I recently converted my 401 from the single 4bbl to the 2x4. I had the original distributor converted to hei by the Sparkman. At the time I told him it was for a single setup and it was "curved" accordingly. The setup does not perform well off the line. My mechanic says he feels the old distributor has too wide a range of advance. (That's my understanding of what he said.) I have the GS "performance" distributor but did not install it. Apparently the performance distributor has a tighter range? I don't think the non-performance can be set to the 12deg initial setting (w/o welding to shorten some slot). Should I have the performance dist converted to HEI, or install it with points and see if it makes a dufference? What vaccum advance unit should I use? Any other adjustments or changes to milk all the romp out? The only differences I know of b/n the 425 GS and 401 non-GS set up is: Displacement (duh) Intake & carbs (duh) Performance distributor vaccuum advance Cam Help is greatly appreciated as always. Rick
Rick, you're on track with your thinking...our nailheads like a total of 30-32 degrees of timing. More initial advance, (like the dual quad spec of 10*btdc), will help low rpm power. I welded up the slot to achieve this. Others recommended putting a bushing on the pin which rides in the slot, maybe that would work. The vacuum advance only comes into play under part-throttle operation. Under full throttle, it shouldn't matter, since there is no vacuum there....it's all mechanical advance. An adjustable unit from Crane can be fine-tuned for better MPG. In a heavier car like your Wildcat, you might not be able to have an aggresive timing curve without it pinging...
I know little about custom tuning an engine. However, one thing I am certain of, the dual 4 dist. is definitely different. The initial timing is 12 deg., and the stock advance has a shorter stroke. Also, the vacuum port on the carb is ported vacuum. I don't know about other years, but on my old '66 the qjet had full manifold vac. going to the dist. and the timing was 2-1/2 deg. I had Carmen set up my dist. and I lost the specs, but I think I remember him saying the advance was all in by 2,800 RPM but I may be wrong. I think the vac. advance is 8 degrees but I may be mistaken about that also. Does that sound right?o No:
a dual quad distributor has the same advance curve as an engine with a dynaflow tranny. i got that straight from Carmen and another Buick restorer i know. Bob
Anyone know the correct tag number for the dynaflow/ 2-4s distributor? The one I have sitting here has 1111055 on it--it came from a '66 425 with a Q-jet on it. I am putting on 2-4's and want the correct dist.
Per the 1965 Chassis Service Manual #1111058 is a dual quad auto trans distributor. #1111055 is a 401 and 425 auto trans distributor
What would be the correct number for a '65 425 with 2-4's and a 4-speed trans.? That is what I need for my car--I am putting a dual quad 425 into my '65 GS 4-speed car.
My Buick parts books show #1111058 for all Dual Quad models. In 1967 this part was superceded by Part #1110993 with the same applications listed. I do not know if there were any changes made. John Zeleznik
I did a little research myself tonight and the buick '65 chasis service manual I have says that the 1111058 distributor is only for the 2-4's cars that have automatic transmissions. It lists the 1111055 as being the correct distributor for all 401 and 425 engines with single 4bbl. carbs, plus for the 425 2-4's with a manual transmission. Since my '65 GS is a 4-speed car, sounds like the 1111055 distributor I already have is the correct one. By the way, I dug up another nailhead distributor I had here and it has the number 1110993 on it--anyone have a clue what that one is for?
