Retrofitting a 69-73 MFI engine to a 1966 carb'd 911?

[blau911]

I was wondering whether or not I would need a later style (1969-73) wiring harness in order to retrofit a 911S MFI engine into a SWB 911 that originally came with carb's? Anyone else done this? I would like to think it's easy, but I have learned to expect the unexpected over the years. And it is never easier than what you would originally expected...

[304065]

Well, that depends on whether or not you want everything to work correctly.

SWB cars are pretty simple. See my post on "SWB engine electrics" for more details, but basically, their electrical console only has the voltage regulator, the coil, a ballast resistor, a relay for the ballast resistor and the fuel pump.

MFI cars are slightly more complicated, they use (after 1969, anyway) a 14-pin connector like the later cars, that has the following circuits:

Thermo-time switch for cold start system (remember, carbs have an accelerator pump and no chokes)
12V connection for CDI unit
Blue wire for D+/61 for alternator (the '66 will have the blue wire running directly to the back of the alternator from the voltage regulator)
Tachometer pulse circuit for MFI speed switch
Oil pressure and oil temperature feeds to gauges; and
Starter circuit (ties into thermo-time switch and to starter solenoid)

So unless you get the electrical console from an MFI car, I would say you are looking at a lot of work to make everything tie into the SWB electrical system-- and it's probably impossible to do that without hacking the original system pretty badly. Even if you do source the MFI console, every one of the useful connections (not all 14 are used, unless you have a sportomatic, but even then, a couple are unused) has to be routed to the input for the MFI electrical console to make it work.

The bigger question is, what flywheel and transmission will you use? The 911S MFI didn't come out until 1969, so I assume yours is either a '69 with a 901 box, a 70-71 with a 911 box or a 72-73 with a 915 (that about covers it!)-- all these boxes have different CV joints than the '66 trailing arms. And the 911 and 915 boxes will require a different flywheel than the 901 trans, their flywheels are flat as opposed to cup-shaped. This would be the real obstacle if you ask me.

Finally, what's the matter with the SWB engine in there now? Why not rebuild it as original, with maybe an update to 2,2 or even 2,4 using the original case and carburetors? Nobody would be able to tell from the exterior, for example, that you had modified the Al case motor to 2,4 S specification-- except for maybe some external oil cooler lines. Something to think about when you consider how few '66s are left in original condition, and how difficult they are to put right after the original engine is gone.

[blau911]

Firstly John,
Thanks for the detailed response. It at least gives me a clear understanding of the issues I would need to deal with.
As for upgrading using the original early 911 engine rather than swapping out for a newer/bigger/faster one, I am generally with you in practice as well as in spirit. Here is my current car:
http://forums.pelicanparts.com/showthread.php?threadid=233864

I am playing with the idea of buying a 2.2S motor. I don't have a car for it yet, but I was leaning toward an early SWB 911, or a 69-73 T roller, or one with a blown engine. It would seem that I would be better off focusing my search on a 72-73 US 911T since the wiring on these cars is already set-up for the same MFI, and also had the same CV joints I would need.
Does that make better sense to you too?

[304065]

Blau,

Ahhh, NOW I understand! By the way, my '66 was originally Irish Green 6606, although some prior owner had gone to Schwarz over the years. When the body is restored it's going back to the original color, and your photos are an inspiration!

First of all, other than storage space, I can't think of any reason why you wouldn't want to get a 2,2S and hold onto it. Obviously, its highest and best use, and greatest value, is in an original 70-71 911S, but waiting around for an S roller could be difficult, I would agree. There are plenty of LWB cars out there, and the 911Ts can still be inexpensively found. . . for the time being anyway. My 911E is actually a 911T shell with mostly 911S parts, the engine is built on a T case, but it's a dedicated race car, always will be.

Dropping a 2,2S into a 911T would be easy to do- the flywheels would match up and if you found a 911 gearbox it would be a nice fit. The AGAOVZA gearing of the 911 box is a nice fit with the 2,2's power and torque. Only issue that I can think of would be adding external oil cooling, but with kits like the Elephant Racing one out there, that's easily added.

Still, given your respect for originality I'm not opposed to the idea of dropping the MFI motor into an SWB car, particularly if it were a Light Ivory 911R-touring concept-- you could get a clear fiberglass engine shroud and do it up to resemble a fuel injected 906-- there is nothing like the throttle response and sound of MFI, and you'd see about 10 hp over carburetors. As long as you were willing to accept some compromises in the subsystems, mabye like this:

MSD "RPM activated Switch" in lieu of MFI speed switch to control overrun

SPST momentary-on pushbutton on dash to control MFI cold-start solenoid, or use '69 2,0 911S pump with integral cold-start solenoid.

MSD 6AL ignition box, or Bosch CDI could be mounted to firewall.

Tach drive circuit comes straight from MSD square-wave output, or from pin "C" on the Bosch CDI (the points trigger)

Yellow starter wire-- as original on '66, just connect it to the solenoid on the 2,2

Blue wire for D+ /61- as original on '66, just connect the blue wire to the new alternator. Be careful hooking up the other wires as the colors are not the same from SWB to LWB.

Anyway, you might have to find a place to hide the MSD box and the RPM switch, maybe in front of the engine on the firewall, or even better, forward in the car somewhere, under the dashboard maybe? But it could be done, and the lighter weight of the mag case would be an advantage, definitely.

Good luck! I really like that Irish Green paint.

[blau911]

Thanks John.
I am also a big fan of irish green (of conda green and viper green too).
When you get around to it, here is the paint formula I went with:
C2S SG111.50
Glasurit - 55
SG111.50

1 Gallon
352-91 = 658.9
A696 = 1858.2
M105 = 715.2
A926= 287.5
A125 = 25.6

Don't rely on Glasurit or any of the other local paint shops to give you the right formula for irish green. Everything that they mixed for me looked like British racing green, which doesn't do irish green justice in my opinion. Irish green has a touch of emerald in it that doesn't make it as dark or murky. Irish green really lights up into a deep warm green when the sun is on it, as you can see from the different pictures I posted on the above link. In fact, I spent a lot of time looking at early cars supposedly painted irish green, only to find that many of the repainted cars were darker, or had more yellow in them. Even the formula that Glasurit uses now is different from the original formula back in the 60's because lead is no longer allowed in paint as it was back in the 60's. The alternate formulas that were used are not the same, just a rough approximation.
I ended up taking a paint chip off of an early car with original irish green paint and had them scan it to produce the formula. The formula above is right on the money (I re-checked the numbers for you too to make sure I didn't make any mistakes).
The company that mixed it for me sells only Glasurit products. They are named Albert Kemperle. They have offices around the country, but I used their office in West Palm Beach. Tehir tel number is (561)842-8556
As for living in NY Hell's Kitchen, I lived in Manhattan for 14 years, and had a 69 911E up there for a summer. Never again.
The only place to keep a nice early car up there is in your living room!!!
BR
Garth Wagner

[Early_S_Man]

Garth,

If you got the engine compartment electrical panel along with the MFI engine ... it would really be a very easy job to adapt it to the early wiring harness with a new replacement 'kit' for a 14-pin connector. All of the exclusive MFI-only wiring is contained in the electrical panel, and everything to the front of the car is generic.

Either way ... it isn't a formidable task!

[Shuie]

I would try to score an entire, non hacked, relay panel from an MFI car. Wire up your own 14 pin chassis wiring harness and plug the engine harness and chassis harness right into it. The electrical seems reasonably doable with the MFI relay panel, and very difficult without it. The fuel system would require some work also. Good luck.

[Grady Clay]

I agree.

We can design a modified relay panel that does no harm to a SWB 911 yet still has all the electrics for MFI and uses the ’70-> 14-pin connection to the engine. You absolutely don’t want to molest the chassis wiring. Also keep in mind that a ‘69 is unique. On the other hand it can have the MFI wiring and still use the ’65-’68 wiring for much else. It depends on what you want.

Best,
Grady

[Pele911]

Blau,
Beautiful car.
let me know if you want to sell your webers. Good luck with the MFI

Jeff

[blau911]

Originally posted by Grady Clay
I agree.

We can design a modified relay panel that does no harm to a SWB 911 yet still has all the electrics for MFI and uses the ’70-> 14-pin connection to the engine. You absolutely don’t want to molest the chassis wiring. Also keep in mind that a ‘69 is unique. On the other hand it can have the MFI wiring and still use the ’65-’68 wiring for much else. It depends on what you want.

"We can design a modified relay panel that does no harm to a SWB 911 yet still has all the electrics for MFI and uses the ’70-> 14-pin connection to the engine. You absolutely don’t want to molest the chassis wiring. Also keep in mind that a ‘69 is unique. On the other hand it can have the MFI wiring and still use the ’65-’68 wiring for much else. It depends on what you want".

Hi Grady,
Tried PMνng you with this message, but your PM box is full...
How much would it cost to do this? There is a good chance that I would get the entire electrical panel with the MFI engine. Assuming this is the case, how difficult would it be to wire myself, and would I need less than the entire relay panel you would offer? With your deisgned wiring panel, would there be alot of cutting and splicing, or would it be a plug and play set-up?

[Grady Clay]

Blau911

I intentionally leave my PM box full. The only way to reach me is by e-mail at gradyclay@hotmail.com


The three issues are electrical, fuel and clutch as everyone has said above. The clutch is very straightforward. The fuel requires three holes in the LR inner fender to mount the MFI fuel filter console bracket. The fuel pump should be mounted on the front cross-member. The most difficult is the second fuel pipe at the tunnel. I ran mine alongside the right of the tunnel and protected it with two layers of heat shrink. There should be no connections in the cockpit.


Here I’ll only address the electrical for installing a ’70-’73 MFI in a SWB (’65-’68) 911. I consider it imperative that if you are going to the effort you should do this absolutely correctly (OE wire and connectors and document it properly. As said above, you want to make everything where it simply plugs into the original wiring with no splices or other alterations.

The best conversion is to use the complete ’70-’73 engine wiring and mating relay panel, complete with 3-pin Bosch CDI. You then need to custom manufacture a chassis-side 14-pin connector with pigtails for connecting to the OE chassis wiring with push-on connectors.

The custom 14-pin pigtail connects the oil pressure gauge, the temperature gauge, tach, switched ignition, starter, the MFI cold start nozzle and a battery connection. This would also be the connection is you wanted to install a heated rear window.

There is one additional red wire to be connected from the B+ at the alternator to the single terminal that needs to be repositioned from the OE relay panel to the new panel.

The engine-to-relay panel consists of three harnesses; the 14-pin connector, the 3-pin CDI connector with its RF ground and the harness from the alternator to the transmission & starter. The two harness wires for the back-up light switch should be sealed off as that connection is provided from the main harness in an SWB. The only addition is a 5 mm red wire from the B+ at the alternator to the repositioned single screw connection newly mounted on the relay panel.

There is a tach compatibility issue if the engine and relay panel are ’71-’73. The addition of the ’69-’70 “SCR” is easy.

Don’t forget the ground wires from the relay panel and the fuel filter console.

The connection to the front mounted electric fuel pump should be a small separate harness like a ’69 E&S and ’70 T, E&S. It should go from a switched terminal at the fuse box and the chassis ground to the pump.

There are probably a loop or two in the B+ circuit that can be eliminated when planning the harnesses with a wiring diagram.

All of this should be done where it appears original. You can use original color-code wires from a donor chassis. The connectors are available from Wurth suppliers. All the harnesses should be in black heat-shrink tubing.

Careful documentation of what you have done is absolutely necessary. You want to be able to trouble-shoot it easily and be able to duplicate it if you want.

Best,
Grady

[304065]

OK, when Grady says absolutely correctly, he means ABSOLUTELY correctly. The LAST thing you want is to make a hack of the '66 and spend the rest of your natural life chasing electrical gremlins.

So here's an annotated version of the diagram, showing you what wires are what color, and what is basically connected to what. Read this in connection with my other diagram, from "SWB engine electrics."

The ENGINE harness (14-pin connnector is as follows)

1 - Yellow to starter #50 and to thermo-time-switch
2 - Unused
3 - Green/Black to oil temperature sender
4 - Green/Red to oil pressure sender
5 - Green/yellow to reverse light switch (on trans)
6 - Grey to reversee light switch (on trans)
7 - Red/Black to thermo-time-switch
8 - Grey/Red to overrun microswitch
9 - Black/Purple (tacho pulse lead) to points connection on distributor
10 - Unused
11- Blue D+/61 to Alternator
12 - Brown (ground) to Alternator D-
13 - Black to Alternator DF
14 - Red to Alternator B+

Now, the SIZES of these various wires vary, my recommendation would be to consult a later wiring diagram, such as the one for the SC, where the wire diameters in mm are listed, and use that size. I don't have time to cross-check that right now, though.

If you have an engine harness for a 70+ car, those wires should basically be included.

Now for the tricky part: the CAR side of the harness, that feeds into the INPUT 14-pin connector on the electrical console.

1 - Yellow to ignition #50
2 - Unused
3 - Green/Black to oil temperature gauge
4 - Green/Red to oil pressure gauge
5 - Green/Yellow to fuse #8
6 - Grey to reverse light
7 - Grey/white to cold-start solenoid on fuel filter console
8 - Black/Purple (tacho pulse lead) to tacho /1
9 - Brown Ground
10 - Black to defrost switch
11 - Unused
12 - Blue D+/61 to Alternator warning lamp
13 - Red to Switched +12v
14 - Unused

[304065]

[304065]

Now, to tie the two together

1 - Yellow to ignition #50 - IN 66 Harness
2 - Unused
3 - Green/Black to oil temperature gauge- IN 66 Harness
4 - Green/Red to oil pressure gauge- IN 66 Harness
5 - Green/Yellow to fuse #8- IN 66 Harness
6 - Grey to reverse light - IN 66 Harness
7 - Grey/white to cold-start solenoid on fuel filter console- NEW
8 - Black/Purple (tacho pulse lead) to tacho /1 - IN 66 Harness
9 - Brown Ground- IN 66 Harness
10 - Black to defrost switch- NEW, '66 did not have electric defrost
11 - Unused
12 - Blue D+/61 to Alternator warning lamp- IN 66 Harness
13 - Red to Switched +12v- IN 66 Harness
14 - Unused

That's about the size of it.

For wire, either:

www.ynzyesterdaysparts.com
or
www.eagleday.com

[304065]

Some wire sizes from the SC diagram.

D+/61 Blue to pin 11, 1.5mm^2
DF black 1.5 regulator to alternator
B+ red to starter, 10mm (that's a big fat one)
B+ red to pin 14, 2.5
Tach pulse lead (TD on the six-pin box) black/purple 1.0
Yellow from ignition switch to starter- 2.5
Red/black from ignition switch to engine compartment- 2.5

and so on.

[ttweed]

Now that we (hopefully) have all the wiring issues covered, I have another question about this kind of engine swap. My mechanic says there is a clearance problem with the body seam on the crossmember at the back of the engine bay in a SWB car when an MFI engine is fitted, due to the pump drive off the cam. He said the early SWB cars have longer seam flanges than the later cars, and they need to be altered (cut or bent over) to allow the belt drive and cover to fit back there. Anybody BTDT and can confirm or deny this?

TT
(contemplating a 2.4S MFI swap into my '67S)