Hot Rod Forum banner

Sbc Deck Height?

25K views 9 replies 5 participants last post by  CNC BLOCKS NE 
#1 · (Edited)
Trying to keep a friend from making a big mistake. What's the maximum a stock SBC block can be decked? I'm telling him I've never heard of less than 9.000. What effect does this have on valve train geometry and the need to mill other surfaces, ie: intake face of heads, intake manifold, and do the valley "ends" also get milled when a block is decked that far? I really need someone truly experienced with this to show him. Thanks.

EDIT: He has a bunch of "expensive" parts and wants to build a 302 using a 350 4 bolt block .060 over already, 283 crank,5.7" I-beam rods, 327 small dome pistons-assembly already balanced. I guess he wants to make up the piston deck height by decking the block. Just seems like a lot to me, on paper anyway. He's probably going to do this no matter what unless someone can tell him it flat out will not work. I've got the heads he wants to use, but I don't want them ruined for anything else in the future. He thinks he can go to a 8.900 deck and a thin shim head gasket. My heads are completely rebuilt/new 461X with SS valves,screw in studs, guide plates, spring kit and milled; got them in a trade deal long ago (10 yrs. +). Wants to put this in his V-6, 4-speed,4.11 posi (55-64 Chev) setup 82' Chevette Scooter.
 
#2 ·
I don't know what the max is but most people just take them down to 9" even to zero deck. What's his purpose for wanting to shave it so far? Hell, my pistons are at zero deck and I didn't cut the block at all. There's more than one way to accomplish this. Why put up with the head/manifold fitment and geometry problems, as you mentioned, when there's no reason to?
 
#3 ·
deck

I would think the fastest way to put an end to it is...

Walk him over to the block and have him measure the deck thickness, then ask him what he thinks is going to happen when he removes about 1/4 of the total thickness to get his 8.900" size.... If that don't stop him i doubt the fact that he is going to spend countless hours trying to get the intake to fit will either...

In my shop i would charge him more to cut .125" per side off the deck then he would pay for a new set of pistons....that might stop him..L.O.L.

Tell him if he does it he can't have your heads!!!!

all-in-all a very bad idea IMO

Keith
 
#4 ·
SBC deck.

Yeah, I even tried to give him a forged large journal 327 crank and told him to just have the rod journals cut down to small journal size and rebalance the crank ( he still has his balance card ) so he could use his rods and pistons, but he was'nt interested. He did buy my 350 4 bolt block ,but I don't think I'm letting him have the heads to play with. I have some other heads I'll just give him for his "experiment". He's an aerospace machinist and his brother's an automotive machinist that does all his work. I wonder what his brother is going to say or do. I guess we'll see. Thanks.
 
#7 ·
Decked out!

Well, just got off the phone with him and told him about all these "opinions". His bother, the automotive machinist, was there so he asked him also. Took a little brothererly rubbing to make him realize the head bolts going into a block about a quarter inch were'nt going to do the job. So, he's going to use his small journal 327 crank, "already balanced to the rods/pistons", if he can get it back. He's hung up on using the thick conversion bearings he's bought and opened. Told him I'm keeping my heads but I have another pair of stock camel humps in decent shape he can have. Thanks for the help. Oh, turns out the reason he bought my 350 block was because his prepped and ready 327 small journal block sitting on the workbench shelf was being wizzed on by their cats; messed up the cylinders and deck on one side pretty bad. Here kitty, kitty,kitty!!!! :nono:
 
#9 ·
CNC BLOCKS N/E said:
The most we have machined of a stock OEM block is .75 finish deck height was 8.950 for another shop and on a Bowtie 7.775 which is 250 off the decks which brought the decks down to the upper water pump bolt holes. This block was machined for a sprint car which runs the water pump off the front of the crank.

Carl did you mean .075"????
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top