SBC Balancer

Anyone recall how many degrees difference there is between the old style timing marks (like on a Vette) and the later style that has the timing tab under/behind the water pump?

Do you mean the early vette ones being @ 12 o clock and the later ones at around 2 o clock?The long water pumps (non vettes obviously) kept the 12 o clock position if I'm not mistaken. All mid 60s up vettes went to the 2 o clock pos. I think early 327s had the 12 o clock pos but not 100% certain. That 12 o clock orientation will most likely give probs w/ a short water pump. Dunno how many degrees the difference is.

The 12 O'clock timing tabs didn't start until they figured out the long water pump- the short one sets right on the timing cover. No idea what year(s) they did all that. I'm trying to figure out the degree thing. I know it's somewhere, or someone has figured it out.

I'll take 60* for $100 Alex. (My best guess)

NO hijack intended, but in a related question....why did GM bother to put out the longer water pumps/pulley offsets?? what possibe install demanded they be further from the face of the block? I can understand shifting accessories around, but what did altering them pulleys buy them??

much less alter timing mark locations....then the obvious followup, two different diameter balancers?? what is it 6" &8"....anyone know what/why??

:bonkers::hi:

Just guessing, but the short pumps were around for a long time. Then cars started getting longer. I suspect it was cheaper to make a longer water pump and change the pulley system than move the engine in an existing chassis.

They used several different balancers- there was a 6 that had a ring that was 3/4 wide, then found that the bigger ones made everything feel smoother, then added weight. Then found the added weight added inertia to the engine, then made a larger diameter for performance.

The whole thing is just an experiment anyway. All the way from the Model T. try this, try that, HEY that worked pretty good, now if we..............

The early style (pre-69) HD had the TDC mark 2 degrees counter clockwise from the keyway; the later style had the mark 10 degrees CCW from the keyway.

The keyway itself aligns with the number 1 journal of the crankshaft in the SBC and BBC engines such that if the keyway is 45 degrees toward the driver's side, the #1 piston is at TDC.

DING DING DING!

We have a winner- that's the information I was looking for!!

Thanks Larry!!:bestwishes: