Generation II block partial metric?
 

My rebuilt short block small block has all SAE threads except the block to bell housing are 10mm metric.

anyone else run across this?

Re: Generation II block partial metric?
 

Starter bolts started going metric around the early 90s.

Maybe you ran into a later casting rebuild.

Re: Generation II block partial metric?
 

I've seen that on the S10 4.3 blocks.

Re: Generation II block partial metric?
 

I ran the bell bolts in ARP site. Gen 2 shows only 3/8/16. Gen 3 LS shows only 10mm.

Fact that every other bolt on block is 3/8 may suggest that someone re tapped for the larger 10 mm for reasons unk. We have not installed starter so will check that...

Re: Generation II block partial metric?
 

The S10 4.3 blocks had 10mm for the bell housing, but the other bolts were 3/8-16.

Re: Generation II block partial metric?
 

Blueprint just postd this to me in email:

We have a few blocks that use metric bellhousing, motor mount, and starter bolts. GM decided to change those in the late 90’s. If we get a block that has those metric bolt holes, we include those metric bolts with the engine. We do not install metric helicoils in engines that had standard bolts.

The metric bell housing bolts were not in shipment. I will check parts listed in shipment. That is why mechanic gravitated to SAE.