Cam Shaft details

erwin928 · 01-09-2015, 05:24 AM

On 16v Porsche 928s is there any difference between the cam shafts of automatic transmission cars and stick shift cars? Thank you

stepson · 01-09-2015, 12:23 PM

No.

Danglerb · 01-09-2015, 01:25 PM

Wow, easy answer, in the 928 no difference based on transmission, mostly I think due to the limited production nature of the 928 having one more type of engine made no sense.

riber.bentsen · riber.bentsen's Garage

Since this thread ended so soon, I have another cam-related question:

Can I mount the high-lift/duration cams from my '86 Euro in my '78 4.5 to give it some more 'oomph'? Both have 16 valves of course.

harborman · harborman's Garage

Always check valve clearance when going to a different cam.

Danglerb · 01-10-2015, 04:48 AM

Link to my thread from 5 years ago when I had a set of 80 cams welded to hot rod spec, All of my Base Circles are Reduced , cams still in boxes, but NOT FOR LONG.

Here is a chart of the stock cams I found at http://www.elgincams.com/c-por4.html

GRIND NO.....SEAT DURATION.... CAM LIFT ...LASH... APPLICATION

STOCK
173/174 246 241 .396 .350 I HYD. E HYD 1980-2 MODEL.

STOCK
203/204 242 235 .435 .395 I HYD. E HYD 1983-84 US “S”

STOCK
155/156 254 246 .435 .395 I HYD. E HYD 1978-9 MODEL

STOCK
187/188 268 255 .472 .432 I HYD. E HYD 1980-83 EUROPEAN “S”

STOCK
211/212 255 247 .472 .432 I HYD. E HYD 1984-86 EUROPEAN “S”

Starting with a 4.5L motor I don't think you would see much gain swapping in Euro S vs 78/79, maybe almost nothing without the larger intake system, which would lose torque on the low end.

stepson · 01-10-2015, 08:07 PM

Are the top of the pistons notched in a 4.5? I honestly don't know if they are, but i would think that not being notched would rule out your hi-lift cam swap.

Opelotus · Opelotus's Garage

Quote:

Originally Posted by stepson

Are the top of the pistons notched in a 4.5? I honestly don't know if they are, but i would think that not being notched would rule out your hi-lift cam swap.

The 4.5L M28/03 engine I disassembled has notched pistons, I think they all do to some degree.

erwin928 · 01-30-2015, 05:51 PM

Looking for used 1980-82 4.5L US left cam (distributor drive) for under $500
Had found one on Ebay. Arrived wrapped in cardboard and tape. Cam sprocket cracked and camshaft end snapped off. :-(

erwin928 · 01-30-2015, 06:06 PM

Can 83-84 camshafts be install in an 80-82 4.5L? Is the process just taking out the original cams and installing the 83-84 or is there shimming involved or it just wouldn't work?

Danglerb · 02-01-2015, 09:27 PM

80-82 cams are the worst, lowest performance, hence the cheapest used, somebody is bound to have one they would sell for $100 or so. Guy on Rennlist has a motor to sell, I'll point him at this thread.

Danglerb · 02-01-2015, 09:32 PM

This is his thread, might as well point you at it.
81 Engine block - Rennlist Discussion Forums

erwin928 · 02-05-2015, 04:36 PM

"80-82 cams are the worst, lowest performance, hence the cheapest used, somebody is bound to have one they would sell for $100 or so. Guy on Rennlist has a motor to sell, I'll point him at this thread."
Can 78-79 or 83-84 cams be used instead of 80-82?
Do you just swap cam shafts or the complete cam towers?
very thankful to those who answer

Danglerb · 02-05-2015, 06:47 PM

You would need to swap both cams, many do like the 78/79 or even Euro, and good to keep the same old lifters with a used cam so swap complete cam towers and don't move lifters around.

stepson · 02-06-2015, 11:59 AM

Quote:

Originally Posted by Danglerb

You would need to swap both cams, many do like the 78/79 or even Euro, and good to keep the same old lifters with a used cam so swap complete cam towers and don't move lifters around.

You are saying to keep the lifters that came with the cam towers with the same cam towers, correct?
If you change cams, keep the lifters that were in the engine.
If you change cam towers, change to the lifters that match the cam tower.
This is what I've always heard, so I'm just clarifying for the masses and posterity.

Danglerb · 02-06-2015, 06:14 PM

Short version, keep the cam with the same tower and lifters without removing lifter or not putting them back in same spot.

What I've been told is that a cam creates a wear pattern on each lob and lifter, so keep used cam lobs with the same used lifters. New cam, new lifters. Old cam and you don't have old lifters or dumped them in a bag without numbering, new lifters.

Cam tower is a safe often convenient way to ship a cam as well.

NOTE obviously many don't follow the above practices and we almost never see failures directly related to cam lobes and lifters, but many of those engines are never run for 10k miles post fix.

stepson · 02-06-2015, 09:08 PM

It makes sense to me that the cam will create a wear pattern on each lobe and lifter.

But what if you have to replace a cam? My thinking is the cam tower surely will also have some sort of wear pattern with the lifters and to leave the lifters with the cam tower? New lifters are going to create new wear patterns anyway. Why not at least use the lifters that "fit" the cam tower?

But what if the cam tower gets broken and is replaced with a used cam tower? Following my thoughts above, I would replace the cam tower and use the lifters from that replacement cam tower if they were available (while keeping the lifters in their appropriate spots)

Is my thinking here flawed?

stepson · 02-06-2015, 09:10 PM

Sorry for the hijack, but it seems to me to be at least mildly appropriate to the original thread intent.

erwin928 · 02-08-2015, 06:50 AM

Good topic. I'm interested. Does that mean if you change cams and you don't have the old lifters you should get new lifters which will require a breaking period when installing in old cam tower?

erwin928 · 02-08-2015, 03:54 PM

Another cam related question. Anyone try the offset keys they sell for the cam sprocket? Did you advance or retard the timing? And lastly Advance would be clockwise, am i right?
Thanks for everyones input