Hi all, I have finally summoned up the courage to tear down my 3.0SC engine after living with a diagnosis of broken head studs for too long. I am pleased to report that dropping the engine was reasonably straightforward. However, on starting to pull the engine to pieces I have a couple of questions.

What I have done so far: removed the CIS and inlet manifold in a one-er; unattached the fan shroud; removed all the tin around the engine, removed the muffler; opened the timing case covers, and the cam covers.

Questions:
1) how do you get the chain off the cam sprocket? I have removed one of the tensioners, but I still can't see a master link that would allow me to break the chain. Also, as in an ideal world I'd like to take the cam housing and heads off in a one-er, are there any cam timing marks that can be seen from the sprocket? will this become obvious once I get the chains off?

2) my intention (if possible) would be to remove the cam housing, heads, and exhaust manifold / heat exchangers from each side in one go. other than a couple of bolts holding the centre side of the exchangers to the crank case; is my supposition correct?

3) finally, the exhaust studs are the ones that are broken. Am I right in thinking the inlet ones don't suffer from this problem, and thus don't need changing? If so, what should I use for the replacement exhaust studs?

Cheers
Matt
1980 3.0 SC

 

Matt,
When the tensioners and the cam sprocket nuts have been removed, the chain will simply slip off with the sprocket. If the chains in your motor are factory virgin, they will not have master links; they will be endless. If you intend to use new chains *without* splitting the cases, then you will have to use a master link joined chain.

It is possible to remove the cam towers and heads in one unit, then disassemble on the bench. Many pro mechanics do it that way. Take the H.E.'s off first, though. Personally, I found it easier to dismantle them on the engine; I'm not a pro (nor do I play one on TV).
Regardless of how you re & re the cam towers, you will still have to retime the cams very carefully apon re-assembly

What studs are broken? You mention head studs, and then exhaust studs. What are we talking about here? Exhaust studs are the ones in the heads that fasten the H.E.'s. If they are broken off flush, they need to be carefully drilled out with a jig, and then, restore the threads as required.

If the head studs are broken, typically in the 3.0 motor, it will be the lower (Dilavar) studs. The upper head studs are regular steel, and seldom break. If they are not broken leave them alone. But do replace *all* lower, Dilavar, studs, broken or not. Use the same steel studs as the uppers (P# 911 101 172 00).

 

Spot on - I meant the head studs on the exhaust side. The chains look to be in good shape, so I've no intention of changing them - right decision?

Does the sprocket have a keyway? ie. any way of marking up the sprocket for the cam timing? The engine is sweet apart from the broken studs, so my intention (if possible) would be to not r and r the heads/cam tower assembly, but just stick them back on with new heads. Is this feasable?
cheers
Matt

 

No need to replace the chains, *if* the tensioners still have the ability to take up any elongation in the chains.

Yes, the cam sprockets are on a keyway. But if you understand how the cams are linked to those sprockets (using the plate with all the adjustment holes), you will see how they must be properly retimed. You cannot just 'mark' anything. After the cams are 'rough' timed (there is a number '930' or dot stamped on the cam end for this purpose), they must then be precisely set using a dial gauge.

The factory manuals and Bentley manuals detail the procedure that *must* be followed, or engine destruction is likely.

 

Matt, FWIW, I have pictures of my engine work at my website. It will perhaps help you understand the cam timing issue and general engine assembly procedures... Lou

http://basketcasemotorsports.bravehost.com/

 

I can't believe no one has told you to get Wayne's Engine Rebuild Book which can be found over on the Pelican Parts board!

 

Could be because there are quite a few people on this board who have built Porsche engines, long before Mr. Dempsey arrived on the scene with his books.

Many of those people are professional (do it for a living) rebuilders and mechanics, and generously share their knowledge here.....without trying to sell us *anything*.

 

being in edinburgh, UK, also means considerable delays and price increases in ordering stuff from the USA. cheers for all your help, will report on progress next week,
Matt

 

Righto, Matt.
Do try to get a copy of the Bentley SC shop manual, if you have any doubts.