Distributor Timing Curve
 

Does anyone have specs for a '67 Sprint for the original timing curve, i.e. mechanical and vacuum advance? I'm getting conflicting information from sources online. Currently in the process of setting up my Holley Sniper to control the timing on mine and I'd like to get it as close to the factory setup as possible for initial fire-up.

Thanks in advance!

I don’t have an answer to your question but was curious what distributor you are using. When I looked into this. , I couldn’t make it work.

1966 Sun Tune Up Cards
 

Should apply to '67 as well.

Jeff:
Do you have only these two sheets or is there a depository of a bunch of them, including non-Pontiac, available somewhere on the interweb? Would be nice to be able to access them all.

Thank you Jeff. The distributor in my engine is part number 1110384 which I can find nothing on... I hooked the timing light up last night and the vacuum advance does give 15° of advance (at the crank) but I think there may be something wrong with the mechanical side of things. I can only make it advance a total of about 11° by 3000 RPM and about 18° by 4500 RPM. Everything I can find says that full mechanical advance should be in the neighborhood of 26 to 28° and as much as 40° for a '67 with a 4bbl :eek: Everything is pretty consistent about 14-15° of vacuum across the year ranges. I guess I'm going to set up the timing map based on the numbers that I can find vs what mine is actually doing. This may be why the Holley computer is trying to pull a lot of fuel out of the map in the cruise area around 3000 RPM. If the mechanical advance is not giving it enough timing in that area, there will be unburned fuel resulting in a rich mixture that the ECU is trying to compensate for by leaning out the map. Thoughts on this?

Here is a shot from a 1969 Motors Manual:

T
I was wondering how you are able to use the sniper timing control with a factory distributor.

I thought you had to have a dual sync type distributor or at least a Hall effect setup to provide the signal.

Chris

I am going to try it using a Pertronix Ignitor series 1. According to Pertronix, the 1 series is the only one that can be static timed because it is nothing more than a Hall Effect switch. The "2" series has built in dwell control and the "3" is a multi-spark unit. There was a guy on the Opel GT forums that made it work. The key is that you have to lock out all of the mechanical and vacuum advance in the stock distributor as well as come up with a plan be able to index, or phase, the rotor. At that point, you install it the same way you would an MSD distributor with the Holley Sniper. Get the engine to 50° btdc, install the distributor and find the "fire" point of the Ignitor and lock it down. Then, move the crank to about 30° and point the rotor directly at the #1 terminal of the cap. From there you follow the same rotor phasing steps that any of the EFI distributors use. I've got the theory down in my head at this point, now all I need to do is create a timing table and do the physical installation of the "new" distributor. Here is what I have done to the distributor as of now.

Well, the theory turned out to be 100% correct! It took about two hours to do the complete installation and timing synchronization and the engine has never been happier. There is a guy on the Holley forum with an excel spreadsheet that you enter initial timing, mechanical advance and vacuum advance along with RPM and vacuum values for both respectively and it calculates a timing table to feed to the ECU. After all is said and done, the engine is now pulling 21" of vacuum at idle and has a much better temperament while cruising down the road. Still working a little bit on the WOT tuning but it's close.

We ended up using the following for parameters:

Crank Timing: 12°
Base timing: 15°
Mechanical Advance: 22°
Start: 1000 RPM
All-In: 4000 RPM
Vacuum Advance: 8°
Start: 5"
All-In: 10"

I may end up adding a couple more degrees of mechanical and/or vacuum but we're going to give it a little run-time and see how she responds.

Nice work!
I had looked for information on a DIY distributor that would work for timing control but never came across anything.
How did you index the rotor?

Thank you!

In the last pic that I posted above you can see a small set screw in the back of the rotor. After using a dremel to remove the indexing tab on the inside of the rotor and tapping a threaded hole, it is now adjustable to any position you need it to be in.

So kind of a set screw. Sounds like a good way to do it.

Exactly. I couldn't find a set screw that was the right size so I took a bolt and cut it down then used a saw to make the slot for the screwdriver. Worked out great!

1110384 starts with 0-4° @ 950 rpm, 16-20° @ 2100 rpm and max 20-22° @ 4800 rpm.
Vacuum advance 1115369 starts @ 4-6 in/hg and gives max 15° @ 9.25-10.25 in/hg.

All degrees and rpm´s @ crank.

Thank you for that info. Turns out, that is very close to the timing map that I built and uploaded to the ECU yesterday and it's very happy with it. The only changes I made from the parameters listed above was to increase the vacuum advance parameter to 15° from 8° then changed the idle to 23° and smoothed out the transitions. I may add a couple degrees at lower RPM to give it a little better punch out of the hole, but so far it's running very well.