1973 MFI vs 1973.5 CIS

[M491Cabriolet]

All things being equal on original 1973 911s, both in very nice, rust free and well maintained condition which car would be more desirable, a 1973 2.4 with MFI, or a 1973.5 2.4 with CIS? What are the various considerations one should make when having both and faced with having to choose only one. Both optioned in the same way apart from the injection systems. Which would be the keeper, and why? Please discuss! Thanks

[copbait73]

Ok, I may have a unique perspective. I owned a '72 MFI and it was a year round daily driver in the Midwest. This was about '80 timeframe, miles about 80K. It never failed to start and made good power but had typical wear on the throttle shafts. I made my own manometer set- up to tweak the air bypasses. This was required about every 1K miles to prevent port backfiring. but cost me nothing. Repeat visits to the Porsche Service would have been cost prohibitive, thus the reason for MFI being changed to carbs and MFI being rarities today.
I now own two 73.5 with CIS. Mine starts and runs well. I even added a turbo to it. I've driven carb, MFI and CIS. CIS fits the character well and makes an old car very street able.
I would not recommend buying an MFI car unless it has a rebuilt system or you plan to spend the $s to immediately do so. I know they have a mystique but I only remember an almost raunchy intake note that I would have gladly changed to anything else.
One final point, the 73.5 was the best and the last longhood. Valuable as a good driver and investment. Thus I have two.
Just one opinion.

[LakeCleElum]

Never owned an MFI, so can't argue that side, BUT:

I've had my 73.5 with CIS for 23 years......Other than having to change a bad "cold-start" valve, it has never failed to start. Runs perfectly right from a cold start up. Outstanding low end torque. Fuel mileage is usually 22-24 MPG......

Only my opinion, but the best driving long-hood made.

[76_rookie]

1973 MFI better throttle response. Had one of each and loved the mfi response. They open up I my experience more so than the cis. Value are also better for early mfi cars. My 0.02$.

[M491Cabriolet]

So, if you had both in your garage and you had to let one go, you would sell the 1973.5? I hear MFI throttle response is better and values are going up faster and greater in MFI over CIS, but CIS is more reliable,economical and enjoyable as a daily driver. Wow, tough choice. Anyone else?

Edit: I missed Copbait73's response. That makes it two for CIS, and only one for MFI. So, is CIS a more attractive car for investment purposes? The one thing that draws me to the CIS is the streetabilty and reliability of the car. I have an MFI car and and considering the insanity of adding a 1973.5 car to the garage. I have no plan to sell the MFI car; I am just looking at the possibility of adding the CIS car as a more frequent driver. I have not found the right car yet, though. I would want one that needs nothing and has working air conditioning.

[willcall]

I would go CIS, as it's far more fun to get the car out on the road & do some driving care free with the misses than to worry about if you'll have a starting/running issue when in the middle of no where. That is In Australia anyway.
Reliability is FAR more important than minimally improved engine response when we are talking about road use.

[regency]

Well........Pretty happy with my 73 MFI T Coupe. I did rebuild everything (E spec), has been a awesome driver every weekend. I forgot who said it, but there weren't too many CIS Factory racing machines ( they were MFI ).

1973 911 MFI T Coupe, Aubergine

Steve

[haycait911]

MFI currently has a huge cool factor so there's some $$ value there. currently.

coolness aside, the last/best/most refined model in any series will always carry a $$ premium.

the 2.4 CIS can't get much simpler, or less cool. from people I talk to in europe, the CIS is highly desirable there.

(but I just bought a 73.5 so I'm probably biased)

[Matt Monson]

Your question is like asking which is better, a penis or a vagina? They each have good things and bad things about them.

But point if fact there was never a 73.5 911S with CIS. The 73.5 was T only. Given the premium on E's and S's these days your question only makes sense if both cars are T's.

[haycait911]

Originally Posted by Matt Monson

Your question is like asking which is better, a penis or a vagina? They each have good things and bad things about them.

But point if fact there was never a 73.5 911S with CIS. The 73.5 was T only. Given the premium on E's and S's these days your question only makes sense if both cars are T's.

I think M491Cabriolet meant 911s, plural. not 911S.

[lateapex911]

I'll tell you what, when you pull the MFI off your car to replace it with CIS, let me have the MFI parts! Oh, what a crime I committed back in '97 when my MFI was acting up, the internet hardly existed, and gus was the only source of the black magic required to keep MFI running right...and I replaced the parts with Webers. Sigh.

[M491Cabriolet]

Yes, that's right, I meant plural 911, not 911S. Thanks for clarifying.

I am happy haycait911 responded as he did ("...the last/best/most refined model of any series will always carry a $$ premium") because it allows for the argument that the 911T with MFI is more like the 911E and 911S, neither of which ever went to CIS but are the considered the best cars to have. So while the last 911T with CIS is most definitely the last of that particular model before moving into impact bumpers, and may even be considered more refined, i.e., lazier or more suitable for a business executive to drive, it probably can't really be considered "the best". I am not arguing this; I'm just playing devil's advocate.

If a 911T with MFI has an original and complete 911S trim package, and upgraded engine internals to 911E or 911S specifications, it is arguably very much like its more expensive and most sought brethren (the pre-impact bumper 911S and 911E). But the 911T with CIS could never be similar to the 911E or 911S without an engine transplant, and then it's market value would probably be directly harmed. Could it be that Porsche AG decided to move the T to CIS to differentiate it from its more race-bred and expensive models as a more relaxed "touring" model? Could one argue, then, that the 911T with MFI is definitely the one to have over CIS? I think so... I don't know for sure, but maybe it is. I want both.

In self analyzing, I know why I can't imagine selling my 1972 911T, and I think the relaxed, "refined" and reliable arguments are why I am on the hunt for a good 1973.5 911T with CIS too. I could drive that to work in a very relaxed, confident manner. Where might I find one of these? How much should I expect to pay? Thanks.

[Sunroof]

I have been a 1973.5T owner going on 15 years now (yep its Sepia Brown). I cannot comment on the MFI although the greatest complaint I have heard is the rebuilding process and the number of experts doing the rebuilding, dwindling. Over time I replaced just about every CIS component where I am now enjoying great dependability in the city and the highway. The thermotime switch was added in 1974 so the 73.5T uses a hand throttle for the warm up cycle. The big quirk about this is that you start and warm up at 2500 - 3000 rpm, which when starting in front of an outdoor café crowd DRAWS ATTENTION!!!!!!!! Gotta love the early cars. For me the CIS is very responsive and easy to work on. The other drawback? That fuel pump sits in the rear drivers side wheel well so its got along distance to pull that fuel. Even with a check valve hot starts can be timely. The CIS ran from 1973.5 to the 1983, a good 10 year run. How long was the MFI used? Overall the 1973.5T/CIS is a great car.

Bob
40-year Porsche owner

[db_cooper]

Back in the day many 1973 T MFI injection systems ended up in a box on the owner floor and many owners changed over to carbs..the MFI is very elegant and sophisticated... but..it required a lot of fiddling.

CIS (K-Jet) was a more reliable fuel system. Aside from a blown air-box from time to time (Porsche did some field service updates that really helped in the early days) K-Jet was a better fuel system for over the road Porsche use.

[Dodge Man]

MFI is the way to go today for resale & the throw back driving experience. I got tired of trying to pass CA SMOG with MFI & converted to 3.0 SC CIS in 86. MFI cars were not prized at that time. I made the mistake of trading in my MFI motor on a "new blank factory case" motor from TRE that got confiscated by LAPD a few years later for being a "scrubbed numbers" case. Talk about a double hit.

[M491Cabriolet]

So, given that I already have an MFI car, how much should I expect to spend on a good 1973.5 CIS car? Does anyone have a car they would sell?

[haycait911]

Originally Posted by M491Cabriolet

So, given that I already have an MFI car, how much should I expect to spend on a good 1973.5 CIS car? Does anyone have a car they would sell?

IMHO, at the moment. with two identical cars, one '73 MFI and one '73.5 CIS. you'll pay more for the MFI car.

when the current fascination with MFI fades, I think the '73.5 will be the more valuable.

look at the history of porsche prices, the last car in a series will always carry a premium, even when it's identical to the previous year's model. in this case there are quite a few differences relating to the CIS that make it a somewhat unique car.

[boba]

MFI took a hit due to many shops that did not know how to set them. Also many running problems that were ignition got blamed on the MFI. A big issue was worn throttle linkage. If you have an MFI car which has good throttle bodies, linkage, set up following CMA you should have a bulletproof package. The MFI cars are more desirable and have higher value. This is not intended to dis CIS, but MFI would be first choice. Lots of people would like to find the MFI that was taken off their cars years ago. If your MFI needs pump or throttle body rebuild it is not cheap but worth it in the long run.

[boba]

The '73.5 will never be the most valuable. It was a T and will always fall after S & E. I could also make the argument that all '73's will fall behind '72's which were one year only cars with the forward placed oil tank and oil door. An argument could also be made that the 2.2S with its high compression would rank ahead of a'73.5. Keep in mind that what makes these cars valuable is not how good a daily driver they would make today but how they communicate the character of Porsche back in the day, and that was MFI.

And remember that CIS was driven by emissions regulations not performance.

[M491Cabriolet]

All understood. I think I agree with everyone, though some are saying different things. The reason is that there are strong pros and cons on both sides of the fence. I do think the MFI cars will always be more desirable than the CIS cars, if only because the E and S stuck with MFI and only the touring version went with CIS at the very end. Maybe it was a beta test of the 1974 which resulted in the 2.7 CIS. I think the drivability of the 1973.5 emission driven CIS car is due to it sacrificing a lot of character for lower emissions. But I am looking for a longhood that is less hair raising as a daily or frequent driver. So if anyone knows where I can find one, please let me know.