Use 2.4 CIS heads for MFI?

DavidPorter · 04-27-2002, 06:16 PM

Forgive the ignorance, but I have a 1973 T engine I want to use in my 1972 MFI car. The '73 engine has what appear to be passages for the MFI injectors blanked off with metal plugs. Is that what those passages are, and is there any way to use these heads with the MFI? I presume I will need to change cams.

Thanks.

Wayne 962 · Wayne 962's Garage

The heads are one of the few things that you can reuse. The pistons cannot be used with any cam except the CIS cam (there are exceptions to this, but if you're running MFI, not really). You can indeed use the heads, as they are basically the same for 2.2/2.4/2.7.

The domes on the CIS are too high to use with the agressive MFI cams. You will need pistons designed specifically for your cam / MFI system.

Your case is somewhat desirable & valuable, because it is the only 7R case that is bored for 2.4L. This case was only produced for 1/2 a year, and is pretty highly sought after by people trying to make reliable race motors based on 2.2/2.4 pistons & cylinders.

-Wayne

Bobboloo · Bobboloo's Garage

Here's a picture of a 2.4mfi head. By the way it's from a 2.4TMFI motor I may be parting out so if you need the heads let me know.

Bobby

DavidPorter · 04-28-2002, 03:24 PM

Thanks for the information. I really have two choices. The original engine in this car is complete and running but tired, has over 120K and I am told needs a FI pump rebuild as well as an engine rebuild.

The extra engine I have is the 1973 CIS 2.4. Supposedly it has 80K on it, but is hasn't run in several years and came without the injection. I have a set of Webers that I could use (with 36 mm S manifolds). They also need rebuilding, but I can do that. I was originally hoping to get this one in the car to buy some time to rebuild the original engine.

Probably way too many variables here, but my original question was whether I can use the CIS heads with MFI, i.e. can I remove the plugs and just stick the injectors in there instead, or is there more to it? Or, can I use the Webers with the CIS cam and pistons?

If I need to change pistons and cam to use the MFI I might as well rebuild the original engine. I'm not really after more performance at this point, and I can always do something more interesting with the CIS engine later on.

Wayne 962 · Wayne 962's Garage

As far as I know, you can adapt the heads to anything. I don't have a '73 2.4L head in front of me, but I would reckon it's the same head...

-Wayne

Bobboloo · Bobboloo's Garage

David,
I've never seen 2.4 CIS heads either but from the sound of your description it sounds like you can. I posted the picture showing the intake with the hole for the injector so you could make a comparison. The 2.7 CIS heads are a bit different in that there is no plug but there is a notch in the side of the intake port to allow the injector nozzle, which mounts in the manifold, to spray.

The Webers can be used with the CIS pistons and even give a performance boost over CIS (at the cost of emissions and MPG's). You would however have to change your fuel pump to one that works with carbs. The carbs would have to also be jetted to work with that particular engine. That is unless they were already set up to run on a 2.4 CIS motor.

Also, just to let you know. If your carb throttle bodies aren't corroded away on the inside or wobbly and are maybe just seized. You might try giving them a bath in B-12 Chemtool. I've done this to throttle bodies I could have sworn needed rebuilding and found out the contrary. Just get a big enough pot to hold them and submerge them in B-12, work the throttle levers and scrub with a toothbrush. The stuff is toxic though so you must wear gloves and do this outdoors preferably with a paint respirator. Also this stuff evaporates quickly and I'm sure is not good for the planet so I would suggest a pot with a lid. Also keep the cans that the B-12 came in so you can pour it back in.

Bobby

mikey74 · 09-26-2002, 04:31 PM

anybody know if i can use 2.4 mfi heads on a 2.4 cis motor??

BK911 · BK911's Garage

I thought CIS injectors were press fit in the heads as opposed to the threaded MFI injectors. ?????

Bobboloo · Bobboloo's Garage

You can use 2.4 MFI heads on a 2.4 CIS motor but you will have to plug the threaded injector hole as seen in the photo above and then put a notch in the side of the intake port for the CIS injector.

CIS injectors mount in the intake manifold.

Bobby

mikey74 · 09-27-2002, 05:15 AM

on the 2.4 cis the injectors mount in the heads just like the mfi. I just didn't know if the cis injectors were threaded in like the mfi ones.

mike

jluetjen · jluetjen's Garage

You might also want to check the port dimensions if you are going to use 2.4 CIS heads on an MFI engine. I've seen conflicting reports as to the actual diameter of the 2.4 T ports. Could you check yours and report back? If they are 32mm, they should be fine for use up to a late model E cam. If they are smaller then 32mm, then you might need to port them or limit yourself to a fairly mild cam like a T cam.