Jim Morton

Mark:

As an FYI, new drivers side GT EX cam in pretty much unobtanium. Used ones too.

I think the whole concept here is to tap S3 cores and put them to use in the S4's.

Although this has all been an interesting continuation of past discussions, I think search should be our friend and let this thread now be:

Bill Ball

That explains why someone complained here recently that the pins he got, despite the correct S4 PN, would not fit. So, the only problem that remains is that the GTS pins must be turned down to the correct diameter.

Tom. M

talked to John today, and the place that did the cams for Threshie was Delta Cams. Their web site is
http://www.deltacam.com/ . Not much info there, but the contact information is there... If I remember correctly, Phil Threshie had them do some sort of plasma coating on the stock cams and then they were reground to whatever profile you needed.

mark kibort

Well, that answers that! maybe that collar can be made via a bolt on device. I bet the axial force is not that great. However, a simple flat surface that is not as complex as the outside thrust bearing surface, might just be doable with something Carl could make.

mk

ShawnSmith

> As an FYI, new drivers side GT EX cam in pretty much unobtanium. Used ones too.

I had also learned this as we shopped for exhaust cams for my 6.5L stroker. The supply of GT cams is essentially zero unless you happen to know someone who's willing to let you pull them out of a GT.

mark kibort

how about fitting new sprockets on my old Holbert cams? There was a guy that hounded me to fix mine for a month. He said they did a lot of work like this for industrial type cams and also 968 cams.
might be worth it. too bad my cams have lost teeth on the exhaust cam as well. 2 of them next to each other , so that sprocket is toast

docmirror

I did a pretty good search for GT exhaust cams after my misque. None, zip, nada. The best guess price I was quoted for making one from scratch was about $1600 mostly due to the gear sprocket on the cam. The S3 cam I have is a good match except of course for the journal.

I'm going to contact Delta and see what they want to get involved with. Carl of course offers a set, should one want to go that route. I'm also investigating the clamp style with a reduced machined yoke that it would fit in just to the left of the first lobe.

Vilhuer

That is problem in early S4 heads. Can't recall exact date when factory changed hole diameter in heads but it was fairly early in S4 production. Must have been done in '88 MY at latest. Exact info is in Jim's documents somewhere. This means there are two different versions of rubber plugs which can't be mixed together in same head, old or new setup. Later rubber and GTS metal versions are direct swap to later style S4 etc. heads.

Landseer

Here's a thread that contemplates specifically the subtopic of the pins.

https://rennlist.com/forums/928-foru...-recently.html

Bill Ball

I gather from re-reading BerNard94's posts there that the new pins are 3.5mm, 9mm long versus the old ones being 3mm and 4mm long, requiring the holder. The changeover was mid-year 87 (he provides engine numbers). So, my 89 should not have the rubber holders but should have the larger feed opening and pins.

Vilhuer

Your '89 and every other '87.5+ engine before '92 MY used 3.5/9mm rubber version from factory. Eventually they will start to leak like older 3.0/4mm version. Whenever valve cover is opened all five (not four as mentioned in other thread) should be changed to GTS version. This is only way to make sure they will not leak, ever.

IcemanG17

GT intake cams are out there.......but extremely limited and your gonna pay big bucks for them.....GT exhaust cams are pretty much NLA

Jim Morton

Bill:

FWIW, Dennis gave me some of the pins. You are welcome to check them out.

I plan to measure them and make something a little different out of aluminum and delrin. Personally, I do not like how the newer style pins have a spherical end the rest on the bearing surface of the cam cap. It's not a big deal, just bad form from a purist perspective.

Bill Ball

Thanks Errka and Jim for the follow-up. It is kind of odd that the factory either did not stick with the long cams, properly plug the oil feeds or just eliminate the rear journals altogether during the 8 years of production. These pins seem like an engineering afterthought. I'm sure there was at least one engineer who looked at these pins and said, "What the Hell is this?"

Vilhuer

I'm sure rubber version fails very rarely during first 10 years of use. One out of five will almost surely fail after 20-30 years. Maybe that was enough for design fault to go unnoticed until GTS years.