I have been watching this string with some interest. You see, I think I may have a “problem” with the curve in my distributor. Long story; I’ll try to keep it as brief as possible.
Right after we (Pat) got my first 200 engine to idle, it still had a problem with very poor throttle response. You’d push on the gas, and it would go flat before it picked up and went (if you were lucky). First thing I tried to do to improve the situation was to monkey with the advance curve.
I had read an article on Ford Six Performance Forum suggesting that improvements could be made by replacing one of the flyweight springs with a lighter one. I’d seen another article about tuning that cautioned not to exceed about 38 degrees total advance (mechanical plus initial), and that the mechanical advance could be modified somewhat by installing the flyweights differently. So… I took my distributor out, managed (with some difficulty) to take it apart, flipped the weights to maximum advance orientation, and replaced the heavier of the two springs with a light one from a “curve kit” that I got from I-don’t-remember-where (probably Summit).
A test drive confirmed that the throttle response was significantly better, but still not very good. If some is good… Well, more is…. I took the distributor apart again… this time without even taking it out of the car… and replaced the OTHER heavier spring with the other light spring from the curve kit. Throttle response was better still.
(Eventually, throttle response was made good with changes to the main jets, from #51 to #57, but that’s another story and off the point here.)
Anyhoo…
The engine is now PROFESSIONALLY rebuilt with a new, milder, cam (264 deg), and it runs really well. Except for the sound it makes when I get on it. When I push it hard, the engine sounds… unhappy. It makes an awful, screechy, anxious sound, and I’m wondering if it might be detonation. As far as I know, those light springs are still in there, but my new cam has an earlier intake close event, which will increase compression pressure at lower engine speeds, so I’m concerned that now my curve might be TOO FAST for the new cam.
Recently I managed to work up the ambition to do a test similar to what Dennis did, and checked the total advance vs. RPM.
Currently, the initial advance is 10 degrees BTDC. By using a combination of my standard timing light and my variable one, I was able to confidently determine the curve is as follows:
(vacuum line disconnected)
10 degrees @ 800 rpm idle (as slow as I can get it to idle);
15 degrees @ 1200 rpm;
25 degrees @ 1600 rpm;
30 degrees @ 2000 rpm;
37 degrees @ 2400 rpm.
Based on the numbers stamped on the weights, I was expecting… I assumed… I was getting 13 degrees of advance maximum per weight, or 26 total degrees of mechanical advance. The figures say 27 degrees at 2400, so I’d say that’s in the ballpark… EXCEPT that I didn’t think to run the engine up past 2400 to see if the mark continued to rise! I’ll need to work up some more ambition, and go run it again.
As you can see, these numbers are MUCH more aggressive than the curve in Dennis’ distributor, and I would very much like to try it with at least one of the heavier springs back in the distributor, but I just can’t work up the courage… the will?... find the time?... to work on it again.
Does anyone have some sage advice to offer on this topic?
Does anyone have a bottle of gumption, or at least a round tuit I can borrow?
I've got a couple of serious looky-loo's for the car. One of them told me he might want to just come get it and drive it home... to Georgia!! I'd really like put my mind to rest on this before I deliver it to anybody!
Gary MacDonald
ROGER's...
EX... '63 Hardtop
Had...
Scarebird front discs
200 w/ CI alum head
C4
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