What year cover are they using to modify?

 

I didn't ask, they didn't say. It will be easy to tell when it arrives as one will have the plug for the factory OBDII crank trigger, one will not.

I'm concerned with the different price that I have for the balancer shell as compared to what's above a post or two though. The one he told me I needed was a 6 bolt one he said...

The one he quoted me was by application a LS1 hub according to their sheet on their website. The guy (Rick) told me not to worry about that though, so

I just hate sending **** back and waiting longer when they/I'm wrong though. Costs more that way too.

 

For a '95 and up, the '96-'97 style should be used as there is more material on the cover for machining. I have a '95 and used the '96-'97 style and just plugged the crank sensor provision hole. On a '92-'94, it appears to have more material than the '95 style, but if you are heavily modifying a '92-'94, it would be in your best interest to upgrade to a vented opti-spark, which would require the later style cover, and in that case, just use the '96-'97 style.

 

Thanks for the advice. I'm on the fence on whether or not I'll be using the factory crank reluctor as a crank signal for the BS3, or using an aftermarket crank trigger. Regardless I'll be going with the 96-97 cover for more seal support. I'm pretty sure that's what ATI will send anyways, just need to confirm it before the order.

As for the opti, I'm going to be either eliminating it completely, and using a distributor stub for the cam signal, or modifying an opti to signal cam position. If I do use the opti though, I won't be using the optical portion of it, I'll have a VR sensor to do the job, so the opti will essentially be just a convenient place to mount it.

 

Ok, I have a '97 timing cover (GM12550032), and NAPA 22306. The NAPA oil seal has an outer diameter of 2.630".

Obviously I need to have the timing cover's bore enlarged... but to what size? I assume this is an interferance fit design. Would 2.625" be too small? Anyone want to share the final size they went with?

I'll probably just give the seal and cover to the machine shop and tell them to make it work but I'd like to see what others are boring out to first so I don't get too crazy. This is a rubber oil seal with a thin steel hoop; I imagine it needs more interferance than say a steel dowel needs just based on compression ability. That, and it's pretty wide so the interferance should be larger right?

5 thousandths enough? too much?

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Edit:
After a few replies, I'm going with 3 thousandths.

Also, Federal-Mogul makes an equivalent oil seal and it seems a bit sturdier comparing them side by side. It's NATIONAL 341022... same dimentions otherwise... just not as hollow in the rim and the rubber "lip" is thicker.

The stock cover's retaining lip is only 2.1" diameter and the new ATI hub OD is 2.25" (what they call "seal diameter")... so it needs to opened up to clear the hub. The lip you leave on there should be at least 2.30" to clear the hub and any mis-alignment, but no more than 2.40" or the seal may not stay put once you start pushing it in or pushing in the hub ).

Someone here mentioned the stock bore is 0.400+" deep (mine was 0.410"), and the NAPA 22306 (and National 341022) are ~0.176-0.180" thick. He bored the stock cover out at the factory depth and used 2 seals, but you'll probably want to check your casting just to make sure there's enough beef there to avoid breaking through. I'm looking at a double seal but only boring down the 0.360" needed to flush-mount the seals... just as a precaution.