In need of 283 .030 pistons - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Bobillot · 07-21-2024, 03:05 AM

Hello Im in need of some 30 over pistons for my 283 truck engine I have some but they are 0.057 at tdc below the deck. I just had the 283 bored and honed to 3.905 and have a new everything for it. But I noticed the deck seemed high and I checked out the new and the old STD pistons.

The new to this engine 30 over pistons have a compression height of 1.78 and the originals have a height of 1.83. So with these pistons its a substantial hit to comp ratio and the engine is going back into my 1975 C30 hay hauling flat bed dump truck so it needs all the power it can get.

So if any one has some mild domed 30 over pistons 3.905" and would be willing to part with them for a reasonable price.

It would get us back hauling hay more efficiently. Thank You for any help!

**truckdude239** · 07-21-2024, 01:30 PM

i can find 1.80 compression height, but i see nothing at 1.83 https://cnc-motorsports.com/keith-bl...ore-3-905.html

scottofksu · Today, 02:44 PM

It might be cheaper to have the block decked... Dial in your compression ratio by decking to the preferred compression ratio relative to your piston volumes and head gasket selection. What heads are you running and do they have good squench potential given your piston surface characteristics? Good luck, brother! I hope your hay hauler gets back up and running stronger than ever before sloppy weather hits!

**Accelo** · Today, 06:37 PM

Your pins and rings have been installed and the block bored to the pistons. So no returns. I assume you are attempting to salvage all the work you have completed.
Other pistons may not fit the block. Forged or cast pistons take wildly different piston-to-wall clearances.
I did the same thing years ago. When I read the "* fine print" It mentioned the lower compression height. In my case, it was .020 lower.
This is done so the people who deck the block are not running into piston clearance issues.

I agree "It might be cheaper to have the block decked". That typically includes the intake manifold machining but not always. Decking the block requires disassembly.

Possibly you can find heads with smaller combustion chambers. That leaves the quench quite large and not conducive to power production.
As an interesting comparison, LS motors have the piston sticking out of the bore at a nominal .005 to maximize the quench.

07-21-2024, 03:05 AM	#1
Bobillot Registered User Join Date: Feb 2018 Location: Washington Posts: 6	In need of 283 .030 pistons Hello Im in need of some 30 over pistons for my 283 truck engine I have some but they are 0.057 at tdc below the deck. I just had the 283 bored and honed to 3.905 and have a new everything for it. But I noticed the deck seemed high and I checked out the new and the old STD pistons. The new to this engine 30 over pistons have a compression height of 1.78 and the originals have a height of 1.83. So with these pistons its a substantial hit to comp ratio and the engine is going back into my 1975 C30 hay hauling flat bed dump truck so it needs all the power it can get. So if any one has some mild domed 30 over pistons 3.905" and would be willing to part with them for a reasonable price. It would get us back hauling hay more efficiently. Thank You for any help! Last edited by Bobillot; 07-21-2024 at 03:19 AM. Reason: typo

07-21-2024, 01:30 PM	#2
truckdude239 Senior Member Join Date: Sep 2005 Location: Lewisville, Nc Posts: 10,233	Re: In need of 283 .030 pistons i can find 1.80 compression height, but i see nothing at 1.83 https://cnc-motorsports.com/keith-bl...ore-3-905.html __________________ David fuller Ase Certified Mechanic Click here to help support our board!! 1971 Chevy c-10 under going a 4.8l LSx swap Build Thread http://67-72chevytrucks.com/vboard/s...d.php?t=421305 2007 Honda Accord my daily 145kmiles 2002 Honda Accord 4 door With 330k(sisters car) 2005 toyota Avalon 228k( brothers car) 2002 Sububran 5.3 245k 2000 Tahoe 5.3l 378 General manager for Marco's Carwash & lube

Today, 02:44 PM	#3
scottofksu Registered User Join Date: Nov 2011 Location: Omaha, Nebraska Posts: 434	Re: In need of 283 .030 pistons It might be cheaper to have the block decked... Dial in your compression ratio by decking to the preferred compression ratio relative to your piston volumes and head gasket selection. What heads are you running and do they have good squench potential given your piston surface characteristics? Good luck, brother! I hope your hay hauler gets back up and running stronger than ever before sloppy weather hits! __________________ Travis' Tribute Truck - 65 C10 Frame Up Restoration http://67-72chevytrucks.com/vboard/s...d.php?t=495073

Today, 06:37 PM	#4
Accelo Senior Member Join Date: Mar 2015 Location: washington Posts: 2,220	Re: In need of 283 .030 pistons Your pins and rings have been installed and the block bored to the pistons. So no returns. I assume you are attempting to salvage all the work you have completed. Other pistons may not fit the block. Forged or cast pistons take wildly different piston-to-wall clearances. I did the same thing years ago. When I read the "* fine print" It mentioned the lower compression height. In my case, it was .020 lower. This is done so the people who deck the block are not running into piston clearance issues. I agree "It might be cheaper to have the block decked". That typically includes the intake manifold machining but not always. Decking the block requires disassembly. Possibly you can find heads with smaller combustion chambers. That leaves the quench quite large and not conducive to power production. As an interesting comparison, LS motors have the piston sticking out of the bore at a nominal .005 to maximize the quench. Last edited by Accelo; Today at 06:45 PM.



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