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Discussion Starter #1
Engine is a 355 with 177 weiand blower. Street strip car running 7.6 / 1/8 th mile. Trying to get a little more out of it so got a spring kit for the distributor. The springs that are in it are the heavy silver ones. Timing right now is set at 17 initial and 32 total , all in by 3000 rmp. I want to bring in timing sooner to see if I pick up any thing. I put the two light silver springs in and now timing is at 17 initial but jumps to 38 total without changing anything else. Looking at the msd instructions do I need to change the bushing too in order to limit total timing ? If so which bushing do I start with?
 

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yea you'll want to change the bushing to limit the total amount of mechanical advance

red bushing (smallest) - 28*
silver -25*
blue- 21*
black (thicker) - 18*

SO for example if your goal is 32* total,
initial would be:
red - 4*
silver - 7*
blue - 11*
black - 14*

some places offer a 10* bushing also

**the above example is assuming the vacuum advanced is locked out
 

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Discussion Starter #4
yea you'll want to change the bushing to limit the total amount of mechanical advance

red bushing (smallest) - 28*
silver -25*
blue- 21*
black (thicker) - 18*

SO for example if your goal is 32* total,
initial would be:
red - 4*
silver - 7*
blue - 11*
black - 14*

some places offer a 10* bushing also

**the above example is assuming the vacuum advanced is locked out



Thanks. Thats what I thought by reading msd directions but just wanted to verfy it.
 

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Mh, strange, that the timing goes up to 38 without changing the bushing. Have you already check the timing with the heavy springs and higher rpm?
I would try one heavy and one light spring first. If the springs are too light, the idle rpm may rise up without any throttle (self experienced :confused:).

Don't go over 36 degrees as maximum.

greets
carl
 

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Mh, strange, that the timing goes up to 38 without changing the bushing. Have you already check the timing with the heavy springs and higher rpm?
I would try one heavy and one light spring first. If the springs are too light, the idle rpm may rise up without any throttle (self experienced :confused:).

Don't go over 36 degrees as maximum.

greets
carl
I was thinking the same. if all you changed is the springs to a lighter set, then it would bring the total in quicker. That's all that would change.
 

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i ran into the same issue when i installed a new msd distributor in mine. The factory calibration (chart A) comes with two heavy springs, i mean HEAVY, and the red bushing. The springs are actually so heavy, that the mech. adv. doesnt reach its full curve untill about 5500 rpm.

Take a look at the charts:


so when he installed the light springs it will now allow the full advance cure in by about 2500rpm and picked up those few extra degrees.
 

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Joe, I know your little blower doesn't make a ton of boost, but beware of detonation--listen carefully when you make your timing changes. Pull a couple plugs after a pass and see how they look--you don't want to be picking up parts off the track!
 

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Discussion Starter #9
Mike. Whats weird is last time I set / checked my timing I was at 17 initial and 32 total all in by 3200. I changed the springs to the light blue from the heavy silver the other day. I didnt put a light on it until I did the spring swap. With the blue sprngs it was at 38 total. It didnt make sense so I put the heavy ones back in and checked it again. Was still at 38 total. Somewhere along the line my timing has changed. I put the blue ones back and Im pulling a few degrees back out. Everything I read says not to go more than around 32 total. But I guess I have been running 38 for a while and didnt know.Last Thursday at the track I lost about 2/10 on my time and trying to fugure out why. I think bringing in thetimin g faster might help if I dont increase total. Also trying a new carb I had built that is boost referenced
 
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