How do you recurve distributors??

[al lkosmal]

Is there a good source regarding how to recurve and test distributors?? A book? I searched.... there is much discussion, but little direction. DIY or is specialized equipment required?

[mb911]

Specialized equipment is needed. I did mine at school (where I teach) It worked well and the car ran a bunch better. I just followed the factory curve chart provided from someone on the board and it took som adjustment of the spring tabs and then I was all set

[Rex Walter]

Al,

I have done a couple at home with a dial timing light. It's a little bit of pain because you have to remove the distributor to make changes, but using the engine as a distributor machine works just fine for the DIY. The advance curves have been posted here in the past, and I have them in shop manuals - you know where I live, and you're welcome to whatever I have.

Rex

[911pcars]

An advance curve is a combination of spring tension, advance weight and shape. There's also a stop that limits advance.

Recurving a distributor can be done in an engine but it's tedious. A proper distributor machine is best. A dyno is even better to plot an ideal curve for your particular engine configuration.

Sherwood

[Early_S_Man]

Here are a few resources:

http://www.jefframin.org/library/distributorRecurving.doc

http://www.imperialclub.com/Repair/Electrical/lit.htm

http://www.reincarnation-automotive.com/Duraspark_distributor_recurve_instructions_index.h tml

http://www.veloce.co.uk/shop/products/productDetail.php?prod_id=V4019&prod_group=Cars%20Vans%20&%20Trucks

http://www.mustangrestorations.com/publications/publications_detail.asp?id=7742

[al lkosmal]

Thanks for the info and the links folks. One of the many, many projects that I have going this winter. My garage is full of boxes. (Xmas presents to myself) My 911 is up on stands, engine out, suspension bits off, etc. Once I complete all of the suspension upgrades, new sways, bushings, Neatrix, etc., my new home brew, high-comp 2.7RS gets installed. I want to be able to recurve the standard 2.7 distributor, to work well with E-cams and carbs, if required.

P.S. Rex, how goes the battle. Got that 2.7S dialed in? When the big thaw comes let's get together for a run with the PNW crowd.

[Rex Walter]

Al,

I got it dialed in!!!! The only time I've had it out was to drive it to the paint shop. It was great! I finally got it running really good. Two more weeks for paint and I can put it all back together - engine rebuild, carpet, seat covers, stereo, and paint. Can't wait.

A run with the PNW crowd is definitely in the cards - but it sounds like I should stop in and see what you are up to!!

Rex

[Porsche_911s]

Al,

Did you ever find the info for recurving your 2.7 distributor?

[Jeff Higgins]

Back "in the day" (late '70's through mid '80's) when I was a fairly serious drag racer, there were kits available for most popular V8 distributors. You would typically get a few different weights and springs, along with a chart that would give a rough indication of which weight/spring combinations would provide a curve close to what you were looking for. I have never seen anything like this for our 911's. Are they out there and I have just missed them?

Wouldn't it be possible to simply get weights and springs (if still available) for a specific application and re-curve any distributor to any factory spec? Say, for instance, to re-curve an early "T" distributor into an "S" advance curve?

[RoninLB]

PMO used to recommend the 2.7 Euro/ RS dizzy. Now I think they sell their own model.

I have seen the 1968 911E dizzy curve recommended for E-cams and carbs.


Afaik pn 123 7010 00 is a Bosch dizzy rebuild kit.

I bought the 2.7 Euro dizzy Bosch pn 0.231.184.004 brand new for less than $300. Pelican doesn't list it in their catalog so you'd have to call them.

distributor lube...

Distributor tuneup

[Porsche_911s]

Pelican does have the Euro dizzy for $476.

So the 1968 911E kit works for the 2.7? If I remember from an earlier thread, the 2.7 CIS is just a "t" curve.

[RoninLB]

Originally posted by Porsche_911s
Pelican does have the Euro dizzy for $476.

So the 1968 911E kit works for the 2.7?

PP quoted me a competitive $279 two yrs ago.. Search around and tell them to match this price from so and so supplier.

I never did the rebuild as the Euro dizzy was so cheap.

[al lkosmal]

Thanks for the info guys. I am waiting for my latest box of goodies to arrive, containing a complete 3.2 manifold. I decided to go EFI with my 2.7X engine. I've purchased a Tbitz CIS to EFI Megasquirt kit and am going that way. I didn't want to use the modified CIS intake, so I bought the 3.2 manifold. I also purchased all the EDIS stuff I need to go crankfire. I will use my CIS distributor to fire this baby up and run it in, but then I will probably jettison the distributor and go EDIS w/Megasquirt n' Spark. I still want to keep this thread alive and I really appreciate all the info. As soon as I complete this project, I have another 2.7S engine up on the stand just waiting for some attention. The torture never stops.

[911pcars]

Someone ever thought of calling John Walker or Steve (Rennsport) for a quote on recurving the distributor? Might be a lot less than buying a new distributor.

Sherwood

[RoninLB]

Originally posted by 911pcars

Might be a lot less than buying a new distributor.

you're definately correct.

I wanted a rebuild, new curve, new cap and rotor. The new dizzy came with a cap and rotor so it was like I could sell the old good one to cover expenses of new over doing the full monty by myself. And I have a pretty part number.

Thing is the Euro dizzy runs 10deg initial w/35deg total. Either you want the curve or you don't?

[Hoss3.0]

A lot of talk about "E" cams and such, does anyone know the set up for a '72"T" that was converted to carbs. I tried a timing adjust at the end of last summer and couldnt get it to 35deg. It was stopping at about 28-30. There is no vacuum advance line on the dizzy anymore as I think it was removed with the MFI. So without the vacuum, I cant get the advance it should have. I will be recurving it soon on a test machine.

[RoninLB]

Originally posted by Jeff Higgins

Wouldn't it be possible to simply get weights and springs (if still available) for a specific application and re-curve any distributor to any factory spec? Say, for instance, to re-curve an early "T" distributor into an "S" advance curve?

not exactly.

sometimes the pin on the dizzy cam-T section that holds the spring has to be moved inward or outward for the low rpm adjustment. Sometimes you can just bend the pin. I never had to do one.

[911pcars]

"I tried a timing adjust at the end of last summer and couldnt get it to 35deg. It was stopping at about 28-30"

What was the initial (static) timing at idle? You have to factor in the static timing setting along with the ignition advance allowed inside the distributor. Thus:

5ºATDC + 35º distributor advance = 30º overall advance
and
0º (TDC) + 35º = 35º total
and
5º BTDC + 35º = 40º total

The above is what occurs using a T distributor. You either have the correct amount if timed at TDC or ATDC and too much advance if the static timing is set before TDC (BTDC).

The S setup is more like:
5º BTDC + 25º dist. advance = 30º total advance
where there is more low rpm ignition advance (for slightly better torque) yet the total is not so much as to lead to detonation. These are general guidelines. If your engine is modified beyond what the factory provided, then it's only an approximation of an ideal spark advance curve for your engine.

In modifying a distributor to "S" specs, in order to increase the static timing, you must also limit the spark timing allowed by the distributor (via the stop pin) so as to not exceed a safe total spark advance. You do this in addition to modifying the weights/springs to conform to the advance curve of the "S" distributor (degree advance/rpm).

If Porsche made 100K 911s each year, you'd probably see several distributor advance kits available from several vendors.

Sherwood