Hot Rod Forum : Hotrodders Bulletin Board - View Single Post - 350///357 build
Thread: 350///357 build
View Single Post
  #138 (permalink)  
Old 12-26-2012, 03:26 PM
cobalt327's Avatar
cobalt327 cobalt327 is offline
Last wiki edit: Intake manifold
Last journal entry: 1980 Malibu Wagon
Last photo:
Join Date: Mar 2009
Posts: 5,031
Wiki Edits: 1616

Thanks: 128
Thanked 616 Times in 565 Posts
Originally Posted by 0trbo4myCHEVUICK View Post
Went to the machine shop today and talked to the guy. He got in his book and said that with the pistons .025 in the hole I would be at 9:7 compression with a 58cc head. He doesent believe me about the pistons being .038 in the hole. He wants me to bring the block up there tomorrow morning so he can measure with his dial caliper. We will see what happens but man im still nervous about tearing the thing apart. Not only because of the labor but because It would be so hard to not change parts and that gets me into more money. I was perfectly on my pre-determined 3000 budget for the entire build. Decking the block only costs 100 bucks if I can handle tearing it down and not digging too deep into my pockets for upgrades. I know my pistons suck and I would like a steel crank but probably arp bolts would be the only thing I do..
If I was in the shoes of your machinist, I might doubt those numbers, too.

The reason is the deck from the factory is supposed to be 9.025", give or take a thou or two. Rebuilder pistons are 0.020" 'shorter' in compression height (deeper in the hole) than stock production pistons.

So he's expecting to see either 0.025" in the hole- uncut deck and stock compression height pistons,


0.045" in the hole- uncut deck and rebuilder pistons (0.025" deck plus 0.020 compression height difference).

BUT! It's entirely possible to be exactly what you say it is. One way to end up at 0.038" in the hole is rebuilder pistons and the deck cut about 0.007". You can look at the deck and tell if it's been machined other than by the factory. One clue is if the suffix code is very shallow or missing altogether- if the block was decked 0.007", the suffix would definitely show it.
Reply With Quote
The Following User Says Thank You to cobalt327 For This Useful Post:
0trbo4myCHEVUICK (12-27-2012)