460 Block Problem
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Joined: Mar 2002
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460 Block Problem
I'm trying to set the piston quench height at 0.035 from the head. Here's what I did.
The block was cleaned and bored/honed to 4.390 for F2404 pistons with 0.002 inch clearance between the block and piston. I polished the std-std 2Y crank with emery cloth and then cleaned it. I put a set of old std main bearing in the block and set the crank in. I tipped the block on the back and set it on some wood blocks so the crank would rotate. I took 4 old pins and turned them to slip fit into the con rods. I took four rods and four new pistons and put them in number 1, 4, 5, and 8. I snugged the rods on the crank (not to final torque). I then used a dial gauge to set each one at TDC and with a mic checked the distance into the hole around the edge of the pistons. Well the data looked really strange. So I pulled the rods and checked them for straightness and rejected a few because they were bent. I then used a single rod and repeated the process. I put it in 1, 4, 5, and 8. I always used another rod/piston on the journal and snugged the rods. Brought them to TDC and got more strange numbers. I changed to a rod with less than 0.0005 inch difference between the wrist pin and rod journal end. I mic'ed the piston piston pin to piston top and both sides were the same. I installed the new rod with the piston and torqued the main and rods to spec's (95 on mains 45 on rods). I'm still getting the difference each hole.
Number 5 front 0.020 inch down
Number 5 outer: 0.024 inch down
Number 5 inner: 0.024 inch down
Number 5 rear: 0.028 inch down
This wouldn't bother me except that the number 8 hole is showing about the same numbers. So I put a straight edge on the deck and it does have a high spot in the middle maybe 0.003 inch between number 6 and 7.
I don't know what else to do. I'm thinking I might have to put a cylinder into the mains and mic the distance to the deck. That way I've eliminated all the other variables from the equation. The block mains less main bearings is 3.295 inches. So I'm thinking of putting a 3.294 bar into the block and checking the deck with a 12 inch depth mic (if I can find one).
I'm really starting to think that the piston bores are not square (at 90 degrees) with the crank. The question really is if the block is that far off can it be used? Should I try to save it or just find another block?
The block was cleaned and bored/honed to 4.390 for F2404 pistons with 0.002 inch clearance between the block and piston. I polished the std-std 2Y crank with emery cloth and then cleaned it. I put a set of old std main bearing in the block and set the crank in. I tipped the block on the back and set it on some wood blocks so the crank would rotate. I took 4 old pins and turned them to slip fit into the con rods. I took four rods and four new pistons and put them in number 1, 4, 5, and 8. I snugged the rods on the crank (not to final torque). I then used a dial gauge to set each one at TDC and with a mic checked the distance into the hole around the edge of the pistons. Well the data looked really strange. So I pulled the rods and checked them for straightness and rejected a few because they were bent. I then used a single rod and repeated the process. I put it in 1, 4, 5, and 8. I always used another rod/piston on the journal and snugged the rods. Brought them to TDC and got more strange numbers. I changed to a rod with less than 0.0005 inch difference between the wrist pin and rod journal end. I mic'ed the piston piston pin to piston top and both sides were the same. I installed the new rod with the piston and torqued the main and rods to spec's (95 on mains 45 on rods). I'm still getting the difference each hole.
Number 5 front 0.020 inch down
Number 5 outer: 0.024 inch down
Number 5 inner: 0.024 inch down
Number 5 rear: 0.028 inch down
This wouldn't bother me except that the number 8 hole is showing about the same numbers. So I put a straight edge on the deck and it does have a high spot in the middle maybe 0.003 inch between number 6 and 7.
I don't know what else to do. I'm thinking I might have to put a cylinder into the mains and mic the distance to the deck. That way I've eliminated all the other variables from the equation. The block mains less main bearings is 3.295 inches. So I'm thinking of putting a 3.294 bar into the block and checking the deck with a 12 inch depth mic (if I can find one).
I'm really starting to think that the piston bores are not square (at 90 degrees) with the crank. The question really is if the block is that far off can it be used? Should I try to save it or just find another block?
Hotshot
Joined: Dec 2003
Posts: 18,423
Likes: 9
From: iowa
yes it can be that far off, but before I did the cyl trick I would have the block lined honed to square the crank main bore up first then check the deck hieght. a possiblility although it would cost a little more just have the block squared to the newly squared crank bore then check the deck hieght again and have it decked that much.
