[455dan]

Originally Posted by Joe-Touring

1971 YC, believe the casting # is: 485428

Indeed, I was really hoping to be able to get a 455 back on the road. Seems like there aren’t many around up here in the PNW.

Not sure of what part of PNW but here is a Spokane ad for some blocks
from ad ( All are standard bore, buildable cores to my knowledge)
has a 428 no main caps, and others including a 455 for $700
couple decent year 400's - 68 WT and YS for what seems pretty reasonable

https://spokane.craigslist.org/pts/d...435800786.html

[RAIV55]

Looking at the test sheet it appears cylinders 1,5 &7 are thin on the major thrust. I would be inclined to find another block rather than doing the work to this one.

Probably wouldn't trust the guy who sonic tested it with a Pontiac, he missed on the cylinder numbering...rookie mistake...

[Joe-Touring]

Originally Posted by RAIV55

Looking at the test sheet it appears cylinders 1,5 &7 are thin on the major thrust. I would be inclined to find another block rather than doing the work to this one.

Probably wouldn't trust the guy who sonic tested it with a Pontiac, he missed on the cylinder numbering...rookie mistake...

What is the consensus for minimums on thrust and non thrust surfaces? The machinist recommended 0.150” on the thrusts, and 0.100” everywhere else.

I noticed that, I am slightly apprehensive about the shop. The owner/main machinist was not the guy doing the sonic check or the sleeve removal.

[Gach]

Let me add this. X-ray vision? All an ultrasonic inspection will do is confirm there is enough material in the primary thrust face to machine out. Blocks corrode internally; they also suffer from coolant erosion and cavitation. I know of two ‘ blocks that had primary thrust face cylinder walls that were less than .090 thick. The MINIMUM primary thrust face cylinder wall SHOULD be .150-.180. Align honing simply insures that the main saddle alignment is correct. It’s a simple process that removes a modicum of material from the main caps and the main saddle. At most, .003 005out of the caps and .001-.003 out of the main saddle. Iron DOES distort over forty years of heating and cooling cycles. Have them check the cam bore alignment as well.

I’m sure you’ve already made a decision, but the above just something to think about.

[Gach]

I would definitely also have the main saddles checked it would be a nightmare to sleeve or what ever way you decided to go, only to find out later, you ended up with main bearing issues same on cam bore.

This was a few years ago, a friend went .030, just a street car. Although he did have it magged, but never Sonic tested. Finally just to see what it would do he line up, with a Chevelle on the street. Second race white smoke coming from passenger side. First thought head gasket. After we pulled it down found nice big long crack.

I personally after checking to blocks found third one to be good. Of cruse my plain was racing.

[hurryinhoosier62]

Originally Posted by Joe-Touring

What is the consensus for minimums on thrust and non thrust surfaces? The machinist recommended 0.150” on the thrusts, and 0.100” everywhere else.

I noticed that, I am slightly apprehensive about the shop. The owner/main machinist was not the guy doing the sonic check or the sleeve removal.

The rule of thumb I was taught was .135 MINIMUM on the primary thrust wall and .100-.110 MINIMUM on the other walls. This assumes you are using the engine for street use ONLY, are utilizing the lightest piston/pin/ rod combination you can afford and are keeping the RPMs down. The lighter the reciprocal mass the less stress on the cylinder walls.

[Joe-Touring]

Originally Posted by hurryinhoosier62

The rule of thumb I was taught was .135 MINIMUM on the primary thrust wall and .100-.110 MINIMUM on the other walls. This assumes you are using the engine for street use ONLY, are utilizing the lightest piston/pin/ rod combination you can afford and are keeping the RPMs down. The lighter the reciprocal mass the less stress on the cylinder walls.

Thanks hoosier, using those numbers, looks like boring out another 0.030” would cause issues in most of the cylinders. Thrust sides on Cyls 5 and 6 being the most affected. I was hoping to reuse the OE cast rods that came with the block, they’ve already been redone with ARP studs. I know Eagle h beams would be lighter, but if I’m springing for forged pistons/rods, it doesn’t make sense to not build a stout 455 with 9.5 or so compression and a RAIV cam. And it seems the vibe is that this block would be the weak link in that setup.

[Joe-Touring]

Originally Posted by 455dan

Not sure of what part of PNW but here is a Spokane ad for some blocks
from ad ( All are standard bore, buildable cores to my knowledge)
has a 428 no main caps, and others including a 455 for $700
couple decent year 400's - 68 WT and YS for what seems pretty reasonable

https://spokane.craigslist.org/pts/d...435800786.html

Some good stuff, though prices seem a touch high. Unfortunately I am on the west side of the mountains, and that’s quite a drive. Thanks for the link tho.