Dan, the best article on the load-o-matic I ever saw was written by Barney Navarro. I can't remember where it was printed (circa 1956) but it was very in depth and made it sound like the finest ignition system ever devised.

I found this on the net: part of a Navarro article on load-o-matics.

"Ford's latest method of controlling spark advance employees an ingenious system utilizing manifold vacuum and venturi vacuum. With this system the flyweight governor is eliminated and in its place is nothing but a diaphragm. This diaphragm not only advances the spark to conform to rpm changes but is also makes load compensation adjustments. All ´49 through ´54 Ford and Mercury carburetors have in addition to the conventional manifold vacuum takeoff, such as is found in the throttle body of most passenger car carburetors, a connecting venturi vacuum passage. The manifold vacuum, as usual, is obtained from a small port in the throttle body located slightly above the butterfly's closed, position, on the side where the butterfly swings upward to open. When the throttle is closed at idling, the vacuum port does not receive vacuum because it is on the opposite side of the butterfly. As the throttle is opened slightly, this port is uncovered and a vacuum is applied to the distributor diaphragm to advance the spark. If the throttle is fully depressed, the manifold vacuum is destroyed and no advance takes place. As speed increases, however, the venturi vacuum increases gradually and advances the spark to conform to the rpm. Letting  up on the throttle increases the manifold vacuum (Provided it isn't let up all the way) and the spark receives load compensation. A balance is always  maintained so that the correct amount of spark advance is supplied for all speed and load conditions. "

check out Red's Headers website for full article. I don't think this is the article I had in mind.

PS, should be able to ship Monday

http://ford-y-block.com 

20 miles east of San Diego, 20 miles north of Mexico

Pete,



Wrong end of the stick? The two coil springs attached to the breaker plate mostly control the rate/extent of spark advance. Adjusting POINT spring to the high # within it's design range prevents point-float, but any higher wears out the distributor cam & rubbing block. Excessive point-spring tension also applies extra drag to the breaker plate, affecting the advance spring settings. So, point-spring tension should always be adjusted BEFORE adjusting the advance springs.

6 VOLTS/POS. GRD. NW INDIANA

[quote][b]John Mummert

check out Red's Headers website for full article.



Interesting point from that article: Plug fouling with daily road use was a big 50s problem for those that ran centrifugal-only distributors. Comments from others on the forum that run successfully with no vacuum diaphragm indicates (possibly) that modern no-lead fuel has changed the situation?


6 VOLTS/POS. GRD. NW INDIANA

Not sure after reading all this as to what springs you originally wanted to adjust, at one point it sounded like the inbuilt points spring, then the 2 advance coil springs. anyhow if wanting to increase/decrease tension of these 2 coil springs the attaching posts can be rotated to do this. i have original ford tool to set these up and is interesting old tool. regards bill.

  AussieBill            YYYY    Forever Y Block     YYYY

 Down Under, Australia

Bill,



Been looking high & low unsuccessfully for that tool (SnapOn MD5). Twiddling those posts with an ordinary wrench a tricky operation while the distributor is running at 2000 rpm in the Sun machine. Would also be handy for point aligning.



P.S. Total of 4 springs to adjust in a dual-point Loadomatic.


6 VOLTS/POS. GRD. NW INDIANA

Daniel: For more info that might be relevant to your question, go back to Home on this site, then to Articles. Scroll to Hot Rod (1956 mag) article. Open, & scroll down to the ignition section. The discussion there may be helpful.

Paul

Thanks Paul,



I had forgotten about that article. Combined with the 55 shop manual rpm/vacuum specs., and other Y-Block performance curve data found, I should be able to come up with a solid baseline for modification.



One MIGHT infer that RPM & corresponding ''inches-of-Hg" specs would indicate a standardized teapot venturi vacuum at that engine speed? Of course, the only way to be certain about a specific carb/engine set-up would likely be to drive around with an accurate manometer spliced into the distributor line, and record the #s.

6 VOLTS/POS. GRD. NW INDIANA

Forgot to mention: After setting up a Loadomatic last night with factory springs/advance curve, I then applied a full 20"s of Hg. (low-load cruising manifold vacuum). Assuming the spark control valve orifice actually passes full manifold vacuum to the distributor diaphragm, that would produce over 50 degrees of crank advance, even if the initial timing was set to factory spec.! No wonder there is so little latitude in boosting initial advance before experiencing low-load rough running.

6 VOLTS/POS. GRD. NW INDIANA

Daniel,

  50 degrees of advance at 20 inchs of manifold vacuum ( this is very low load, low throttle application, cruise condition) IS NOT EXCESSIVE. This is what is desired for HIGH MPG. AS soon as you give it throttle, the manifold vacuum drops, the timing retards, and the rpms pick up.

  I feel you are trying to fix a problem that does not exist. If your engine pings, there is a problem. If there is no pre-ignition (ping) then there is no problem. Pete

This brings up an interesting point: The engine damage likely from prolonged pinging under load (pre-ignition/detonation) is well documented. But, what about rough-running from hyper-advance at low load? Aside from disconcerting, what are the long term effects, if any?

6 VOLTS/POS. GRD. NW INDIANA