Jetdriver69

On my 82 5 speed we had set the timing at about 28 degrees, stock is 23 degrees at 3000 rpm for the 4.5L. I have noticed good higher rpm performance but idle is a little bit rougher than the stock setting. I understand the 23 degree setting was for emissions but does advancing the ignition really help performance that much at a sacrifice of a rougher idle?

Has anyone found a good happy medium for ignition advance for the 4.5 without me experimenting with each degree of advance or should I just start back at 23 degrees and go from there?

BTW, the engine is a complete new rebuild, all new ignition parts, new vacuum lines, fuel lines, rebuilt injectors.

toofast928

If the idle is rough, I would back off 2 deg. 28 degree is an estimate of the quality of your timing light and T-Belt tension if the cams are dead on the mark (round tooth belt never aligns the cams). Don't want to chance engine knock.

Now a programmable MSD box can find some more torque.

joejoe

My '81 had the distributor reset 1 tooth advanced, and adjusted full advanced. It would run very close to our '86.5. Problem was it would get about 10 mpg whether romping on it (great fun) or driving conservative. Another odd addition to the car was the deletion of the intermediate muffler and putting in a second cat. It did pass california smog (twice) before the vacuum advance/retard part fell off inside the distributor. Still it almost passed, guess the second cat helped some.

mark kibort

on the dyno, the 84 Ljet, got 2 less hp and 2 more ftlbs of torque for a 3-4 degree advance change. needless to say, we went back to stock to get more HP in the useable operation range.

Jetdriver69

I set the timing to stock, 23 degrees and the idle was very smooth with decent throttle response. 28 degrees is just a tad too much as the engine will hesitate just a hair when gunning the throttle from idle to 3000 rpm when the rpms wind back down to idle.

Hope that made sense.

We tried 25 degrees and the idle is still smooth but with a bit more throttle response at lower rpms. I think we will try this setting for a while and can always go back to stock if needed.

Will advancing the timing adversely effect gas mileage?

Thanks!