zero backlash for distributor drive gear

rennzeit · 03-04-2017, 07:59 PM

Hi,
I'm building up a 2.4 (85x70.4) engine with GE60 cams on my numbers matching engine case.

Now I'm checking the distributor play and getting none. The distributor fit is quite tight as well. I checked and the gear is the right smaller (25.1mm) clockwise size, and the crank gear is also the correct clockwise gear. The spec books and manuals all say to check the distributor backlash, but offer no suggestions of what to do if it is too tight.

Any suggestions?

thanks,
dug

faapgar · 03-05-2017, 07:07 AM

It is possible the gear on the crank is from a 3.2.Looks the same but has less backlash than a 2.0 - 2.7.Fred

rennzeit · 03-05-2017, 10:46 AM

Hi Fred, seems like it would be the other way around?
Distributor gear on 2.0-2.7 is 25.1mm. 3.2 is 25.8.
So wouldn't late crank gear have more backlash?
Or did they also change the shape of the "teeth".
Is there a part number on the gear?
thanks,
dug

faapgar · 03-05-2017, 12:17 PM

You are correct.3.2 crank gear would increase backlash.There is a 930 part # on the 3.2 gear.Fred

strictly · 03-07-2017, 04:09 AM

Quote:

Originally Posted by dug@project914

Hi Fred, seems like it would be the other way around?
Distributor gear on 2.0-2.7 is 25.1mm. 3.2 is 25.8.
So wouldn't late crank gear have more backlash?
Or did they also change the shape of the "teeth".
Is there a part number on the gear?
thanks,
dug

Hi Dug, can i ask where you measured the distributor gear? I have a 3.2 on carbs, and a recurved 2.7 distributor (BUT NOT YET FITTED) - but it sounds like i need to change the 2.7 distributor gear to the 3.2 one for it to mesh correctly with the 3.2 crank gear (i'll be unable to measure back lash, so for me i'll just have to assume its okay).

Sound right?

I can't find the 2.0-2.7 distributor gear part number, but i did find the one for the 3.2 which I can order 93060242402.

faapgar · 03-07-2017, 10:39 AM

Hi,it has been years but I had a customer with a 2.4 S DISTRIBUTOR in a 3.2 and there was more backlash than stock.I thought it might beat up the brass drive gear but after 5 years & 20,000 miles it stayed the same.Not ideal but did not fail.You can check the back lash with a dial indicator.Fred

strictly · 03-07-2017, 11:54 AM

Quote:

Originally Posted by faapgar

Hi,it has been years but I had a customer with a 2.4 S DISTRIBUTOR in a 3.2 and there was more backlash than stock.I thought it might beat up the brass drive gear but after 5 years & 20,000 miles it stayed the same.Not ideal but did not fail.You can check the back lash with a dial indicator.Fred

Hi Fred, good to know about that experience, so i could run with the 2.7 dizzy gear if i wanted to, thats good for piece of mind, i'll decide between the two options, when i look at it deeper when im ready to fit the thing, bit of work yet.

P.S Dug, i just read you signature, some nice /6's there - is that a genuine GT?

rennzeit · 03-07-2017, 12:23 PM

Quote:

Originally Posted by strictly

Hi Dug, can i ask where you measured the distributor gear? I have a 3.2 on carbs, and a recurved 2.7 distributor (BUT NOT YET FITTED) - but it sounds like i need to change the 2.7 distributor gear to the 3.2 one for it to mesh correctly with the 3.2 crank gear (i'll be unable to measure back lash, so for me i'll just have to assume its okay).

Sound right?

I can't find the 2.0-2.7 distributor gear part number, but i did find the one for the 3.2 which I can order 93060242402.

Hi,
The 3.2 distributor doesn't have a magnetic pickup or points, because the 3.2 DME controls the ignition using a pickup on the flywheel. So you can't just swap to a 3.2 distributor. The only clockwise distributor with 6-pin CDI style magnetic pickup is the early 76-77 turbo, but it's rare and also used the smaller gear like the 2.0-2.7, so you would have the same problem you have now. You could find a junky old 3.2 distributor to get the gear and swap it, but I haven't done that myself and I'm not certain it would swap without machining. Sound like with Fred's experience, your best option is just run the 2.7 dizzy.

The alterative, which I'm considering since my bottom end is all together already, is to switch to a crank fire setup.

cheers,
dug

rennzeit · 03-07-2017, 12:29 PM

Quote:

Originally Posted by strictly

P.S Dug, i just read you signature, some nice /6's there - is that a genuine GT?

It's a factory 914-6, and as real as any non-factory built GT with all the GT parts I've found for it. It's a slippery slope and I think I've hit rock bottom! The engine is together now, it's the one I'm talking about in this thread. And the factory GT flares are on and it's been painted. Now I just have to put the rest of it together