Question: Magnesium MFI stacks on a 1972 911?

[M491Cabriolet]

I'm wondering if anyone knows if using a set of earlier magnesium stacks on a 1972 911 is possible, considering the magnesium stacks don't have cold start fuel squirters near the bottom like the plastic stacks did. Any info would be greatly appreciated!

[Bobboloo]

Yes they are usable. You can put any of the 2.2 mag stacks on either 2.2 or 2.4 throttle bodies. The 69' 2.0 stacks however have to be mated to 69' 2.0 throttle bodies.

Both the 2.0 and 2.2 mag stacks used cold start injectors in the air cleaner housing so you could do the same. Porsche switched to the later 2.4 style probably to prevent a chance of a flame up and it probably does a better job as well.

[jbell959]

Bobby is exactly right.

Just get yourself a set of mag stacks, velocity stacks, and the matching 70/71 MFI air filter housing and you can replace your plastic stacks and 2.4 air cleaner.

Curious why you want to move to the mag stacks? Are you planning to bore them out?

[M491Cabriolet]

Thanks. To answer your question, I have a 2.4 engine going through a rebuild now. That engine has 2.4 911S pistons and heads, and 911E camshafts. This was originally equipped with MFI, but a PO removed the MFI and put on Webers. I have a couple of MFI setups in storage for it. One has magnesium 911S stacks and throttle bodies, the other has Magnesium 911E stacks and throttle bodies. One of my pumps (now on my car) is a 2.4 911E pump. I have another, freshly rebuilt 2.2 911 pump, and a good 911T pump. My idea is to use the rebuilt 911E (010) pump with the magnesium 911S stacks. I hope the 010 911E pump will work alright with the 911E cams and 911S pisons and heads. I will have to find a 1970/71 MFI air cleaner assembly with cold start injectors in it. DO you think the 010 mechanical fuel pump will work with this engine?

[jbell959]

The 911S stacks and throttle bodies will work great. The throttle bodies will match the 911S intake ports on your heads. As I said, the 2.2E pump will work but I think your best option is to use the 2.4E pump and adjust it or have the space cam in the 2.4T pump swapped with a S space cam and adjusted to S specs (then sell your rebuilt 2.2E MFI pump)

I would still give Henry a call or send him a PM. He knows much more about this than I do.

[Zeke]

The key here is what bell said, the right air box. The squirters for the mag stacks are in the box and it will be metal, not plastic.