Acceptable SBC Balancer Seal Surface Diameter??
 

Hey Guys,

For a 383 balancer (I'm guessing all SBC's are the same), does anyone know the acceptable range of dimensions for the diameter where the balancer seals with the front main seal?

I have a leaker at the front main, possibly oil pan. So I tore it all down and replaced the timing chain cover, and appropriate gaskets of course. I'm about to re-install the balancer and folks have said to use the speed sleeve that pounds on the balancer "just incase". There are no grooves that can be felt, and I don't really know much background about the balancer age / mileage. I feel like this is overkill, and I'd rather just put a set of micrometers on it to see if matches what the factory specs should be.

Thanks,

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

What is the seal number? The SK/CR seal handbook will contain the design dimensions for literally tens of thousands of seal numbers.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

Thanks for the lead, I used summit to search for my front main seal using an '85 SBC engine, then sorted by SKF mfg's only. I came up part numbers 23698, 22353, and CR15141

I then google SKF/CR seal handbook and came up with this Link. But when I use CTRL-F and search any of those part numbers, I get no hits.

I found this Page, but I don't see any tolerances on the shaft diameter. It just says it should be 2.25.

I would thought maybe a chevy factory service manual or something would have specs to show wear items and their acceptable ranges.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

Year doesn't matter. 55-up are all the same.

2.25 doesn't seem right. I just measured a brand new aftermarket one and came up with 1.77". 2.25" seems reasonable for the OD of the seal.

I'd say probably 1.75" is as small as the damper dia itself should ever be. Probably a lower limit of 1.765" might be more appropriate.

Not sure how you came up with that dia but it's wrong. Here's the correct part for a small block Chevy front crankshaft seal. Yerbasic 9845.

https://www.turtle.com/2126277/Product/timken-9845

Why are we asking this question?

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

I have a speedy sleeve on the shelf. I will try to measure it tonight. I will measure the hub on a balancer also.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

I have an oil leak at the front main seal area. I put all fresh gaskets and a new timing chain cover in and was about to reassemble, but an old timer told me to just slap the speediseal on the dampener while it's all apart "just incase".

The dampener feels smooth but I have no idea how old it is. So I was just hoping I could take a measurement of the dampener (Calipers / micrometers), see if it's in tolerance, and just rule it in or out. I'd rather not put a speedisleeve on if it doesn't truely need it.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

Gotcha.

For the oil leak, take a look at this, before getting all wrapped up in damper dia & Speedi-Sleeves.

https://www.thirdgen.org/forums/atta...-bolt-hole.jpg

If there's NOT a bolt in that hole, put one there. 3/8"-16, maybe ½ - ¾" long.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

The speedi-sleeve is .010" thickness. So it will change the overall OD by .020".
The balancer's hub measures 1.764"

If you are using one of those cheap chrome timing covers, most likely that is the problem. They are never stamped precise. Look at the hub in relation to the seal and you will find that it is not centered. You will have to file the holes for the 2 locating pins oblong to get it to sit correctly.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

Just me, but if there is not a groove where the seal rides, no reason for a sleeve.

Assume you will lower the oil pan and put the timing cover on? The bolt thing back up.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

Boy do I owe you a beer. Sure as hell, this bolt was missing, and I verified with a mirror and flashlight it's a thru hole, not a blind hole. Hopefully next weekend I'll be able to run it and have it oil free.

I didn't put 2 and 2 together when the father-in-law said he moved the grounds around a little bit. The old ground path was 1 ground cable per hole, he combined them to 1 hole (for whatever reason) and left the other hole unoccupied.

Thanks for the awesome tip, I don't know if I would have caught that.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

USE A SHORT 3/8"-16 bolt. The fuel pump pushrod is what you will bottom out against if you use too long of a bolt.
Don't forget the sealant.

Re: Acceptable SBC Balancer Seal Surface Diameter??
 

That hole would have had the smog pump bracket under it originally, in your car. People usually create that leak when they decide to "clean up the engine bay". Probably isn't related directly to ground wires. It was actually originally put there, in 1955, for the motor mounts... they were up there, looked kinda like big sway bar end links, and the pad on the side of the block that every car has used since about 1958 wasn't there yet.