Dumb timing question

[Rt Jam]

This is what I intend to do. 3000 as stated above was just an example. I still need a way to lock in my rpm’s, be it 3000, 3500, or whatever. How do you know what rpm you are at with one hand on the linkage and the other aiming a timing light.
Im just going to use the idle stop screw.
Ill go get a longer one if needed.

This is a good question. Sorry if I assumed what you are working with but my timing light has a tachometer right on the light.

I find TDC and mark it if it's not easily seen. Then set the dial back. Line up the marks. Rev the engine and it's a single button on the light to switch from tach to degrees.


For your information. Sounds like what you are trying to achieve is the total timing but I think what will end up happening is if you move it. You MOVE everything.
Say you do your procedure and decide to advance it 10 deg. If you rotate the distributor you are advancing everything. Initial, cruise, total etc.

The spread or change needs to be know. From initial to total and how much vacuum advance adds.

Initial should be 10 to 20. Around 10 for mild camshaft, 20 for more.

Total should be 25 to 35. This well depend mostly on your combustion chamber. Power will dictate the actual number. A dyno or trap speed will tell you best number or just use history to get it close.

Then when it's all done. Manifold vacuum advance to get the ignition timing high for light throttle cruise and idle.

 

[Baker7888]

This is a good question. Sorry if I assumed what you are working with but my timing light has a tachometer right on the light.

I find TDC and mark it if it's not easily seen. Then set the dial back. Line up the marks. Rev the engine and it's a single button on the light to switch from tach to degrees.


For your information. Sounds like what you are trying to achieve is the total timing but I think what will end up happening is if you move it. You MOVE everything.
Say you do your procedure and decide to advance it 10 deg. If you rotate the distributor you are advancing everything. Initial, cruise, total etc.

The spread or change needs to be know. From initial to total and how much vacuum advance adds.

Initial should be 10 to 20. Around 10 for mild camshaft, 20 for more.

Total should be 25 to 35. This well depend mostly on your combustion chamber. Power will dictate the actual number. A dyno or trap speed will tell you best number or just use history to get it close.

Then when it's all done. Manifold vacuum advance to get the ignition timing high for light throttle cruise and idle.

Thanks, i was not aware that the dial back lights had a tach. That certainly would be worth it for me. However I am going to use what i have (standard light) and not drop ~$200 and be out the few days of shipping wait. I do intend to graph my results to determine whats in the distributor, what the vac advance provides, etc, but contrary to your suggestion above, i intend to set total first (34-36 all in without vac canister) and initial will end up where it ends up. Which I will also record. I will just get creative with holding the throttle open somehow. Thought this was a simple question but guess I’ll see myself out now. Lol. Thanks for the help.

 

[Baker7888]

Thanks guys. Pouring here now. I did not realize the advance lights read rpm. Well it just so has it that they have one in stock at the parts store for $100. If it makes life easier i suppose its money well spent. And i can check it against my marks on the balancer. As long as i can get to it before Monday Ill be happy.

 

[64nailhead]

You can get an Actron dial back timing light that displays rpm’s for less than $100.

But if you want to use a standard light, then you can as long as your balancer is marked (timing tape.) and you definitely need to go beyond 3000 to make sure your ‘all in’ timing is at 3000-3400. And yes, you can definitely use the idle screw, but it’s not really necessary. You can use your hand in the throttle lever. I’m confident that you can tell the difference, by ear, between 3000,3500 and 4000 rpm’s (unless you’re deaf). Just remember to unhook and plug the vacuum line.

And FWIW, I use my timing light on every engine - LS, Austin Healey, computer controlled or not. It’s an invaluable tool.

 

[John Canon]

You could use a popsicle stick in the gap for the idle screw. Tape together pieces to make 1, 2, and 3 thicknesses, like a feeler gauge.

 

[Baker7888]

You could use a popsicle stick in the gap for the idle screw. Tape together pieces to make 1, 2, and 3 thicknesses, like a feeler gauge.

Thanks. Good idea

 

[Baker7888]

So I went with 36 degrees all in, which on my stock distributor was about 4k. This put me at only 10 degrees base. Once i hooked up the vac canister i was at 31 degrees which tells me the can adds 21 degrees at idle ~850 rpm. I think i should get an advance kit and try to get the all in rpms down lower. She’s running nice though

 

[Rt Jam]

36 - 10 = 26 spread. That's pretty good. You can leave that alone unless you want a higher initial timing but if the manifold vacuum advance is adding 21, I'd say, go with it.

The advance kit will help you get that total in sooner. Just what you need if you have a tight or stock torque converter. I've even stretched or removed the big spring.

 

[Baker7888]

T

36 - 10 = 26 spread. That's pretty good. You can leave that alone unless you want a higher initial timing but if the manifold vacuum advance is adding 21, I'd say, go with it.

The advance kit will help you get that total in sooner. Just what you need if you have a tight or stock torque converter. I've even stretched or removed the big spring.

Thanks RT Jam, good info. I am actually running a T10 close ratio. Wondering just how soon i want to be all in. Edit: Just want to add, this is a cruiser so Im not nescessarially trying to squeeze every last inch out of it but i do want it to work good. I am typically easy on all of my equipment

 

[Rt Jam]

The earlier the better. Torque will be higher at partial throttle with more timing but if it rattles, you'll know you went too far.