How to??

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DesertRat

DesertRat

Leading edge boomer
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I have researched the timing curve thing on this thread and have been running my motor no load for a couple days. 273 Hi-po pretty standard stuff. Lunati hydraulic cam a little bigger than the stock 235 hp cam but not much. It seems to like 15 deg initial or a little more but I have a stock 2V distributor with vacuum plugged and it goes to 45+ at 3000. Can someone post photos of how I can limit the mechanical advance, welding slots or springs or whatever? I have converted my distributor to the Pertronix ignition module and have not had it apart further than that. TIA------DR!
 
There's a slotted plate available where you can limit it to how much advance... I don't have the link, but someone can post it...
 
I used the FSM to break down the distributor in my 66 273. It lays the steps out pretty well.

I also use the Pertronix Ignitor. I bought the Mr. Gasket 925B spring kit and used one spring in place of my heavy spring.

Here's the link Krazy was referring to FBO Systems
 
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**EDITED Part Number for Mr. Gasket Spring Kit to 925B in my last post!!! My memory is not as sharp as it used to be:)
 
HP 273 was DP right?

I got a reman to use the Pertonix III cause my DP was not comparable. I wanted a stock appearing unit and was going to get one of the limiter plates FBO sells. Glad I did not, the reman had angled slots that will not work with that plate! It is designed for the electronic units Mopar offered with straight slots!

I printed a 360 degree template from the net and cut a hole to lay over the distributor. Put a piece of wire on the rotor to measure the advance to the template. Welded and filed the slots to what I needed. It is a little crude but got the advance to a degree of what I needed.

Only use 1 spring for quick advance.
 
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DesertRat said:
I have a stock 2V distributor with vacuum plugged and it goes to 45+ at 3000.
Click to expand...

This is a single point? I don't know if the FBO limiter works with dual, I'm sure you can get ahold of them

Crackedback, I think, posted a set of measurements for recurve slots, but again, I think they are for single point. I would guess that a "starting point" could be based on a percentage decrease in the slot length of "what you have." You'd have to carefully measure the advance of what you have now.

Basically, you just weld or braze the slots shorter and file them out. Be careful not to damage the SIDES of the slot or the pegs may "catch" There was a Hot Rod or similar article

Here we go

Mopar Electronic Ignition System - Mopar Muscle Magazine

Here's one from Jalopy Journal

Fixing a bad curve....

Bear in mind that as you read about this, "traditional" distributor specs were given in DISTRIBUTOR degrees, which gives you TWICE as much advance at the crank

I think I got this from Crackedback. Again, these are distributor degrees

Dimensions for Mopar distributor slots, in DISTRIBUTOR degrees

Modifying advance slots
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
 
My distributor is just a standard 67 single point 2V setup that has had the Pertronix ignition module installed and the ballast resistor removed so it gets the full 12V. I have done no other mods to the distributor but if I understand the tuning I need to do to my build I need to limit the mechanical advance so initial and mechanical total come in around 36 deg +_ at about 2000 to 2500 RPM. I am not interested in changing distributors, just modifying the one I have to that end. Thanks for the help all. I have been testing the motor for a couple days and I can tell it is going to be a sweet runner for a little 273 4V hi-po setup. Details are on my build thread------:)
 
You might have a CAP distributor, they had a bunch of advance, and base time was very retarded (-5).
They also had a vacuum amplifier, different vacuum advance. Might want to check the bottom of distributor cam part with slots. The number there, with an "R" is the advance in distributor degrees, 2x is crank degrees.

You can often find distributor timing specs in FSM, they vary by engine, w/ w/o CAP, trans and carb. The specs are in distributor degrees, same with test RPM, so you will need to calculate back to crank RPM and degrees. They are good starting points.
 
Sounds like he has a single point unit. The FBO plate should work. Otherwise measure your stock plate and modify as necessary. My dual point likes 10° before with my cam timing. I replaced the heavy stock spring with the Mr. Gasket spring and it's all in at around 2000 with a 4 speed and total of 35°. It runs very well.
 
Today I installed the limiter plate and springs from FBO. I am running 16 initial and set the plate for an additional 18 for a total of 34. On startup I had my 16 initial but under throttle it was slow to come in and went above 40. Also I got some backfire for the first time since I started it. Tomorrow I will pull it back down and move the plate to 16 and put in weaker springs to see if I can make it work. I am still a little unclear if I connect the VA after I get this part done. It does want to run like a hot rod and that makes me happy, sounds really strong and all. I checked the compression again and it is coming up, rings seating I guess. All the oil leaks are fixed and it runs at 200 degrees at 2000 RPM. Tomorrows work is all cut our for me. Still no dash temp guage or center aftermarked tach but the rest of the electrical seems to be working good. Not perfect but acceptable considering I gutted the electrical like a codfish and re-did it all-------------------------
Cheers to all, time for a shower and a libation:)-----------------DR--------------
 
FBO recommends using direct manifold vacuum, and it can increase your cruise MPG by upping the advance as much as into the low 50's at lower cylinder pressures.
 
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