[RocktimusPryme]

This is a bit of a compound question.

1. Would you still bother with vacuum advance on a high-effort street engine?
(Specifically, I'm putting together a drag week project)

Im generally inclined to say even if it veers on the "strip" side of a street/strip car that the vacuum advance is still going to make the engine happier and cooler on the road trip portions of a drag n drive event.

I want to use an ignition box. 80% because of the Rev Limiter (Possibly even a 2 step) and 20% because of performance advantages of a CDI ignition. I just don't want to annihilate an expensive engine by unloading it if you lose a $40 U-joint.

So Question 2.

2. What is the best type of distributor to trigger with a CDI box that still has vacuum advance for cruise?

Probably needs to be small cap, I tentatively have my eyes on tunnel ram, so a big cap HEI might be a problem.

Bascially for every engine family under the sun there is a "Billet" option that is just a mechanical advance 2 wire distributor. Then there is a "Ready to Run" which looks the same but has three wires and doesn't need an ignition box. Both made by MSD and in house brands like Jegs and Summit.

Then there big cap HEIs and small Cap Pertronix II and IIIs available but I think those might be hall effect and the CDI boxes want a magnetic pickup. One of the Pertronix distributors actually has a built in Rev Limiter.

[ta man]

Check out Progression Ignition.ditch the MSD..I have one..wish they were out years ago..Rev limiter..adjustable timing curves..start retard..

[JLMounce]

Seconded, if you’re staying carbureted, check out the Progression ignition. It does what you needs.

[Tim Corcoran]

I am using an OEM distributor with a Petronix conversion and an MSD 6AL. Works great for me and the price is right.

[BB70]

I was in the same boat as you except I have a Crane HI- 6 box and wanted to keep it. I had a locked out MSD 8563 dist and wanted to add a vacuum adv for the same reasons as you. I found a good deal on a R2R MSD dist, eleminated the module in it and bought a adj vac adv can, since my camshaft and combo only made 5" vac at idle with the locked dist in it- 36 deg timing. I am pumped about the results, more idle vac, able to lean the idle settings, but no test drive yet as I'm not done with painting it yet.

John

[RocktimusPryme]

Progression is a good idea and one I have considered.

My only issue with Progression in a drag n drive scenario is if it dies you arent likely to be able to get a replacement. Where if you have a Digital 6 die, you are almost certainly going to be able to buy a replacement from another racer or something. I also don't think they have a two-step option built in, but maybe a separate 2 step box could be hooked up.

Maybe the move would be to use the progression and then carry an inexpensive ebay HEI, or one of the cheaper branded Ready to Run models as a backup.

There is also a programmable Aces ignition box that looks pretty promising, but I don't know if you can program extra cruise idle into it. I might email them about it.

https://acesefi.com/products/high-ro...MaAm5rEALw_wcB

If the pertronix in a factory distributor works maybe one of the Pertronix distributors would work the same.

[Formulajones]

First question, absolutely run a vacuum advance. Even on higher effort 700-800 hp NA street engines I run a vacuum advance. There is no downside to them, only benefits.

On the distributor, it's really personal preference. I run an MSD box on pretty much everything and trigger them different ways.

My preferred method on the daily drivers is to use the factory points distributor. If you want dead nuts reliable this is the way to go. If the box ever fails I can switch wires on the coil in a hot minute and drive away on the points.

On the more radical stuff that uses the MSD box, I've run the complete MSD stuff on those for about 30 years, with the MSD billet 2 wire distributor, vacuum advance, and the digital 6 with 2 step, timing retard and start retard etc....
All of that stuff for me has been reliable and trouble free for decades on 2 different cars. Bought that stuff back when they were still in Texas decades ago and have had no reason to touch it. Even though they have now moved most everything over seas like everyone else has, it doesn't stop me from buying their product and I still have good luck and great customer service from them. In fact I have another billet MSD 2 wire setup with vacuum advance and a digital 6 box sitting here ready for the new build I'm doing.

I trust that stuff on a drag and drive event, hell I drive them all over the place now several hundred miles away. I would just pack the necessary pieces in case something happens, you can never be too prepared. Chances are you won't need it.

[Dragncar]

Stock single point, best thing ever to trigger a MSD if you run below 8000 RPM.
Points last forever, simple is good.
Its all I have ran for over 35 years and have yet to have a ignition issue.
While I watch person after person have problems.

[RocktimusPryme]

Im not opposed to that. My only question is, don't old distributors get worn out? I would be worried about starting with a bad core.

[Dragncar]

People do rebuild them
If you can find a cast iron unit I have yet to find one all worn out. Must have bigger bushings or oil them better.
Picked up a very nice one from a member for 120$ awhile back.
Think they are 65 and earlier. Mine is from a 65 GTO I believe.

[Formulajones]

I'm still running original 50 year old distributors in the daily drivers that trigger a box with points.

Dragncar is right, it's super reliable. Like I said the biggest benefit is acting like a back up if the box dies, I swap the wires on the coil and it runs on the points.

Good distributors are out there, shouldn't be hard to find one that's good to use. So many people dump them for the new wiz bang stuff anymore the old points distributors I see are practically given away.

I'm not saying this is the route you should go. I still like and use MSD stuff and the thought of new is appealing. It's a tough call and personal preference plays a roll.


Good luck on the drag week adventure, that'll be a great time.

[Cliff R]

+2 on using a factory points distributor to trigger the MSD.

The good news is that it is rare to see bushings worn in a factory points unit unlike HEI's which for some reason often have a heavily worn lower bushing and shaft.

You must use good points. I use and prefer NOS Delco USA made points. Highgrade made some good sets, as well as Mallory and Accel. Obtain two sets and put one set in the glove box with a small screwdriver and headlamp.

All this fancy electronic stuff is fine, but keep in mind that they ALWAYS fail. Not a question of if it's a question of when. Over the years I've tried/tested just about everything on the market for distributors, modules, coils, etc. Some worked really well, but eventually every single one took a chit and I ended up going back to my stone stock HEI with nothing more done to it that add a positive stop for the mechanical advance and custom tuned the vacuum advance to add the correct amount of timing at light engine load.

I'd also add here that bug-zapping distributors do NOT make any more power on the dyno or advantages in ET or MPH over stock parts, provided they are all set up to do the same thing at every RPM. I killed that myth decades ago right on the dyno and backed it up with back to back track testing.

I'd add here that I actually saw a very slight improvement with a stock HEI vs an MSD billet with a 6AL box. The HEI is just a little more precise at the reluctor with it's "knife-edge" points vs the big fat trigger on the MSD's, plus MSD's rust all to chit if you stare at one too long! Not sure if they ever addressed that problem but most I've had in here look like they were put on the bottom of the ocean beside the Titanic for a couple of years before they showed up here!

I'd also use the VA as suggested above. No negatives from using it at any power level when the engine will see light load for extended periods. It allows for a leaner mixture to be burned, so you will use less fuel, less carbon build up, and not lighten up you wallet as much on long runs.......

[firechicken]

Progression.
I have the HEI model for 4yrs now I think. No issues andI don't carry a spare distributor around.

[ta man]

Originally Posted by firechicken

Progression.
I have the HEI model for 4yrs now I think. No issues andI don't carry a spare distributor around.

What I like with mine is I removed the MSD box and separate coil..with zero loss in performance. Great for tuning at the track..no wrenches neeeded,timing lights etc..don't even open the hood.

[RocktimusPryme]

You are making progression sound good. I might call them and ask if a 2-step box can be added to their distributor.

I did message Aces to ask if their system allowed for additional cruise timing.

I talked to them at PRI last year and liked them. I’ve been wanting to try one of their items.

Edit. Progressions website says that Launch Control can be added for $200.

So $769 total for the unit I need.

[Formulajones]

Last I heard progression still had not adapted the use of factory tachometers which killed any idea of me trying it, so Im betting adapting 2 steps and things might be a no go. Plus the whole "use your cell phone" thing to program it turned me off.
Guess that's ok with some of you tech junkie guys so not a concern there.

[RocktimusPryme]

Using the cell phone is a big plus for me lol.

An additional 2 step may be a no go, but their latest models advertise an integrated launch control option for extra money.

"Launch RPM rev limiter is triggered by 12V input. Choose hard limiter or soft limiter with random progressive spark cutting. Tunable retard curve for the first 2 seconds of the run. Also tune the delay time to sync limiter release to the trans brake or clutch release"

THe same package also offers an option for nitrous and data logging.

Im not sure the difference between soft and hard launch control.

[Singleton]

I've had the small cap Progression distributor for a couple years now, no issues with it in about 7-8k miles. I regularly use the anti-theft feature from the phone app when out and about, and when the gto is locked in the garage. They didn't offer the newest features such as launch control and data logging when I bought mine. Been considering sending it in and having it added

[i82much]

i am happy with the r2r and a programmable 6al2. i would probably be just as happy with a points or hei unit, and 800 bucks or so richer ...

[Goatracer1]

If it would work for you I use a HEI with nothing inside except the magnetic pickup. I've been using it on a supercharged 428 for 20+ years.