Rob Edwards

Early set of S4 valve covers, casting date = 86, part # is 928 104 461 07, which is in between the -06 listed for 86 in PET, and -08 listed for '87. The curious thing is that there are 3 small holes on each cover. Anyone with an early '87 got any clue what these are for?

FWIW, pretty sure these are painted. my blast cabinet with girly man compressor is able (albeit slowly) to take these to bare metal. Not a chance on the 90, 91 and 93 covers I've had stripped.

soupcan

I have the original set off my late 87 same 3 holes/part number. They had the original powder coating also.

AO

This is from the early '87 I had.

Rob Edwards

Compared to AO's early '87 production motor, the pattern for the plug wire brackets is different on the 1987 S4 engine brochure photo, I wonder whether those holes were for some stillborn plug wire brackets?


EDIT: Probably shoulda looked more closely before hitting 'post', I think I disagree with myself. Nevermind.....

PorKen

Something (not used) on the 1-4 side at the back, instead?

Wiring loom holder?

BPG_Austin

I've recently run across 2 sets of these covers, bboth with model year 86 in the castings. My old flip wing '87 had the intake without the center ribs (I've seen VERY few intakes without them) but did not have the 3 holes up front in the cam covers. I'm guessing very very few early S4's had these castings. The holes in both sets I've seen were never tapped from the factory. It was a stillborn mount for something that was changed very early on. Porsche must have used the original batch of castings on the very 1st S4's.

edit: Rob, look at the other 2 spark plug clip bracket holes not being used. I bet they aren't tapped. Leads me to believe you were right about the different wire routing?

FWIW, I've also seen castings with the 3 holes cast into the ribbing, but not drilled from the outside. Perhaps another change before deleting them altogether.

KenRudd

So, are they functionally equivalent/interchangeable with later S4 covers? Any advantages or disadvantages?

Rob Edwards

Totally interchangeable across all 87-95 motors. I have a set of these early covers on my stroker, which has 91GT heads. No pluses or minuses AFAIK.

KenRudd

Thanks!

So what are the differences between the S3 covers and the S4 covers? I though I had seen a write up on that at some point, but search was no help, and I don't have a set of S3's off the engine that I can hold side by side.

Rob Edwards

I've never seen the underside of an S3 cover, but here's a comparo of the exteriors:

BPG_Austin

Ken, the S3 and S4 cam covers aren't interchangeable. They have different mating surfaces to the heads. Its very noticeable when you have the 2 side by side.

KenRudd

Thanks! Even from Rob's picture, it's clear there are differences in the mounting holes as well. An additional bolt right in the center under the "S"

BC

They don't look too different, but they are very different with how they attach.

danglerb

Was this part also used on the 944 S2?

KenRudd

I appreciate it. I can now sell my surplus -07's and be comfortable I am not misrepresenting them.