Carbs on a 3.2 Motronic engine?

thrown_hammer · 07-12-2004, 05:55 AM

Is it possible to run Weber or PMO carbs on a 3.2 and use the DME to control the spark side? Does anyone make a chip to do that? Is it even possible?
I dont need a bunch of posts from people that wouldnt do it. I already know that.

jmz · jmz's Garage

I have heard of this being done. I can't offer any real world experience unfortunately.

I have always liked carbs but not so much anymore. I am actually getting tired of the stincky, troublesome things. I also don't much care for mild cams either. ...so carbs are good in that way.

I am actually thinking of going to EFI on my car.

BB911SC · 07-12-2004, 07:40 AM

It should work. Spark is run on a map and is independant of fuel. The only problem will be that you will not be able to optimize the timing for your new found power potential. If you upgrade any internals, you should probably go to an old recurved dist or one of those crankfire units.

JTH 36 · 07-12-2004, 08:20 AM

I am running carbs on my 3.2.

I bought a Long Block along with a recurved distrubutor from Henry at Supertech Perfomance in SOCAL.

Henry should be able to help you out with any questions you have on the conversion.

He has done quite a few of them. His website address is

http://www.supertecperformance.com/

Jeff

thrown_hammer · 07-12-2004, 08:36 AM

Cool. I won't bother him yet. So you dont use the DME at all?

JTH 36 · 07-12-2004, 08:48 AM

Nope,

With the recurved dizzy we were able to use my original CDI Box.

My Car is a 72E coupe. We used Webers, CDI box, New Distributor, and SSIs.

I dynoed it last year and got 220 HP and 213 ft lbs of torque at the wheels.

I think the Carbs and exhaust made a pretty good difference in the power.

jmz · jmz's Garage

alot of people just use the 2.7RS type dizzy. ...gotta go back to points or a pertronix though. The SC dizzy spins the wrong way.

JNadal · JNadal's Garage

http://brentwoodrocketscience.com/

TRE Cup · TRE Cup's Garage

we've done a number of 3.2 dme to carb conversions. PMO has the kits or hardware to help you complete the conversion if you have carbs and manifolds already. On the distributor- get a new copper coated drift pin that holds the drive gear on the bottom of the shaft. Remove the drive gear from the 3.2 dizzy and install it on a 2.7 RS dizzy (dizzy available from our host or PMO) Why? the 2.7 rs dizzy has the wrong size gear and will be a little sloppy with timing curve. With headers or SSI style heat exchangers the motor really rocks! easy 250 hp with no other changes
have fun

cvfncrew · cvfncrew's Garage

I have a rebuilt set of weber 46s. Will they work on a stock 3.2l?

Jeff Alton · 07-13-2004, 11:52 AM

Can you just get a chip programed with correct advance curve, or do you really need the 2.7rs dizzy? I remember BA saying they did one and kept the motronics for ignition.

Jeff

TimT · 07-13-2004, 01:48 PM

I have a 3.2 w/ 10.5: pistons, 20/21 cams, weber 40's, SC distributor ( drive gear swapped, and recurved),MSD 6AL in my 914

its "fun"

stlrj · 07-13-2004, 04:32 PM

With the air flow meter unplugged I wouldn't get any advance on my 3.2. Looks like the DME needs the AFM signal to get the advance to move.

Joe

thrown_hammer · 07-14-2004, 10:01 AM

Quote:

Originally posted by catca
Can you just get a chip programed with correct advance curve, or do you really need the 2.7rs dizzy? I remember BA saying they did one and kept the motronics for ignition.

Jeff

I just read that last night. Doesn't mention who made the chip though......

Steve W · Steve W's Garage

It doesn't matter who makes the chip, it'll still work, you just won't get the vacuum advance variability without the air flow meter in the equation. RPM dependent timing should still work, and advance timing as the rpm's go up, as you still have an rpm sensor. You could lock the WOT microswitch on and thus be at the ignition curve of the WOT map all the time. The car should still work pretty well, but might not be as efficient at light part throttle loads. I might look into something like a map sensor as a substitution for the vacuum advance signal and feed that to the AFM plug. There are four wires on the AFM plug. Ground, AFM power (about 4.5 volts), afm signal out, and air temp sensor. You could wire the first three to the MAP sensor, and put a fixed resistor of about 2.2K on temp sensor wire to simulate a stock sensor.

Jeff Alton · 04:21 PM

Hmmm, this has some promise. Steve, how well will this car run with the carb/motronic combo? Or is the 2.7rs dizzy the only way to go for best performance??

Jeff

thrown_hammer · 07-15-2004, 05:16 AM

I will have to read it over again, but the engine was a US spec engine with no internal mods. They changed the exhaust and went to carbs and put out some big numbers. I think there is a market for such a chip.....

ruf-porsche · ruf-porsche's Garage

Quote:

Originally posted by jmz
alot of people just use the 2.7RS type dizzy. ...gotta go back to points or a pertronix though. The SC dizzy spins the wrong way.

Couldn't you just reconfigure the plug cables on the dizzy to match the revolution of the dizzy?

jpnovak · 07-15-2004, 10:28 AM

Ruf, You can not just change the direction of the plugs wires on an SC dist. There are two major differences between the SC and the 2.7/3.2 dizzies. First is the pinion gear on the bottom will not mate with the input shaft. Second the weights on the dist are orientated to spin the wrong way. You will have zero advance.