Ok, my 496" is a pig...for some reason it has its best throttle response when the timing is high! it dont want to run when timing is:: 12* initial, and 37* total I've tried the lightest springs on my msd but it really loves alot of timing, Im thinking of making locking it out at 35* and calling it a day... any Pros or Cons to locking the advance?

 

For street driving, driveability and economy will suffer. For a race car, locking out the distributor removes one more variable. Since in a racing application, the ignition should be at full advance by 3000 rpm, a race car will rarely be operating below full advance.

My distributor is locked out around 37*. I can advance it more but performance doesn't increase. My ignition has a start retard that can retard the timing up to 20* while the engine is cranking over to prevent it from kicking back. Over 500 rpm and the ignition goes to full advance.

The weights control how much mechanical advance is in the distributor. The springs control how fast the advance comes in. Very light springs and it goes to full advance at low rpm. Heavy springs and it gets to full advance at high rpm. You can mix and match the springs to fine tune the rpm that the distributor reaches full advance.

Finding how much total timing where the engine makes the most power is trial and error. It's easiest on a dyno. Once you find the best total timing, any other changes you do such as jetting, plug gap etc won't change where the engine likes the best timing. Every engine is different so the best timing on one engine may not be the best for yours. Power adder engines typically use a much lower timing while NA engines can still make power at 40+ timing.

Unless you're positive that the timing marks are accurate, don't believe what your timing light says. Many years ago, I had an adjustable timing pointer and the engine was making it's best passes at 45*. I finally installed a degree wheel and using a piston stop, determined where the exact TDC was. Turned out the timing pointer was off 8* so what I thought was 45* was actually 37*. When I originally had it set at 37*, it was actually at 21*. No wonder it ran better when I kept advancing the timing.

 

i hate winter my local track is done for the year, i just got the car on the road and dying to know what its gonna E.T?! haha
I've got the lights springs, and the 18* bushing in the dist now, and the secondary pump cam advanced 1 notch, seems to do its best, its amazing how performance motors are so critcal on there tune.. compared to a stock engine.. its set for 19* intial and 37 total according to my tab.. and seems to be its happiest as far as it being responsive with out nosing over when i stab it from idle... thanks for the help, still learning alot, this is only my 3rd build.

 

run more initial, like 22-24 and limit the advance slot size. Then you can keep vacuum advance for low load running and increase economy.

 

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I didn't have any answers to your problem, but I wanted to get emails when somebody answers, so I just typed "subscribe."

 

I have my distributor locked out and have absolutely no problem starting it. I have one of those Walmart everstart batteries with a CVR mini-starter and even in the hottest/coldest of conditions I have no problem. The car also manages to get around 13-14mpg (with 3.92's, no overdrive, and a 9.5" converter...)

 

im locked around 39deg. have an msd 3 stage retard box with 25deg retard while cranking, but the car starts better without it unless its hot outside and the engine is hot.

 

With the distributor locked out that’s one less thing to worry about when racing. My racecar has been that way since I raced the car for the 1st time 5 years ago

 

we run the dist locked as well, the most benefit is cleaning the idle up in gear when staging the car...and one less thing to break, I have broken the springs in a MSD dist before...Rob

 

What cam is in this motor. BBC's usually want 38deg timing.

Racey cams want full spark timing at idle.

If the motor is hard to start hot, install a ignition power interupt switch to disable the spark for hot cranking.

The switch goes on the 12v power feed on a HEI or on the small red power switch on wire on a MSD box.

If you drive on the street keep the vac advance system functional but limit it to around 10-12deg at high cruise.

 

So I'm gonna ask a stupid question. What is the best way to lock out the distributor?

Dan

 

MSD dizzy put in the lockout bushing
Stock dizzy, weld the slots and you're set

 

i'm a fan of welding.

actually...i'm a fan of no distributor, but that's a whole 'nother story

 

A lot variables at play, and now two engines are alike, sometimes even if built identical.

The biggest key is what Stephen mentioned, the correctness of your balancer/tab. Unless you checked the timing marks/tab vs TDC you have no way of knowing for sure what the true timing numbers are.

 

Very true. But needs to be done regardless if the timing is locked out or not. I've had mine locked out for a long time. 38 deg. adv., street driven, and never have had a problem starting. Whats your compresion at?