them around.

As to the chain housing, Porsche added one stud and some bushing dowels at the same time or about the time they went from the 6 stud to the 11 stud exhaust valve cover. So I'd guess that the 964 and newer chain housings might bolt on.

I'm less sure how much trouble it would be to convert to the spring loaded chain ramp system with or without the internal oil line (and this might be the only reason to want to use these chain housings).

What I really might care about is the revised rocker shaft system where the shaft is just bolted at each end to the cam carrier. That sure would be nice for top end work and for removing a source of grime producing oil seeps. Did that come with the 993s? But would cam carrier compatibility with the pre-964 heads still prevail?

Walt Fricke

[Bill Verburg]

Did that come with the 993s? But would cam carrier compatibility with the pre-964 heads still prevail?

It did and the 964 and 993 cam towers are certainly interchangeable, there was also a change in the oil supply for the cams and lifters

there was a discussion here w/ no resolution.

again a WAG if you don't want the hyd. lifters and go w/ the mech. adjusted versions, maybe

[Walt Fricke]

Thanks, Bill

I've seen the diagram on that other thread in various places in the past and knew the general path for oil to the hydraulic rockers (which I would not want, but that's easy to fix - make them solid). I didn't know about the grooved cam journal.

I notice that these cam carriers are held to the heads by bolts, not studs, but that should not be too great a challenge if the holes and the locating pin are still in the same old places. Getting oil to the rocker shafts could be done by external lines if a guy didn't want to use cams based on 993 cores. Being pressure oiled (rather than spray through two holes) might improve rocker shaft and bushing longevity.

The real attraction for me for a race motor is the speed with which the 993 style rockers can be removed and reinstalled. That's a significant time drain with the pinch bolt system (which leads sometimes to foul language when done with the engine in the car). The bolt-on system would make lifters using the old cap end system for lash adjustment feasible for us Joe Sixpack racers who don't have a bunch of mechanics at our disposal.

But I just bought a set of 3.2 cam carriers for the 2.8 I am (eventually) going to assemble, so I'm not apt to be looking to experiment soon.

I am unrepentant for diverting this discussion, since the original question was answered quickly: 964 heads won't work with a 930 case. However, I would offer this observation: I think you could use 3.2 or earlier heads on a 964 case. I've seen 2.7 heads used on a 930 case despite the difference in head stud spacing. Of course it was expensive and required not only machining but also welding so the head washers and nuts had something better than a fin to bear against in one location.

Walt Fricke

[Bill Verburg]

yes, certainly heads thru '89 3.2 are interchangeable w/ some caveats re head gaskets.

and yes the 993 rockers are easily changed out, I had my valve covers off yesterday.
This is what you see



With headers on the other one you don't even need to drop the exhaust.

[KobaltBlau]

so, following walt's lead, would the old shimmed rockers work with 993 heads, or did the 993RSR use a shim lash arrangement? (reference materials not handy )

[Bill Verburg]

The RSRs did have the shim adjusted valves

[KobaltBlau]

Cool, I thought I remembered that. Thanks Bill, and nice picture!

[Tyson Schmidt]

Originally posted by ChrisBennet
I've seen a 964 cam housing casting number on an '88 or '89 Carrera. The hardware on a 964 cam housing is different than an earlier cam housing. The most obvious difference is that the 964 valve covers are held on with 6mm studs and the earlier housings use 8mm studs. The oil feed fitting is different as well.
-Chris

What you saw is from a 964 Turbo. Those cam towers came on the 3.3 Turbo that came in the '91 and '92 Turbo.

It would probably be possible to adapt the plumbing so the case could feed the cam towers via the chain housings so you you could use all 964 or 993 hardware on a 3.2 case.

You'd just have to run a line from the case to the chain housing, and thread some sort of fitting into the chain housing to accept it.

[strokher racing]

Those are 91 turbo cam towers. Here is a pic of mine off my 91.

Eric

[ChrisBennet]

Originally posted by Tyson Schmidt
What you saw is from a 964 Turbo. Those cam towers came on the 3.3 Turbo that came in the '91 and '92 Turbo.

It would probably be possible to adapt the plumbing so the case could feed the cam towers via the chain housings so you you could use all 964 or 993 hardware on a 3.2 case.

You'd just have to run a line from the case to the chain housing, and thread some sort of fitting into the chain housing to accept it.

No this was/is my friends '88 or '89 Carrera cab. I'm refering to the (casting) number that you see between the valve covers.
The casting number started with "964".
AFIK, his motor his stock. I've never seen this on another Carrera.
-Chris

[Bill Verburg]

The '89 up 3.3 liter M64/50 used the 964 part # for the cam towers

and they also used the 964 chain housings, the right side was the same as the 964, the left has a different part #

[Carrera3.5L]

Originally posted by ChrisBennet
No this was/is my friends '88 or '89 Carrera cab. I'm refering to the (casting) number that you see between the valve covers.
The casting number started with "964".
AFIK, his motor his stock. I've never seen this on another Carrera.
-Chris

Don't worry Chris, you're not going crazy. I've seen it on my motor and other late 3.2L motors as well.



Ralph

[ChrisBennet]

Thanks Ralph, I was beginning to think I was having another Senior Moment.
-Chris