CIS conversion to MFI system

tcuuh · 01-09-2004, 04:47 PM

Has anyone done a conversion of a CIS system to MFI? I have a 73.5T with CIS and was told it was not difficult to convert to MFI. I can obtain an entire MFI system (linkage, lines, MFI, air cleaners, etc.) for an older model T. Apparently the runners on these can be ported out to "S" specifications. I was also told that since on my heads the injectors are in the heads I can pull them out and put my own threads in to mount the MFI injectors. I have done a little research and see that there is a heater line that connects the left heat exchanger to the MFI system and I will need to get the oil feed lines to the MFI system as well. If I do this and port the MFI velocity stacks as well as my heads this may be similar to a 2.4 S with MFI. I was also told that there is a plug at the back of the cam tower where the cam goes through for the Gilmer belt drive. I was told I can simply pop this plug out so the cam can extend back where the drive pully goes.

Any thoughts? Since I am doing a complete restoration and engine rebuild I would probably do as Wayne suggest in his book and put S pistons in for higher compression. I think he suggested using the "E" camshaft.

P.S. I bought this car with a pretty thorough inspection and the level of rust I could find in the floor pan. I started scrapping the rustproofing away and found more rust. I have preceded to remove all of the undercoating with a propane torch and a lot of elbow grease. This is my warning to you! Where there appeared to be well adhered rustproofing I found that it had delaminated and started to rust anyway. Caveat Emptor!!!

Bobboloo · Bobboloo's Garage

If only it were that simple.

Unfortunently you can't bore T stacks out to make S stacks. The throttles yes but the stacks no. You might be able to do it with 2.4E stacks but really the best route is to buy a set of S stacks and throttles. It's bound to be cheaper.

If you can't locate any S stacks then 2.2E mag stacks can diffenently be bored out to work.

To tap your heads fo MFI injectors first you need to weld up the notch for the CIS injector. Then drill and tap.

To make use of the S MFI then you need S pistons and cams. So you might as well bore your case for a 90mm RS P+C set and build a 2.7RS motor. It won't really cost any more than building a 2.4S motor. In fact it might cost less.

If you stay at 2.4 liters then the E cam you spoke of is a good choice so forget about the S MFI just get an E setup. It'll be cheaper and it'll work better. A lot of people prefer a 2.4E for the street over the S anyway. Go with the S piston though.

I have a set of 2.4E stacks and throttles by the way if your interested.

Randy Webb · 01-10-2004, 10:25 AM

I think I'd convert to carbs -- a lot less trouble. Check with the state for what emissions issues you have to comply with. IF there are a lot (say in Houston or DFW areas) then you have a good excuse to swap in the whole 993 powerplant/computer.

svandamme · svandamme's Garage

MFI pumps are calibrated for the engine they are to run with too, which might not be so simple if you're engine isn't one that had a MFI pump to start with.

tcuuh · 01-10-2004, 03:26 PM

Thanks for the info. I assume the carbs would also be an easier conversion and may pass my inspection (I am about 40 miles south of Fort Worth) at least for now. There criteria increases each year and I may be subject to those requirements. MFI would be easier to pass as it looks just like what came on it originally. Also, my cost estimate for carbs, w/ S pistons and cam would be ~$2000. The MFI w/ pistons and cams I can get for ~$1500. I assume that Eurometrix could rework the MFI pump to whatever specs I want. I am waiting for Wayne to chime in with his vast experience about this. He has suggested previously that I just convert it to a 2.7 CIS. To me that cost would be even higher with all the machine work involved plus I would have to update my CIS system (my airbox is blown). Who knows today I spent about 3 hours grinding away the remnants of undercoating on my floorpan. So the engine is really the last thing I need to do.

Randy Webb · 01-10-2004, 06:30 PM

Well, I'm a CIS hater (pulled one of mine last month & will put in a bigger motor with carbs). If you aren't grandfathered for carbs - you might also look around and see if an EFI system would work. They are much more accurate than the MFI systems, so you could wind up with better hp and better emissions performance.