Scientific Test Results on Timing

Right! You've got the adjustable MSD vacuum advance on the Distributor. Gotcha. I'd like to try one of those too. That's a heck of a way to get the equivalent of the old dwell chimed in just right. Picks up any slack in the pivot arms. Neat stuff.

 

The distribitor is an MSD Streetfire. It comes with a stop that you install yourself to regulate how much vacuum advance you want. There are 4 different selections. Then, you can loosen or tighten the screw in the canister nipple to slow or speed up advance. I have mine set to come in quick. There were old Ford dizzys that had adjustable cans on them. You unscrewed the fitting on the canister and removed/replaced washers to lighten or increase spring tension on the diaphragm.

 

Thanks, I'll check mine out again.

 

There I was minding my own woodgrain dash business and I found this site on Flathead V8 Fords. and on this tech page are about a dozen items on HEI, MSD, Pertronix, Mallory and other ignition systems:
http://www.btc-bci.com/~billben/flathead.htm

Here's the woodgrain dash item:
http://www.flatheadv8.org/dashgrain.htm

Ah heck, here's another on old radio plastic wood painting:
http://pages.cthome.net/ptf/antiquelinks.html

And painting your own exterior woodgrain:
http://www.woodgraining.com/

 

I came to this conclusion by testing and verification many years ago. I'm thinking you missed the most important part of, and point of what I said....................at wide open throttle.

If you did your test at a steady state, light load, 3000 RPM cruise than you will indeed have vacuum at the ported source. "wide open throttle" is an entirely different story. The fact that your vacuum canister has 6 degrees, or that some other canister has some different amount has nothing to do with "wide open throttle" and my statement to that fact.

 

Thank you.

That is what I said and that was my point. Perhaps he missed it in the translation.

 

http://classicinlines.com/spark.asp

Here's an article with David Vizard and Steve Davis that has some great info on the subject.
I may switch from ported to manifold vacuum after reading it to see if it will help smooth out the idle on my new engine.

 

The purpose of the spark advance system is to light the fire earlier as engine speed increases for more complete combustion. A smoother idle is a "side effect" when ignition is advanced. You can do the same thing by advancing the initial timing a little, just not far enough to cause hard starting.

 

I read the article and it appears that hooking to straight maniford vacuum would be an advantage to engines with hot cams, but not so much for mile ones. Also, the statement that hooking the canister to ported was for emissions, I am not sure is so accurate. I had a '55 Ford back in the 60s and the vacuum advance was hooked to ported and this was long before emissions was an issue.

 

The new cam I have is quite a bit more lumpy.
So I'm having to do some fine tuning to get it running smooth at idle.
I had to bump up the timing over 12 degrees, any further and it started stuttering.
And I think my carb might need a bigger jet.

 

If you have a big cam, you will probably never get a smooth idle. That is one of the drawbacks (or benefits) of that type cam. There used to be Rhodes lifters. I guess they still make them. They were supposed to give a smooth idle even with a big cam, then off idle provide the lift the cam was designed to give. A slightly lumpy idle sounds good. I had a 360 Plymouth with a 292/480 Lunati and it sounded great.

 

It's not that big, just larger enough to require some tuning.
I think the lift is under .500 but that's significantly bigger than stock on an engine that has problems breathing. It has larger valves and some pocket porting.

 

.500 is pretty much lift. Stock non-performance is around .400 + or - a little. I had a 318 with a Crane 260/.427" and it sounded stock. A lot has to do with lobe separation, centerlines..gets really complicated. I guess a cam choice is one of the hardest decisions when building an engine. I have found that when building a mild engine, pretty much stick with the factory hi-po cam specs. A 340 cam (272/.454) works well in most small block Mopars. You might go a little more, but not a lot without other mods. I have a 350 Chevy that I am considering a cam upgrade for. Every time I look at the catalog, I come away more confused..........

 

Andy.......On that site about the distributor advance, did you read the story about the kid that was killed in his Mustang? A good and scary insight into how unsafe the older collector cars really are and were.

 

Yup. I agree. I think if I went into building/owning a "classic" car I want to resto-mod it just to have some modern safety features.