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[fredo74]

Ok, I've got the distributor converted to duraspark and the TBI all plumbed and running. I set the motor to TDC on the compression stroke for #8, stabbed the distributor, put all the plug wires on, checked 'em twice, and fired it up. I proceeded to unplug the timing test connector and set the timing to 0*. Shut the motor off, plugged it back in and fired it back up. I revved it and watched it with the timing light and it advanced instead of retarding (so i knew i had the duraspark wired correctly), but it still hesitates and backfires under more than half throttle revving. So these are the things I'm wondering right now:

1. Maybe I don't have the reluctor ring aligned correctly on the distributor shaft. The writeup on the front page was a little hazy on how to align it since the distributor housing will turn when at TDC.

2. Maybe I need more plug gap with the GM coil than the old coil and points setup. I believe they are at the factory .30 setting, but I was considering opening them up to .35 or .40. Kinda curious what everybody else is running for gap.

3. Maybe something I'm missing all together...like it won't run worth a crap until I have a chip in the computer other than the 350tbi truck chip.

If anybody has any ideas, I'd sure appreciate the help. Thanks in advance.

[Bill usn-1]

Well...
I kind of need some more info.
Like what all did you install?
Knock sensor?
EGR?
temp sender?
Tell me everything you have hooked up and if anything is different than stock(chevy).

The computer will hold the timing to 20* @2000rpm until it goes into closed loop. (O2 @600*)
So being up to temp(temp sender) and having the O2 installed is very important.
Also the knock sensor or "lack of" will tell the computer you are pinging and will retard the timing.

Do you have the SES light intalled. Can you read any fault codes?
Got a laptop and winaldl with cable?


for the reluctor. Ihave found it good to set the trailing edge of the rotor on the trailing edge of the dist cap terminal with the timing mark on 0* on number 8. In other words the rotor will be just passing the terminal. That way as it advances it will be coming back across the terminal.
I lock the reluctor down centered on the mag pickup.

On all of my first installs I just centered everything with the timing at 0* and they all ran fine. The above was just the results of a little more learning curve on distributors.

You will definately want a chip for your motor. They like more timing then the 350.
When you get everything else right, then you could try moving your timing up a few degrees and see if it helps. Sometime the computer gets confused when you do it so just do a little at a time.

[fredo74]

Got it.....I realigned the reluctor as you instructed, and then i found a vacuum leak. Amazing how much better it runs with those two issues solved.

[brendan]

you can open your gap up to .045.

[fredo74]

Originally posted by brendan
you can open your gap up to .045.

Thanks. I went ahead and did that after I looked in the haynes manual I had laying around and saw that the factory tbi trucks were running .045. It's still got a weird bog off of idle, but I'm pretty sure that has a lot to do with the chip.