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Mechanical Advance Timing

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chevy
28K views 34 replies 6 participants last post by  ggevaert 
#1 ·
:DHello,

The engine I purchased online (350 sbc) has a mechanical 4 degree advance (in the timing chain) which I verified manually.

So, next step is to do the timing and I need some assistance.

For a stock chevy engine advance is 6 degrees, so, for this engine do I:
1. add the 6 degrees to the mechanical 4 degrees for a total of 10 degrees.
2. put it at 2 degrees with the thought being that it is 4 degrees below zero (retard) so plus 6 is 2 degrees
3. other thoughts are appreciated.

Cheers
Gary :D
 
#28 · (Edited)
Stumped

Ok, I'm officially stumped and need some assistance. I'm using the MSD HEI advance medium springs. Initial is set at 17 degrees

1. with no springs and the stop advance screw in it stops at 36 degrees perfectly all the way up
2. With medium springs an NO stop advance screw I get 42 degrees at 4500
3. with medium springs and a stop advance is stops at 31 degrees all the way up.

huh? :confused: if the springs by themselves go over 36 and the stop stops it at 36 would that not have it stop at 36? I just don't get it.

I have played with over 3 different companies springs (Morose, MSD pro billet springs, MSD HEI springs and I have a mr gasket HEI kit on order). I have played with light all the way to heavy and numerous combinations of lights, mediums).

I made another screw and shaved it down to stop at 40; testing with springs showed it to stop, yup you guessed it, at 31.

I'm not sure where to look next. Any thoughts are appreciated.

I used a screw as the picture that F-Bird'88 sent, maybe another approach is needed? what are the alternatives (short of buying the pro-billet one with the built-in stop)

BTW, confirmed timing with another timing gun, a non-dial back light.

Thanks for any help
Gary :welcome:
 

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#29 · (Edited)
Just my two cents,
Your distributor looks just like the MSD HEI Streetfire that I have laying around. I had issues with the advance mechanism not being as smooth as I thought it should be in certain positions. With no spring yours may let one weight get out in front of the other and bind(see pic,near thumb). I had to grind the end of one weight to keep it from catching. It may never have got to that position in normal use with springs. I'm just too picky(anal).
I swapped the weights out with a MSD Advance Kit PN 8428 and it seemed to be smoother.
However, I bought a MSD rev limiter module that was advertised to fit Stock and aftermarket HEI's, but low and behold it wouldn't fit in the streetfire????
I made a mod to it to get it to fit, but was still disapointed.
I decided to use an older MSD 8365 Pro Billet I had on another engine instead.
Something sure doesn't make sense with your timing being more advanced with springs vrs none. You sure the harmonic balancer outer ring isn't moving around on the hub(doubt it on a new engine)? Brush a thin line of paint across the two(from center outward) to be certain. You'll alwas know in the future if it has if the lines aren't straight.
I suspect the weights aren't as smooth as they should be, but thats just me. Might try the kit I mentioned.
Good Luck!
ssmonty
 

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#31 ·
Ongoing distributor saga

Hi SSmonty,

I tried swapping out weights with the advance kit specified from MSD for the streetfire and I didn't like it; the timing came in all at once at around 1800 (from 18 to 32 in about 200 rpm). All the different kinds of springs did was move the all-in point around but there wasn't a smooth curve so I went back to the stock setup. I have not played with shaving or changing the weights as that would be somewhat final so don't want to go there yet.

I checked the weights movement and there is no binding anywhere.

The MSD advance kit 8428 is the one I'm using now (since it is the one actually for this unit - the pro-billet kit was not)

I put a bright green line on the balancer since the day I got the engine and its still bang on.

I'm now actively saving up for a pro-billet unit but until that time I'm going to play with the Holley setup and maybe, when I have patience back, play with the ignition advance again :)

Thanks for all your continued help :thumbup:
Gary
 
#32 · (Edited)
distributor

Thanks F-Bird'88, I'm going to check the advanced weights but since the whole distributor is new I don't think it would be warped; then again you never know.
I am more convinced now that the pro-billet (made in US of A) is the way to go. I read an article about a week ago where MSD was indicating their streetfire was chinese made and was their attempt to stay in the market they were losing to low cost alternatives. The way I read it they were pretty much apologizing for the lower quality of the unit.
Personally I don't like to scrimpt on certain things and the streetfire was a mistake so I'm going to correct that with a pro-billet. I already have a friend who will take the streetfire off my hands for a stock application and he will give me 90% of the units value so that helps.

I have multiple threads but they are not related. One is for mechanical advance (this one), one if for holley setup - transfer slot and one is for Holley setup - Choke. I guess you could say they were all related to engine tuning but I personally like to keep subjects separate as change-of-topic questions get lost in the discussion sometimes.

As for Cam shaft and torque converter specs; they are:
Cam: 450 lift, 224 duration, 206 lobe centre
Torque converter: new 1500 stall unit from GM - 2 years old now. (long story, had a 2500 in there and it went bye-bye when the transmission fried and now I have a rebuilt thm-375 tranny with 1500 staff as recommended by the tranny shop).

Thanks for the feedback, I guess my next step in this thread is to get the HEI Pro-Billet and go from there. I'll update how that goes when it comes in.

Cheers :welcome:
 
#33 · (Edited)
Torque converter

Thanks! I'll play with the timing tomorrow.
The torque converter is a bit trickier as I have to order one, drop to the tranny, blah blah blah, you know the deal.

I think I need to read up on the torque converter and how it works as I know the basics but not how/when it kicks in when you have a 1500 vs a 3000. i.e. does putting a 3000 in gear do nothing when the idle is at 1000 or does the car try to move (my 1500 will try to move). Do you need to be reving at 3000 (or close to that) before the car starts the move. Not that familiar, yet, with workings of the torque converter when it comes to actually when they engage. Another area for me to read up on; exciting!
There was probably a good reason why the engine/tranny combo came with a 2500 stall.
When I destroyed the tranny pump, and therefore parts of the tranny, through improper spacing of the torque converter (another lesson learnerd) the tranny shop recommended/put in a 1500 unit. But they never asked what engine setup I have. jeez.

I did not pick the specs on this engine so what's the deal with this setup F-Bird88, is it a street/strip type of setup or more agressive than that?
I do want to be able to drive the setup on the road :D and I'm concerned about the high stall.

Thanks for all your continued help!

Ps. the mech advance stop will be much easier when I get my MSD 8365 in :)
 
#34 ·
converter

Hi F-Bird'88, Thank You for all the excellent info!
Now I know why the tranny guy explained to me that this was the best way to go. jeez.

I have attached a picture of what I have installed now; I could not find any info on what its specs are other than what the tranny company told me (1500 stall). I even looked at their bill and it does not list an actual model, only that it was a 'rebuilt torque converter'.

Anyway, I don't need it to be low rpm hiway cruiser, I was just wondering what I really have on my hands here. My goal all along is to build this setup the way it was meant to be; I acquired the engine as it is so now I am working towards maximizing it the way it was mean to be. If that requires putting in a 3000 stall 10" converter then that is what I will do.

Any recommendations on a torque converter company? Or maybe I should ask if there are any i should stay away from. I'll call a couple of companies and do some research. I'll call my friend who works the parts counter at the local GM dealer to see what he can get me in the GM line as well.
I have a THM-375 with a stage 2 shift kit hooked up through a BOP plate to the SBC 350.

Also, on the rear-end; I have been saving up to get that done as well; wasn't planning on doing it until later in the winter but may have to forgo that second coffee in the morning to get it in sooner. Currently it has the original rear-end in it from when the truck had a straight 6; in other words 2.73 rear end. So, what does that mean for driving it until I get that done? how will that affect the trucks driving manners?

Thank You :thumbup:

Gary
 

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#35 ·
Torque converter

Talked to a couple of torque converter companies and they all recommended a 2400-2600 stall converter for my Cam specs. My local performance transmission shop recommended the same thing so I ordered a custom built 10" one for $500 bucks. Should be here early next week. :thumbup:

Now to the job of taking tranny out and once back together back to the disitributor and holley setup. Should also have the MSD 8365 later this week.

Cheers
 
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