How do YOU set timing?

[ChuckN]

The C10 was running really poorly when I left, so I turned tail back home thinking I’d lost a vacuum line. I was checking things out and bumped the distributor and it turned freely, so I found the culprit. I clearly remember tightening it but engine vibration must have loosened it.

I tried what I did before to get the engine up to 3500 for 35 degrees total, but being by myself, I didn’t have somebody to mash down the pedal to hold it there, and the screw on the carburetor only let it run to about 2700 before bottoming.

So I set it to 12 degrees initial without the vac advance, and it seems nice and snappy again.

Having a standard HEI distributor, there’s no timing adjustment for the curve. So do you guys usually set to total or do you guys sent it to initial? Or maybe there’s some thing that I don’t understand that you can do both with these distributors? Thanks in advance.

 

[Matt69olds]

Timing & Vacuum Advance 101 -good article by GM engineer

www.460ford.com

Even though this is info from a Ford forum, it’s good info.

 

[DoubleDingo]

I have never set total timing, it's always been base with no vacuum. I don't own one of those fancy timing lights. Your method sounds right to me if you're not checking total timing.

 

[fast 99]

Both advances need to work for the engine to run properly. Start by checking advances. If they don't work your wasting your time. Check vacuum advance operation by hooking to a vacuum source, either engine or pump. If it won't hold vacuum, or advance timing, it's bad. Then raise the engine RPM to around 2500 without vacuum advance hooked up. Timing should increase, if not it's stuck. A total of 35 might be ok depending on application. Need to look up the specs to know for sure. Some are as low as 22 others much higher than 35.

Most pre-computer vehicles are checked this way.
Generally speaking, GM Ford AMC Chrysler work the same.

 

[ChuckN]

Both advances need to work for the engine to run properly. Start by checking advances. If they don't work your wasting your time. Check vacuum advance operation by hooking to a vacuum source, either engine or pump. If it won't hold vacuum, or advance timing, it's bad. Then raise the engine RPM to around 2500 without vacuum advance hooked up. Timing should increase, if not it's stuck. A total of 35 might be ok depending on application. Need to look up the specs to know for sure. Some are as low as 22 others much higher than 35.

Most pre-computer vehicles are checked this way.
Generally speaking, GM Ford AMC Chrysler work the same.

Thanks for that. Yeah, everything is completely functional.

Apparently 1. I need blue loctite on the distributor clamp bolt or 2. I just didn’t have it as tight as I thought I did. It’s a Peformer RPM so softer aluminum- maybe I just didn’t want to go all Hulk on it. But that’s what started this whole thing, loosened up and then rotated out of time.

I believe when people speak of 35 degrees of total, it’s typically at 3500 RPM, correct?

Honestly, if it’s running like it should next time I take ‘er out , then whatever it’s at will be good enough. I’m not running this thing down the 1320.

 

[fast 99]

Don't need blue. Make sure both fingers of clamp are on the base. Timing should be all in around 2500. If the motor is aged 3500 might make for an oil clean up on isle 1. Too fast for a stock motor not under a load.

 

[ChuckN]

Don't need blue. Make sure both fingers of clamp are on the base. Timing should be all in around 2500. If the motor is aged 3500 might make for an oil clean up on isle 1. Too fast for a stock motor not under a load.

Motor has less than 1000 miles on it. Some kind of a lumpy cam that makes about 13 of mercury, Performer RPM intake, long tube headers, 60s vintage camel hump heads- somewhere in the ballpark of 10:1 with flat top pistons I’d guess, bored .030 to 355ci. Guy I bought the truck from in fall put it in newly rebuilt and hadn’t run yet at the time.

 

[75gmck25]

Sounds like the cam will want quite a bit of timing , but with iron heads and 10:1 compression you will need premium gas to prevent pinging. Stock distributor with 20 degrees of vacuum advance may be too much for cruise (it may ping at light throttle) if you raise base timing.

You may also want a high stall converter and/or a low rear end ratio to use that cam. You need to get the rpm up quickly and out of the lumpy cam, low power rpm range.

 

[ChuckN]

Sounds like the cam will want quite a bit of timing , but with iron heads and 10:1 compression you will need premium gas to prevent pinging. Stock distributor with 20 degrees of vacuum advance may be too much for cruise (it may ping at light throttle) if you raise base timing.

You may also want a high stall converter and/or a low rear end ratio to use that cam. You need to get the rpm up quickly and out of the lumpy cam, low power rpm range.

For sure, it’s on my list. That, and a 3:42 rear end.

So far I haven’t heard any pinging, fingers crossed. Honestly it was running great and wasn’t complaining about anything until the dizzy spun.

 

[GTX63]

Most everyone of my sbc distributors vacuum advance is pointing somewhere between the #4&#6 plug. So if I was on the road with no tools when the distributor spun around, I know where to rotate it close enough to get me home. I also set total timing and rarely ever use a timing light. That has worked for me for 40 years.

 

[ChuckN]

Most everyone of my sbc distributors vacuum advance is pointing somewhere between the #4&#6 plug. So if I was on the road with no tools when the distributor spun around, I know where to rotate it close enough to get me home. I also set total timing and rarely ever use a timing light. That has worked for me for 40 years.

You’re speaking my language. As soon as I get it where I want it, I’m going to take a little punch and mark the intake/distributor collar and make a mark so I can reorient if I’m ever away from home.

 

[SirRobyn0]

Everyone here has given you great advice, I'm going to add this.

If you want 35 degrees total timing you should set that at 3K or wherever the advance stops going up in the RPM range. Once the engine is at idle check the base timing with the vacuum advance disconnected and take note of that reading for example 12. Then if the distributor gets bumped again or you have to pull it out for some reason you don't have to go though the process of hovering over the fan with on hand on the timing light, one hand on the distributor and the one hand on the throttle trying not get anybody parts in the fan or belts.

 

[GTX63]

You’re speaking my language. As soon as I get it where I want it, I’m going to take a little punch and mark the intake/distributor collar and make a mark so I can reorient if I’m ever away from home.

I knew an old timer, years ago, he set the timing on his Chevies by ear and by start. What I mean is, he ran them to operating temp (190-200F), moved his distributor until the motor smoothed out, then advanced it a little more, and shut it off.
He would restart them about 60 seconds later and if it fired right up, he would advance it maybe another 1" and repeat. Once the starter dragged, he knew to back it off about 1 1/2", lol.
The guy didn't own a timing light that I know off, and he didn't understand terms like valve lash and indexing a camshaft, but he knew how to build them and tune them.

 

[Matt69olds]

I have never set total timing, it's always been base with no vacuum. I don't own one of those fancy timing lights. Your method sounds right to me if you're not checking total timing.

You don’t HAVE to own the fancy timing light. If you know the balancer diameter and some simple math you can easily calculate where to put the new mark

 

[SirRobyn0]

I knew an old timer, years ago, he set the timing on his Chevies by ear and by start. What I mean is, he ran them to operating temp (190-200F), moved his distributor until the motor smoothed out, then advanced it a little more, and shut it off.
He would restart them about 60 seconds later and if it fired right up, he would advance it maybe another 1" and repeat. Once the starter dragged, he knew to back it off about 1 1/2", lol.
The guy didn't own a timing light that I know off, and he didn't understand terms like valve lash and indexing a camshaft, but he knew how to build them and tune them.

Right, I've known guys that did that, and I've known guys that set timing with a vacuum gauge. I get it to some degree but you can also be pretty far off with those methods and if your running a loud exhaust you might not know it' pinging until it's to late. Even if your running a quiet exhaust it might be fine until your pulling a long hill on a hot day with a load. It's all about a persons comfort zone I suppose. I will absolutely set an engine by ear if for some reason the balancer is off or spun, but I'd want to fix the problem in the long run and set it with a light, but that's me.