3.2 had G50, 915 challenges?

gimlet911 · gimlet911's Garage

I never post. Always search. Never say never. Can't find the answer to this one.

Transmission wise, what hoops will I be jumping through to mate a 3.2 (was G50 from an '88) to the 915 in my '74?

Thanks...Dave

Matt Monson · 11-19-2009, 03:14 PM

Really the only thing you need to worry about is getting the right clutch and flywheel assembly for the conversion along with notching the bellhousing of the gearbox so that the DME can read the trigger points. Patrick Motorsports is a great source for the conversion parts (clutch and flywheel stuff). Where in Colorado are you? I can definitely recommend a local shop that can do the notching for you, though it's possible to DIY the job if you are handy and have the right tools.

Flat6pac · 11-19-2009, 04:44 PM

Put the short 915 bell housing bolts, the 84-86 flywheel, mount your 915 clutch pkg. Notch for the flywheel pickups on the trans bellhouse.
Now you just need to layout the harness down the body.
Your 74 trans will rev too quickly with the torque and horses because of the short gears.
Bruce

KTL · 11-19-2009, 04:53 PM

There's really no "custom" conversion-ing at all that would lead you to use the expertise of Patrick Motorsports. Don't get me wrong, they offer a huge service to the Porsche community and have been great pioneers in the conversion department. But in this case the 3.2 engine simply needs to have the shorter engine case studs (from a 915 car) that join transmission bellhousing & engine together. This is because the G50 uses longer studs.

The clutch and flywheel are basic factory 915 units that are the same as those found on 84-86 911 cars. It's a simple bolt-on installation of the 84-86 9 bolt flywheel, ring gear, clutch & flywheel assembly. Always double check for the ring gear before you put the engine & trans together and reinstall drivertrain in the car. Nothing's more aggravating that hearing that starter just spin away with no flywheel teeth to grab!!!!

The trans bellhousing notch is very simple too. Just line up the transmission next to the engine and you'll see exactly where to notch it. A hacksaw and Dremel tool with a carbide bit will make short work of that job. Just don't cut at too fast of an RPM because the transmission case alloy gets too hot and will foul the cutting bit with metal shavings and you have to continually pick the bit clean with a sharp-pointed tool.

1976 TN Porsche · 11-19-2009, 06:40 PM

I have a 1976 911S I took a the 2.7 out of and am just about ready to put my 3.2 in. I am runnig Carburetors ( Weber 40IDA 3c ) on mine. I hade to find a 9 Bolt flywheel from a 3.0. I used the short studs from the 2.7 and the same clucth from the 2.7 and everything went right together. I am going to put the engine / transmission in the car this weekend.

Flat6pac · 11-19-2009, 06:52 PM

But the 40IDA s are too small for the application.
Bruce

1976 TN Porsche · 11-19-2009, 07:02 PM

I talked to Richard at PMO and he sugested I put in 36 vents, 145 mains jets, 60idle jets, 180 air. Going to try that setup.

KTL · 11-20-2009, 05:49 AM

Quote:

Originally Posted by 1976 TN Porsche

I have a 1976 911S I took a the 2.7 out of and am just about ready to put my 3.2 in. I am runnig Carburetors ( Weber 40IDA 3c ) on mine. I hade to find a 9 Bolt flywheel from a 3.0. I used the short studs from the 2.7 and the same clucth from the 2.7 and everything went right together. I am going to put the engine / transmission in the car this weekend.

Keep in mind in this instance the 84-86 3.2 flywheel is needed for the timing sensors. You didn't need this flywheel because of carbs which don't use the Motronic sensors/ECU