First off this is just a fact finding mission. I just wanted to see what others have to say about this subject. Recently I have spoken to a number of people that are locking their distributors out and just running a preset timing with no advance. The main reason for doing this is fewer broken and moving parts in the distributor. (i.e. advance springs, weights, etc..) Well I was thinking in the 28 years that I have messing around with this stuff I don't think I have ever had a broken advance spring or weight? Others that I have talked with say they just bring their entire advance in early and not to lock the distributor out because it can make for starting a hot motor difficult. I know there are ways around the hot start issue (i.e MSD #8984) and a switch to turn off and turn on the ignition after you start to crank the motor over but why would you want to mess with that? So are there any benefits at all to locking out your distributor for a performance street application? Just curious what everyone’s thoughts are on this subject?

 

None. Probably one of the worst things you can do.

 

I use springs albiet, not the original ones. As per Lars and others, 36deg at 3000RPM using Mr. Gasket black and silver spring (kit #927 or #928). There is a friend of mine with a 350 modified to 383 for track use. His advance springs are removed and weights welded in place. As you state, hard starting. I had an Accel dual point POS on my 1970 350/350 that was always 'kicking' the springs off. I properly shimmed the AC/Delco and found it to be a better distributor.

 

I have my distributor locked out at 32*. This provides a lot of initial timing for a good idle and response. There is no worry of getting the curve in quick enough, over advance at HIGH rpms or possible retarding at high rpms. I never have any hot start problems, even locking it as high as 40*.

I have though recently added some vacuum advance. My centrifugal advance is still locked but vac advance will still work. I made a limiting plate for the vac advance to limit it to 4.5*. I have it connected to "manifold" vac. So basically I have 32* locked + 4.5* vac....giving me 36.5* at idle and cruise but dropping off to 32* at WOT.....(atleast I hope it is)...

Works great on my setup, no running hot, responsive and most important no pinging or WOT detonation.

650hp BB with AC driven in this brutal Houston Summer.

 

Well put. We locked out mine at 38 on my last 468 that made 708 HP N/a. It loved it and the car worked great that way. I farted around with advance kits on previous BBC motors this was by far the best deal.

 

on my l88 build ( no vac advance ) timing is not locked but almost , meaning that i have full advance , 38.5 deg , at 1700 rpm, via lighter springs on my msd. the reason was mainly to keep the engine running at idle and overcome the cam stall ( ZL1). the car is a blast and runs really cool. the tuning has been done on the dyno

 

Never seen it myself either. The locked distributor has it's advantages on the race track, not on the street.

 

We've run them both ways, depending on the engine: A locked distributor has its application, and it's not for all engines and all uses.

All of our drag cars are locked. Advance serves no purpose in a dedicated drag car. Timing is locked between 32-38, depending on the engine and what the dyno results showed for the power at various timing lead points. We have ignition cut-off, so we can crank the engine over with no ignition and then hit the spark to fire the engine without difficulty.

In radical street engines producing a lot of power with big cams, timing advance lockout can work great: These egnies, not suitable for vacuum advance, require initial timing of anywhere from 24-30 degrees, resulting in a centrifugal curve that is so short that it serves no purpose. These engines are also run on gasoline of adequate octane rating, and in an rpm range, so that low-rpm "lugging around detonation" does not occur.

For all other street applications, I cannot think of any reason to lock out the timing - it's a downright bad idea for most mild performance engines that are intended to be street driven. I've never heard of or seen a broken spring, and I've never seen a broken factory weight: The only defective weights I have seen are aftermarket weights.

If you have an engine that's mild enough that it will idle under 900 rpm, use the advance system and modify it to perform as it should.

Lars