I Need More Advance For High Cr

[skinner2k3 3]

I know the ignition advance curves vary between 1600 and 1900 distributors but does anyone know in what way?

 

I need a dizzy with more static advance to compensate for a hefty skim retarding the cam timing. As when I get the cam timing correct the dizzy needs more advance than is possible with the standard slots.

 

Failing that I am probably going to have to file out the dizzy slots for more clockwise movement.

 

Is there an alternative? I was thinking perhaps file a new slot for the rotor arm at 180 degrees to the old one plus a few degrees to get the extra advance?????

 

Cheers

[petert 589]

I need a dizzy with more static advance to compensate for a hefty skim retarding the cam timing.

 

But surely when you advance the cam to put it in the right spot the ignition timing will also be in spec? How much lift are you running at TDC?

[skinner2k3 3]

With the cam set at 3mm lift TDC the engine will not start unless the distributor is fully advanced and even then it is not happy.

 

As I advance the cam relative to the crank and increase the lift away from spec I get more adjustment on the dizzy and can increase the ignition timing and it runs better.

[petert 589]

Your priority has to be getting lift at TDC correct, then elongate the slots in the dizzy body in order to get the base timing correct. Careful filing with a small round file does the trick.

[skinner2k3 3]

Completely agree, cam timing takes priority. Just hope there is enough meat on the dizzy lobes to file out enough clearance.

 

Thats my evening sorted.

 

Thanks.

[Anthony 1,003]

It might be worth trying another dizzy - I've seen dizzy's before that have needed to be nearly fully advanced on a completely standard engine, and yet a replacement can be on the retarded side of halfway despite being identical parts. I assume it's wear and tear that causes the problem as the dizzy otherwise appears to work fine and make decent power.

[skinner2k3 3]

That interesting to know.

 

I think I only have 2 1900 distributors, the other is the tappy one.

 

Been advised to try a 1600 dizzy due to more vac advance and less mechanical thus suiting the cam.

[skinner2k3 3]

Ok so had a stock take on my distributors and do only have 3, 2 x 1900 and 1 x 1600. Unfortunately the 1600 vacume capsule was shot as was the spare 1900's. So I now have a 1600 distributor with a 1900 vac with filed out slots which is giving me enough advance to run the cam somewhere near the correct lift at TDC.

 

This time tomorrow morning it will be on the RR and we shall see if its enough.

Edited June 8, 2010 by skinner2k3

[timstemi16 0]

i agree try another dizzy if possible, some wear inside and lose advance at high revs. Not so much a problem with static timing though. cam timing definately takes priority. could grind out the slots though to give more adjustment. Cams may be adjusted but depends on piston/valve clearance, what power curve is required. Mappable ignition of some sort is probably the best way forward as it can be set for different engine speed and load

[sideways danny 0]

if you've gone that wild you need proper management to control the ignition. By advancing the dizzy to help start/idle you're also advancing at the higher rev range and with high compression and wild cams you're just going to det the engine apart

[Baz 421]

A 1.6 dizzy will suit a 1.9 that needs more advance certainly more than a 1.9 item, but ultimately you'll need a re-curved/weighted dizzy, or as Danny says above, do away with it and run mappable ignition.

Edited June 14, 2010 by Baz