Rattle and a surprise on an SC

[Marwil]

Rough running after a spirited Coffee Run in July. I thought it was #6 as it had a distinct rattle and miss evident with the stethescope. Started with #1 - 90% leak down...WTF? All others inlcuding #6 were 5% or less.
So - possible culprits for #6 are, loose rocker shaft, discombobulated adjuster, or broken spring, or ...
For #1 most of the sound of hissing air appears to be coming out the exhaust meaning it is something exhaust valve related. Burnt valve, bent valve, adjuster?

Will need to investigate further when time permits. I do have 98 mm pistons with Moritz style JE pistons ready to go and I have a set of lightly used M1 cams sitting on the shelf. I also have a spare set of large port SC heads that need rebuilding. If I have to drop and rebuild the question becomes do I split the case to replace mains, intermediate shaft bearings and chains or wait till a later point to do so.

Anybody know a good head rebuilder in Eastern Canada? I could also reach out to Cgarr on this forum and ship them out to him for a rebuild.

[PeteKz]

Start by taking off the valve cover on that side and see what the rocker/adjuster are doing. Most likely a valve problem and you will have to drop the engine. SC bottom ends are very robust. If there's no damage beyond the valve, do not split the case. Just fix that head or heads.

[Marwil]

Thanks the for the input PeteKZ, sound advise as a starting point. If I do have to drop the engine and pull the heads I may do my timing chains as they have stretched. Is it worth using the split chains to replace them or leave them be?

[PeteKz]

How do you know he chains have stretched? These also usually last a long time. I have no experience with the master link chains, so I'll let the pro engine builders reply.

[porschedude996]

Originally Posted by PeteKz

I have no experience with the master link chains, so I'll let the pro engine builders reply.

I would also like to hear thoughts on closed link and master link chains. I’m rebuilding and first bought chains with master links. I was only planning on tensioner upgrade and feed new chains in. Are the ones with the master links any less relevant or weaker? Years back having a chain drive motorcycle without master links was thought to be stronger. But we’re they kidding themselves?

[dannobee]

The master link chains with the e-clips have a problem with the e-clips coming off and ending up on the drain plug magnet. This has been documented both here, and what I've personally seen.

To each their own, but I personally would not use the master links.

Still skeptical? Search here for chain link clips or magnet clip, I'm sure you'll find some of the threads.

[porschedude996]

Originally Posted by dannobee

The master link chains with the e-clips have a problem with the e-clips coming off and ending up on the drain plug magnet. This has been documented both here, and what I've personally seen.

To each their own, but I personally would not use the master links.

Still skeptical? Search here for chain link clips or magnet clip, I'm sure you'll find some of the threads.

Not skeptical at all. Thanks, I’ll be sending the master-link chains back. Funny thing is they a OEM Porsche parts.

[Henry Schmidt]

Originally Posted by Marwil

Rough running after a spirited Coffee Run in July. I thought it was #6 as it had a distinct rattle and miss evident with the stethescope. Started with #1 - 90% leak down...WTF? All others inlcuding #6 were 5% or less.
So - possible culprits for #6 are, loose rocker shaft, discombobulated adjuster, or broken spring, or ...
For #1 most of the sound of hissing air appears to be coming out the exhaust meaning it is something exhaust valve related. Burnt valve, bent valve, adjuster?

Will need to investigate further when time permits. I do have 98 mm pistons with Moritz style JE pistons ready to go and I have a set of lightly used M1 cams sitting on the shelf. I also have a spare set of large port SC heads that need rebuilding. If I have to drop and rebuild the question becomes do I split the case to replace mains, intermediate shaft bearings and chains or wait till a later point to do so.

Anybody know a good head rebuilder in Eastern Canada? I could also reach out to Cgarr on this forum and ship them out to him for a rebuild.

Sounds like a broken head stud or two. We've seen as many as 8 on a running engine.

[Marwil]

With all due respect Henry, I don't think it's a broken head stud - I used Supertec head studs when I did the top end 9 years ago

I will give is a look though - need to find time to start wrenching.

[Henry Schmidt]

Originally Posted by Marwil

With all due respect Henry, I don't think it's a broken head stud - I used Supertec head studs when I did the top end 9 years ago

I will give is a look though - need to find time to start wrenching.

Nope, a Supertec head stud did not break.....I guess I needed a little more information.
I look forward to see what you find.

[Gonbad]

Originally Posted by Henry Schmidt

Nope, a Supertec head stud did not break.....I guess I needed a little more information.
I look forward to see what you find.

That was hilarious!

[Henry Schmidt]

Originally Posted by Gonbad

That was hilarious!

Which part?

[G450X]

I think he was referring to your “forum diagnosis,” albeit with limited information, that it might be a head stud.

He then replied that it has Supertec head studs - that seemed to catch you off guard!

I also have a set of Supertec head studs for my pending 3.0 to 3.2 build, they will give me piece of mind over those pesky old dilavar head studs…

[Henry Schmidt]

Originally Posted by G450X

I think he was referring to your “forum diagnosis,” albeit with limited information, that it might be a head stud.

He then replied that it has Supertec head studs - that seemed to catch you off guard!

I also have a set of Supertec head studs for my pending 3.0 to 3.2 build, they will give me piece of mind over those pesky old dilavar head studs…

I am often asked to give engine advice with limited information and given that the number one failure in 78-83 911 SC engines is head stud failure, it seemed like a reasonable assessment.

BTW: Thanks for buying my head studs, they never break.

[porschedude996]

Originally Posted by Henry Schmidt

I am often asked to give engine advice with limited information and given that the number one failure in 78-83 911 SC engines is head stud failure, it seemed like a reasonable assessment.

BTW: Thanks for buying my head studs, they never break.

Keep the comments and your thoughts, views, and opinions coming. You are a wealth of information.

[G450X]

Originally Posted by porschedude996

Keep the comments and your thoughts, views, and opinions coming. You are a wealth of information.

Agreed, the forum is my go to for the wealth of knowledge available here. I am very appreciative of the experts that donate their valuable time to keep the “less affluent” enthusiast’s vehicles going!

I have yet to visit a “paying shop,” in over 13 years thanks mainly to this forum. A pending engine build will probably go to an expert, but I will attempt some basic work to save money (remove engine, some tear down, transport to a shop).

My old 911SC keeps on going year after year. I have rebuilt several brake calipers, replaced the steering bushing, resealed the airbox, replaced brake light switches, diagnosed odd battery drains, replaced/adjusted the shifter & bushings, adjusted the valves, replaced the spark plugs, etc….

This is a fantastic forum with expert contributors! Many Thanks!,

[porschedude996]

Originally Posted by G450X

Agreed, the forum is my go to for the wealth of knowledge available here. I am very appreciative of the experts that donate their valuable time to keep the “less affluent” enthusiast’s vehicles going!

I have yet to visit a “paying shop,” in over 13 years thanks mainly to this forum. A pending engine build will probably go to an expert, but I will attempt some basic work to save money (remove engine, some tear down, transport to a shop).

My old 911SC keeps on going year after year. I have rebuilt several brake calipers, replaced the steering bushing, resealed the airbox, replaced brake light switches, diagnosed odd battery drains, replaced/adjusted the shifter & bushings, adjusted the valves, replaced the spark plugs, etc….

This is a fantastic forum with expert contributors! Many Thanks!,

How many miles on the engine?

[G450X]

Miles on my 3.0 - I really don’t know, I bought it 13 years ago and the odometer was broken at 160k, original 85 mph speedometer(Speedo works). I probably put around 3k per year, so maybe 200k miles??

The seller told me the odometer broke “that year,” but it had good paint (1 repaint Glasurit he said) decent interior and it drove good (best of around 10 SC, Carrera, and 964’s that I drove).

I was shocked at the number of ratty cars out there that were misrepresented by the sellers!

[safe]

I ran a master link chain for a couple of years on an 2.7. No issues. You had to install the e-clip the right way, if it really matters I don't know.

[porschedude996]

Originally Posted by safe

I ran a master link chain for a couple of years on an 2.7. No issues. You had to install the e-clip the right way, if it really matters I don't know.

Thanks, I’ve always followed the advice on motorcycle chains for most of my life. Bullet end or closed end facing the direction the chain moves. In the case of a motorcycle, I guess it reduces the chance of something hooking the tangs on clip that would pluck it off the link.