Rotor Phase on BBF with no crank trigger?

Try to figure out how i can check phase with locked out timing and no crank trigger.

Rotor phasing is only required with a crank tigger , locked timing the distributor mechanism does not move and fires where the rotory button is at when the magnetic pickup in the dustributor is signaled by the reluctor inside the distributor and sends ignition box signal to fire.

Crank triggers are supposed to be more accurate , but 7000 rpm with a small diameter reluctor is a slower actual speed than a magnetic pickup on a crank trigger at 7000 rpm . The larger diameter spread has to be going much faster .

KY JELLY wrote:Rotor phasing is only required with a crank tigger , locked timing the distributor mechanism does not move and fires where the rotory button is at when the magnetic pickup in the dustributor is signaled by the reluctor inside the distributor and sends ignition box signal to fire.

Crank triggers are supposed to be more accurate , but 7000 rpm with a small diameter reluctor is a slower actual speed than a magnetic pickup on a crank trigger at 7000 rpm . The larger diameter spread has to be going much faster .

Thanks KY

To check with lock out dist. same way as a crank trigger. hole in the cap and a timing light.

A lock dist can be off

KY JELLY wrote:Rotor phasing is only required with a crank tigger , locked timing the distributor mechanism does not move and fires where the rotory button is at when the magnetic pickup in the dustributor is signaled by the reluctor inside the distributor and sends ignition box signal to fire.

Crank triggers are supposed to be more accurate , but 7000 rpm with a small diameter reluctor is a slower actual speed than a magnetic pickup on a crank trigger at 7000 rpm . The larger diameter spread has to be going much faster .

"has to be" crank is at 7000 rpm dist. is 3500 rpm. wheel travel in feet per minute is very high to the dist'ers. So it is.

I'm not a big fan of either, I will take the light springs anyday. But that's just me.Never could see the difference in performance w/it being locked,just the kicking back on the starter shit.

Ive phased the rotors w a locked dizzy and no CT, you have to slot the holes in the cap adapter though.

If it wasnt phased on the sb car when that 102 jet comes on the dish strainer would become a projectile.


Youd be surprised how far one can be off, you factor in the delayed signal of some of the boxes then it gets really f-cked up.

DanH wrote:To check with lock out dist. same way as a crank trigger. hole in the cap and a timing light.

A lock dist can be off

for once I agree 100 percent with Dan lol.

I can see that being an issue if you are pulling timing with a retard box

bbf-falcon wrote:I'm not a big fan of either, I will take the light springs anyday. But that's just me.Never could see the difference in performance w/it being locked,just the kicking back on the starter shit.

In my Mallory I run a light set of springs when it fires up no kick back the timing is all in by 1500rpm but I don't run NOS either and works fine for me.

Ok. Im retarding timing with my box and the rotor is way past the post with no retard. This is a duraspark dist. Is there an adjustable rotor button for these. I tried adjusting the reluctor but all that did was change the timing

You have to move the rotor on the distributor shaft, The stock one is push locked. You need something where the rotor screws down onto the distributor, so you can slot and twist it.

I've cut one in half, Twisted it and screwed it back down...but I would like something a little more sturdy..

To change the rotor phasing, change the relationship of the reluctor wheel to the rotor by making an offset groove for the reluctor wheel roll pin.

Tommy, I tried that already. I still had to rotate the distributor to get the timing back where it was...I tried multiple locations with the reluctor. Maybe I haven't found the sweet spot..?

8liter, is this on the turbo car??

Well after about 10 tries I finally got the spark on the leading edge of the button...lol

Yes,its my turbo car. Randy, that's a good idea. Thats probably easier than the 10 different grooves I filed in the reluctor....lol

How hard would it be to spline the shaft where the rotor attaches and make a matching splined rotor? (The fine'r the splines the more accurate you could get it. I would have thought someone would have made something like this all ready.)

When my engine was on the dyno we found that your timing at 4,000rpm is not what it is at 6,500rpm. Even when the distributor was locked the timing moved. That made the dyno time well worth it's money for me. As to how it's moving we could never find a exact reason, only theories.

jones,

belt or chain? Timing variation because of RPM....

kim wrote:jones,

belt or chain?    Timing variation because of RPM....  

That's on a locked distributor! you have to ask; is the differance between the camshaft and crank or between the pick-up and rotor?

It's a roller chain,

MSD 8578 351 Pro Billet, small cap with a bronze gear change to fit the 521. It is solid roller camshaft but it's nothing big as its a pump gas engine. I would have guessed the belt version to have more give.