Anyone use the FBO advance limiter plates?

Hey gang,
Anyone use the FBO timing advance limiter plates? I am experimenting with the timing on my new 426 HEMI and seeing timing, especially initial, has a drastic effect on performance. It appears my hemi likes more initial timing in the 16-18 ranges, maybe more but don't want to push the total advance window past the 34-36 range. With this plate, it seems I can up the initial but keep the total in check while utilizing my vacuum advance functionality.. I recently had my original Presolite dual-point restored with Pertronix guts to be used as a trigger for my MSD6 system. The plate will eventually go in there if it helps.

I used it, worked as advertised.

Troy, I have used Don's distributors for a while. I like his way of using manifold vacuum to introduce more timing while at light load and then using mechanical when there is little to no vacuum at heavy load. I actually put one in my 472. Haven't been able to drive it due to this brake issue, but the same setup worked great on my 505 stroked six pack motor. Call Don and talk to him about your setup and he'll work with you on what you want. Good guy to deal with, or has been for me anyway!

Just got off the phone with Don.. Nice conversation and I ordered two plates and the documentation and springs... So, we'll see... Looking forward in tinkering with the car..

Over the past couple of weekends I have taken the Daytona out with the new modifications I did to the electronic distributor I use for my MSD6A trigger. I'm happy to say there are noticeable improvements. The HEMI fires up rather nicely, idles better when cold and the acceleration is MUCH improved. I have some tweeking to do I believe, but I think I have the timing & fuel-air ratio dialed in rather nicely. The setting now is 20 initial using the 14 slots to give me a 34 total mechanical advance.

Just to clarify, EVERY vacuum advance distributor uses the vacuum to add timing when the engine is lightly loaded. And the mechanical advance happens regardless of load, acting as the baseline that the vacuum advance adds to.

The magic happens in tuning the two kinds of advance for a particular engine/car combination. Sometimes that's not so easy to do.

R.

Troy, what did you do for springs in the Presolite Distributor and what RPM does the total advance come in at? Thanks

X2 Absolutely the best bang for the buck for limiting mech total. $22 to your door. EDIT has slots for 10-12-14-16 or 18 deg of mechanical allowed.

Where do you get one for $22?

The plates are a very nice piece. Up to $25 now IIRC.

so how do you dial it in to get exactly what you need both initial and total? I need like 18 initial and 34 total on mine..How do you use this plate to get both? Sounds like I need this to replace my old JB weld limiting the ttaol ive had forever..lol

http://www.4secondsflat.com/Mopar%20Mechanical%20timing%20limiter%20plate.htm

The laser etched numbers on the disc designate the amount of mechanical advance so for instance...

If you want 18 degrees of initial timing you just set the plate on the 16* slot 18 initial+16 Mechanical= 34* total

If you want 24 degrees of initial timing you set the plate on the 10* slot for 24 +10= 34* total

If you want to lock down the distributor with NO Mechanical timing at all then just drop the plate over the 0 round hole

Nice! I definitely need this!

I agree well worth the 22$ and I got the tuning guide as well.

I have 3 in use now. followed the guide book and wow what a difference it made on my junk.

1)I have in my bone stock 318 a points dist/stock springs/vac pod hooked up full vac and run the initial at 14* with plate set on 18* for 32* total.

runs great on 87 pump gas with no ping and 18mpgs on hwy.

2) 273 points dist/MrGasket light springs/initial on 14* with plate on 18* NO vac pod used.

runs about the same as set up #1

3) 440 230/245 @ .050 whiplash cam-initial set at 34* with plate locked on 0* no vac pod used.

the whiplash cam loves it and made it much more street friendly as a daily driver.

wish I had learned to do this 35 yrs ago.

set the initial with "the vacuum gauge method" then set the total (initial+plate amt) to the std for your eng which will get you close (ie 35 for a SB) then toss the heavy spring with the elongated loop & sub in a MP/mr gasket/transdapt light spring in its place for a start & mix/match from there so you are aways under the pinging point at WOT up thru the gears on your hottest/driest (most likely to ping) day & there is silent ping & peoples' hearing varies so give it a margin. Any spring combo advances in a linear rate no matter which spring you change (once the elongated loop one is tossed). then plug in the can & adj its tip in rate with a 3/32 allen wrench (CCW delays it/takes more in hg to activate it/total amt stays the same) so that you are same as above AWAYS under the ping point in everyday driving under varying load/RPM conditions. there are different cans that offer a different TOTAL available & you can work with the notch on the arm on the can to limit the total in addition to working with the prior tip in rate & this is for PORTED & Don a FBO is a MANIFOLD guru which has a different procedure & many people swear by tho I ain't never tried it (yet) but I was loaned a copy of the "tuning to win" booklet & I was not impressed with it. YMMV

Much better than the set total timing and let initial fall wherever it may per the MP books followers.

Just installed one a couple months back. More initial without the total going into heavy ping range woke my car up considerably.

The design is pretty genius, and hats off to the guy for keeping a fair price instead of gouging customers for it.

Now if only someone would come up with an equally genius/affordable tool to get the top shaft retaining clip out easier. That was seriously the longest part of the process for me. LOL

This looks a lot better than welding up the slots then filing them down to get it correct. This takes a long time.

It's clever, but its not better if the engine will be used at high rpm. For high rpm, its better to take advantage of the advance's geometry by shortening the inside (rather than stopping the weight moving at the top).

^^^ I am willing to do this, how does it work better?

With an electronic, start with a 13 or 15.
As the weight moves out, more spring force acts against the outward motion of the weight. This slows the advance, gaining a degree or two in the top end or at least offsetting retard from slew rate.

Red arrow is force of the spring acting on the weight.
White arrow is acceleration force of the weight on the spring.

Let's take that and see how Troy, the OP might apply that.
1967 specs are helpful because they show us the curves before they started manipulating things for emissions - especially idle.
If the 426 distributor in use already has a non-CAP advance curve, then bumping initial to 14* or even 16* may be fine. This will depend on the fuel and specifics of the engine, as well as use. Drag race only will tolerate quicker advance than an engine that gets really heat soaked. The advance can be slightly delayed by putting a little more tension on the primary spring.

If the distributor has CAP type advance, its going to be more work. It may be possible to simply move the secondary spring perch so that the long loop engages around 5* out instead of 12* out. Maybe that's what the factory did, or maybe they used a different spring, and/or a different cam plate. Only someone who has had these distributors apart and looked for these things will know. From the specs we can be pretty certain that a higher rate primary spring was used on the non-cap versions. The tension was adjusted so they both start moving just above idle.

This graph is in distributor degrees and rpm:

When these distributors were installed and set to the specified initial timing, the off-idle timing curves were very similar. Ford service manuals explicitly advised that the timing could be increased in 2* degree increments for better performance, or reduced a little if fuel or other conditions required. I've not seen that in Chrysler documents, but I suspect the same applied.

Notice below that setting the initial for the non-cap distributor at 14* will result in something close to 34* at 2800 rpm. However doing the same with the CAP distributor wouldn't work out so good unless the secondary spring was made to engage at 5 or 6* distributor degrees. That could be done by welding the inside of the slot, or with a different spring or by bending the perch. I can't say which might be best without having one apart and measured. Even then it can take a few tries. As always, someone with experience doing them will save time.

This graph shows timing, its in engine degrees and rpm.

i have such an animal that would work perfectly for this. i made it a ton of years ago because i got SUPER tired of always juggling around with 2-3 mini screwdrivers to remove that spring. anyone out there willing to guide/help me set up a sellable item ? i'm old, and not literate in patent processes, plus, i'm not up on marketing that would be for an item that "may" have limited interest. then, there is the possibility of showing this item and having it ripped off, making someone some bux, while i get no credit.

A pair of extended snap ring style plier with outward facing, small concave tips.

I use a pair of thin needle nose pliers to spread the vertical legs apart (3 or 4 tries) then when it is expanded as much as it can I grab on one of the legs & whip it around to the open side & up all in one motion. it distorts the clip a bit but they are very non brittle (I forget what the word is for the opposite quality) & will easily withstand this. sometime in the future I'd like to thread the shaft for another type of holddown.