Total Advance Timing Problem

[LT-102]

Installed a new Proform HEI distrubutor and the total timing advance is out of site, like 60 degrees total. With intial timing set at 15 degrees I have a total advance of 30 degrees @3000 rpm WITHOUT vacum advance. With the vacum advance hooked up I have around 60 degrees total advance. The vacum advance is non-adjuatable. Will an adjustable vacum advance cure this. Thanks in advance for your help.

[crazy longhorn]

Yes, I have a crane advance on my HEI,& have limited the pull to .090 to give 8 degrees of timing. depending on comp ratio,cam ect, somewhere in the range of 8-12 degrees on vac timing should work. i am supprised that the mechanical advance is only giving 15 degrees........my stock HEI goes 20. I set @ 14 initial,34 total(without can),+ 8degrees on the can to give 22 degrees @ idle,& 42@ 3200 (no load, with can). good luck ....Al

[MikeB]

You've got some strange problems -- probably due to that imported distributor. Proform stuff is just not up to industry standards. But, that's another story. With the vacuum line disonnected and the carb port plugged, you should start with prox 10 degrees at idle. Then you should play with different weights and springs for somewhere around 32-34 mechanical advance, all "in" by 2000-2200 rpm. (If you have stock heads, your engine may like more total advance.) After you get that working, reconnect your vacuum line. Your idle advance should jump about 10-12 degrees, which means 42-46 max combined mechanical and vacuum advance at 2000-2200 rpm. Are you sure there's no allen adjustment screw in the vacuum canister? Many years a go I bought an Accel HEI. It came with adjustable vacuum advance and a set of springs. I had just the opposite problem -- too little advance too late. Good luck. Next time buy "quality" like GM, Accel, Mallory or MSD (the best).

[crazy longhorn]

You might try buzzin the eng to 3200 to see if it advances any more. i installed a proform in my bro inlaws 455 olds,& it wasnt all in till 3200 or 3300. also the can was not adjustable,we installed a crane can. if you limit the pull on the plunger on the crane to .105-.110, you should have 10 degrees of vac timing. I didnt use the crane limiter provided, just tack welded a strip of sheet steel in front of the plunger(you can also use sheet metal screws). good luck......Al

[Sinister]

i just picked up a proform distributor today, PAW sells them as their base HEI distributor...
looked at it and a mallory HEI, and they were basically identicle, the finish on the proform just slightly better, haven't hooked it up yet though, i'll keep my fingers crossed...

[MikeB]

My Proform comment is based on their stuff being made in Southeast Asia, as are the "Power Plus" copies of Edelbrock manifolds. Have you seen how cobby their castings are? All this stuff costs less for a reason. Lack of adjustable vacuum advance and cobby castings are just examples. Things you can't see are poor heat treat and high machining tolerances. Proform also sells roller rocker arms for around $130, but you'll never see them used by a racer or experienced engine builder.

[crazy longhorn]

Sinister, we didnt have any problems with the Proform dist that I installed in my bro inlaws cutlass.........other than the vac advance was not adjustable. good luck(that was a $22 fix).....Al