I would like to fine tune the mechanical advance on my truck, 85 360 in a W350 crew cab. I'm thinking "All In" around 3000 RPM. Currently it seems to be about 4000 RPM. What spring/springs would get me in the ball park? I know this could be some trial and error. Stock distributor, Would just the one light spring get me close? Or some other combination???? Thanks for any ideas.

I would set the initial with the vacuum gauge method or to 15-18 would get you close then shorten the slots to get 35 total (initial+slots) & the $22 FBO plate is the fastest/easiest/cheapest way to accomplish this then toss the one heavy spring with the elongated loop on one end & sub in a mr gasket 925B or MP light spring in its place for a start keeping the OE light spring. any combo of one or two springs will let the weights advance in a linear rate. here's a chart tho the crane kit is no longer available there are chebby and hardware store springs that can be subbed in. always keep the OE light spring. you want to be close to the pinging point but never over it. you also do not want the advance to start any less (point X) than 100-200 RPM above the hot in gear idle speed which is what you will see at the stoplight. EDIT (1) mr gasket 925B spring will give you full advance at ~1200 RPM and both of em at ~2400 RPM

thank you for the chart. That helps to know what to expect from some of the options out there. I didn't think about trying 2 light OEM springs. As for timing I'm currently at 18 initial and 16 in the plate. This was a surprise as I've always found too much in the plate.

Where can this FBO plate be found?

FBO plate is da Bomb! Best part available for Mopar market--easy as pie

I agree FBO plate in both of my trucks now. 3rd plate on the bench for the 88 police engine I am fixing up.

my 440 with whiplash worked out at 18* initial 18* mech 36* total med spring all in by 3000rpm. vac pod blocked off.

318 roller cam whiplash worked out at 14* initial 18* mech 32* total light spring all in by 2500rpm. vac pod hooked up.

I played with the firecore dist and never got it to work right. dist failed 2x coil failed next. CD coil still did not fix issure. so it is on the bench as a paper weight.

I will be going back into the 440 dist and will give it a try with the FBO locked out on 0* and install a pertronix point conversion.

pertronix points conversion = 80$ FBO = 20$ 100$ total

ez pz and cheap.

You might wanna give it a visual just to confirm everything is copacetic in there as 2 common slot lengths are stamped 11 & 17 (22 & 34 on the crank). the 11 is ~.406" and the 17 is ~7/16 (.4375")

This is a great bargain and not just because I have used one in a friends bracket race 360 Dart Sport. As I recall it comes with 3 sets of springs in various strengths.

On their site it shows the plate @ $22, plate w/spring assortment $32. Instructions online, but they also sell packages that include a coil, coil & distributor, etc.

Yes it will

Yes, I would agree with you. Like I said I was "surprised" I have not looked into this one yet. I did open another that i had here from a truck and the slots were .375. It was stamped 76 ??

I don't want my advance to start coming in until 1200 (idle will be 1100-1200) but all in by 3000. I've got the FBO plate already installed, planning on 22 initial with 12 in the dist.
Any idea what combo of springs will do that? thanks.

No I dont have a specific recommendation but as you know it'd take something stiffer than what is in the chart then work with when it maxes out. point X is the most important (when it starts). it's gonna take alot of trial and error and grinding the tips of the weights to fine tune is an option in addition to springs. the MP/transdapt/mr gasket spring kits only have (1) pair of springs each & they are very light. EDIT I would call Don at FBO & find out if any of the springs in his (3) piece spring kit with the OE light spring or a combo of his springs will give you a point X at 1200 or above for your needs. MORE EDIT I ain't tried this yet (just thinking out loud) but I'm thinking a person could drill the weights & melt in lead to increase the rate. SB & BB weights are different & the SB ones look like a comma at the beginning of a sentence and BB, the ones at the end of a sentence. MORE EDIT the heavy OE spring with the elongated loop on one end, a person could cut/rebend that loop to make a "regular" spring out of it, it is heavy tho

I had a chance to look into this today. Just wanted to thank Rapid Robert for the chart he posted. I used two stock light springs and ended up just what i wanted on the first try. This distributor also had a short slot .380 "in the plate". So with my 18 initial, I ended up at 35 degrees right at 3000 RPM.

Dr. Charles... I can tell you that with what I used, I still had 18 degrees at 1500 RPM. The stock setup i was up to 21 at 1500 RPM. It would seem that the stock heavy spring with the long loop lets the weights take off quicker (advance), but then hold it back later. The two stock light springs hold the weights a little bit, but then advance quicker... Hope this helps

when did the advance start? I wanna compare that to the chart, showing 900 there

Thanks. If I'm reading this right, you had two light springs and no advance (18 initial) at 1500?

The loop in the heavy spring actually keeps the spring from providing any tension at all, until the weights have moved out some under control of the other spring. From what I've read it's really slow advance once it kicks in (just a couple degrees up to 5000) because it's so stiff.

Don at FBO suggested I start with the two silver springs (from his kit) and see how it goes. I think they're the stiffest of the three pairs he provides.

Yes that is what i'm trying to say. I had 18 at idle and at 1500 rpm. At 2000 it was 26 degrees. So some time between 1500 and 2000 rpm is when it started to advance. 2500 rpm 28 degrees, 3000 rpm 35 degrees.

I should add that these two light springs didn't look exactly the same. But they came out of stock 81 and 85 truck small block distributors.