I haven't seen any recent threads on these two blocks so I'm assuming this is old news, but I wanted to bring it up again for those who are planning on building a roller cam'd 383. I had read that the 880 blocks were some of the strongest Chevy made so I naturally had to have one. I'd been buying parts for my 383 build for some time and got a good deal on a set of new KB135-.040 and had to buy a set of 5.7" rods. Thinking how sweet this was going to be I did some more searching on the 880 block and found that the bore length was shorter on these?? Sure enough I grabbed my digital caliper and went to measure, 5.6". OH! Wait lets do the math: 5.7" rod + 1.433" compression height +1.875" (1/2 the stroke) totals 9.008". Now minus the std deck height of 9.025 gives another .017" to take from the 5.6" bore length which gives 5.583" of cylinder bore to work with. If you add the 1.433" compression height with the 3.75" stroke gives a 5.183" (BDC) where the center of the pin will be in the bore and if you add the other half of the pin diameter .4635" totals 5.6465", hmmm? This puts .0635" of the pin outside the cylinder along with .8665" of the piston skirt ??? I can see why some guys have piston slap along with busted skirts. Looks like 6" rods only with the 880 blocks.
I swapped my 880 block for a 638 out of a 95 3/4 ton truck. The 880 blocks began in mid 95 with the ending of the 638's. Is there actually any metallurgical benefits of the 880 over the 638?
I swapped my 880 block for a 638 out of a 95 3/4 ton truck. The 880 blocks began in mid 95 with the ending of the 638's. Is there actually any metallurgical benefits of the 880 over the 638?