cbeatty

I have read about the low comp.pistons on this site.I have a 1970 olds 350 with 72 7a heads.block bored 60 over. Back in 95 I had all the work done to the block. The new pistons thay gave me had the small dish in them aprox 2 &1/8"diam.x 1/4 deep. low comp.right? I have the crank in now and am looking into pistons before I put them in.the replacment pistons by speed venders are big bucks. Can I use cady or buick pistons? If not I need to find some one with 60 over slugs with no dish! I had a 1970 buick 350 motor that ran well.All I am looking for is to make the olds run as well. Any help will be great.

cutlassefi

You can try to find some 425/.068 over 350 pistons or you could make up that cc difference by 0 decking the block and cutting the heads.

cbeatty

Sounds like that would cost as much as getting new pistons? I did think of doing that but not about changing the pisons to 425/.068'S Cheep chevy parts are all over the place! I was hoping for the same on olds. Wishfull thinking ha!

cbeatty

Thanks for the info. will look for pistons @ a good price first. I have a good buddy base on chevy parts and will look into rods and crank grind. chevy pistons I can find.

captjim

For $200 you can get the heads and block milled. New SBC pistons and rods will cost a lot more than that, plus 400 SNC bore is .008 larger than a .060 over Olds. You can get to 9 to 1 by milling the block and heads.

joesw31

EGGE machine sells flat top .060 pistons for your 350 at a good price. There part number is L2320-8.

cbeatty

if I can get 9 to 1 with just milling and not changing pistons thats great.I wonder about the intake bolting on right? It's not for racing just going in a large car. Needs to have some *** to it!

coppercutlass

find out what cc's the pistons are., If you have the 14cc you can get 9 to 1 by milling the heads and using a thinner head gasket assuming your pistons are in the cylinder around .025 . Which i found is common with the sbo ., also those heads have more than 64cc bringing it to a true 64cc will acheive this but then you also have to mill the intake. I had this same issue when building my current motor after finding out the shim gaskets i bought where for a 330 and would not work wit my 350 due to water port lay out i said screw it went to flat tops and ran a .040 gasket and im at roughly 9.75 to 1 compression. If you buy cast units you can get away with not balancing them as long as they are withing factory spec wheight wise thats what i did worked for me others have diffrent views on my method

captjim

Definition; PERIOD

A punctuation mark ( . ) indicating a full stop, placed at the end of declarative sentences and other statements thought to be complete, and after many abbreviations.

captjim

Definition; PERIOD
A punctuation mark ( . ) indicating a full stop, placed at the end of declarative sentences and other statements thought to be complete, and after many abbreviations.

Dude, your posts are really hard to understand.

coppercutlass

i use my phone and its hard to hit the alt ket and period. i know my post are hard to read but it makes some sense gimmie some slack here . Ill keep it mind from now on punctuation. i went back and took care of it

cbeatty

heads are 64cc! dish held aorox 64 mil of fluid. pistons have dish thats 2 1/8"wide and aprox. 1/4"deep.Wondering at 60 over how much of a dog it will be? Not racing just want it to have some *** for getting into traffic.

coppercutlass

with a compression ratio around 9 to 1 even the high 8's a nice towing cam will do great. i had a 9 to 1 well almost 9 to 1 combo do high 13's in my 72 cutlass i ran 87 on it with a 3.42 it cuised nice and had a lot of pull to it .

cbeatty

I was asking if it will have anything running the pistons I have. The heads need to go to the shop for ck-up may have them milled some?

cutlassefi

Another incorrect assumption. I promise you on a stock factory motor the balance still isn't right. Have you ever balanced an engines rotating assembly? I've done dozens and dozens, they're very seldom even close, even with the "original" parts.

coppercutlass

its not an assumption its how i built my motor and it has lasted all summer cruising and i put 20 runs on it so far . i have built a few motors none of them balanced just used carefully picked factory parts none of them had any bad vibrations . i know the factory engines werent perfect but they lasted and they were beat by people like me with a lead foot and those tolerances and high and low limits where set by engineers so im going to go ahead and believe that . we have very diffrent view im not saying your wrong im not saying im right . im willing to take a risk because i build my own stuff i dont pay anyone to put my stuff together i only pay for things i dont have equipment for . but just for kicks my current motor has 5 1972 rods 3 fom 1970, pistons are 69 flat tops , crank is 72 and no balancing some how it does not have any bad vibrations. i think im doing ok considering i read about alot of people having issues with brand new paid for engines . thats just my experience others may vary

coppercutlass

cbeatty well the pistons, head volume, and deck height control compression . compression makes power a flat top will yeild more compression with less machining a dished piston will need deck milling, head milling thinner gaskets etc. to make the compression needed for the cam you are running. those pistons will work just depends how you want to go about it. new pistons means a balance job depending on how you go ., machining may cost as much as the new pistons probably less both will have their cost's all in what the wallet allows lol

captjim

Heads can be milled to about 58 cc. As for your pistons, it depends how far in the hole they are. Mine were .053. If yours are down that far, it is hard to get a decent Cr. But, you can have a car that is fun to drive in the upper 8.xx to 1 neighborhood.

joe_padavano

Give US some slack. Keep in mind that you are asking other people to take the time to answer a question that you have. Sorry for the preaching, but the LEAST that you can do is to make it easy for us to understand what you are asking.

coppercutlass

i went back and fixed it. i also never asked a question i was just putting in my 2 cents .