73.5 7R case/ heads?

[raspy2point2]

Can I use my CIS heads off my 911T case for MFI or carbs. What has to be done to the CIS injection ports or do I have to sell the Heads and get other heads that work with either MFI or carbs ? Thanks Chris Early S reg.#205/ R-Gruppe#144

[YTNUKLR]

The '73.5 CIS injector port in the head might work for an MFI injector, but for some reason I think the thread is different, so you'll have to tap/drill it out (I think). I also don't remember if the '73.5 CIS injector port is aiming right at the valve. MFI injectors do.

Otherwise, they will work. Likely need some porting unless you are making an MFI 2.4T.

Cheers
Scott

[Bobboloo]

MFI heads have the injector in the head. It screws in.

CIS heads have the injector mounted in the intake runner. A notch is in the intake port of the head for clearance.

To mount MFI injectors in CIS heads you need to weld up the notch and then tap the heads for injectors.

If your CIS heads need rebuilding it would be cheaper to find a set of MFI heads for cores to start with.


If you go with carbs then no machining is necessary. Just find a set of carb manifolds and mount them.

[Eric911S]

Hello: I have some MFI heads just tell me what you want to use them on. Thanks Eric

[raspy2point2]

Thanks all for the replies-- As I bought a long block; it turns out that the heads had a valve job and new valve guides so I was wondering could they be useful on my hot rod 2.8 liter twin plug engine I want to build. My attention went to the intake flanges because the CIS injector ports are located within the flange of the intake manifold slightly on the side of the two post flange and I thought that might be a problem if I wanted to use these heads for carbs or MFI as the flange is not the usual all flat mating surface for the intake maniflod to sit on. I have heard of welding up unused holes on heads before but I am new to engine rebuilding to different configurations. Thanks Chris Early S Reg #205 R- Grouppe #144

[Eric911S]

Hello: You will have to take the engine apart for the second plug hole. I would have the heads welded at the port then port to suit your engine plans. They will work just fine for carbs but you will have to drill and tap for injectors if you want to use stock MFI stuff. This is not difficult but may cost you more than getting MFI heads and going through them. Hope this helps. Thanks Eric