Hi All,

I have been playing around with my timing as of late. Just seeing how the car runs at different settings. But anyway when I set my 80 HEI at 36 degrees at 3000 rpm the idle setting is about 24 degrees! What are you guys seeing with this deal? I have talked to Lars and he says that is a by-product of the 80 HEI, slow and short curve. Also I am surprised that the sound of the exhaust changes dramatically when the timing is moved around.

Joe

 

Mines at 13 initial. Sounds like it's time for some lighter springs in your distributor.

:cheers:
Pat Kunz

 

I'm running around 14 in my car.

 

12 degrees BTDC. :smash:

 

Two. That's right, two puny I-got-too-much-compression-and-damned-93octane-gas degrees. Still goes like a scalded cat, though I do get some pinging still at WOT.

JB


[Modified by JB, 10:57 AM 9/30/2002]

 

I do. I guess it might be time for a new distributor.

 

I have about 20* initial. Q-Jet with a fairly radical cam.

 

According to Lars, your timing @ idle is irrelivant.
You dont drive your car @ idle so therefore it doesnt apply.

Stew

 

Joe, I'm at 12 degrees. Rod

 

I use an MSD timing computer and have my curve fixed in the distributor. I only set the total timing and that is around 3000rpm. I bring it up to about 35oo to be sure, set the timing at about 38degrees then check the idle but let it fall where it wants. Since the msd pulls about 20 degrees out of it I get about 18 at idle. The MSD also pulls 20 out for starting. I also have an MSD adjustable timing pot in the car so I can add or pull timing out while driving down the road.

 

on my 72, pointer reads 12 but it really is 10.
33.5 total WOT.
87 octane, no pings.

 

Xracer, did you confirm that your distributor is through advancing at 3,000rpm? Many distributors, especially those on emission controlled engines, don't reach full advance until much higher rpm. If that's the case, a reading taken at 3,000 rpm may be way lower than what the actual total advance is and it would also result in a higher initial setting. Keep in mind that the springs control the rate of advance, not the amount of advance.

 

Vetterodder is right-on-the-money, again!

quote: "According to Lars, your timing @ idle is irrelivant.
You dont drive your car @ idle so therefore it doesnt apply."

Maybe true for stock or near stock builds. Less true for performance builds. ;)

 

Take your distrubutor apart and clean and lube everthing, you only have 11 degrees mechanical and you should have 15 degrees bet you find some rust in the advance assembly.

When I had the stock HEI on mine I was at 21 degrees at idle and 36 degrees at 3000RPM. I do not use a vacuum advance it is for emissions and better gas mileage two things that my car doesn't like :D

 

quote: "According to Lars, your timing @ idle is irrelivant.
You dont drive your car @ idle so therefore it doesnt apply."

Maybe true for stock or near stock builds. Less true for performance builds. ;)

[/QUOTE]

Could you explain your last sentence? Why is Lars' statement less true for performance builds?

 

When you install a high performance cam, the stock distributor settings no longer apply. Smart tuners will try to run as much advance and as quick an advance curve without pre-detonation, to optimize the new high performance build. A stock distributors timing setup will not be ideally setup for best performance, almost guaranteed. That's why a high performance distributor should be tops on the list when you run a hi-po motor. You can then optimize both total and initial timing settings and the rate of advance. Doing just one adjustment without the others is leaving too much power/drivability on the table.

Does that make sense?

 

6* for me, once i get my suspension squared away, Im gunna bump it up to about 12 and see how that goes.. :smash:

 

OK, I am running 36* advance all in by 2600 rpm. I am using the stock distributor with lighter springs. Stock distributor weights will give about 20* - 22* maximum advance, rest is from initial.

Are you saying I can do better with some other ignition set up?

Check my signature for my mods.

 

Started 18, now 20 runs great, but I also have a magnum cam.... before engine mods I was running 10 with stock cam... also replaced dist as well for optimal performance

 

Maybe. How's that for an answer, LOL. Actually, your 20 degree mechanical advance HEI is a decent one. But you should experiment a little to see if the engine performs better with a little more initial advance while retaining the same weight springs. If it performs better, without predetonation, you should bush the distributor to limit the mechanical advance accordingly. The same type of experimenting needs to be done with the springs. Some engines may like more initial with a slower advance curve and vice-versa.

Also, be aware that some fast-burn type heads actually need less advance (34) for optimum performance. So, 36 deg total for all engine builds may not always be optimum. If I remember correctly, when I was running smog heads, my optimum total timing was 38 based on 1/4 mi track times.

The guys with the big cam many times need the extra initial timing to help maintain an idle. Therefore, to just let the stock mechanical advance dictate the inital advance settings is not a good "general" performance tuning recommendation. Some guys, like you, maybe lucky to fall upon a near ideal setup. While others might try it and end up frustrated.





[Modified by nunus79, 9:19 PM 9/30/2002]