FBO plate over advancing

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The measurement I used was how far the pins would travel in the slot……… not the length of the slot itself
 
PRH said:
The measurement I used was how far the pins would travel in the slot……… not the length of the slot itself
Click to expand...

Yup, that sounds more like the right concept. Thank you. Looks relatively close here.

20230911_193351.jpg
 
Agent_Orange said:
one more observation:

Halifax got me thinking, my tbar is a 15, so 30* at the crank. I wanted 16* at the crank, so roughly half the slot. The picture below has the 16* slots under the tbar. The inside of both pieces are flush, the fbo plate should restrict the travel by more than it does.

my micrometer needs a new battery, so I wasn't able to get slot readings last night

View attachment 1716141203
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Maybe try calling FBO. He might be able to clear things up.
 
This is why I threw the plate in the garbage and welded and filed the slots. I was one and done after that.
 
Agent_Orange said:
one more observation:

Halifax got me thinking, my tbar is a 15, so 30* at the crank. I wanted 16* at the crank, so roughly half the slot. The picture below has the 16* slots under the tbar. The inside of both pieces are flush, the fbo plate should restrict the travel by more than it does.

my micrometer needs a new battery, so I wasn't able to get slot readings last night

View attachment 1716141203
Click to expand...

You can get a pretty close reading with a decent ruler that meaures in tenths.
 
Here is how I check mine on the bench. I printed 7" degree wheel, I cut a small pie shaped section out of it, and put a hole big enough for the rotor to fit through snugly, so it won't easily slip. With the shaft of the distributor in a bench vice, put the rotor with the degree wheel in place in /he top of the distributor. Spin the body of the distributor so that one of the locking tabs is lined up with the degree wheel. Now holding the body, you can rotate the rotor until it stops, and measure the amount of advance you have. It won't move much, but it doesn't have to, whatever you have at the distributor doubles at the crank. For example 8 degrees at the distributor is 16 at the crank. It's easy to make, and will keep you from installing the distributor over and over. I would have thought there would be something like his available, but I have never seen one.

20230913_193133.jpg
 
Couple of comments.
- I use something similar to post #34. Very accurate.
- I have found that most manufacturers quote dist degrees [ not crank ] on dist components. A vac adv unit I have been working on has a '9' on it; 9 dist degrees, 18 at the crank.
- the limiter plate is a clever design, should work ok, as long as it doesn't catch on something to cause it hang up.
 
Cuda416 said:
Ok, I was trying to eliminate the dizzy rotating a bit.

I don't have an FBO plate, but you could measure the slots to make sure it's the correct slot. I know they are marked but it's something else to eliminate.

dist. degrees / slot size
6.............. .340
7............... .355
8............... .375
9............... .390
10.............. .405
11.5 ........... .420
12.............. .435
13.............. .445
14.............. .460
15.............. .475
16.............. .490
17.............. .505
18.............. .520
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can someone verify these numbers are correct? Either my old caliper is off, the fbo plate or the chart.

20230914_191214.jpg
 
halifaxhops said:
Sounds like you're on the right track. I have said this hundreds of times. DO NOT TRUST A DIAL BACK TIMING LIGHT unless the advance mode is verified. Heck I have seen 0 off also. The potentiometers wear out and gives assuming results. Check it with a timing tape or against a digital light or it will drive you nuts. Also that advance cam will only give you 15 dist degrees maximum The FBO plate can only keep that or go lower something to keep in mind also.
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I trust a decent brand digital light, but not an analog with a dial. Just think of all the variables. How the dial is installed....it could be clocked a little off. The knob might be off a little. The sticker with the degrees might be off some. And on and on.

All of this talk about the inaccuracy of the limiter plate is exactly why I still recommend the tried and true old school method of welding and filing the governor slots.

And to those who say "run it stock", all I can tell you is, you've never curved a distributor, or done one correctly, because you'd never say that. There's a possible honest 25HP to be made there if done correctly.
 
Dont worry about the numbers on the plate, you already know it is misleading. Use that initial setting of 16* you placed it at and work your way back on the plate until you get the actual 16* you need. I have never used the FBO plate, But I did 3D print my own version using the same chart posted in this thread, and it is very accurate. This issue is the very reason I started measuring as described in post#34, that method lets you know exactly how much advance you are getting.
 
DARTLARRY said:
Dont worry about the numbers on the plate, you already know it is misleading. Use that initial setting of 16* you placed it at and work your way back on the plate until you get the actual 16* you need. I have never used the FBO plate, But I did 3D print my own version using the same chart posted in this thread, and it is very accurate. This issue is the very reason I started measuring as described in post#34, that method lets you know exactly how much advance you are getting.
Click to expand...
This is exactly what I decided last night. Found what advance slot the engine likes. This weekend, I'm going to weld and file the the Tbar to match and toss the plate in the glove box. Probably not necessary, but it will ease my mind.
 
I have plenty of electronic advance cams all different slots if you know what you need. $20 and the ride.

DSC01956.JPG

Dont get me wrong the FBO plates are great for limiting mechanical advance.
 
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I generally trust Mopar parts over aftermarket when I have a choice. I scrounge junk yard distributors for different advance plates and have located 11° and 13° plates. This gives 22° or 26° advance allowing initial timing of 10-12° which works very well with my 284/484 cam.
 
DARTLARRY said:
Dont worry about the numbers on the plate, you already know it is misleading. Use that initial setting of 16* you placed it at and work your way back on the plate until you get the actual 16* you need. I have never used the FBO plate, But I did 3D print my own version using the same chart posted in this thread, and it is very accurate. This issue is the very reason I started measuring as described in post#34, that method lets you know exactly how much advance you are getting.
Click to expand...
Misleading. You're being too nice. They are flat out WRONG. When you pay 45 bucks for a thin piece of metal, it ought to at least be RIGHT.
 
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