vac advance or not for FE Cobra

[lippy]

The 6530 has a MAP averaging function for just that reason. Works perfectly.

Separately, can you post or provide a link to the ignition curve you mentioned?

[olddog]

Originally Posted by lippy

The 6530 has a MAP averaging function for just that reason. Works perfectly.

Separately, can you post or provide a link to the ignition curve you mentioned?

Lippy I mapped it in an Excel spread sheet. If you PM me with your email, I can send it to you as an attachment if you like.

Each line in the series is named 10, 30, 50,,,, ect this is 10% load, 30% load, 50% load respectively.
Click on the thumb nail and it will open another window you can see it fairly well

[olddog]

I decided to graph the same data with Advance on the Y axes and % Load on the X axes. There is a line (series) for 750 rpm, 1000 rpm, etc. You will notice that for 4000, 5000, and 6000 rpm the advance curve is identical, so the three lines are on top of each other and look like only one line. Also 90% load is pretty much WOT on a normally aspirated engine, but I left the boosted engine data as I find it interesting.

In my opinion this shows what the vacuum advance would do to the timing, as you opened the throttle. The previous graph in the previous post shows what the mechanical advance would do as the rpms increase. However with an EFI computer you have a different mechanical at every load and a different vacuum advance at every rpm.

[CHANMADD]

Chuck the MSD......get an HE I with vacuum......
Hey ......All the automotive engine designers add ignition advance at light throttle.....why wouldn't you?......are you smarter than the engineers...?

[Gaz64]

Originally Posted by CHANMADD

Chuck the MSD......get an HE I with vacuum......
Hey ......All the automotive engine designers add ignition advance at light throttle.....why wouldn't you?......are you smarter than the engineers...?

Agree.

All street cars (including high performance) should have functional vacuum advance.

[Jaydee]

After reading that great article on manifold vacuum dizzy. I changed mine from ported to manifold vacuum. The idle is much better and throttle response is quicker as well. Next week it's going on the dyno so I'll be able to tell what the advance is doing. With no load it seems like a lot of advance as I rev it. But I guess it can't ping unless the engine is under load, and as there will be less vacuum the the advance should be less. It all makes sense now.
JD

[davids2toys]

Originally Posted by r67cat

I posted this a couple of years ago. Still relevant. Rick

Here is one of the best definitive articles on vacuum advance. I converted my 66 428FE from a non vacuum MSD back to a Ford dizzy with a Pertronix ignition and vacuum advance. Unless you are running your car at WOT, you should run vacuum as this article so perfectly explains. You will improve cooling at idle, drivability and plug fouling. Take your information from a power train engineer and not from a backyard hobbyist. Rick

Distributor Tuning and Theory - Part 1 - Hot Rod Forum : Hotrodders Bulletin Board

Rick, this was an awesome thread! I have the MSD pro billet dist with no vacuum advance at all. I guess my thinking was same as the carb, Mechanical, no vac secondary's. Vac anything is for sissies with regular cars, not Hot-rods. I guess I may have to re-think this whole thing, especially since my car sees no track time at all, just aggressive street driving. Again, thanks for posting this very informative information.
Dave

[r67cat]

Dave, your welcome. Our cars are running the same power plant and I am sure your results like mine will confirm the science. That said, BB or Small block, short of a dedicated race car, vacuum advance should be the norm. Beautiful car by the way. Rick

[davids2toys]

Yes, you are probably right! How crazy is your cam and are you running an Aluminum flywheel? That might make some big differences for sure?
also, thanks for the compliment. Any pics of your car?
Dave

[fordracing65]

I thought the msd pro billet distributor had vacuum advance. Does it not.

[lippy]

Originally Posted by fordracing65

I thought the msd pro billet distributor had vacuum advance. Does it not.

Nope, it doesn't

[blykins]

Originally Posted by fordracing65

I thought the msd pro billet distributor had vacuum advance. Does it not.

They make one with a vac advance and one with a mechanical advance.

[fordracing65]

Originally Posted by blykins

They make one with a vac advance and one with a mechanical advance.

What is your preference on the engines you build for street strip.

[blykins]

Mechanical.

[cycleguy55]

Originally Posted by blykins

They make one with a vac advance and one with a mechanical advance.

Pro-Billet w/o vacuum advance (requires MSD 6, 7 or 8-series ignition) : https://www.msdperformance.com/produ...ord/parts/8594
Ready-to-run w/ vacuum advance (no external ignition box required): https://www.msdperformance.com/produ...ord/parts/8595

[fordracing65]

I'm confused now. Lol. Blykins likes mechanical. I'll go with his recommendation.

[blykins]

Whatcha confused about?

MSD has a Pro Billet distributor with mechanical advance and they also have a Pro Billet distributor with vacuum advance, set up to run without an ignition box.

[patrickt]

Isn't the only MSD distributor that fits an FE, and has a vacuum advance unit on it, that funky "Ready to Run" job that they have?

[blykins]

I believe so. You could always run a Mallory or a factory Ford distributor if you wanted a vacuum advance. Or you could do it the way lippy does it.

[fordracing65]

What are the pros on not using vac advance??