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big block chevrolet head swap


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  #1  
Old 12-09-2018, 08:10:17 PM
Tracy T Tracy T is offline
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Question big block chevrolet head swap

i have a 1995 454, and i believe it is the gen v engine family. basically a boat anchor as far as performance. i have a set of 1965/1966 closed chamber heads that i think should wake this motor up! casting # 3856206. so here comes the questions, what length push rods to use? i am thinking use stock rockers, valve springs etc. i know i will have to use special head gaskets made just for this conversion and i may have to do some machine work to the valve covers. i haven't done my home work as far as intake manifold or exhaust manifolds yet. not looking for a drag racer just something that should pull like a 454 should and maybe a little bit better mpg. also thinking about ditching the dished out pistons for flat tops. i also may have a issue with coolant temp sensor, mine has two, one in the head and another in the intake. i am listening, what have i missed?
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Old 12-10-2018, 03:33:17 AM
Greg Mosley Greg Mosley is offline
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Default Re: big block chevrolet head swap

Greetings Tracy T. I would consider doing more research on your BBC cylinder head exchange. I don't believe your CC heads will successfully interchange to a Gen V block. GM made some significant water passage changes to the block deck with the Gen V. platform. The 702 castings which I believe you have, tend to shroud the valves. In the day they were designed for a .180 dome piston and higher octane. Your Gen V. heads are OC. and probably have a larger valve diameter. Better flow characteristics. My suggestion would be, install a set of flat tops, an appropriate cam for the application along with proper tuning. As the saying goes (KIS) Keep it Simple. Enuf Said.
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Old 12-10-2018, 09:18:44 AM
Tracy T Tracy T is offline
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Default Re: big block chevrolet head swap

supposedly the victor head gasket 4918 & 4923 takes care of the coolant passages. i could probably research this until the end of time and know nothing for sure until i tear it down. so far the only real difference i have found is push rod lengths are different, and i suppose that could be due to the older design having adjustable valves. it does get rather conflicting when looking up heads by application, because some bridge the gap. in other words they were used prior to the gen v and also on the gen v.
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Old 12-10-2018, 10:12:56 AM
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FWurth FWurth is offline
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Default Re: big block chevrolet head swap

Don't think I'd open such a can of worms, too many Frankenstein creations laying around as it is. Always end up with more problems than success. I've never been a fan of mixing up a mish mash of parts to try to create a few extra ponies. Leave that to the race builders, they don't mind throwing away piles of cash. There are way more design changes over the years for those units than most suspect, EPA mandates in later years basically required an entirely different internal design.
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Old 12-10-2018, 10:30:27 AM
Tracy T Tracy T is offline
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Default Re: big block chevrolet head swap

IMHO the epa should have been castrated in 1972! remember air injection reactors? what a joke! basically pump fresh air into the exhaust manifold to get a better reading out the tail pipe.
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Old 12-10-2018, 12:04:28 PM
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Marv in Minn Marv in Minn is offline
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Default Re: big block chevrolet head swap

Quote:
Originally Posted by Tracy T View Post
remember air injection reactors? what a joke! basically pump fresh air into the exhaust manifold to get a better reading out the tail pipe.
i had a new 1968 Camaro with the air pump. one day the highway patrol was checking emissions right by my driveway. when i came home, they checked my car before i could drive in, checked fine. i pulled the belt off and had them check it again, no difference. but they wouldn't let me run without the belt on
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Old 12-10-2018, 12:16:13 PM
Tracy T Tracy T is offline
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Default Re: big block chevrolet head swap

mary, i didnt realize the air pump was on vehicles in 68, so back up a few more years on how i feel about the epa! detuned, decompressioned, burn more fuel, less power is some how cleaner? blah!!!!
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Old 12-13-2018, 09:31:38 PM
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Tom Cwach Tom Cwach is offline
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Default Re: big block chevrolet head swap

I have a 1994 c30 454. I was looking at mark V 366 heads. They are closed chamber. The original TBI is a problem blocking performance. The computer is not capable of working over about 4500 rpm. Vortec heads have a small chambers but no exhaust crossovers.
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Old 12-13-2018, 10:00:50 PM
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Default Re: big block chevrolet head swap

We have a mid 90s motor home on a GMC 3500 chassis. It has the Throttle Body 454 in it. Beautiful running engine and not bad on fuel, but like all later EPA engines, it's not the butt kicking horsepower beast of it predesessors. No slouch though, it will easily cruse at interstate speeds with the big coach 32 ft rv, no problems. Unless you are at the drag strip, no one ever needs any engine to reach those high RPMs, the torque curve on most big block engines are in the lower rev range where it's needed to do practical work. High rpm = high fuel consumption.
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Old 12-13-2018, 10:39:17 PM
pegasuspinto pegasuspinto is offline
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Default Re: big block chevrolet head swap

tracy, is your 454 throttle body or plenum with port injection?

The Vortec engine is supposed to be an improvement, I have a 1996 vortec 454 and it's OK but not a hot rod. 10mpg no matter what I do lol.

I have throught about what I could do to massage a bit better performance and fuel economy out of it...

Supposedly the 1995 was 230 horse, and the 1996 was 290 horse...
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