Total Timing?

[crackedback]

Shane,

Just tell them you want 36* total advance by 2500rpm. Your initial timing has nothing to do with what they are doing.

How so? Please explain this approach.

Here's my issue with this approach. If they put 36* in the distributor, I'll guarantee his car will run like crap at idle and be really sluggish. He'll have ZERO initial advance because all the advance is buried in the distributor.

It's a two piece puzzle. A distributor machine has no idea what a particular engine would need for mechanical advance. A stone stock 318 might run on 6 initial and 30 mechanical. A nasty roller 340 would need something entirely different for advance curves but you'd get exactly the same thing if you asked for 36* total advance without additional info.

Figure out what the engine wants using a vacuum gauge. Remove the distributor. Tell the guy with the distributor machine that you have x* of initial and want a total of say 36* at the crank, all in by 2500. You might also tell them the idle RPM so you don't have mechanical advance leaking in at idle.

 

[70Duster440]

I agree with Crackedback - all good, valid points. My mechanical advance doesn't even start till over 2000 PRM.

 

[GTS Registry]

How so? Please explain this approach.

Here's my issue with this approach. If they put 36* in the distributor, I'll guarantee his car will run like crap at idle and be really sluggish. He'll have ZERO initial advance because all the advance is buried in the distributor.

It's a two piece puzzle. A distributor machine has no idea what a particular engine would need for mechanical advance. A stone stock 318 might run on 6 initial and 30 mechanical. A nasty roller 340 would need something entirely different for advance curves but you'd get exactly the same thing if you asked for 36* total advance without additional info.

Figure out what the engine wants using a vacuum gauge. Remove the distributor. Tell the guy with the distributor machine that you have x* of initial and want a total of say 36* at the crank, all in by 2500. You might also tell them the idle RPM so you don't have mechanical advance leaking in at idle.

His engine sounds real similar in set-up to my 340, that's why I did not hesitate to recommend the changes that I have done. I have that set up with my M/P distributor and I drive my GTS on the street with no problem, plus I race it regularly with outstanding results. It is FAR from sluggish off the line. No vacuum advance at all-all mechanical. When I take it to the track, I run my initial up to 20*. Around town I keep it at 15*.
If my set-up was different from Shane's, I would not have suggested it.

 

[beepahh]

why do you want to run vaccum advance not really needed....get set up on a dyno machine and all guessing will be elliminated and you will know exactly the timing t hat works for your set up have fun...

 

[crackedback]

His engine sounds real similar in set-up to my 340, that's why I did not hesitate to recommend the changes that I have done. I have that set up with my M/P distributor and I drive my GTS on the street with no problem, plus I race it regularly with outstanding results. It is FAR from sluggish off the line. No vacuum advance at all-all mechanical. When I take it to the track, I run my initial up to 20*. Around town I keep it at 15*.
If my set-up was different from Shane's, I would not have suggested it.

So you have 36* total when it's at 15 initial?

If so, your distributor doesn't have 36* of advance in it if you are running 15 initial with 36* total, it's got 21* mechanical.

Shane asking for 36* in the distributor could have some real detrimental results.

 

[GTS Registry]

So you have 36* total when it's at 15 initial?

If so, your distributor doesn't have 36* of advance in it if you are running 15 initial with 36* total, it's got 21* mechanical.

Shane asking for 36* in the distributor could have some real detrimental results.

If that's the way you are looking at it, then YES that is what I have.

But as I said before I have a TOTAL of 36* at 2500rpm. That is what I told the guy doing the distributor that I wanted 36* TOTAL. I did not have to break it down for him with what I run initial at (15), nor "actual mechanical" advance(21). He just wanted to know what I wanted the full advance to stop at. Does that make sense?

 

[70Duster440]

It's also important to know at what RPM the mechanical advance starts. You wouldn't want to be into the mechanical advance (because of weak springs) at your desired idle RPM. That'll cause all kinds of tuning issues.

 

[crackedback]

If that's the way you are looking at it, then YES that is what I have.

But as I said before I have a TOTAL of 36* at 2500rpm. That is what I told the guy doing the distributor that I wanted 36* TOTAL. I did not have to break it down for him with what I run initial at (15), nor "actual mechanical" advance(21). He just wanted to know what I wanted the full advance to stop at. Does that make sense?

I bet your guy said time it at 36* at 2500 or so when you picked it up.

My guess your dist guy took a stab at what he thought the initial should be and set the curve to follow. He may not have asked you directly, but, he figured out a safe initial point based on the engine/components.

You don't have 36* in the distributor if I'm reading what you wrote correctly.

 

[GTS Registry]

I bet your guy said time it at 36* at 2500 or so when you picked it up.

Um, no. You got that backwards. I told him I wanted 36* total. I don't have to set anything at any rpm other than my initial timing.

My guess your dist guy took a stab at what he thought the initial should be and set the curve to follow. He may not have asked you directly, but, he figured out a safe initial point based on the engine/components.

He may have asked me about my initial mark, but I don't recall that in the conversation we were having.

You don't have 36* in the distributor if I'm reading what you wrote correctly.

Sorry if I'm not explaining myself in engineering terms that will satisfy your quest to prove me wrong. I do appreciate you telling me what I have in my distributor, and what the guy who worked on it did to it. Maybe next time someone asks for another member's opinion, or for help, I'll just leave that to the guys who know more than I do. I do apologize to Shane for trying to help him, when obviously, I'm not qualified to open the hood of my own car without help from total strangers.

Maybe I'll just switch mine back to points and just follow the timing directions on the sticker on my fender well instead.

 

[crackedback]

Maybe I'll just switch mine back to points and just follow the timing directions on the sticker on my fender well instead.

Yeah whatever... I'm trying to figure out exactly what you have.

You say have 36* total, fine. Have you checked it at 2500,3000 etc?

If you have 15* initial at idle and 36* total, then the distributor has 21* in it. Otherwise, if it has 36* in it, you have 51* total.

He may have asked me about my initial mark, but I don't recall that in the conversation we were having.

EXACTLY! He had to have asked you that question or gotten the info from you indirectly without you remembering. I can't set up a distributor properly without that one tidbit of info.

The guy setting the curve has to know what you want for initial if he's going to make sure the distributor stops advancing at the desired total number. Unless he's one of miss cleo's employees. There are 36-37, 1 degree increment combinations, to get to the 36* total number on a zero or BTDC initial number.

I'm not being a smart ***, just trying to understand your position.

 

[Longgone]

With all the talk of initial, mechanical, and vacuum advance I was just wondering Shane, what grade of gasoline are you running that the engine was pinging on with just 12* of initial timing? What kind of compression does the engine have? You`ll need no less than 91 octane with a lot of timing and moderately stout compression. Run 93 if you must. Pinging or detonation is really bad for your car, avoid it at all costs.

 

[whitey]

Gee, I have a distributor from Mancini (non-adjustable), With vacuum line disconnected I have 36.5/37* at 3000 RPM, 11* initial (vacuum line connected at curb idle (850 RPM)) and 52* @3000 RPM with vacuum line connected. Like I mentioned before I followed an article from Mopar Action/Muscle which ever (October 2003). My 360 LA with Magnums heads, Professional Products intake and Holley Street Avenger runns like a Champ.

 

[Johnny Dart]

Old thread,but I find it interesting.
GTS Registry runs his car at 15 initial- 36 total. Doing the math,he has 21deg built into the distributor.36-15=21
But when he goes to the track he likes to run his car at 20 initial.
20+21=41deg total. Holy Kaboom Batman !
Rob (crackedback) You must have been pulling your hair out with this one.

 

[abodyjoe]

Read this.

 

[67Dart273]

I've just GOT to get that distributor machine rebuilt, LOL

 

[aprfct0]

I would like to know what octane gas Shane is running as well. Octane and timing go hand in hand the higher the octane you run the higher the timing can go. If you consistently use the same octane the best way to set your timing is adjusting and driving until you find the correct set up for your specific engine depending on cam and compression etc.