it's amazing what some timing can do ... ignition timing that is.

[garage C20]

i was up late one night checking out some videos on dyno runs on YOUTUBE and came up on one guy who was showing how his shop sets the ignition timing and setting the the idle on a edelbrock carb on a Chevy (link posted below). i thought i had mine set just fine but i was wrong. i normally just set the initial timing at idle with the vacuum disconnected. i set it at 12 deg and lock it down. i never thought to check the timing at 3000-3500 rpm. well... i did that this morning and was it WAY off. i was only getting around 20- 22 deg of total timing.. to say that this motor was a dog is an understatement. i thought the motor was tired and was in need of a rebuild. so, i advanced the total timing to 33 deg advanced (vacuum disconnected). now i can run down the freeway with more than enough power and very little throttle. i can spin my 33's at the stoplight and even bark them in second. (kind of hard with my hard to shift man tranny). i connected the vacuum to the ported vacuum side of the carb and this truck has never run better. i hope this little tip can help someone else.

http://www.youtube.com/watch?v=EEeKYZS-Stg

[Stepsideride]

wow I need to get a balancer like that set my timing that way.

[garage C20]

if you look one the summit catalog you can pick up a balancer cover. that is what i did. it has etched timing marks on it and is only around $35... all i had to do was remove the lower pulley and slip it over the stock 8 inch balancer.

[GMC Guy]

did you hook your vacuum advance up to ported or full manifold? i have mine hooked up to full manifold, and running about 12* initial timing, but i should check it at 3000-3500 prm as well.
i'm always looking for a little bit more....

[garage C20]

i hooked it to the ported side... i think the distributor doesn't give me enough advance so i may have to modify it. that is why i wasn't getting enough advance at 3000 rpm. i forget what the initial advance is but it was a bunch more than the 12 deg i normally set it at. so i thought it was best to hook it to the ported vacuum port.

[turner15]

this cold be my problem

[Pyrotechnic]

If you are running an HEI, beware that the centrifugal advance has no positive stop, so there's not a hard limit on the advance. The advance may appear max out at 3000-3500, but chinese reproductions or worn out HEI's will usually slowly creep in an extra 3-4 degrees at around 4000-4500. You need to consider this as part of your total timing. Rev it up to check if you have the advance creep issue or not.

If you run an engine driven mechanical fan I would suggest removing it for this. Sounds over cautious but I've seen pictures of fan blades through hoods. Once you know how much advance your distributor adds, you can simply set it by the initial timing so you only have to do this once.

[garage C20]

Originally Posted by Pyrotechnic

If you are running an HEI, beware that the centrifugal advance has no positive stop, so there's not a hard limit on the advance. The advance may appear max out at 3000-3500, but chinese reproductions or worn out HEI's will usually slowly creep in an extra 3-4 degrees at around 4000-4500. You need to consider this as part of your total timing. Rev it up to check if you have the advance creep issue or not.

If you run an engine driven mechanical fan I would suggest removing it for this. Sounds over cautious but I've seen pictures of fan blades through hoods. Once you know how much advance your distributor adds, you can simply set it by the initial timing so you only have to do this once.

good points..... i am running a stock HEI but with a proform "tune up kit" with different weights, springs and module. i will check for the advance creep. i am running a engine driven fan on a HD fan clutch. but i will pull it before checking the timing at those speeds. my buddy was nearly killed when a flexfan cam apart while he was tuning his motor. it hit him right on the jaw. a glancing blow and embedded itself in the hood of his truck. 3 day in the ER and major surgery to repair his face. another inch or two and he would have been killed for sure. safety first.

[motornut]

Yup they brake,in my 78 sub goin to work i pulled hard off a light heard a big bang..running rough.....thought engine blown/gone...,WHAT can't stop no brakes........able to pull ebrake abit to coast to a stop.....pop hood, brake fluid all over??...my new lines were leaking?had to leave it till next day......closer look one of the fans four blades broke off and went threw both master lines at/to the portioning valve......someone told me later this was a recall i duno

[qu1cks1lver56]

I always set timing at 3000-3500rpms, whether its got any advance or if its a locked out race distributor, just the way I was taught, I thought everybody did it lol.

[billnorman]

Checking the timing at higher RPM is the right way unless you have a distributor machine. European cars have been doing this for decades. Also, on flex fans, they will kill you. I lost a friend when his disintegrated and almost decapitated him when he revved a motor up. Most motors are happy at 32-36 degrees total. With knock sensors, newer motors run as much as they can for maximum efficiency and power. Timing and compression are vital keys to power and economy.

[asphaltburner]

I'm shocked!
Todd.

[Stepsideride]

Im runnin an Electric fan..learned my lesson a few years back...water pump nose broke at 3 grand on the Interstate at my exit no less...fan put a nice hole in my hood too.