Distributor springs and Timing

[Redfalken]

Hi all,

I've been fiddling around with the timing on my `62 (with a `68 200ci and Ford-o-matic) and came across a page talking about adjusting the advance curves on your distributor http://www.bob2000.com/dist.htm

Out of curiosity, I pulled the plate out of the distributor to look at the springs and noticed that one was considerably beefier than the other. I took a photo that can be seen at http://home.comcast.net/~purlgurls/distsprings.jpg

Are these springs supposed to be the same size or are there many different combinations depending on the advance curves you're looking for. I've never dealt with this type of "fine tuning" so it's all new to me. Maybe it's something I shouldn't worry about or mess with? Also, I notice the numbers stamped above the slots on mine are "13R" and "15R" while the web page I mentioned has them marked with an "L." Anyone know the difference? And...there is a rubber sleeve over the limit pin on mine and that's not mentioned on the web page. Is this stock or someone's attempt to change the 13 to a 12?

Also, I have a video that came with my Autolite 1100 when I had it rebuilt at Pony Carbs and they mention the general position of the distributor should be that the vacuum advance line points between the 5th and 6th cylinder EXCEPT my `68 should point more directly towards the firewall. Well, if I'm at 12 degrees BTDC I'm pointing between 5 and 6 and I seem to run better adjusted a little more advanced than that. It would never run well pointing towards the firewall! Does this mean I don't truly have a `68 (my casting numbers on the block read 17 C8DE G015-B) or does it have something to do with the distributor that's in there. I'm not sure exactly what year they first started putting centrifugal weights in but I recall it was late 60s. Note: I just put in a rebuilt harmonic balancer in about 3 months ago so I'm pretty sure my timing marks are accurate and I've also checked that I'm firing to #1 when I'm at TDC of the compression stroke.

This all started when it began idling rough and would almost die at stoplights. New plugs and a good set of performance wires helped a lot. My plug gap is .038. Then I noticed a lot of oil leaking out of the top of my coil so I put in a new MSD Blaster 2. I had a Pertronix Flame Thrower in but wasn't impressed that it only lasted 3-1/2 years. The rotor and cap are 6 months old and look good. My old plugs were in OK shape considering they had been in for quite awhile. The ones in cylinders 4, 5, and 6 had a fair amount of dry black soot on them. I understand that means it could be running too rich. My compression numbers are (front to rear) 158-157-156-146-156-154. I have 19lbs. of vacuum at 700 rpm in park. Also, I have a Pertronix unit in place of the points.

Anyway, I'm at the learning stage with "engine fiddling" so I thought I'd see if anyone had any comments on my situation. It's running pretty good now but still runs a bit rough until it's good and warm. I only have a 10 minute drive to work with lots of stoplights so it doesn't get a really good chance to warm up in the chilly months.

Thanks...

 

[Anonymous]

actally i was surfing the web for some vac advance info and i ran across an article where someone used a heavy and a medium spring, so thats probably what u got, i'll see if i can find that article again

 

[Anonymous]

i ran across this in my searches, it should help explain that.



Damon recommended using one Blue (heavy) spring and one Silver (medium) spring for the mechanical advance. This will allow the advance to start at about 800 rpm and be fully in at about 2800 rpm. I decided to use both Blue springs instead. Both blue springs start advance at about 800 rpm and is full in at about 3200 rpm. Don't ask me why, I just felt this was better for my truck. I don't think Damon has ever worked on pickups much, as far as performance goes. The earlier advance would probably work great on Camaros and other lighter cars, I just think that by trucks being heavier the later advance is better. Maybe I'm wrong, I have been before, besides, I have other problems to worry about. While checking my advance with a dial-back timing light, I noticed that instead of 20 degrees of centrifugal advance like it is supposed to be, I had about 23 degrees. You know what this means don't you, yep, my distributor weights and pins are probably worn. Time for a rebuild. I might end up buying a new one instead of rebuilding the old one. I haven't made my mind up yet. Decisions, decisions.

 

[MustangSix]

The reason behind using two different weight springs is to get a less pitched advance slope at a certain rpm.

The weight will pull the light spring first giving you advance that rises until the resistance on the second spring is met. Then the slope changes, with less slope than the earlier half.

 

[67 Falcon]

Check out April Mustang and Fords, there a good article on tuneing the distributor. Russell

 

[Lazy JW]

It is perfectly OK to mix springs in order to achieve a desired advance rate. Sometimes two heavy springs are too slow and two lighter springs are too quick, using one lighter and one heavy will be somewhere in the middle. I am guessing that someone put a piece of rubber tubing over the limit pin to further limit the amount of advance on the upper end so as to allow more initial advance and mixed the spring weights to bring the curve into a desireable range. Whoever did this apparently knew what they were doing.
Joe

 

[Anonymous]

I've seen the rubber 'tubing' thing in original dizzys, my guess it was to limit the advance by a degree or two...

That one article 'Timing tips' seems to explain most of it, the "15L" and "10L" are the amount of advance on DIZZY degrees (which is half of the crankshaft degrees) so like it says 15 is 30 crank deg, and 10 is 20 crank deg. The slot that the pin is in is the one that it's using, you can flip it around, but it's also been a real pain for me to get that little clip back in the groove.. I haven't played around with the advance on a 6 yet, I've done it on many v8's. I know it's dependent on many factors, but what is a good guideline for a performance curve for our sixes?

I couldn't tell you what the "L" and "R" mean on the slots, my guess is the Ford V8 dizzys turn counter-clockwise, and judging from the vacuum adv location on the I6's that the dizzy turns clockwise. So they probably mean Left and Right?