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-   -   Does anyone have any suggestions on pistons for a Chevy 350? (http://www.hotrodders.com/forum/does-anyone-have-any-suggestions-pistons-chevy-350-a-171123.html)

DEMONSPEED 01-06-2010 09:50 PM

Does anyone have any suggestions on pistons for a Chevy 350?
 
Thank you for reading. Heres the deal, The machine shop called me and told me my motor has to be bored a minimum of .20 over to get everything straight. I'm wanting to go .40 over to a 357-358 and i need a set of decent pistons. I'm wanting to spend around $120 dollars or preferably less for a set. I do not know what to look for when buying a piston. All i know is i want the highest compression possible. They have to be at least as good as stock which was around 9:6:1. Preferably 10:1 or better. If anyone on here could help me out i would really appreciate it. Thanks in advance, Rob.

DoubleVision 01-06-2010 10:24 PM

Chevy 350 pistons come in all types, sizes, materials, you name it. Your talking about the most popular engine in the world. Speed pro hyper pistons fill the bill nicely for a street engine. I wouldn`t be looking for the highest compression ratio either, unless you are ready to run race gas. anything over 10:1 will require higher than 93 octane fuel. Summit racing carries a complete line of speed pro pistons. If you look at the chart it will give you the idea of what compression ratio and etc. the piston will give with the current specs.

DEMONSPEED 01-06-2010 10:56 PM

Ok i did not know higher than 10:1 requires higher than 93 fuel. I found a few piston and ring kits. What is better dished or flat tops?

cobalt327 01-06-2010 11:51 PM

Quote:

Originally Posted by DEMONSPEED
The machine shop called me and told me my motor has to be bored a minimum of .20 over to get everything straight. I'm wanting to go .40 over to a 357-358 and i need a set of decent pistons.

Rob, if the block will clean up at 0.020" over, go w/that. There's no point to go w/a larger than needed oversize- there's no difference in power, and the smaller overbore will make for a more durable engine.

The 'best' piston for this case is a likely going to be a flat top, if you are starting w/a clean slate. You can use FT pistons and choose the cylinder head's chamber size to make the CR you need to go w/the camshaft that's going to be used, as well as what gas you plan to use.

But this can change if the heads you are going to use don't have the 'ideal' chamber size. Then, dished or domed pistons may be called for.

It's a balancing act. Everything is interrelated.

DEMONSPEED 01-07-2010 12:44 AM

There's really not a difference in power? I figured the few cubic inches would have a small effect on power. The reason I was asking about the dished or FT pistons was because I have a large combustion chamber, around 76cc I think. I can't find 305 heads or I would go with them. Right now I have supposedly the worst casting GM heads around. I've got a Lunati .515"/.515" cam and I was going to run 93 octane gas.

cobalt327 01-07-2010 12:57 AM

Quote:

Originally Posted by DEMONSPEED
There's really not a difference in power? I figured the few cubic inches would have a small effect on power.

The increase will be minuscule. I'd take the thicker cylinder walls any day.

Quote:

The reason I was asking about the dished or FT pistons was because I have a large combustion chamber, around 76cc I think. I can't find 305 heads or I would go with them. Right now I have supposedly the worst casting GM heads around.
I wouldn't buy domed pistons just to use those heads w/high test. No return on the money spent, power-wise. I'd instead use FT pistons and cheap gas- until my budget will allow Vortec's or something.

327NUT 01-07-2010 01:16 AM

I'm sending you a PM on a good place to buy engine parts. By the way and I know you're 15 but these guy's have been there ...done that, they're giving you good advice. Build a nice dependable. streetable engine the first time, you can and WILL build a bigger one as you get older.

DEMONSPEED 01-07-2010 01:58 AM

I'm going to go ahead and say thank you to all of you that have helped so far before I forget. http://www.summitracing.com/parts/STL-H345NP20/ So given the info I have gathered from you all how do these sound?

cobalt327 01-07-2010 10:06 AM

Quote:

Originally Posted by DEMONSPEED
I'm going to go ahead and say thank you to all of you that have helped so far before I forget. http://www.summitracing.com/parts/STL-H345NP20/ So given the info I have gathered from you all how do these sound?

Looks OK to me. I don't know if they're available for less somewhere else, but the piston itself looks good.

The spec: "Compression Distance (in) 1.560 in." is an important one- this means that the quench distance will automatically be 0.020" 'better' ( higher in the bore at TDC) than if you used rebuilder-type cast pistons that often have a 1.540" compression height.

Keep this spec in mind so you can tell the machine shop, should you have the block decked. It'll make a difference as to the amount of material that needs to be removed to get the quench right.


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