Fastcamaro87

Ok i bought a new Harmonic balancer, and I am having a few problems:

1. They are different sizes, the diameters are both 6 3/4in. but the thickness of the outer ring is different, fig 1.
New:1 5/8in. Old: 1 3/16

2. BTDC marking in relation to the key way on the crankshaft is different, fig 1. according to the timing marks on the new one, the marks are 30 degrees apart, fig 1.

ok heres my questions,
1. Is it possible for the outer ring to have moved on the old one?
(the elastomer ring is sticking out bout 1/8 inch)

2.before i took the motor out, it ran good, and i had replaced the distributor 2months ago,and the timing and everything was ok, i set it using the marks on the old balancer


misc. info :
they are the same length on the hub that slips over the crank snout, fig 2. The thickness of the outside ring doesnt really bother me as much, because the old one is a solid outer ring, and the new one is a hollowback one, fig 3. also both dampers weigh the same.
Before i took the motor out, it ran good, and i had replaced the distributor 2months ago,and the timing and everything was ok, i set it using the marks on the old balancer
I am rebuilding the motor, it has 140k miles on it,

Jester

Most SBC Balancers use a 2 o'clock timing pointer. On thirdgens, you can't really see it there, so they moved it to 12 oclock. I'd guess your balancer is one of the 2 oclock ones. You'll have to get another balancer, or re-mark that one as accuratly as possible to match.

It's possible that the old outer ring moved..many do as they age.

Fastcamaro87

when referring to 12:00 and 2:00 where is the reference point?

Jester

Standing in front of the motor looking at it. 12 oclock is straight up, 2 o'clock is 60 degrees clockwise.

Fastcamaro87

is the keyway on the crank the refference point? when its at the 12:00 position on the crank snout, or when BTDC marking is at 12:00?

rezinn

When #1 is at TDC I believe the keyway and the balancer will point to 2 o'clock(not exactly, though).

Guest

Psssssst..... Jester... TPI cars have a 2 o'clock balancer.

I dunno whats up with that other balancer you got, its nothing I have ever seen before. I would see if it lines up with the pointer when the engine is at TDC. You wont have to put it on to do that, it will go far enough to check it without pressing it onto the crank.

Jester

no kidding. hows that work? TPI cars have the same pully/accesory system...I wouldn't imagine you could see it there. Oh well..guess I'll have to find one to poke my head under and look.

SSC

Some marks are different and some cranks are keyed different. If you timed the car a month ago and it seemed to be right on then I would suggest that you pull the new ballancer line up the keyways and grind a mark according to the old ballancer, then fill the old mark with paint. If you were to swich timing tabs that might work but It might not. Can you exchange the ballancer for the proper one?
SSC

irocbsa

My VBelt TPI engine has a 2 o'clock and the serp. RS has a 12 o'clock. Its a pain in the *** to see the timing mark on the RS.
bsa

mrr23

what you have is a 350 balancer. the 305 engines came with the mark at 12:00. same position as the keyway. the 350 engines came with the timing mark at 1:00 to 2:00 depending on year. when you oredered it, did you tell them you had a 305? aftermarket doesn't really make them for 305's even though they are the same except for the timing mark. to see the timing mark on the 305's, you have to look between the water pump and timing cover. i don't know why they did it other than to be able to tell the difference between 305's and 350's at a glance.

86TpiTransAm

To the original author... the keyway on the crank should be about 2 o'clock when at TDC so if you have the 2 o'clock timing pointer then the timing mark on the balancer should be at the same place as the keyway when installed at TDC. If you have the 12 o'clock timing pointer then the timing mark on the balancer will be at 12 o'clock when the keyway on the crank is at 2 o'clock.

I have an '86 with the 2 o'clock pointer but it's a v-belt setup so it's really not all that hard to see. On the '86 TPI the air ducting is not just a big round hose coming off the TB and going to the air box like some newer TPIs but rather there's a big black box looking thing right in front of the TB and if the timing pointer were 12 o'clock I definitely wouldn't be able to time it then.

That's not necessarily true. As stated above the TPI engines have the 2:00 mark. That includes 305 TPI engines such as the one I just removed from my '86 TA. It all depends on the year and the application.

mrr23

and me owning the same 86 t/a didn't see that on mine. i just looked and you are right on that. so, he got the wrong year balancer then.

E-Z Rollin

The 6 3/4x 1 3/16 is a 305,327,350 damper, the 6 3/4x 1 11/16 [5/8] is a 267,305 damper. The probelm is the timing tag for the first damper isn't the right one for the second damper,get the proper timing cover for the damper or an adjustable timing tag. Then bring the #1 piston to TDC and adjust your timing tab.

Guest

Jester the TPI air inlet is in the way of having the timing mark at 12. Kinda hard to see behind the water pump when theres a piece of rubber and a throttle body in the way.

Jester

lol I noticed that..but there is the alternator/PS bracket at 2 oclock. Little harder to push out of the way or peek around I would have thought. I guess it isn't.