OK - I'm almost embarassed to ask for help since I grew up with a family full of mechanics, but I just can't seem to figuer this out:

First, let me tell you what I have in the ignition. - New mallory HEI distributor, MSD 6A - medium springs on the advance weights. Brand new plugs and Taylor 8MM wires.

I'm trying to get optimal tuning out of the engine - it's a 10:1 327 (.010 over), Edelbrock aluminum heads w/68cc chambers. Cam is in the neighborhood of .500 lift - not sure of the brand - engine built by my brother for me a while back - he no longer has the specs...edelbrock 600CFM carb, Edelbrock performer intake, headers.

Anyway, here's my dilemma: when I time the engine, I am getting approximately 22-24 degrees with the vac can disconnected and the line plugged. I'm getting nearly 50 degrees total. The car is holding about 15" vacuum.

If I time it for the best vacuum reading, I get about 17", and the total gets up near 60 degrees total timing with nearly 30 at idle? However, I am afraid to try to run the car like this!

One thing I can tell you is that I have an aftermarket balancer - I've heard that these sometimes have the keyway at 10 degrees advanced instead of TDC.

The car runs well timed conservatively (the lowest that I've mentioned), however, I don't know if I have a technical issue due to the balancer or if the engine actually likes that much advance.

Any thoughts? Really hurting my brain on this one...

Thanks

Luke (aka Paul)

 

 

If the engine is really that advanced, the engine is probably running too lean.  If you richen it up a bit with some jet changes, the timing will peak lower, and the car will run stronger.

I can't believe you've got that much timing without some detonation going on. I'd have to suspect the damper ring has moved, is incorrect, or the light is off. Just an opinion....

Ken, ya got me one this one.....Why/how would a lean condition change the actual timing? I'm befuddled, and its not that hard to do....or did I misunderstand ?

And yes, we have no detonation. But, Dr. Ken is onto something! I pulled a couple of plugs last evening and they are white! However, could this just be a result of the efficiency of the MSD? Should the plugs still be tan to light brown if you're looking for a lean condition with an MSD?

I'll put #1 on tdc to check the damper. It's a new damper from Proform - I don't think there is a ring that can move on this one.

LukesVette38830.1824537037

One thing I can tell you is that I have an aftermarket balancer - I've heard that these sometimes have the keyway at 10 degrees advanced instead of TDC.

[/QUOTE]

 do you have the old / original balancer? Is it the same size?

You could put a ruler or something straight from keyway to outer ring , measuring distance to zero marks on both. Hope I explained it good enuf

Original balancer is the same size.  I just found the data card from the balancer. It states that all after market balancers (including this one) have the TDC mark 10 degrees left of the keyway. Translation - reads 10 degrees advanced on the factory pointer at TDC.

So my reading is off by at least 10 degrees. The lean condition may be the additional difference. Guess what I'm doing today!!

The lean condition does not increase the timing per say, but a lean condition requires more advance than a rich condition to create the peak cylinder pressure at 10 degrees after top dead center.

The 10 degrees ATDC peak burn pressure is not to be confused with timing.  Timing vaires a great deal to accomplish the 10 ATDC burn pressure, which is ideal for almost ANY gas engine.

Increase RPM need advanced timing.  Decreased RPM needs retarted timing.

Colder conditions require retard, Hotter conditions require advance.

Lean requires advance, rich requires retard.

There are more factors than just these, and they all combine to form a complex timing map.  Each of these is what is required not to start the burn, and not even the goal of finishing the burn, but creating peak pressure as the result of the burn.

If peak pressure is reached later then 10 AFTC, the engine loses power and ecomony, and raised emissions.   If it peaks before then, all of the above occours, and the engine can run hot and create advanced stress wear in the engine.

Bottom line, if the engine is running lean, the timing can be set more advanced to somewhat compensate for the problem, and run well.

[QUOTE=kstyer]

The lean condition does not increase the timing per say, but a lean condition requires more advance than a rich condition to create the peak cylinder pressure at 10 degrees after top dead center....

Bottom line, if the engine is running lean, the timing can be set more advanced to somewhat compensate for the problem, and run well.

[/QUOTE]


That's what I was looking for! Thanx, Ken!

Results: Balancer keyway is 10 degrees advanced. That's 10. I stepped the the primary side up one jet in the rich direction, and the engine reacted as Ken explained. I am actually getting more power than before!! Timing came back down another 5 degrees!

I am currently at 14 degrees initial and 38 total w/ 16" vac. Much more in the range!!

Thanks team!

 

LukesVette38831.418900463