#8 heads...what to do?

falconsfan · 07-07-2007, 06:01 PM

What machine work do ya suggest for these heads? Intake valve size? Exhaust valve size? I'm looking to get about 300HP.

GoldOlds · 07-08-2007, 04:43 PM

The valve sizes of the #8 heads (1.875/1.622) will not make getting 300 hp a challenge. The 79 cc combustion chamber size, on the other hand, will. What do the tops of your pistons look like? If they're not flat (if they're factory pistons, I'm sure they're dished to one extent or another), you've got a fair bit of milling to do. Afterwards, you'll need to shorten the pushrods or install a shim kit because of the Olds non-adjustable valvetrain - I'll admit that I'm not 100% sure of what I'm talking about here, so get some more opinions/advice. You'd be better off to find a set of #5, #6 or #7 heads - these all have 64 cc chambers. These heads all provided at least 9.0:1 compression in their day (the pistons they were used with might have had shallower dishes than your late 70s 350). Just my 2 cents; most others here will know better than me!

- GoldOlds

falconsfan · 07-09-2007, 03:55 PM

Thanks for your input.

I have a chance to grab some #6 heads....Dont know if that will pan out....Would like more input on the #8's if someone out there has some more advice.

07-07-2007, 06:01 PM	#1 (permalink)
falconsfan Member Join Date: Oct 2006 Posts: 45	#8 heads...what to do? What machine work do ya suggest for these heads? Intake valve size? Exhaust valve size? I'm looking to get about 300HP. __________________ Rick Knipe Franklin, NC 73 Cutlass S 87 Cutlass Salon

07-09-2007, 03:55 PM	#3 (permalink)
falconsfan Member Join Date: Oct 2006 Posts: 45	Thanks for your input. I have a chance to grab some #6 heads....Dont know if that will pan out....Would like more input on the #8's if someone out there has some more advice. __________________ Rick Knipe Franklin, NC 73 Cutlass S 87 Cutlass Salon

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07-08-2007, 04:43 PM	#2 (permalink)
GoldOlds Senior Member Join Date: May 2007 Location: Chatham-Kent, Ontario Posts: 117	The valve sizes of the #8 heads (1.875/1.622) will not make getting 300 hp a challenge. The 79 cc combustion chamber size, on the other hand, will. What do the tops of your pistons look like? If they're not flat (if they're factory pistons, I'm sure they're dished to one extent or another), you've got a fair bit of milling to do. Afterwards, you'll need to shorten the pushrods or install a shim kit because of the Olds non-adjustable valvetrain - I'll admit that I'm not 100% sure of what I'm talking about here, so get some more opinions/advice. You'd be better off to find a set of #5, #6 or #7 heads - these all have 64 cc chambers. These heads all provided at least 9.0:1 compression in their day (the pistons they were used with might have had shallower dishes than your late 70s 350). Just my 2 cents; most others here will know better than me! - GoldOlds