Bought my first timing light, giving it a go. what degree?

[Mrturner1]

well after asking a million questions about all the things I'm doing to my C-10 front to back, it became obvious that I need to be fluent with my motor and tuning if I'm gonna get the most power and reliability out of whats already there, and without farming out the labor for everything. So I got a timing light from Oreilly's Auto Parts. It's the mid grade one with a dial on the back that goes from 0 to around 60 or 80, something like that.

My question is, what timing do these trucks typically like? Or is there even a standard? I have an MSD distributor, big lumpy cam (not sure of specs YET) Edelbrock Performer intake, and Edelbrock 650 carb. Long tube headers and 2 1/4 pipes to flowmasters that dump after the rear axle. Not even sure if those things are info you guys need but I figure if timing is unique to everyones ride, the info may be important.

I have no idea what the timing is now, so if somebody could tell me how to find out with my new timing light, id appreciate the insight. Also not worried about having to run premium gas, as thats what I put in every time anyway.

Thanks guys
Matt

[davepl]

There's no standard, since you've got a modified engine - and even the "standard" rating on the tuneup sticker isn't really valid anymore with the gasoline we're running.

Sounds like you're going to want a lot of initial timing with that setup; I'd start at 12 and see if you can get a decent idle (stock was more like 4 to 6). It might take more. If you can get away with less (like you can get it to idle low enough and smooth enough) less is more.

With a dial-back light you'd set the light to 12 and adjust until the balancer read 0, if it works like I think it does.

The problem you (and others with modified engines) will face is that when you get enough initial (static) timing by turning the distributor to get a good idle, you'll have too much total advance when all of the mechanical (RPM) is in. So in a lot of cases you'll need to lock out some advance or get an adjustable can. I'm lucky that the shop down the road still has a distributor machine and knows how to use it, but that's very uncommon these days. Hopefully it won't ping and you'll be fine.

To find out what it's at now, you could do two things:

- Set the gun to 0 and try to read it off the balancer if it's marked that far, or
- Adjust the gun until the timing mark reads 0 and then look at the gun to see where it was

So, if you turn the adjustment until the reading is 0 at the balancer, and then look at the gun and it reads "8", you were likely 8 degrees BTDC.

Keep the vacuum advance line disconnected (but plugged so you don't have an air leak) while adjusting things. There should be NO vacuum advance at idle. If there is, it's usually because the carb is out of adjustment and the idle transfer slots are uncovered because the throttle blades are open too far, usually to get it to idle. More timing can fix that - sometimes.

That's a start anyway! I found my stock 402 wanted about 10 degrees with today's gas but with a cam and mods it could be more. I wouldn't go more than 16 unless someone else here has had luck with that... beyond 10-12 you might be crutching another unknown problem with timing.

[Mrturner1]

Originally Posted by davepl

There's no standard, since you've got a modified engine - and even the "standard" rating on the tuneup sticker isn't really valid anymore with the gasoline we're running.

Sounds like you're going to want a lot of initial timing with that setup; I'd start at 12 and see if you can get a decent idle (stock was more like 4 to 6). It might take more. If you can get away with less (like you can get it to idle low enough and smooth enough) less is more.

With a dial-back light you'd set the light to 12 and adjust until the balancer read 0, if it works like I think it does.

The problem you (and others with modified engines) will face is that when you get enough initial (static) timing by turning the distributor to get a good idle, you'll have too much total advance when all of the mechanical (RPM) is in. So in a lot of cases you'll need to lock out some advance or get an adjustable can. I'm lucky that the shop down the road still has a distributor machine and knows how to use it, but that's very uncommon these days. Hopefully it won't ping and you'll be fine.

To find out what it's at now, you could do two things:

- Set the gun to 0 and try to read it off the balancer if it's marked that far, or
- Adjust the gun until the timing mark reads 0 and then look at the gun to see where it was

So, if you turn the adjustment until the reading is 0 at the balancer, and then look at the gun and it reads "8", you were likely 8 degrees BTDC.

Keep the vacuum advance line disconnected (but plugged so you don't have an air leak) while adjusting things. There should be NO vacuum advance at idle. If there is, it's usually because the carb is out of adjustment and the idle transfer slots are uncovered because the throttle blades are open too far, usually to get it to idle. More timing can fix that - sometimes.

That's a start anyway! I found my stock 402 wanted about 10 degrees with today's gas but with a cam and mods it could be more. I wouldn't go more than 16 unless someone else here has had luck with that... beyond 10-12 you might be crutching another unknown problem with timing.

Ok awesome, thats definitely enough to go off of as far as timing goes. I was a little disappointed though, because I was hoping for at least a Geewgaw and a Whatzit haha thanks for the help man, I really appreciate it