sb head work - The 1947 - Present Chevrolet & GMC Truck Message Board Network

itchy · 06-26-2009, 09:56 PM

Has anyone ever grinded a sbc head comb. chamber out from a 64cc to 72 cc. I am running -22 disc pistions. With thick head gaskets. But wanting to get my compression down to 8.0 or less. Wondering how much grinding there is.

chevybuldr · 06-26-2009, 09:59 PM

Thats a ton of grinding not sure it would be worth it. Sounds like you are putting a blower on. Why not just sell those heads and put the money into another set.

Marv D · 06-28-2009, 10:49 AM

I would not EVER consider attempting doing that. The chamber is thin enough and prone to cracking. Besides, unles you have a cnc program for THOSE heads,, it's more likely you'll just screw up a set of heads with oidd shaped chambers of unequal volume. Why make a less than ideal situation worse! What kind of motor are you building that you have -22cc dishes, a thick head gasket (yuck) and need a 72cc chamber. A +.030 over 350 with a standard 0.025 deck, normal 0.041" thick FelPro head gasket, -22cc dishes and a 64cc head is at 8.2:1 compression already. If your building a blower or turbo motor,, I think you should listen to chevybuilder. A set of the "RIGHT" heads for the build would be a drop inthe bucket in terms of build costs.

itchy · 06-28-2009, 05:40 PM

Start from the top :
2 Edelbrock 1407s - 750 cfm
871 BMD blower 12 lb boost
Dart heads 230 cc 64 cc c chamber
2.02 / 1.60 1.55 spring
Comp Cam # 300BR-14 114 lobe
0.575 - 0.575 lift
255 262 Duration @ 050
JE Pistions -22 D shape dish
.030
Eagle forged 4340 h beam rods 5.7
Eagle forged crank 3.750
mallory distributor / msd box

Marv D · 06-28-2009, 05:59 PM

NICE package ichy,, what cubic inch motor? With only a 5.7 rod I'm assuming it's not a 4" stroke. I was always taught that a forced induction motor doesn't need a lot of runner x-section. Why the 230cc intake ports with such a small (realitively) valve? Was it to get the big exhaust side?

Again, unless your zero decked, wouldn't 8.2 work? Maybe I'm missing something but at worse I'd go to a full dish instead of the D-cup before I'd whack on the heads in any way.

itchy · 06-28-2009, 09:17 PM

Attachments are always better !

Outlaw72 · 06-29-2009, 02:11 PM

Listen to Marv....

Never try to open a set of 64cc heads that much. They sell heads with different combustion chambers for a reason. The best way to change the chamber is to buy big and then mill it down if you need to. Head manufacturers give specs on how to mill and how much you can go. Please do not try to port a 64 chamber out to 72 or 76 cc........

06-26-2009, 09:56 PM	#1
itchy Registered User Join Date: Jun 2009 Location: Calif Posts: 7	sb head work Has anyone ever grinded a sbc head comb. chamber out from a 64cc to 72 cc. I am running -22 disc pistions. With thick head gaskets. But wanting to get my compression down to 8.0 or less. Wondering how much grinding there is.

06-26-2009, 09:59 PM	#2
chevybuldr Registered User Join Date: Oct 2008 Location: Livermore ca Posts: 699	Re: sb head work Thats a ton of grinding not sure it would be worth it. Sounds like you are putting a blower on. Why not just sell those heads and put the money into another set.

06-28-2009, 10:49 AM	#3
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: sb head work I would not EVER consider attempting doing that. The chamber is thin enough and prone to cracking. Besides, unles you have a cnc program for THOSE heads,, it's more likely you'll just screw up a set of heads with oidd shaped chambers of unequal volume. Why make a less than ideal situation worse! What kind of motor are you building that you have -22cc dishes, a thick head gasket (yuck) and need a 72cc chamber. A +.030 over 350 with a standard 0.025 deck, normal 0.041" thick FelPro head gasket, -22cc dishes and a 64cc head is at 8.2:1 compression already. If your building a blower or turbo motor,, I think you should listen to chevybuilder. A set of the "RIGHT" heads for the build would be a drop inthe bucket in terms of build costs. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral. Last edited by Marv D; 06-28-2009 at 10:50 AM.

06-28-2009, 05:40 PM	#4
itchy Registered User Join Date: Jun 2009 Location: Calif Posts: 7	Re: sb head work Start from the top : 2 Edelbrock 1407s - 750 cfm 871 BMD blower 12 lb boost Dart heads 230 cc 64 cc c chamber 2.02 / 1.60 1.55 spring Comp Cam # 300BR-14 114 lobe 0.575 - 0.575 lift 255 262 Duration @ 050 JE Pistions -22 D shape dish .030 Eagle forged 4340 h beam rods 5.7 Eagle forged crank 3.750 mallory distributor / msd box

06-28-2009, 05:59 PM	#5
Marv D Registered Truck Offender Join Date: May 2008 Location: hells training ground (aka Ariz) Posts: 3,118	Re: sb head work NICE package ichy,, what cubic inch motor? With only a 5.7 rod I'm assuming it's not a 4" stroke. I was always taught that a forced induction motor doesn't need a lot of runner x-section. Why the 230cc intake ports with such a small (realitively) valve? Was it to get the big exhaust side? Again, unless your zero decked, wouldn't 8.2 work? Maybe I'm missing something but at worse I'd go to a full dish instead of the D-cup before I'd whack on the heads in any way. __________________ Still playin with trucks, even at my age! When you're dead, it's only a problem for the people around you, because you don't know you're dead. .....It's kinda the same when your STUPID. I just did my taxes and reviewed my SS statement. Thanks to the current administration it looks like I will only have to work till noon on the day of my funeral.

06-28-2009, 09:17 PM	#6
itchy Registered User Join Date: Jun 2009 Location: Calif Posts: 7	Re: sb head work Attachments are always better ! Attached Images

06-29-2009, 02:11 PM	#7
Outlaw72 Hay Team!! Join Date: Jun 2003 Location: Ft. Worth, TX, USA Posts: 366	Re: sb head work Listen to Marv.... Never try to open a set of 64cc heads that much. They sell heads with different combustion chambers for a reason. The best way to change the chamber is to buy big and then mill it down if you need to. Head manufacturers give specs on how to mill and how much you can go. Please do not try to port a 64 chamber out to 72 or 76 cc........ __________________ 1972 Chevrolet Cheyenne LWB "Orange and White" 8)



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