1975 2.7l splitting the case

mspell · 07-20-2017, 07:09 AM

After pulling the engine and closer inspection, my main timing chain sprocket is worn and the flywheel end has a bit of vertical play. So, it's looking like we need to split the case to replace the sprocket and see what's going on with the crank or bearings. No pulled head studs, compression is fine. So...

If it's the original engine I'd rebuild vs. replace with something else. What next? Case savers, cams/Webers/higher compression pistons? Any suggestions to do stuff "while we're at it"?

mspell · 07-20-2017, 07:12 AM

hdrockerroller · hdrockerroller's Garage

A lot of people update the head studs at this point.
Someone can chime in and let you know if there were any issue with 1975 head studs or not.
Mine was an 83, and they had less than optimum head studs, so now it has race tech studs.

Targalid · 07-20-2017, 08:28 AM

Wayne Dempsey's book on rebuilding Porsche 911 engines uses the 2.7 as his example. I recommend you read the book to see the decision tree he uses to determine what needs to be done.

carwash · 07-20-2017, 08:46 AM

i didn't realize that the cases could be split and resealed without doing a full build... my case halves are leaking terribly, besides that that motor is great. I had planned to do a full tear down and build, but not if i dont absolutely have to.... is this possible ?

smokintr6 · 07-20-2017, 09:02 AM

Carwash,

Anything is possible.... though likely when you take the engine down you will find components that are near the end of their life, and you would be wrong not to replace them.

I'm not a mag case expert, but I thought when you split them it was best to have the halves sent to someplace like Ollie's to be straightened and re line bored? I've also heard a lot about time certing. I try not to know too much about mag cases, for fear that I might accidentally allow myself to buy one

carwash · 07-20-2017, 09:04 AM

Mine is a 1970 2.2 liter.... so it's not mag... but i'm probably better off doing a full tear down anyway. Sorry OP for the hijack, I'm a dick.

Trackrash · Trackrash's Garage

Quote:

Originally Posted by Targalid

Wayne Dempsey's book on rebuilding Porsche 911 engines uses the 2.7 as his example. I recommend you read the book to see the decision tree he uses to determine what needs to be done.

+1

Life and 911s are all about choices. It's time to do some homework.

A lot depends on budget, originality, and smog testing.

If it was me, I would tear it all down. IF the cases are not warped consider a rebuild.

2,7s, by the way, don't have problems with the head studs, like the SCs. But the studs will pull out of the case. The big issue is the cases on the 2,7s are prone to warpage. You may want to price repairing the cases before proceeding.

Upgrading to an SC motor is a great alternative, IF you can find one that won't need to be rebuilt.