Electronic distributors and tuning them.

[Kern Dog]

You must really feel strongly to post it twice !

The FBO Stuff arrived today.

This looks simple enough.
I got springs too.

First though, I want to plot a graph of my curve in the MP distributor.

 

[Kern Dog]

This mock up is on an LA distributor.

I welded the slots some 3 or 4 years ago but don’t have a wild enough 318 or 360 that needs it. The T can be used on a big block though.
You can see the dowels in the weights at rest…

The T slides off. Sometimes the T is held in place with a clip, some with a screw.

Set the FBO plate on the weight dowels where you want it…

Then put the T back in and reassemble.

Set the air gap and install.

 

[Jonas Nordstrom]

I am also running a FBO plate.
I did put 18 as initial adding 16 on the plate...though the engine did not like that and became "nervous", hard to describe but you could really feel it when driving away.
Lowering initial to 16 and adding 18 on the plate got it smooth and happy, giving it a strong steady pull from idle.

 

[Kern Dog]

My MP distributor is adjustable but you need the plastic gauges to test fit in the gap to set the advance amount. I had mine set to 14 degrees total way back when I was detonating a LOT. Back then, I was at 10.85 with a .039 head gasket and .012 below deck. I later swapped in .075 head gaskets that dropped the compression to 10.2. The whole time, The initial was at 17, total of 31. Since I rebuilt the engine in 2022, I bumped it to 19/33. I had lowered the compression to 9.8 but now I have quench since I switched to these pistons:

Without a dyno or drag strip, I have to just wing in terms of where to set the total timing. It has been debated where the optimal timing is but Don at FBO has opinions...

34 degrees, huh? Looks like my 14 degree spread in the existing MP distributor matches what Don suggests as a goal.
Ultimately, what matters is how my own engine responds. I understand that a modern aluminum head has a more efficient combustion chamber compared to the classic iron heads which supposedly means that the engine doesn't need as much timing to make power. I've heard of guys running 38 degrees of timing with iron headed 383s and 440s.
I do know that with the cam I currently have, I do need a LOT more initial timing to avoid it feeling lazy from a stop.

I was advised to use this cam back 10 years ago. A guy at FABO thought it would possibly reduce my risk of detonating based on that old principle of
Big cam to bleed off compression at low speeds...an old time tactic that has as many critics as supporters. It runs strong from 3000 and up, to the point where it is still pulling hard at 6000 rpms where I wimp out and upshift!
I did have the Mopar Performance 284/528 solid cam for several years. It idled a LOT smoother and made a LOT more idle vacuum, enough to support the power brakes. This Lunati is overkill, I know. I do have intentions of a cam change someday. I'm not a drag racer. I'd prefer something in between this and the 528 solid, maybe a roller to reduce the risk of cam and lifter failure.

 

[Jonas Nordstrom]

My MP distributor is adjustable but you need the plastic gauges to test fit in the gap to set the advance amount.

What are these "plastic gauges" to check advance?
...sounds like something I need.

I have an adjustable vacuum control and had to adjust down a bit to not get pinging at wot. (At 16 initial, add 18. Low comp engine.)

 

[68 Sport Satellite]

What are these "plastic gauges" to check advance?
...sounds like something I need.

I have an adjustable vacuum control and had to adjust down a bit to not get pinging at wot. (At 16 initial, add 18. Low comp engine.)

They're plastic wedge shaped "keys" with varying thickness. I used them to set my adjustable advance Firecore distributor also.
Summit Racing SUM-850535-1 Summit Racing™ YH and YT Series Advance Curve Kits | Summit Racing

Each key is stamped with a number indicating degrees of advance. In my experience they are not all that accurate, but they get you in the ballpark. It was a lot of trial and error to find the correct key that gave me the adjustment I needed. So pretty much pick a key based on the number you think you need and then select one smaller and try it and go from there. Between the plastic tolerance and the little bit of movement that happens when removing the key, it won't be spot on.

I like the FBBO plate. I bought one also, but have not tried it yet. I'm curious to hear how accurate the slots are compared to the numbers stamped on the plate.

 

[Kern Dog]

What are these "plastic gauges" to check advance?
...sounds like something I need.

I'll try to snap a few pictures this afternoon.
********************************************************************************************************************
I did look but so far, I can't find my container of the gauges. I have a few more places to check.
I did get the chance to put a timing light on it today.
1000 rpm idle, 20 degrees initial timing. Mopar Performance electronic distributor. I hope to have help from the wife tomorrow to map the curve in 500 rpm increments. 100, 1500, 2000 etc.
I remember reading years ago to set it for it to reach full advance by a specific rpm point. People would say it is all in by 2500, 2800, 3000, all sorts of different numbers.
Bonehead logic tells me there is no one size fits all number. A heavy car with tall axle gearing may want the total advance to come in later to avoid detonation. Automatic transmission cars may want the all in point below the stall speed of the converter, I'm sure there are variables to consider.
I'm curious to see what you guys have yours set to for your street cars.

 

[Charlie71rt]

Thanks bee1971, nice article on rotor phasing, post #98

 

[Cranky]

I'll try to snap a few pictures this afternoon.
********************************************************************************************************************
I did look but so far, I can't find my container of the gauges. I have a few more places to check.
I did get the chance to put a timing light on it today.
1000 rpm idle, 20 degrees initial timing. Mopar Performance electronic distributor. I hope to have help from the wife tomorrow to map the curve in 500 rpm increments. 100, 1500, 2000 etc.
I remember reading years ago to set it for it to reach full advance by a specific rpm point. People would say it is all in by 2500, 2800, 3000, all sorts of different numbers.
Bonehead logic tells me there is no one size fits all number. A heavy car with tall axle gearing may want the total advance to come in later to avoid detonation. Automatic transmission cars may want the all in point below the stall speed of the converter, I'm sure there are variables to consider.
I'm curious to see what you guys have yours set to for your street cars.

I've been saying that for years....there is NO one size fits all. However, I've never had a car that wanted what the book said to give it....