Questions about recurving the distributor

Hi, Before I pulled the engine from the car I took some measures of the mechanical advance and it was not so good, 10 degree initial was 10 degree even at 2200 rpm, then it started to move and at 3500 rpm it was 34 degree and at 4000-4500 I reached 36 degrees.

The car did not ran as good as I was hoping and after some research I found out the the Mopar BB really likes 16-18 degree initial and the idle was much better but then I had to end up with 42 total advance so that was not the way to go.

Got myself a Mr Gasket 595B spring kit and was planning to change the harder spring in the distributor to one from the kit, I also planned to weld the slot in the plate to a maximum of 18 degree, is it a 26 degree plate.

But when I dismounted the distributor it only had one spring! and I guess it is the hard one because it is really stiff compared to the mr gasket, I dont know where the other spring is, mayby the chinese or mexican guy had a bad day at work.

It is a Mopar Performance distributor, approx 10-15 years old.

The problem is if I can go with both Mr Gasket springs or will it be to soft?

Or shall I order a set of Trans-daps 4450 spring kit, are those harder than the mrgasket?

Or shall I try to get my hands on one softer original spring? Finding one of those in Sweden is harder than locating Jimmy Hoffa so I hope the 4450 kit will do the work

And as always, I am very thankful for all the help I can get!

And this is not the end, next chapter will cover the vaccum advance...

how much initial advance you need may depend on the camshaft or lack of low rpm cylinder pressure. .015" is equal to 1 distributor degree in the slot. reducing the slot .060" on each side should yield a 9 degree plate; if you have a 13 degree plate. the 2 very light springs might bring the advance in too soon.

I am not an expert on this subject but I do know that the Mopar Performance distributors have a problem with the vaccum advance. I just bought a Mopar reman from bperacing.com. The one I bought was designed more for street use. You can no longer by the one you have and they are happy for that. Give them a call and talk to someone in the tech department to get the professional explanation.
Here is a link to there website and a brief description of problems you may be having...http://bperacing.com/distributors

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Do you have access to a distributor machine. I know it is a piece of prehistoric equipment but the only way to really set up a distributor.

I'd try the two 'soft' springs, and see how it acts.

Don't know much on the Mopar performance dists, but all work off the same basics. Some have an adjustable stop built in, to set full advance.
I've only used older Mopar dual point, then to Mallorys.

With the lighter springs, if your advance comes in too quick, at least you've got a starting point. Even seen combinations of 1 light /1 medium spring, to customize the coming in rate.

Waiting to hear about the vacuum advance. Is it adjustable?

i've built a bunch of mopar electronic distributors. the only issue i've ever had was if the reluctor gets too close to the magnet, and thats my fault not the distributor. i've done all kinds of curves and changes. most of this depends on camshaft. FBO has a plate they sell that can be used to alternate/change the number of degrees in a distributor; might be worth looking into.

OK, thanks for all the help, I found a FBO plate and spring kit here in Sweden! Will have it on tuesday. A friend of mine has a Sun distributor tester but he lives to far away but it was a cool machine,

The next issue was the vacuum advance, it is marked with a 9 and I guess it means 18 degree advance, I took my new Mityvac and measured it to around 16 degree so I guess 18 is correct.
First it was really hard and it needed 15 in/hg to start working, I took a hex key and adjusted it so it starts pulling at 10 in/hg and have full advance at 15 in/hg, that is the lowest I could go on the adjuster.

I have to measure the vacuum during cruising since I have a new cam (mp 284H) and I don't know the vacuum yet, is it wise to for example adjust it so it start working just above the vacuum I have at idle or what shall I aim for? Is it better to use the cruise vacuum as a guide? Shall I use the ported vacuum or not?

i always use the timed port. there are some variables depending on what carb you have. i take vacuum readings at cruise rpm and then adjust the vacuum canister to where it's full open matches the cruise vacuum reading. the carter/edelbrock afbs will give a higher cruise vacuum reading because they tip into full manifold vacuum. holleys have their timed port higher in the venturii bore and generally the readings are a few inches lower.

Another thought is limit the mechanical in the distributor & adjust rate with the springs, get the total you want from the initial timing & don't use the vacuum at all. That worked on my street 383 with points years ago. Otherwise I have an iron Hemi mechanical distributor that has all the advance in by 1300 RPM. Worked on my drag cars & seems fine with my Satellite both street & track.

Just got a mail from Don at FBO who sold me the plate and spring kit and here is his advise for me:

Start with 20 degree initial timing, put in the plate so it is limiting the advance to 14 degree, that gives me a total of 34 degree advance.

Try to keep the springs hard enough to reach full advance at 2800-3000 to start with and work my way down towards 2500 rpm, this is where my stall speed is, if it starts to ping go back one or two steps.
There is no need for full advance under 2500 rpm in my case.

The vacuum should be connected to full vacuum at the carb, not ported, with the engine at idle it should add 10 (of maximum 18 degree) degrees of advance to a total of 30 degree at idle, this gives me a timing from 20 degree up to (20 ini + 14 mech ad + 18 vac ad) 52 degrees depending on rpm and load. I will try this in a couple of weeks and see how it works, Don seems to be a guy who knows what he is doing so I am hoping this will end up well.