I'm just looking for some advice on what to do. I have a beautiful 1979 Porsche 928 but the water pump tensioner failed, the car overheated and blew the head gasket. I had the engine rebuilt but it turns out that the damage went deeper than anticipated and the cylinders are 1/400 out of spec. The mechanic says I need a new lower block or have machining and sleeves installed. Has anyone had this done? I love the car very much and money really isn't an issue but I'd like to keep the car original but at what price? I guess I can try to find a used lower block but then the numbers won't match. Is that really a big deal though? If the numbers aren't going to match anyways, should I just find a re-built 4.5L or 4.7L engine and put that in? Again, the numbers won't match but is that a big deal? I just want the car back on the road. Where can I even buy a used lower block or rebuilt engine? Any advice or wisdom is appreciated.

 

I'd try 928 International and talk to Mark Anderson. He may have what you need. I'd stick to finding a 4.5 short block or complete engine. the 4.7L uses a different FI system. You could also try Ebay, Craigslist or FB Marketplace. Sometimes engines come up there. Save the old block with matching numbers for the next owner or rebuild it yourself at your leisure. Good luck.

 

I think that it all depends on how important you think Matching numbers are. My ‘79 is completely original, but recently I was afraid I killed my engine (long story short it took me 6 months of work, but it’s still ok). I was already looking to find a replacement engine, and to be honest, after working for 17 years on my car I didn’t think it was that important. What I think is important that I could keep working and driving in my classic Porsche
It’s too much fun to work and drive a manual 70’s Porsche with a 4,5 liter engine.
Matching number is important when you sell it, which would be the least fun day in my life.

 

Unless this is a pristine 79 manual that's worth $50k just put a different engine in it. If you're going to get a used engine that you do some maintenance on like OPG, cam seals etc before installing, find a 4.7L and swap the cams from your 79 over to it )better lift and duration). The slight compression and displacement inrease is nice.

My 79 blown head gasket thread may have some useful engine swap info for you

https://rennlist.com/forums/928-foru...ad-gasket.html

 

That's the kind of response I was looking for. Thanks for sharing.

 

Thank you for your thoughts.

 

I've never heard "1/400 out of spec." What does that mean exactly? And that was discovered AFTER a rebuild?

Running hot ruined the block, really? I thought heads were the first to warp from heat.

Do you trust your mechanic?

 

He's saying that 2 of the cylinders are not exactly round. The engine rebuild focused on the head gasket and top end rebuild. Before the engine was put back in the car, it was running and tested fine. After it was put back into the car, it was running fine but then we started having fuel issues. After that was resolved, there were compression issues.