Need big block head advise - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Blackhawkdc · 03-29-2003, 08:45 PM

I'm building a 496 stroker for my truck. Looking at around 550-575 horse from the compination. Not a high revving combo, but I'd assumer it needs good flowing heads still. I'm looking at World Merlin cast iron heads. Either 310cc or 345 cc intake ports. What would be the recommendation? Engine will be built to about 10.2:1 compression, domed pistons, roller cam, somewhere around 300 degrees. STarting out with either a single-plane manifold or Tunnelram, with fuel injection eventually. Any advise here? Am I headed in the right direction? The last engine I built was a 7000+ RPM Small block, so a slightly different deal than what I'm used to.

Thanks in advance.

PS. I've got a pair of Generation V heads for sale if anyone's interested.

Class of 69 · 03-29-2003, 10:32 PM

If you don't have either the heads or pistons , either size will work, you just match the pistons to the head to get the comp ratio you want.. If your referring to oval or rectangle intake ports, the rectangle will flow more air and produce more power. As for not high reving... that conbination will easily turn 7,000 rpm all day!!! Don't believe a properly built big block can't stay together over 5500 rpm, I had a highly modified LS5 that I yanked the stick at 7200 rpm on any time I felt like it for 7 years, and never broke anything in the engine! We won't mention the drive train at this time tho... ENJOY, and HANG ON!

beau396 · 03-30-2003, 03:31 AM

Most advice that I have heard from pro builders and dyno tests indicate that the smaller/shorter runners are always better for a lower revving street motor. Stock oval ports make more torque and horspower then rectangular ports up to 5,000 rpm. Due to higher velocity in the runners from the smaller diameter. Also if you use aluminum heads you can run .5-1 pt higher of commpresion because of better heat dispersion. For the h.p. that you are looking to make I would personally chose the smaller runners for better low end torque. Be careful about over camming the engine also.

chevy2racr · 03-30-2003, 03:43 AM

look into Pro Action heads. damn good flowing out of the box heads, you can get SBC heads outta the box flowing 312

doug72 · 03-30-2003, 10:07 AM

Try to find a set of open chamber 049 casting GM heads. They will get you close to what you want and are very streetable. They will work with your domed pistons.

Doug

chevy2racr · 03-30-2003, 11:38 PM

Welcome Doug, see this was ur first post

doug72 · 03-31-2003, 08:17 AM

Yes, it was and thanks for the welcome. I have been watching this page for a week or two. Bought a 72SWB stepside last weekend and just brought it home yesterday. A friend had been working on it for the past few years and decided he needed something bigger for the family. It is nearly complete. i will be posting with a bed problem later today. the 2 rails that run along the sides of the bed that support the wood floor have been cut off and I need replacements. Where is a good place to get them?

Doug

03-29-2003, 08:45 PM	#1
Blackhawkdc 440 american Horses Join Date: Mar 2001 Location: Anoka, MN USA Posts: 470	Need big block head advise I'm building a 496 stroker for my truck. Looking at around 550-575 horse from the compination. Not a high revving combo, but I'd assumer it needs good flowing heads still. I'm looking at World Merlin cast iron heads. Either 310cc or 345 cc intake ports. What would be the recommendation? Engine will be built to about 10.2:1 compression, domed pistons, roller cam, somewhere around 300 degrees. STarting out with either a single-plane manifold or Tunnelram, with fuel injection eventually. Any advise here? Am I headed in the right direction? The last engine I built was a 7000+ RPM Small block, so a slightly different deal than what I'm used to. Thanks in advance. PS. I've got a pair of Generation V heads for sale if anyone's interested. __________________ Seth Petro 1969 Chev Short Step 425hp 350, TH400, big tires, fast truck 1979 Pontiac Trans Am 1991 Saturn SL1 - gas mileage! (and free) 1977 Buick LeSabre - for sale May America bless God, and may God bless America

03-29-2003, 10:32 PM	#2
Class of 69 Registered User Join Date: Mar 2003 Location: Stillwater MN Posts: 1,166	If you don't have either the heads or pistons , either size will work, you just match the pistons to the head to get the comp ratio you want.. If your referring to oval or rectangle intake ports, the rectangle will flow more air and produce more power. As for not high reving... that conbination will easily turn 7,000 rpm all day!!! Don't believe a properly built big block can't stay together over 5500 rpm, I had a highly modified LS5 that I yanked the stick at 7200 rpm on any time I felt like it for 7 years, and never broke anything in the engine! We won't mention the drive train at this time tho... ENJOY, and HANG ON! __________________ 69 GMC K10 ..some restoration required....still..

03-30-2003, 03:31 AM	#3
beau396 Registered User Join Date: Nov 2002 Location: oak harbor wa Posts: 61	Most advice that I have heard from pro builders and dyno tests indicate that the smaller/shorter runners are always better for a lower revving street motor. Stock oval ports make more torque and horspower then rectangular ports up to 5,000 rpm. Due to higher velocity in the runners from the smaller diameter. Also if you use aluminum heads you can run .5-1 pt higher of commpresion because of better heat dispersion. For the h.p. that you are looking to make I would personally chose the smaller runners for better low end torque. Be careful about over camming the engine also. __________________ '67 C10 short box fleet side wood bed small rear window frame off restoration. 396BB,Th400, ps, pwr disc 5 lug, posi 3.07, 2000 Suburban 60/40 pwr seats, 2.5" front drop 4" rear, powder coated running gear.

03-30-2003, 03:43 AM	#4
chevy2racr So Many Ideas, So Little Money Join Date: Sep 2001 Location: Marshalltown, IA Posts: 1,610	look into Pro Action heads. damn good flowing out of the box heads, you can get SBC heads outta the box flowing 312 __________________ 72 Blazer 3/4 ton running gear 4.10s NP205/TH350 350 4in lift half doors 71 C10 with 454 99 S-10 5.1L SBC 700R4 09 Malibu Marshalltown, Iowa

03-30-2003, 11:38 PM	#6
chevy2racr So Many Ideas, So Little Money Join Date: Sep 2001 Location: Marshalltown, IA Posts: 1,610	Welcome Doug, see this was ur first post __________________ 72 Blazer 3/4 ton running gear 4.10s NP205/TH350 350 4in lift half doors 71 C10 with 454 99 S-10 5.1L SBC 700R4 09 Malibu Marshalltown, Iowa

03-30-2003, 10:07 AM	#5
doug72 Registered User Join Date: Mar 2003 Location: Plano, Tx Posts: 59	Try to find a set of open chamber 049 casting GM heads. They will get you close to what you want and are very streetable. They will work with your domed pistons. Doug

03-31-2003, 08:17 AM	#7
doug72 Registered User Join Date: Mar 2003 Location: Plano, Tx Posts: 59	Yes, it was and thanks for the welcome. I have been watching this page for a week or two. Bought a 72SWB stepside last weekend and just brought it home yesterday. A friend had been working on it for the past few years and decided he needed something bigger for the family. It is nearly complete. i will be posting with a bed problem later today. the 2 rails that run along the sides of the bed that support the wood floor have been cut off and I need replacements. Where is a good place to get them? Doug

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