1979 K-10 timing issues

[1979ChevyK10]

Got a '79 K-10 with a 350, and can't time the damned thing. I can get it to run decent, but when it does, the mark on the balancer is roughly 25 degrees advanced, and when the mark is on 0 degrees on the tab, it runs like a Ford. The timing cover and balancer are the same ones that came on the engine. I've checked firing order, replaced plugs, wires, and dizzy cap, and might replace the dizzy tomorrow. I checked the timing chain I don't know how many times, I've checked damned near everything. The last two things I can think of are dizzy, and possibly a slipped ring on the balancer. Any suggestions are welcome.

~James~

[wfolsom]

Did you unhook your vacuum advance when you set the timing ?
Your balancer could very well be bad
I'd change it before I would the dizzy

[1979ChevyK10]

Yeah, I unhooked the Vac Adv first, and I have a brand new dizzy in my parts locker, so it'll probably be first. Thanks for the help, and THAT is one badass 'Burb.

[wfolsom]

It's for sale or trade lol

You could also be a tooth off on the dizzy

[1979ChevyK10]

Yeah, I'll dick with it tomorrow, see what happens. I don't have enough money/toys to buy/trade for that beast.

[Jmac72]

Are you running a stock cam or aftermarket?If its aftermarket there may not be anything wrong.Are you using a dailback timing light or just guessing on the 25 degrees?The factory timing tabs are not always accurate either.You might check the springs and weights,just to make sure they are moving freely,and not stuck.

I have had several aftermarket cams that like 20 degrees or more timing at idle.As long as it runs good,and starts good,it doesn't matter what its at.If it is set to high it will start hard when warmed up.If it does that just back it down a bit and go with it.

You can also hook up the vac advance,and idle it up to like 3k rpm and just set timing for total advance.If you have a big aftermarket cam,sometimes that way works better.

[1979ChevyK10]

It's a stock replacement cam.

[SUBURBIAN]

Don't replace the distributor. Are you checking the timing with the engine warm and carb choke open? What's the idle speed? Have you verified that the mechanical advance is NOT partially activated at idle? Are there any vacuum leaks? What is vacuum signal at idle? Have you verified balancer/pointer location at #1 TDC (both lifters down in the bores)?

Deeper...Did you install the cam "dot to dot"? Are all of your lifters "lifting"? Did you run a dedicated cam break-in?

[1979ChevyK10]

I checked it warm, and the choke open. Idle speed is unknown, don't have a tach, I would say 800-900RPM, I don't even know about Mech Adv, but Vac Adv hose is unplugged, the cam is dot-to-dot, and the lifters are lifting, the cam was a cam put in last year.

[SUBURBIAN]

Mechanical advance (rightfully called centrifugal advance...sorry) is a weight and spring setup inside the distributor, under the rotor. As the distributor shaft is driven, and as the engine speed increases, centrifugal force opens the weights at a rate based on the spring tension. If the springs are worn out or the weights are stuck, it could be activating earlier (lower in the rpm range) than it should....giving you the 20-something degrees of timing that you're reading. A certain degree of spark advance is set with the orientation of the distributor housing in relation to where the rotor is. This is your initial advance...stock is 8 degrees. Warmer cams like more initial advance. Centrifugal advance plus initial advance equals total mechanical advance...should be around 34 to 36 degrees. With vacuum advance of around 10-15 degrees (ideal in most applications) your total could be around 50 or so. If you know these things, I am not trying to insult you...trying to help.

Also, the damper could be out of orientation with the timing pointer, giving you a false reading, but is less likely.

What happens to the timing if you slow the idle speed? If it decreases, your weights/springs are allowing advance at idle and need to be replaced.

[bowtie44s]

It doesn't matter if you're a tooth off or 180 off if you have the wires in the right place. You need to find true tdc to see if your marks are right. You aren't supposed to be at 0. That's just for the tbi trucks. 25 doesn't sound that bad. Some are just like that. Run it where it runs good.

[Jmac72]

With everything being stock your idle speed is a bit high,and that will change the timing.If it runs good,and starts good when warm.I say shut the hood and start driving.

[SUBURBIAN]

25 initial is pretty high for a daily driver/mild cam/lower CR engine. Not to mention that it's a lot of stress on the crank/flexplate and starter. I could see that number as an idle reading with the vacuum advance hooked up. That's part of the purpose of vacuum advance, it can be looked at as a way to retard timing when it's not needed. It could be argued that the engine needs less spark advance as the vacuum increases. That's how vacuum advance works.

[bowtie44s]

25 initial is pretty high for a daily driver/mild cam/lower CR engine. Not to mention that it's a lot of stress on the crank/flexplate and starter.

Thats probablly not what time he's actually running. If he didn't find true top dead center that 25 is just a number that means nothing. The mark on the balancer is usually close but he said his may have slipped.

[1979ChevyK10]

I did take the time to find true TDC. And the dizzy's Mech Adv parts are covered in a light coat of rust, it's the original dizzy from '79, and the weights are a little tough to move.

[1979ChevyK10]

The latest problem is that I CANNOT get it to run without missing in the low RPM range, and I have an orange spark. Am getting a new coil tomorrow, have already polished terminals and replaced rotor, plugs, and wires.

[SUBURBIAN]

You will probably be after a distributor re-curve kit next.

[1979ChevyK10]

Coil didn't make any difference, I'm running out of options. What's a recurve kit?

[trickedout420]

its the mechanical weights at the bottom end of the distributor..your rusted hard to move ones..

[SUBURBIAN]

Coil didn't make any difference, I'm running out of options. What's a recurve kit?

Replacement parts for distributor guts. New weights, new springs, new bushings. You might try some wd40 on the old stuff first...but if the springs are brittle, it may not work.