Gen V or Gen VI head ?

[docHoladay69]

Hello from Wyoming I have a Gen V 454 that we stroked out to a 496 balanced Eagle rotating assembly with a Lunati hydraulic roller cam and lifter 610 Lift and had the heads rebuilt and machined to accept the bigger valve springs and installed the comp cam conversion kit for adjustable rockers how ever i was not able to install the aluminum roller rockers due to not enough studs length ordered stamped steel roller tip rockers and I was able to put them on but not enough room to correctly adjust them, so my question is has anyone had the rocker arm stud holes machined out from 3/8 to 7/16 so you can use longer ARP studs I know the Gen V heads don't flow real well so i bought a set of Gen VI heads and I am going to have them machined for the bigger valve springs and machined and tapped out to 7/16 Studs. Or should I not waste any more money and just buy a set of aftermarket heads, I did not build it for high rpm's but for low end torque the cam makes the most torque at 4200 rpms, I am open to all types of input on these subject just want my Suburban running again?
P.S. Please Help

 

[Grumpy]

welcome to the web site!

"Has anyone had there Gen V Bbc rocker arm studs drilled out from 3/8 to 7/16 so you can run longer ARP studs for a bigger cam and full roller rocker arms and stud girdles ?"
a good machine shop can do that but keep in mind you'll need to check, as it is possible for the rocker stud threads to go into the intake runners,
on some heads and use of a rocker stud girdle significantly strengthens and reduces chances of head damage from rocker stud flexing

"quote)No, you cannot directly put Generation VI big-block heads on a Generation V block without modifications, primarily because the cooling passage configurations differ between the two generations, creating a potential sealing issue for the head gasket. While the Gen V and Gen VI blocks share some similarities, the factory head designs are not always interchangeable due to these water jacket changes. However, most aftermarket heads are designed to be compatible with both Gen V and Gen VI blocks, and specific head gaskets are available to accommodate the differences.
Key Differences & Issues

• Cooling Passages:
  The most significant difference is in the location and configuration of the coolant holes, particularly the upper ones near the lifter valley.
• Gasket Sealing:
  The changed water passage design in the block and head can create a very thin area for the head gasket to seal, making direct placement of OE heads difficult.

Solutions

• Aftermarket Heads:
  Many aftermarket head manufacturers design their products to be compatible with both Gen V and Gen VI blocks. Always verify with the manufacturer before purchasing new heads.
• Specialized Gaskets:
  Use a head gasket specifically designed to accommodate the differences between Gen V and Gen VI blocks. Fel-Pro offers gaskets, like the PN 1047, that address this issue.

How to Identify the Generation

• Gen V (1991-1995):
  These engines feature a one-piece rear-main seal, a revised oiling system, and no mechanical fuel pump pad.
  
  
• Gen VI (1996-2001):
  These are identified by the presence of factory hydraulic roller lifters, multi-port fuel injection, and a six-bolt aluminum timing chain cover.

"

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Pardon Our Interruption

 

[docHoladay69]

Thanks for the response I knew that the Gen IV heads wouldn't interchange due to coolant passages but i wasn't aware of the gen VI not working on Gen V blocks I have watched several videos of people using gen VI heads on Gen V engines because they flow better and nothing was never mentioned about the coolant passages or a special gasket like you have to use to interchange Gen IV heads and that spokes me because i don't want coolant leaking into the lifter valley, But as we all know you can't trust what you see on UTube LOL. I found this attachment on google but i am definitely going to do more research now that you point this out Thank You.

 

[Grumpy]

I've only seen it done a couple times, and in each instance coolant leaks were eventually an issue,

Ask Anything - February 2014 - Car Craft Magazine

In February's "Ask Anything", Jeff Smith answers questions from readers on blocks, MAF modifiers, and more.

www.hotrod.com

but I'm not sure which head and intake gasket combo was used and yes the mods were eventually worked out,
Id point out that there are aftermarket heads designed to make the swap easier, and Id contact
raylarengineering.com

(866) 496-8181​

L18 Vortec 8100 8.1L GEN 7 Big Block Chevy 496cid Performance Packages - Hot Rod / Muscle Car Performance Parts - Raylar Engineering

L18 Vortec GEN 7 BBC 8100 8.1L engine swaps for hot rods, street rods and muscle cars. Performance parts, kits and packages for the GEN 7 big block chevy 496cid.

www.raylarengineering.com

as they are the experts in this field

 

[Grumpy]