CIS 2.4 73.5 rebuild and Upgrades

[rockreid]

OK, my engine runs well and strong. This again is my project 73.5 Gulf Blue Targa that had not run since 1988.. I assembled the 2.4T engine together stock CIS. This is the original 7R case engine, and this car has matching numbers with 915 tranny. This was my first Porsche engine build, and it some ways it shows. After a month of driving a slow leak has developed that might be from the flywheel o-ring area or somewhere along the split case seal in that area. The clutch lever gets a nice lubricating layer of oil after a long drive. How nice. After its initial puff of smoke on startup, I also see a small amount of blue smoke in the exhaust under throttle. I bought one of those $30 USB borescopes and it revealed a small puddle of oil in Cyl#3 after sitting cold for a day. Thankfully no little bits of anything unusual and metallic. Nice healthy looking top of a piston.

Ok, I'm thinking. Possible a broken ring or perhaps not paying attention to the ring gaps when I was assembling. This means a top end teardown which does not really concern me. However what does is the exterior oil leak and that will probably mean splitting the case- which is where this is all going. "As Long as I'm in there..." has set in.

Being this is 2015, I thought I might bring the upgrade topic up again. I know there are a few threads already about the limited upgrades available to a CIS 2.4T engine, but these threads are years old and I was wondering if any new products or services are available now that might make me pull the trigger. I know my engine case has a certain $Dollar value and don't plan to to alter it for wider diameter cylinders.

Hmmm.. keep it stock or enter the dangerous steep $$$ hill of Porsche upgrades....?

[Flat6pac]

Basically with the set up CIS T you can install S cams.
Did you have a valve job done when you opened the engine originally?
Bruce

[E Sully]

The later 2.7 liter CIS S cams are about all you can do if keeping the stock intake.
If the oil leak is from the seal by the flywheel, no need to split the case to replace it. Still have to split engine and tranny though. Pull it out and push in the new one. Mine leaked a little the first time. I set it too deep in the recess. Second seal worked great, I just made sure not to set it as deep as I did the first time.
Oil leak in cylinder 3 could be a valve guide seal. This would not show up in a compression or leak down test. Local shop has a "go- no go" tool to check clearances they were willing to lend me. Did you check ring end gaps when putting in the new rings?

[rockreid]

the PO had the heads redone but no paperwork with them. The work looked good to me with a visual inspection with new looking valves and valve guides. No cracks, gouges on pistons or anything weird. New grey colored stem seals were installed, the same that come with PP rebuild kits. My mistake I guess not taking out at least one set of springs and measuring valve guide side play.

I'm pretty positive it may have something to do with these old pistons or cylinders not being in spec anymore if it isn't a ring problem.. this engine had 110,000 miles on it before it was disassembled. No piston slap or any weird noises however. Just a bit of a valve tick on the right side. I'll address valves on its 500 mile service as per Wayne's Book.