full timing question

[reaperz1]

so i looked at tach, dwell, points meter the tach only goes up to 2500 rpm. how would i do my full timing with that since i can not go to 3000rpm. also want to make sure i get this right i go to 3000rpm and put it on 32 degrees. i just want to make sure i understand this correctly

[geezer#99]

Eventually you want to get to around 32 to 34 degrees all in by 3000 rpm.
First you need to know how much initial timing your motor combo will use without encountering hot start problems. Considering your elevation that could be anywhere from 14 to 20 degrees (or more) initial. Depending on your set up.
Once you know max initial then you can recurve the dizzy to give you the mechanical timing that when added to the initial gives you your total at 3000 rpm.
Another thing about your elevation that helps is you can have your timing all in at a lower rpm. Your combo might like it all in by 2500 rpm.
You gotta experiment.
Do you have a stock motor or any mods?

[DBD]

easiest way is with a dial-back timing light, and aftermarket tachs - either one you mount on the column or just one you can connect for tuning are cheap.

I kinda approach it the other way - get to 36 degrees by 3K, then figure out if you need to back off the initial. then you need to tune the vacuum advance too. most engines will do OK on a 36-by-3K curve; perfect takes a chassis dyno

[reaperz1]

after i do this how much more should it advance after 3000 rpm, the motor is pretty much a stock 402 30 over with an rv cam in it, 4 inch air filter. so i was playing around with it and checked the initial it was like 20 degrees from the shop, they told me it was at 12 what maybe they did it by ear. I have it at 16 degrees went to 2500 rpm and watch the needle where 3000 should be it is at 34 degrees.

so say if my initial is at 20, to get a total of 34 degrees timing at 3000 rpm would be 14. I am just playing around with it right now. because when i got it to the shop 20 intial rev it up to about 3000 it was around 50. from what i have been reading that sounds way off

again thank you

[reaperz1]

I have the hei distributor summit brand, how do you adjust the vacuum which direction is most vacuum and the least

[Captainfab]

Are you checking the timing with the vacuum advance disconnected?

[DBD]

The goal is to get all the mechanical advance in by 3K by adjusting the springs as needed; if you're seeing advance after 3K, then move to progressively lighter springs, one post at a time, until it's all in by 3K. like captainfab said, this is all done with the vacuum advance disconnected and plugged.

vacuum advance tuning a bit more tweaky - basically you add advance until you get pinging under load - remember that vacuum advance is only under load, while mechanical is strictly rpm...that's why we set the mechanical first. it's tweaked a couple of ways - how FAST it comes in is set by using an allen wrench inside the nipple, how MUCH comes in comes from limit bushings on the arm, just like you might use under the mechanical advance plate. in weird situations it gets a little more complex, but 90% of the time the kit does just fine.

here's the tuning kit:
http://www.summitracing.com/parts/MRG-6011/

[storm9c1]

Depending on the distributor, vacuum advance can also be limited by a stop plate on the draw arm.

[DBD]

Yep, and the Crane one has a really nice ratchet stop plate too.

[crazy longhorn]

I would shoot, 34-35 total on that BB...all in 2800-3000 (heavy truck). The Crane advance is a nice adjustable pc, but I would not use the Crane limiter, on the vac advance? Do your own stop, & cut it from the front side....generick figure is 10 degrees , @ the crank on the vac advance (more like 8, on the high compression versions). Hook that vac can to full manifold source @ the carb. Yes, you will be running 44-45 degrees @ lite throttle cruze....its a slow burn, in the lower rpms, & it will handle it. When you drop the hammer (WOT), the advance will back out Understand, that I tend to tune on the very ragged edge....I want it ALL! Take it for what is is worth, & tune to fit your ride? Longhorn

[reaperz1]

yes i did timing with vaccum advance disconnected, all right cool so there should be no more advance for mechanical after 3000. I am going to have change some things around in the distributor. I will let you know how it goes when done. will have to wait untill next week when i get paid though. can not wait.

again thank you all

[geezer#99]

You can have mechanical advance after 3000 rpm.
I've seen them still advancing up to 4500 rpm.
Depends on the springs and weights.
And as you can read, everybody arrives at the desired 32 to 34 degrees all in by 3000 rpm a different way.
Those who live close to sea level can just set total of 32 at 3000 and not care what the initial is because most dizzy's have 20 degrees in them and at sea level due to higher air density your initial can't be more than 12 to 14 degrees.
You and me( who also once lived at your type of elevation) need to find max initial and then adjust the dizzy mechanical. Also due to air density. Less air with the fuel needs more time to start the burn so you need way more initial advance. Sometimes double what you need at sea level.
I've had motors you could hear detonating at idle hot and still start at first flick of the key. That was with 22 degrees initial. That motor went to the west coast and wouldn't run or start with more than 10 degrees.

[reaperz1]

so at pep boys, they have a msd advance kit, I also looked at summit what is the difference between an advance kit and a advance curve kit just am curious they look the same also which ones should I stay away from.

thank you

[reaperz1]

do you guys have a picture of the stop plate on vacuum advance I probably go ahead and remove and where i remove on distributor or the vacuum bezel
thank you

[geezer#99]

If you haven't found your max initial and recurved your mechanical then you don't know if you need to limit your vac advance or not.

[reaperz1]

My max intial is 22 degrees, at 3000 rpm it is at 50 degrees and still advance after 3000, so will the msd advance kit fit my needs

[reaperz1]

I am going to have intial at 18 degrees no problems starting, at 22 degrees i have problems starting sometimes

[geezer#99]

With 18 initial you'll want 14 in the dizzy. Here's a wiki on limiting your mechanical. It's for an hei but works the same on a points dizzy.
http://www.crankshaftcoalition.com/w...EI_distributor

Any curve kit with lighter springs and weights will get you all in by 3000.

[reaperz1]

I bought an accel advance curve kit model 31042 not sure what springs are light or heavy or mesuim. One is blue,white and red

[reaperz1]

ok I figured it out on the springs, still how some more playing to do but it is a whole lot better, have a medium and soft spring at 3000 36 degrees 3500 at 40 degrees and stops there