Needed a spare engine to run my car while the the original 2.4 engine is out for a full rebuild.
Starting point was a “reasonably priced” SC engine (1980 Euro 930/09, 188 hp, big port) from a Porsche wrecker. Being a freshly retired mechanical engineer, one target was to do most of the job myself and to gain experience for the planned 2.4 project. I worked on a wide range of modern and classic cars for the last 40 years, tackling all kind of jobs including some engine work, but had never dared a full engine rebuild (except the model airplane engines of my childhood
).
Targets:
Having fun and accept the challenge.
Get reliable spare engine within a reasonable budget.
Engine suitable to be converted back to CIS for potential future resale.
Gain experience for next 2.4 project.
Individual jobs:
Rebuild 3.0 engine.
Convert engine to Weber carbs (parts from 2.4).
Convert to early style exhaust with SSI (parts from 2.4).
Install 55 A alternator and fan/housing (parts from 2.4).
Add complete external oil cooling system to car.
Prepare exhaust for O2-sensors.
Install new 123 ignition distributor with Bosch 3-pin CDI.
Program distributor with 930/10 ignition curve.
To cut the story short I'm glad to report that break-in of the engine has been completed and it runs strong and without leaks. All-in-all I spend just shy of 3.000 € (ca. 3.600 USD) on parts incl. the new distributor and not counting the additional jobs such as oil cooler system and of course without expense for tools and my own labor. Probably could have saved 500 € by reusing valves, piston rings and some other components that were still within spec.
Engine was missing some parts (distributor, fan...) and has not been running for quite a while. No history other than the engine was sitting in a Porsche workshop for many years and of course no warranty whatsoever. Anyway price was right and prices for used engines seems to keep going up all the time. Positive surprise was to find high compression 9.8:1 pistons, installed together with all the CIS components from a 930/10 engine. Strange was to find cylinder heads modified with 935-style flame-rings instead of the stock CE-rings.
Luckily engine turned out to be in good shape without any unexpected damage. Mahle Nikasil P&C fully within spec and main and rod bearings only showing minor wear. Just the IMS-bearings were showing significant wear marks. Exhaust valves were rusty (from bad storage) and covered with a thick layer of carbon deposits. After cleaning all valves probably could have been reused, but decided to use a new set of TRW valves anyway. Valve guides were worn beyond acceptable limits, so a full top end rebuild was necessary.
Guess without Wayne's book and the invaluable resource from this forum, I would have not been able to complete this challenge. Many thanks to everyone for all contributions. It remains a complex job and I can only recommend it as a DIY project if you are fully committed and willing to spend many hours in your workshop plus plenty of time doing research and preparation. Of course you also need a suitable workshop and a good set of tools. I now also have a better understanding for the prices charged by professional engine builders.