on mine it added a couple of degrees initial and limited it a few at the top. If I recall it was between 2-4 both ways. I also kept the stock vacuum advance and my cruise total (vac and mechanical combined) is around 50*.
If that's the case with mine too that means I'll only be able to run up to 8 degrees initial and that doesn't really seem worth messing with. Total at 36 right now with initial of 6. If it gives me 32 I can run a couple more initial. If it only gives me 34 it will have to stay where it is I guess. I may missing something but I don't see how I can possibly do 12 initial with what I'm working with.
Think about this. The distributor turns at half the crank speed. That means that 1* of distributor rotation equals 2* at the crank. That bushing will restrict the mechanical advance at least 10* or so. The only way to know for sure is to install it and check. If you notice, your feeler gauge set has a number of blades. Stack a combination of them together that add up to .086 or .104. Pretty simple.
Had a little time this afternoon. Took some pictures. It looks like my vacuum advance arm has some kind of bushing on it. Is that normal? Can you tell from the pics if the mechanical advance has a bushing? I tried to slide the mr gasket one on but it doesn't seem to want to go on. Any tricks to this?
Yeah, they can be tough to get on. Sometimes you need to spread the weights a bit as you try to push it all the way on. It is easier if the distributor is out. Make sure it goes all the way on. A bit of epoxy isn't a bad idea either. Looks like there is a bushing on the vacuum advance arm. Can't say I remember ever seeing that, but it will work.
I finally got all the springs. I made a block off plate for the vacuum advance and installed the bushing from the mr gasket kit on the mechanical advance. I set total advance to 34 and my initial ended up being 18. I tested my block off plate with a vacuum pump and it is limited to 10 degrees. I installed two silver springs and reset initial to 12 but it was erratic and would mostly be at 12 but would jump up a few degrees on occasion at idle with the silver springs. I removed these, reinstalled the stock springs and set initial at 12. It was not erratic with the stockers and held 12. I removed these and installed one blue and one yellow and did no other adjustments but my initial went back up to 18 when I did this and max at 34. Is this normal/ok? I hear no audible knock.
Sounds to me like your initial timing is 12 degrees, and you're getting six more at idle due to excessively weak springs--or an excessively fast idle. 34 total seems reasonable. Some engines like more, and some want less. Ten degrees of vacuum advance may be fine. When you get the advance-at-idle sorted out, re-connect the vacuum hose and consider experimenting with a little more vacuum advance. Ten to fifteen degrees of vacuum advance is likely good.
Idle is spec 700 rpm with a steady 16" vacuum. Springs are new from the Crane kit. Weak or lighter whatever you wanna call it. Lighter sounds more positive. Anyway, with my blue/yellow combo advance is supposed to start at 800 rpm but it's looking more like there's some coming in at idle due to the lighter springs. It seems to fluctuate between 12-14-16 or so at idle with these and idle is smoother than with two silver springs where it's more erratic between 12 and 18 and almost feels like a miss so I took those out and the blue/yellow seems a reasonable compromise if it's ok. The silver ones are fine but I don't like the erratic idle/timing fluctuation with those.
Sounds good. You can try a blue and silver, or 2 blues. The weights vary in size in these distributors, so the larger weights have more leverage on the springs. That's why you should experiment with combinations of springs. In general, you don't want any mechanical advance in at idle, but it is OK if the idle is satisfactory to you. What happens is you may lose that mechanical advance when you put it in gear and the RPM drops. That may make it want to stall or make the idle rougher. If you don't notice that, I'd say it is fine. You can play with it and see if you can fine tune it. If you want, you can even use a stock spring with a Crane spring. Looks like you are getting there. Good job.
My car is a 4 speed with A/C. I did turn on the A/C which bogged it down but it didn't idle rougher or want to stall, just idled at a lower RPM. Below is a good spring combination chart. What could I expect a stock spring in combo with a blue, silver or yellow Crane spring to result in? Right now with my blue/yellow combo I have all advance in by 2600 rpm so should I really mess with it? [TABLE] <tbody>[TR] [TD]Spring Combination[/TD] [TD]Start Advance – Engine RPM[/TD] [TD]Full Advance – Engine RPM[/TD] [/TR] [TR] [TD]Blue/Blue[/TD] [TD]800[/TD] [TD]3200[/TD] [/TR] [TR] [TD]Blue/Silver[/TD] [TD]800[/TD] [TD]2800[/TD] [/TR] [TR] [TD]Blue/Yellow[/TD] [TD]800[/TD] [TD]2600[/TD] [/TR] [TR] [TD]Silver/Silver[/TD] [TD]600[/TD] [TD]2200[/TD] [/TR] [TR] [TD]Silver/Yellow[/TD] [TD]500[/TD] [TD]1800[/TD] [/TR] [TR] [TD]Yellow/Yellow[/TD] [TD]500[/TD] [TD]1600[/TD] [/TR] [TR] [TD]Blue – Heavy[/TD] [TD]Silver – Medium[/TD] [TD]Yellow - Light[/TD] [/TR] </tbody>[/TABLE]
I wouldn't mess with it. Sounds like it is fine. Can't tell you what would result from spring combos. Try it and see.
It would be funny if ,after all of this,you find out your problem was valve springs that are weak or worn out.I did not read the all thing here,I'm assuming that those springs were never changed or checked. Bruno.
I guess it depends on whether the car is performing better, and the top end power is better. He hasn't told us yet:grin:
