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Author
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Topic: .030 milled off my 351c deck. Will this cause any major problems?
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70coupe
Gearhead Posts: 459
From: Toronto,Ontario,Canada
Registered: Aug 2000
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posted 10-20-2003 03:44 PM
  
I had to have .030 removed from the deck of my old block on both side of course due to some marks from my last motor that went south. I'm going to use flat tops again but do you think they will be out of the hole or will it be ok? The machine shop will cut the pistons for free if they need to. I imagine this will bump my compression up a touch with my closed chamber heads. I do have a set of open chamber heads that are set up for screw in studs if need be.
Thanks------------------
351c 4v clsd heads
60'1.580
1/8 [email protected]
1/4 [email protected]
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 10-20-2003 04:30 PM
It all depends on how far in the hole the pistons were to start with. The last motor I built that we zero decked, we had to take .035 off one side, and .042 off the other side to bring the pistons up to zero. It will bring your compression up some, but I wouldn't worry about it much as it will have much better quench and not be anymore prone to detonation than it was before.If the pistons stick out, or if the compression is too high, you can put a slightly thicker head gasket on it to lower the compression. With flat tops, I wouldn't use the open chamber heads, it will lower the compression too much.
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67357C
Gearhead Posts: 475
From: Newcastle, WA.
Registered: Aug 2003
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posted 10-20-2003 06:42 PM
Interesting subject, I'm glad you interjected KV.The one reason I did not put my own motor together and had the shop do it was for this reason alone. few people realize what "blueprinting" entails; it is not the mere adhering to bearing tolerances, combined with balancing. But in the context of this discussion, it is making sure that all cycinders produce the same exact compression. From my personal experience this involves having the crank indexed to make sure all throws are exactly alike, then sizing the rods to make sure their lengths are all exactly alike, then reassembling the bottom half of the motor to extract what your TRUE deck height is. Deck height can vary from side to side AND can also be from end-to-end (block taper). I believe the proper terminology for correcting this is having the block "square decked", this is if you don't wish to have a "zero deck" and zero decking a motor without preassembly is asking for huge problems. I conveyed this to my builder, and emphasized this is what I wanted, now whether he did it or not, I'll never know, unless I stand there and watch every operation he does, or measure it for yourself.
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kid vishus
Gearhead Posts: 6098
From: middle of NC
Registered: Oct 2000
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posted 10-20-2003 06:47 PM
SBC motors are notorious for the deck being way out of whack. The last one I did was the first cleveland block that had the deck different from side to side. It was also a little off front to back, but I can't remember how much exactly. We decked it off the crankshaft centerline. That's the most accurate way to do it.
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V8 Thumper
Gearhead Posts: 4377
From: Arizona
Registered: Dec 2001
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posted 10-20-2003 09:47 PM
When I had my Mexican block machined, I had it four-corner decked to .005 in the hole. My machinist bored and honed cylinders 1, 4, 5, and 8. Installed the crank, piston and rod in #1 and took a deck height. Follow the procedure for the other three, record the measurements and compensate for the deviations on the mill.One side was even, the other one was out by .007 front to back. He cut the even side square to the crank centerline, took off .012 to get the desired height. On the caddy-wampus side he cut .009 at the front to .016 at the back to duplicate identical deck heights on both banks  ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html [This message has been edited by V8 Thumper (edited 10-20-2003).]
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V8 Thumper
Gearhead Posts: 4377
From: Arizona
Registered: Dec 2001
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posted 10-20-2003 09:52 PM
Pistons .005 in the hole, .030 compressed MLS gaskets for a quench height of .035 which is tight but desirable for detonation supression like KV said. Quench that sung needs good rods or max rpm of under 6k; I chose good rods   ------------------
1965 GT coupe, 333ci aluminum headed/solid cammed stroker, four speed, 3.70:1 9" All Blue Oval, no blue bottle
http://mustangsandmore.50megs.com/V8Thumper.html
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