3.0 trans to a 2.7

[4sd911]

Can a trans from a 3.0 SC be used in a '74 2.7? Can the speedometer be back dated to the '74 mechanical type?

Also is there a benefit to go with the aluminum case 915 over the mag case 915?

[carrera turbo]

the answers are yes and yes.

if you still have the 2.7 then the higher gearing will be noticeable as the ratios are different.

the alloy is stronger than the mag case but if your not running big power i would stay with the old 2.7 tranny.

good luck

cheers ed

[4sd911]

I'm considering going with a 3.0 motor and may get the trans also. I'd like to keep the engine compartment stock so I'm thinking of just using a 3.0 long block and using all of the 2.7 Fuel and ignition components. I understand that if I use a 2.7 distributor drive and the brass crank gear it should work?

[RWebb]

Originally Posted by 4sd911

....

Also is there a benefit to go with the aluminum case 915 over the mag case 915?

- the very best 915 is the late Mg models

they need to be hot rodded a bit tho

http://forums.pelicanparts.com/porsche-911-technical-forum/332597-best-year-915-transmission-post4242866.html#post4242866

[carrera turbo]

so looking at a chart on that link from rwebb, looks like ratios are the same after 74 so i was wrong on my statement above.

I'm considering going with a 3.0 motor and may get the trans also. I'd like to keep the engine compartment stock so I'm thinking of just using a 3.0 long block and using all of the 2.7 Fuel and ignition components. I understand that if I use a 2.7 distributor drive and the brass crank gear it should work?

as far as using the 2.7 injection on the 3.0 i wouldnt, if your getting a 3.0 complete just move the ignition and regulators etc. over to the other car.

my last swap i just swapped the alt and larger fan from the 2.7 over to the 78 3.0 moved over the ignition box. and had to move a couple of pin connections on the engine harnes to get evry thing to work correctly.

good luck i found all info i needed to swap on this forum in the search box.

cheers ed

[Matt Monson]

Originally Posted by 4sd911

Can a trans from a 3.0 SC be used in a '74 2.7? Can the speedometer be back dated to the '74 mechanical type?

There are two ways to do this on your 1974.

The easy way is to wire up your car and use the 911sc electronic speedo drive.

The hard way is to install a mechanical speedo drive on the 911sc transmission. The problem here is that the 911sc pinionshaft doesn't have an allowance for the speedo drive gear. Basically, you need to get a pinion set with the speedo drive gear(could use your '74 if it's any good). This obviously requires breaking into the "good used" gearbox you just purchased, replacing the ring and pinion, and in essence rebuilding the gearbox. Then you'll need to install the tailcone from your 1974 gearbox with the balance of the speedo drive components onto the 911sc transmission. Not very feasible for most folks.