109 block and hot air blocks


Jan 14, 2003
Hi my question is are the later 109 blocks the same as the older hot air blocks? are they as tough? thanks
The blocks are basically the same but there are a few differences. Deck height is taller on the earlier blocks and there's some minor differences in the oil passeges and that's about all. Strength is the same for all of them.;)
The mains/caps are the same and are equally weak.
The location of the head bolt threads are different on the 86-87 109 block. The threads are countersunk deep in the block. The engineers did this to provide a more stable deck surface when the heads are torqued in place. IMO, this make the 109 block a better choice if you have a couple of blocks to choose from. Brian is correct, the strength of the main cap area is the same.