Cap loose in block register questions

[Six_Silver]

I just recently picked up a block for cheap that has a loose cap in the register. The motor had the two steel center main caps. I am assuming the motor was detonated severly, damaging the bottom end.

The #3 cap is the one that is loose. The block shows signs of metal transfer from the cap. The rest of the caps were tight in their registers.

Now I took the #3 cap and placed it in the other locations, and it will take some effort to fit into the register. I only did this too see if the cap was loose in all the registers, but it is only loose in #3 (where it came from).

So what I would like to know is if the block is junk. If I buy new caps and have a line bore done, will this be ok? Or is the #3 register on the block bad?

And since the #2 cap was still tight, can I re-use it? The crank that came out showed wear only on the #3 main journal. Obviously I will have a line bore done.

Thanks fellas.

 

[Lee Thompson]

Block

I/m sure this is not what you want to hear. The block is spread and not a good one for high HP. I have heard of people taking a center punch and hitting the side of the cap to put raised specks in it to tighten it up. A band aid at best. You would really be best to locate another block. Definately don/t put any $ in machine work in this block.

 

[KendallF]

If the #3 cap is a steel one, you could weld it and re-fit it to the register. I am not expert enough to tell you if the block spreads or the cap shrinks under detonation. If the bearing spins I understand the cap heats and shrinks at the sides, making it loose in the register.

In any case, it seems like a gamble to use the block when there are so many 109 blocks still out there. We just picked one out of the U-pull-it today for $50, complete long block.

 

[Six_Silver]

Thanks for the info guys.

I was thinking that it wouldn't be worth using this block.

Anyone else have any insight on whether the block is junk or not?

 

[Louie L.]

The cap can be welded up and remachined to have a tight fit. Another thing...detonation alone will not cause the damage you describe. Improper machine work can allow the cap to walk with out any detonation.Good Luck

 

[NC87GN]

I just went through boring/honing for 2 steel mains in my 87 block. The steel caps had to be shaved a little on the sides to allow them to properly fit into the register. In short you might be able to purchase 2 "new" steel caps that are oversized to fit the block register. Maybe an option for you..?? If you go this route you need to bore and line hone due to the new steel caps.

Mike Banas
87GN

 

[ThikStik]

Micale speaks of milling to make the caps fit tightly-he says shops that just tork and align bore are skipping a step. That s what my machine shop did , but mine do get tight just before settling in block. Im not sure what Nick mills to effect the fitment but i bet your ok if there is a good machinist like his who can tighten it up.

 

[Six_Silver]

Originally posted by ThikStik
Micale speaks of milling to make the caps fit tightly-he says shops that just tork and align bore are skipping a step. That s what my machine shop did , but mine do get tight just before settling in block. Im not sure what Nick mills to effect the fitment but i bet your ok if there is a good machinist like his who can tighten it up.

Thats a good point and something that I was considering as well. If the flat area on the block around the studs where the cap sits is milled flat, and that same area on the cap is milled flat, there should be no problem if a line bore is done after this. I would of course get rid of the bad caps and buy new ones if I did this.

Any other thoughts?

 

[ThikStik]

Yea, flatness (squareness) has to occur-I think your case invlves a challenge of tightening the registars. My main question when putting my first 3.8 motor together was how to repeat the positioning of the caps especially the thrust cap. Lucky me for noticing that it would go down any old way when installed albeit tightly. So i learned about the rapping of the c shaft to align it. But Micale said that is not necesarry if machinist did milling right, that it should registar itself correctly. YOurs just may become tight by the time it /and block is shaved down. I say a good machinist can do it.
Dam these dowel-less wonders!