MIDNIGHT BLUE

following lars tech tip and trying to get to 36 degrees is not working i have a 1970 with a 1970 LS6 motor in it with out springs the car just will not start with light springs it will not start with 1 light and 1 heavy i can start the car the best that i was able to get was 25 degrees total my when i re-checked i was at 6 degrees btd. but had to put heavy springs on in order set timing and idle with lighter springs the advance would start to kick in and rpms would clime i'm not shore what the timing is on this motor can't find any info on it GM told me that it is an LS6 they also told me that they built 2 LS6 motors they said that it is on off road use only motor it did seam to run strongh with heavy and timing at 4 degrees any help would help :confused:

Vetterodder

What is preventing you from setting it to 36º total? Is there something blocking the distributor when you try to turn it farther? Keep in mind that the springs don't affect the amount of timing, only the rate at which it advances. The lighter springs may cause centrifugal advance to start below idle rpm but that shouldn't be a problem if you're setting your timing at total anyway. Depending on the springs that are used, total may arrive anywhere from 2,000 rpm to 5,000 rpm so make sure it is through advancing before you set it.

bigvette1

VetteRodder has it right. There are 3 components of timing. Initial, centrifigual and vacuum advance.

Are you using an advance light? Only way to really tell the story.
If this is a stock distributor, maybe the bushing that controls how far the centrifigual will go is frozen.

36 degrees is not a problem. The one other thing is if the harmonic balancer is stock and 32 years old, the counter weights will slip and 0 will not be zero. Run the engine to TDC on #1 compression and see where the timing marks line up. With trouble starting, I bet you actually setting initial at >12.

MIDNIGHT BLUE

thanks for you r input i will try again and yes i'm using an advance timing light the balancer seems to be fine the motor was bought new in 1980 and has less then 1500mil on it

Phlash

Have you checked you split shafts on the distributor. If you grab the rotor, can you move it which should swing you weights out. I have seen the shafts rust together so there was no movement. Also, what shape are the bushings in on the distributor housing? It has been too many years since I have messed with them, but is there a chance your advance plate for the vacuum advance is messed up. Just food for thought.

Phlash 72 BB Roadster :seeya