Core exchange or keep the 3.0?
 

Just wondering what you would do.

My 1979 3.0 needs a total rebuild. I am going to purchase a rebuilt 3.2 but wondering if I should keep my 3.0 or do the core exchange. I have had the car since I was 5, it was my moms, I have kept it all original but I don't care about numbers matching up. I'm never going to sell this 911.

Part of me would like to get another early model 911 down the road and perhaps I should keep this engine to rebuild for that car???

Maybe this 3.0 isn't worth holding on to and I can just get another rebuilt 3.0 or 3.2 down the road for that car? And that's a big if because I don't even have that next car yet.

What would you do?

I’d be tempted to keep the 3.0 if storing it is not an issue and you’d be happy with the displacement down the road.

My reasoning is that these motors are not going to get cheaper so if you get out now and try to get back in later, you’re losing money.

Even if you decide down the road that you want a higher displacement 3.2 or 3.6 the core value of the 3.0 will also be more valuable. Maybe not a lot, but some.

Edit: The advantage of a complete 3.2 or 3.6 is more modern engine management. If you wanted to convert to something like EFI/ITB then it’s a moot point as you’ll likely discard those bits. The 3.2 and 3.6 are probably cheaper starting points in the sense that you have more affordable HP upgrade options. If I were going to start a project car CIS wouldn’t be at the top of my list for a starting point.

I would keep it at least short term if you have the space and are at least thinking of a project car at some point. You could always sell it later and probably for a bit more than is currently offered as a core exchange.

Keep your car numbers matching. Build your 3l as a 3.2.

I would keep it with the car.

I'd let your goals and cost dictate if you put it on a shelf for later or rebuild it for the car now.

Assuming I had the funds to burn at the time, I would likely install another engine in the car and take my time rebuilding the original 3.0 as an enjoyable project.

Create a SoCal hybrid bastard child and have fun.
A 3.6 Mezger is the premier air cooled motor.

Keep the 3.0
 

Keep the original 3.0. The early U.S. spec SC’s have better flowing CIS/heads and are easier to build into a powerful and free revving engine. Drop in higher compression pistons and 964 (or similar) cams and SSI’s with a free flowing exhaust. If the budget allows, a Max Moritz 3.2 P&C swap is a proven upgrade.

If the 915 needs “attention,” consider shorter gear sets for a mechanical advantage.