Harmonic balancer question (with pic)

[1967C20]

OK, first let me say that I did do a search on this site for info on harmonic balancers and it did answer a few questions but I still need a little advice. My engine is the original ('67) 327 that came in my truck. In the picture below, what I assume to be the original balancer is on the left (rubber has deteriorated, don't want to reuse it). It measures 6-1/4" and has a thick profile. The AutoZone replacement balancer (middle) measures 6-1/8" and has a thin profile. A generic SBC balancer that I bought from Jegs (right) measures 6-3/4'" and has a thick profile, plus the timing mark is in a different position (I assume because the pointers changed at some time). Why the differences in diameter and thickness? Am I right to say that it doesn't matter which balancer I use as long as I have the correct pointer and it points to zero when cylinder #1 is at TDC?

[woodridge]

My guess is that the balancer from Jeg's is for a long water pump with the timimg tab located so you see it looking behind the wp. You could remark the new one if you had some way to accurately index it.

[Richard H.]

I agree^^^^^^ The key here is belt alignment and and shaft fit.

[Premium72]

had the same issue when i was piecen mine back togeather. you seem to be on the rite track.

[1967C20]

Thanks for the input, guys. The timing tab that came with my new timing cover lines up with the Jegs balancer at zero degrees when #1 is at TDC. The other two balancers show 6-8 degrees after TDC on the same tab when #1 is at TDC, so I am assuming they would require a different (or stock) pointer. All three have the same overall thickness from front to back so I don't think pulley/belt alignment will be a problem unless the new one doesn't seat in as far as the stock one did. I guess I'll go with the Jegs balancer unless someone sees any reason why I shouldn't. So, does anyone know why the difference in balancer diameter and ring thickness?

[airdale94]

I went through this with my 283. It has a big 6 1/4". Suppose to have one with the pulleys welded to it, very small. That one in the center is a 327. That's the one I'd go with. That's the one I'm going to put on mine.

[1967C20]

airdale, I see what you are saying about the one in the middle. It looks like all the balancers pictured in the 1967 shop manual although I have never seen one with the pulley welded to it. However, as far as I can tell, the balancer on the left is the one that came on the motor from the factory. Any one else have any thoughts?

[prg machine]

I am reading from " how to re-build your Small Block Chevy" by David Vizard.............."....Be sure to use the right size damper.............their are basicaly 3 different sizes: truck engines usually use the large thick ones, as do high-performance passenger cars, while most intermediate -performance passenger cars use the midle-size one. Low-peformance models use the small one . The 400 uses one of it's own due to external balancing of that engine."

My qoutes aren't exact to the word, but as stated in the book. If your 327 was a truck engine then that is why the thick balancer.

[jhow66]

Pulley mounting surface on all balancers are the same distance from block no matter what size or year. 'C20 the orange one was used on higher HP 327's and in most trucks. Any balancer can be used on any SB- you just have to adjust for the tab and timing mark location.

[1967C20]

Thanks prg and jhow, that's what I needed to know. My 327 is the high-output (for trucks anyway) 220 HP version for '67 so that would explain the thicker balancer. I know I had seen 283's and 327's with the thinner balancers, but now I know why. I'll go with the Jegs balancer since it is closest in size and weight to the original. Thanks!

[6470chevy]

chevrolet small block parts interchange manual says 6 1/8 is 262 and 307
6 3/4 X 1 3/16 is 305 327 350
6 3/4 X 1 11/16 is 267 305
all balancers interchange except 400sb gm pn6272225
if you are spinning that 327 up there the bigger balancer is the best bet
remember the timing tab is the only thing to watch out for make sure it is the same