Piston types. Dumb queston but i'm, askin anyway - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Broken_down? · 12-07-2006, 02:25 AM

been looking recently for a complete engine rebuild for our 350. I understand everything in the kit except it ask what type of piston style. It lists: Flat, Dome, Dish. Which of the 3 is best and why for a stock build.

thanks

turbochevy · 12-07-2006, 02:32 AM

just depends on what you are looking for.....
what are your plans for the truck?

Broken_down? · 12-07-2006, 02:54 AM

My plan is to restore her back to complete factory. Everything!

If I get my way and find 327 somewhere then I will drop that back in and restore it back to factory. As it sits the truck is a 68 with a 71 350. I so want to get rid of this 350 and put a 327 back in. But no one around here sells the 327...

*Billla* · 12-07-2006, 06:15 AM

There's not one that's "best" - they're means to get different CR, with dished pistons giving the lowest CR and domed the highest. If you check the kit listing, it will give the CR with each set - probably based on a 64cc chamber.

Myself · 12-07-2006, 11:50 AM

At 76cc or 64cc chamber volume, either way, the flat-tops will be a good choice for stock to mild performance builds. Won't cause any detonation problems.

Robznob11 · 12-07-2006, 12:17 PM

yes go with the flat tops, most all sbc heads have small chambers 64-76 some after market heads are even 54cc so with that in mind unless you want to run race gas domes are out of the question not to mention you have clearance issues, no then with the dish you will give up an optimun compression ratio and you motor will not likley exceed 260 hp. flat tops are the best choice becuase you can get about 9-10 to 1 comp ratio witch will work well with all mild tricks you want to add later like cams etc. they also work best if you want to bump them with a small bit of n2o. there are 2 different types of flat tops some with 2 valve reliefe and some with 4 i like the 2 so that you dont give up that extra crunch. also with the flat tops you can fool around with head gaskets to alter your comp ratio and go from mild to wild but thats all the secreats im gonna tell you so good luck...

*Billla* · 12-07-2006, 05:50 PM

Quote:

Originally Posted by Robznob11

also with the flat tops you can fool around with head gaskets to alter your comp ratio and go from mild to wild but thats all the secreats im gonna tell you so good luck...

Gaskets vary a bit around .040...you're not going to go from "mild to wild" with that

crazy longhorn · 12-07-2006, 06:48 PM

Im not here to talk too much about compression, but more about Quench. No IMO , a 327 or 350 should be set up with a 2 valve releief flattop to keep the compression up on a good street motor.....but... You also want the comp ratio to reflect proper Quench (piston to head clearance), & that should be in the .040-.045 range, with a .035 minimum for steel rods running under 6500 rpms. the tighter you can cut that quench, the more compression you can run without detonating that pig! Also, the more timing you can run without detonation.....ei , a 10 to 1 mill(with proper quench) will run better, with less detonation,& more timing than a 9.5 to 1 mill that has too much quench distance! That is why gasket thickness should not set the comp ratio

Now you can "fudge" on the comp ratio, by running a hotter cam,(static comp ratio vs dynamic comp ratio) or aluminum heads.....they loose a lot of heat, & will allow higher ratios(lots of debate there, but generally 10.5 to 11 to1 on alum heads works). best of luck.....

L

ETsC10 · 12-07-2006, 12:18 PM

Broken Down,
I've rebuilt a 327 (still on the engine stand), for my C-10, using forged flattops and a mild RV cam (268). With what I've chosen I think I can get away with regular gas; just barely. The large journal 327 cores are still out there but, being a 2 year only, they are scarce. Plus there are a bazillion Corvette owners looking for the same block. Good luck! ET

BCOWANWHEELS · 12-07-2006, 10:00 PM

Aa 1971 350 Is A Excellent Engine. The Best Yr Of The 350,s Is 1970 & 1971. Most Likely You Got A Set Of 461 Heads, Steel Crank, Hi Nickel & Tin Block. If It Was Mine It Would Take 1000.00 To Buy It As A Rebuildable Core. You Know There 300 Hp Stock Right ? Just Build It Back Completely Stock Except Install Hard Valve Sets On The Exhaust Ports Of The Heads.
Bob

12-07-2006, 02:32 AM	#2
turbochevy Senior Member Join Date: Nov 2006 Location: Chatsworth, So Cal! Posts: 226	Re: Piston types. Dumb queston but i'm, askin anyway just depends on what you are looking for..... what are your plans for the truck? __________________ 1970 Chevy C 10 SWB

12-07-2006, 06:15 AM	#4
Billla Account Suspended Join Date: Sep 2005 Location: Monroe, WA Posts: 3,814	Re: Piston types. Dumb queston but i'm, askin anyway There's not one that's "best" - they're means to get different CR, with dished pistons giving the lowest CR and domed the highest. If you check the kit listing, it will give the CR with each set - probably based on a 64cc chamber.

12-07-2006, 11:50 AM	#5
Myself Registered User Join Date: Oct 2005 Location: Northern Arkansas Posts: 1,149	Re: Piston types. Dumb queston but i'm, askin anyway At 76cc or 64cc chamber volume, either way, the flat-tops will be a good choice for stock to mild performance builds. Won't cause any detonation problems.

12-07-2006, 12:17 PM	#6
Robznob11 Registered User Join Date: Feb 2004 Location: brownfield texas (west texas) Posts: 1,936	Re: Piston types. Dumb queston but i'm, askin anyway yes go with the flat tops, most all sbc heads have small chambers 64-76 some after market heads are even 54cc so with that in mind unless you want to run race gas domes are out of the question not to mention you have clearance issues, no then with the dish you will give up an optimun compression ratio and you motor will not likley exceed 260 hp. flat tops are the best choice becuase you can get about 9-10 to 1 comp ratio witch will work well with all mild tricks you want to add later like cams etc. they also work best if you want to bump them with a small bit of n2o. there are 2 different types of flat tops some with 2 valve reliefe and some with 4 i like the 2 so that you dont give up that extra crunch. also with the flat tops you can fool around with head gaskets to alter your comp ratio and go from mild to wild but thats all the secreats im gonna tell you so good luck... __________________ The Ghost 67 short wide full custom. 550 hp LSX, 4l80E, narrowed 9". Body dropped w/air ride! ........................ ___ .........________//__{\_____ ,,,,,,,/__(⊙)___//___/__(O)_/ @disciple2.rc 💪instagram💪 LED TAILS Last edited by Robznob11; 12-07-2006 at 12:17 PM.

12-07-2006, 06:48 PM	#8
crazy longhorn Fabricate till you "puke" Join Date: Jun 2002 Location: Ill Posts: 9,402	Re: Piston types. Dumb queston but i'm, askin anyway Im not here to talk too much about compression, but more about Quench. No IMO , a 327 or 350 should be set up with a 2 valve releief flattop to keep the compression up on a good street motor.....but... You also want the comp ratio to reflect proper Quench (piston to head clearance), & that should be in the .040-.045 range, with a .035 minimum for steel rods running under 6500 rpms. the tighter you can cut that quench, the more compression you can run without detonating that pig! Also, the more timing you can run without detonation.....ei , a 10 to 1 mill(with proper quench) will run better, with less detonation,& more timing than a 9.5 to 1 mill that has too much quench distance! That is why gasket thickness should not set the comp ratio Now you can "fudge" on the comp ratio, by running a hotter cam,(static comp ratio vs dynamic comp ratio) or aluminum heads.....they loose a lot of heat, & will allow higher ratios(lots of debate there, but generally 10.5 to 11 to1 on alum heads works). best of luck..... L __________________ 69 longhorn,4" chop,3/5 drop, 1/2 ton suspension/disc brakes,1 1/2" body drop,steel tilt clip, 5.3/Edelbrock rpm intake/600 carb, Hooker streetrod shorties,2 1/2" exhaust/ H pipe/50's Flows , 6 spd Richmond trans,12 bolt/ 3.40 gears.... Last edited by crazy longhorn; 12-07-2006 at 06:50 PM. Reason: spelling

12-07-2006, 12:18 PM	#9
ETsC10 Hand Crafted C-10 Join Date: Aug 2006 Location: Burien, WA Posts: 5,180	Re: Piston types. Dumb queston but i'm, askin anyway Broken Down, I've rebuilt a 327 (still on the engine stand), for my C-10, using forged flattops and a mild RV cam (268). With what I've chosen I think I can get away with regular gas; just barely. The large journal 327 cores are still out there but, being a 2 year only, they are scarce. Plus there are a bazillion Corvette owners looking for the same block. Good luck! ET __________________ . Forum Guidelines and Rules Buying and Selling Code of Conduct Become a Board Supporter! Truck FAQ Ellen... the boards artsy-fartsy, eclectic, truck-lovin' gal-member...

12-07-2006, 10:00 PM	#10
BCOWANWHEELS Registered User Join Date: Nov 2006 Location: KINGSPORT,TN. Posts: 3,035	Re: Piston types. Dumb queston but i'm, askin anyway Aa 1971 350 Is A Excellent Engine. The Best Yr Of The 350,s Is 1970 & 1971. Most Likely You Got A Set Of 461 Heads, Steel Crank, Hi Nickel & Tin Block. If It Was Mine It Would Take 1000.00 To Buy It As A Rebuildable Core. You Know There 300 Hp Stock Right ? Just Build It Back Completely Stock Except Install Hard Valve Sets On The Exhaust Ports Of The Heads. Bob



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