MFI, or leave Webers on my 72S?

RetroSC · 09-10-2003, 07:58 PM

Been going back and forth on this since I started the restoration last month. Here's the deal, the weber's that are currently on it run pretty good, and I'm familiar with them. However, I do have all the MFI parts to reinstall and it all worked fine according to the PO, said he could never get it tuned just right though, whatever that means. So, am I really going to gain much with the MFI over the webers and is it worth the hassle for a MFI novice.

Also, this is a car for ME, not to sell, so I'm not really concerned about value with or without MFI, just the driving pleasure. Carbs have much better throttle response than my SC/CIS, could the MFI be that much better?
Thanks,
Bill

Tim Walsh · Tim Walsh's Garage

I'm a huge fan of MFI so I'd say go with the MFI. It makes a great sound, gives just as good if not better response than the webers, stays in tune longer than the webers and it produces a touch more HP.

Tyson Schmidt · 08:19 PM

No, the throttle response isn't that much better. Webers, when properly set up, have similar throttle response to MFI. MFI has 10 more horsepower, and most of that is in the higher rev range.

MFI makes a better fuel system for the track, where an extra 10 HP on the top end really counts. And it doesn't suffer from the float bowl slosh issues that can result in fuel starvation under high conering and braking G's like the Webers.

But for the street, stick with the Webers. Unless you like fiddling and learning. It's a phenomonally steep learning curve properly setting up MFI.

JSDSKI · 08:29 PM

Well, 2.4S's are pretty rare and should be preserved (IMHO) - at least those that are not "rust in motion" - and kept in their factory spec's if possible. So that means MFI. And a lot of people would love to own a stock 72S with the MFI setup intact. So you'd not lose any dollar value in the change - in fact you might even gain some value.

MFI is a lot of fun to drive - it's kind of a direct time warp to factory racing cars of the late 60's and early 70's. It's pretty cool that you can drive the same system to the grocery store that once howled at LeMans. There are probably some PCA or Pelicanites in your area with MFI cars. Ask for a ride and then decide.

But if you decide to keep the weber's - let me know. I'm in the market for a 72S MFI set up

Tim Walsh · Tim Walsh's Garage

Tyson,
I'm not familiar with webers at all but I haven't had much trouble tuning my MFI system or any of my friends. Are webers really that much easier or just different? I guess part the MFI thing is that I'm a kid who'se never even driven a car with carbs so that's part of why it's not so bad for me.

RetroSC · 09-10-2003, 08:25 PM

Man, that was quick. Guess I need to find somebody local with MFI, I do like webers though and I'd never sell the MFI system. I'd say that just having it adds some value to the S if, god forbid, I had to sell it someday. 10 HP though?? That would be nice

Tyson Schmidt · 09-10-2003, 08:26 PM

Well, MFI is easy to adjust, once you're comfortable and familiar with it.

But in this situation, a bird in the hand is worth two in the bush. He knows his Webers work great. He doesn't have any idea, however, what condition his MFI pump is in. Except that the previous owner states that he gave up trying to adjust it. That tells me it probably needs a rebuild.

He definitely should hang onto the MFI system, but why mess with success. If his Webers weren't working well, I'd say try the MFI. If it already had the MFI installed and it worked well, I certainly wouldn't tell him to scrap it for the Webers.

I prefer MFI, but like I said, if it ain't broke don't fix it.

Zeke · 08:31 PM

Keep the MFI with the car if you don't install it. Someday you may run out of things to do. Hah! Is the pump drive gear still on the front of the motor?

I'm a little confused about the signature line. What's being back dated? You can't go back much from a '72S.

RetroSC · 09-10-2003, 08:30 PM

Tim, that's good to hear you don't have much trouble with it. Just talking to some local's, It seems everyone's split on the difficulty of running MFI... The PO, switched to weber's because he said he could never get it just right. Either strong down low and dead up top, or vice versa, so that make me kinda nervous reinstalling it.

RetroSC · 09-10-2003, 08:32 PM

Yeah Milt, it's still there. That's a good idea though, maybe I'll befriend a local P-car mechanic someday.... get him to mess with it

skinnerd · skinnerd's Garage

I guess I'm with Tyson on this one. As long as the Webers are working...no need to mess with your setup. If you knew that the MFI system you have doesn't need any rebuilding, I'd say give it a try if you were game. But it does seem like a bit of a gamble. Rebuilding the MFI pump or throttle bodies ain't cheap, and for most of us would be an all but impossible DIY project. I'd just hang on to the MFI system... you'll know when it's time to install it...

ps Great picture of you... I wish I looked half as intelligent when I'm working on my cars!

Neilk · 09-10-2003, 08:44 PM

Bill,

Don't listed to Tyson, he doesn't know anything. I will reluctantly take your MFI and dispose of it properly. Just tell me how much the shipping is.

Neil
'73 911S targa with webers

Tyson Schmidt · 09-10-2003, 08:52 PM

Neil as absolutely right. I don't know anything.

But the only way I'm going to learn, is hands-on. So why don't you ship me that gawd-awful MFI set-up so I can tinker with it and maybe learn something. I'll even pay for shipping just so you can relieve yourself of the annoying storage duties. whaddaya say?

JSDSKI · 09-10-2003, 08:55 PM

Neil,

MFI systems run better in California. I will provide free long term care without increasing your medicare bill. You can come out and visit the old thing anytime. I'll even get you into the Tonight Show.

Your Pal,
Scott

RetroSC · 09-10-2003, 08:56 PM

Wow, I've heard this MFI stuff is worth some change... proven wrong once again by the pelicanites. I'll get this junk in the mail ASAP, it's kinda dirty though, hope you don't mind.

JSDSKI · 09-10-2003, 09:01 PM

You're tickets and limo are waiting.

dd74 · 09-10-2003, 09:31 PM

One question RetroSC: in your first post, when you said SC/CIS, I got the impression you were trying to adopt MFI to a 3.0. Or are you speaking of another car entirely?

Halm · 09-11-2003, 03:02 AM

You might give Gus a call at Pacific and repeat the PO's "tuning" issues with him. He could probably tell you if the pump needs work. And while you are at it, call Matt at Eurometrix and tell him the story too. Maybe you have a TB issue as well.

targa911S · 09-11-2003, 05:03 AM

it's an S ...it's supposed to have MFI. Period! You won't regret it.

RetroSC · 09-11-2003, 09:56 AM

dd74, yes different car. I also own a 78SC, this is on my 72S.

I think I've made my decision, for today anyway

.. gonna leave the carbs on for now, got enough on my hands with rest of the project. Maybe when it's all done, I'll readdress the issue. Or, maybe I'll be sick of working on cars altogether, sell it, and get a boxster

.

Kidding!