964 Intake Distributor

[Steam Driver]

I have been looking into these since I am planning on using a plastic 964 intake plenum on my SC?EFI conversion.

Exactly when did the change from aluminum intake runners to plastic occur? According to what I can glean from the parts manual the aluminum runners and related parts that connect them were for '92 and prior, and the plastic items were from '93 up. However a friend of mine has a '94 964 engine that has the aluminum intake runners.

There are several other differences in these parts. The AL runner model (on the aforementioned 964 engine) has the TB "built into" the connecting tubes, whereas the later plastic one uses a separate TB (which has a bolt pattern that will mate with the SC TB, BTW). Also, and this was really curious, the unit I looked at has two flapper valves in the lower tube, rather than one in the center of the unit I have.

None of this is really relevant to what I am doing, but I am curious as to exactly when and maybe why the changes were made.

[nickd]

The plastic intake was on everything beginning in early 1991. Anecdotal, the change seems to coincide with the revised head gasket seal cylinders/heads and cars that had the later version of the rear shock towers. All changed for early ‘91.

Not sure what your friend has, but the TB is external for both the plastic and alu intakes. Perhaps you’re thinking of the 993 varioram (which isn’t exactly an internal TB)?

[Steam Driver]

Thanks for the info, but I have to disagree on the TB part of it. If you look in the parts book for both parts (AL vs Plastic) you will see that their is no TB shown with the center plastic section with the AL runners. His engine definitely isn’t Vario-Ram.

[nickd]

I misunderstood your description. Yes, the alu TB and center housing are a single piece, which connects between the left and right manifolds. The plastic intake TB and center housing are two pieces.

[al lkosmal]

Steam,
This seems like a cool project. I know this has been done before, so maybe the parts are readily available for the conversion, but......What will you use to adapt the 911SC 2-bolt intake mounting pattern to the 3-bolt, 3.6 intake mounting pattern?

regards,
al

[Steam Driver]

I am not using the three-bolt pieces that mount on the heads. I have made AL adapters that bolt on the SC heads; they also have the injector port. Then the plastic 964 intake plenum goes on that via the normal rubber sleeves w/clamps. I can provide pictures of this stuff but I don’t have access to them at this time.