C2:67 Distributor-Correct Position?

[Gerard F.]

Thanks to all who gave me advice on the distributor. I got my original back on and timed. Is this position, the correct one for an original:


The vacuum advance is about 45 degrees right of centerline and the adjustment door is just about straight forward. There is also less bend in the tach cable then with the reversed dimple replacement. However to get 6 degrees BTDC the vacuum can is only about 1/8" off the coil.

I found that the original distributor moved about 14 degrees CW from the position of the reversed dimple distributor that it replaced. Here's the position of the reversed dimple distributor:


I guess if I had an automatic where the spec was 4 degrees retarded, the reversed dimple replacement would be the way to go. With my original and the position in the picture, there would be no way to get to 4 degrees retarded without going to the next gear tooth CCW or a full 28 degrees CCW. Maybe that's why they make some of these replacements with the gear reversed to the dimple.

I just took a run, and everything runs like brand new with my original distributor and original patent pending cap. So I think I'm ready for Flagstaff, here's the distributor I'll be coming with:


Having fun,

Jerry Fuccillo
#42179

[Duke W.]

Re: C2:67 Distributor-Correct Position?

That appears to be correct. With the 10-16 degrees initial timing range for some earlier 327s that had only 24 centrifugal instead of 30, the distributor would be clocked up to 5 degrees CCW relative to where yours is at 6 degrees. If the gear is on backwards the timing cannot be advanced to the upper limit, which was useful back when octane was higher. If the gear is on backwards you can barely achieve 10 before the vacuum can hits the manifold. Then if you reclock it one tooth CW the vacuum can hits the coil bracket with the timing overadvanced.

The initial timing range for your engine is 6-12. If you want to experiment, you can advance it to the detonation point within this range, then back it off about 2 degrees. If your engine has AIR then it has ported vacuum advance, which is a recipe for hot running at low speed, and it will increase the propensity to detonate when you increase load because the combustion chamber boundaries run hotter.

The PG/AIR setup has a centrifugal curve with 40 degrees maximum advance combined with 4 degrees ATDC initial timing. The purpose was to retard the map below about 1500 to heat up the exhaust gas. It's possible that the gear was installed "backwards" on that distributor in order to achieve the 4 degrees ATDC initial timing. The only way to know for sure is to see the assembly drawing for that particular distributor. The PG/AIR setup was an oddball driven by the California tailpipe emission test in '66 and '67.

I don't recall ever seeing a PG/AIR 300HP engine, but the spark advance map is a recipe for detonation and burned valves. If I owned one I would convert it to the non-AIR 300 HP setup including full time vacuum advance. As long as the pump was installed the change would be undetectable in Flight judging.

Duke

[Gerard F.]

Re: C2:67 Distributor-Correct Position?

Duke,

Thanks for your advice. My car is a Pennsylvania car, no A.I.R., just a 327 base engine, 4 speed with a 3:08 rear. I'm now back to my original configuration with my original distributor on an untouched engine. It drives now like it used to in 69 when I brought it to CA from NY. Got an average 20 mpg at high speed on that trip.

So now I'm a happy camper, this was the last major thing before going to Flagstaff later this month. The rest is just cleanup. Maybe, I'll see you there.

Do you think I'll ever see 20 mpg again with the CA gas. (I do about 15 now on a trip with the replacement dist., but I just had to turn the idle down)

Thanks again,

Jerry Fuccillo

[Duke W.]

Re: C2:67 Distributor-Correct Position?

The year round oxygenate requirement in CA gasoline reduces energy content by about 2-3 percent relative to non-oxygenated fuel, so fuel economy will be that much less relative to vintage fuels that had no oxygenate. Some markets require onxygenate only in winter.

Schwarzenegger even asked the EPA for a waiver since the value of oxygenated fuel vis-a-vis' reducing emissions is questionable, but it's turned into another federal farm subsidy program.

Increase your initial timing as I previously suggested and you might see slightly lower fuel consumption. Also keep cold TP at 32 all around and maybe even increase to 35-36 for long highway trips. Higher TP reduces rolling resistance.

I won't be making the trip to Flagstaff.

Duke

[Paul L.]

Pic - Dimple Incorrect 10*

[Paul L.]

Re: Pic - Dimple Correct 10*

[Gerard F.]

Yep, 14 degrees difference! *NM*