timing

W5R

New member
no sir, coil gap is just that, coil gap. timing is changed with the key in the flywheel by most, or using a degree wheel, lapping compound and timing light by others.
 

Jody / ARC Racing

Site Supporter
With a Billet flywheel it doesn't change the timing until you get up around .090 which you can not reach on most engines. However you can tune the engine by moving the coil up and down because it does change the spark length and reduce magnet drag at high RPMs.
 
With a Billet flywheel it doesn't change the timing until you get up around .090 which you can not reach on most engines. However you can tune the engine by moving the coil up and down because it does change the spark length and reduce magnet drag at high RPMs.

Agreed! It takes resistance out of the coil. All the coils are not the same. This needs to b tuned on every engine.
 
While we're on the subject, what are most of you guys running as far as coil gap ? I've had good been running with .020 to.026 . jmo
 

sCREamnClones

New member
....... you can tune the engine by moving the coil up and down because it does change the spark length and reduce magnet drag at high RPMs.
Note that this can get a BSP dq'd, however....by relieving the threads off the coil mtg screws (.100diax.50) it will allow abt a 5* sweep in coil adjustment.
 

alvin l nunley

Site Supporter
Question for post number 3
Very interesting. But I wonder, is this really true, or just your guesstimate. Do you have any links I can go to see how this happens?
 
Question for post number 3
Very interesting. But I wonder, is this really true, or just your guesstimate. Do you have any links I can go to see how this happens?

I can tell you that when the coil is further away, you can tell by hand there is less resistance when rotating the engine.. for what thats worth :)
 

Jody / ARC Racing

Site Supporter
I run .070-.080 on most Box/Pro Box engine that we build. The magnets in our flywheels are strong enough to use that much gap, this is why we tell you NOT to use less than .030 coil gap with our flywheels. It can damage the coil. More gap, less magnet drag, more upper power. Yet another advantage...

When the new CL-2 and BSP-3 cams came out people and myself included found we had a dip in the torque curve around 6000 on the Dyno. Moving the coil up to .070-.080 helped solve the problem, along with jetting and timing changes.

Al that info comes from 25+ years of building flywheels, and we dont build nor post info off of guesstamations.
 

Jody / ARC Racing

Site Supporter
Note that this can get a BSP dq'd, however....by relieving the threads off the coil mtg screws (.100diax.50) it will allow abt a 5* sweep in coil adjustment.

There is no rule on coil gap. You do not have to use trick bolts or dill the coil, you can get .070-.080 with a total stock set up.
 

alvin l nunley

Site Supporter
I'm no ignition expert, but I think I know how they work. When the magnets pass the coil, and the inductance gets high enough, the ignition fires. I can't see how the gap can affect that. If there is an affect it's got to be a real small.
I know if I could, I'd be out in the shop with the timing light proving this to myself.
I can almost see a bigger gap causing less drag, but how you going to prove that?

Comments compliments criticisms and questions always welcome.
 

sCREamnClones

New member
I'm no ignition expert, but I think I know how they work. When the magnets pass the coil, and the inductance gets high enough, the ignition fires. I can't see how the gap can affect that. If there is an affect it's got to be a real small.
I know if I could, I'd be out in the shop with the timing light proving this to myself.
I can almost see a bigger gap causing less drag, but how you going to prove that?

Comments compliments criticisms and questions always welcome.

No need too 'prove' it, IF....it can't be 'Dis-proved'! :) (It 'sounds-good' 2me though!)
 
I'm no ignition expert, but I think I know how they work. When the magnets pass the coil, and the inductance gets high enough, the ignition fires. I can't see how the gap can affect that. If there is an affect it's got to be a real small.
I know if I could, I'd be out in the shop with the timing light proving this to myself.
I can almost see a bigger gap causing less drag, but how you going to prove that?

Comments compliments criticisms and questions always welcome.

Put the coil at .030, have the crank installed, no piston yet. Spin the flywheel with your hand, then put the coil at .050 or more, repeat the process. I bet you can tell the difference.. Now how much it will make in actual power???? I have a big name builder engine apart now, I noticed how easy it turned, before I checked the coil gap (which was like .050)
 

mike00b

New member
I'm no ignition expert, but I think I know how they work. When the magnets pass the coil, and the inductance gets high enough, the ignition fires. I can't see how the gap can affect that. If there is an affect it's got to be a real small.
I know if I could, I'd be out in the shop with the timing light proving this to myself.
I can almost see a bigger gap causing less drag, but how you going to prove that?

No need too 'prove' it, IF....it can't be 'Dis-proved'! :) (It 'sounds-good' 2me though!)

Nothing can ever be proven or disproven. A more appropriate wording, Al, would be whether the claims made are 'significant' enough to justify accepting them as routine practice.

I, too, am interested in whether those changes would make the difference that is being claimed. Without numbers (data) and how the data was compiled (method) they are just... words. (FYI: Comparing how the crank spins between different coil gaps is not quite enough for me. There are other factors to consider. There will always be other factors to consider, which is why nothing can 'proven' or 'disproven'.)

So, if you have numbers and can tell me how those number came about, please feel free to send me a PM or IM (whatever its called on here).
 
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