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#1 |
Registered User
Join Date: Nov 2009
Location: Gilroy,CA
Posts: 193
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do I have a Gen IV big block?
Assuming my 1973 GMC 454 is all stock, is there a good chance that I have a Gen IV 454 motor? Seems like there is a whole lot of variation. 2 bolt, 4 bolt. oval port, square port, peanut port. oval large, oval small, oval standard. rectangular head. standard head. open chamber, closed chamber heads. can all this be cleared up by the casting #'s? I'm just trying to buy an intake manifold, and I'm getting all these promts at Jegs and Summit
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#2 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,460
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Re: do I have a Gen IV big block?
Yes it's a Gen IV. Should have the large oval port open chamber heads. What is the casting number of the heads?? Get the last three and go to Mortec.com to find out what they are. Last 73 454 I had was 049, good street heads.
__________________
2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#3 | |
Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: do I have a Gen IV big block?
Quote:
I run the 049 oval ports on my Camaro with 2.19 & 1.88 valves. They build great power and torque. Without the casting numbers you don't know for sure what heads are on it. It could have peanut port truck heads on it or large oval port passenger car style heads. Doubtful anybody put rectangular port heads onto a truck.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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#4 |
Registered User
Join Date: Nov 2009
Location: Gilroy,CA
Posts: 193
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Re: do I have a Gen IV big block?
thanks. I gotta find time to pull the valve covers off and check when the baby goes back to sleep (high maintenance, like her mother). anyone else have trouble reading the block casting in the back with the motor installed. I'm considering bustin' out a work light and a mirror
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#5 |
Registered User
Join Date: Nov 2009
Location: Gilroy,CA
Posts: 193
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Re: do I have a Gen IV big block?
time out. gotta check out a 1971 Chevelle for $1200. Looks like baby and I are going on a trip
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#6 |
Account Suspended
Join Date: Jan 2009
Location: galt ca,
Posts: 749
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Re: do I have a Gen IV big block?
you just listed about 9 names for 3 basic types of heads.
oval port and retangle port are completley different. small oval are peanut port. closed chambers and retangles stopped being made well before you motor was. it can have either small or large oval. |
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#7 |
Account Suspended
Join Date: Jun 2009
Location: Tipton IN
Posts: 81
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Re: do I have a Gen IV big block?
What was the best block and best heads for the big block? What years were the good ones produced?
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#8 |
Account Suspended
Join Date: Jan 2009
Location: galt ca,
Posts: 749
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Re: do I have a Gen IV big block?
once again, do some searching.
990 rectangles are going to be great high hp heads and completely wrong if used on a 7.5:1 83 454 towing setup. |
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#9 | |
Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
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Re: do I have a Gen IV big block?
Quote:
For a dedicated tow rig or tow truck the peanut port heads are the best choice but for a street car or truck the 049 large oval ports are the preferred heads. Rectangular port heads don't build much low end torque so they should be limited to use on a race car that sees high RPM. After 65 when they changed the cam oiling method in the block they are all pretty much the same other than 2 and 4-bolt main caps. Many casting numbers can be found with both. The tall deck truck blocks can handle a little more stroke but require a special intake (or spacers) and taller distributor. Some aftermarket intakes have the mount lowered so they can use a standard SBC / BBC distributor. You can have a 2-bolt block machined for splayed main caps and make it stronger than a 4-bolt block but for the money involved you are better off just getting an aftermarket splayed cap block like the Merlin or Dart blocks. John Lingenfelter built 2-bolt, cast crank, stock rod, oval port 454's putting out 600 hp reliably with nothing but good rod bolts and main studs so any big block can be easily upgraded to handle quite a bit of power.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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#10 |
Account Suspended
Join Date: Jun 2009
Location: Tipton IN
Posts: 81
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Re: do I have a Gen IV big block?
What heads would have come on a '83-'87 K30 454?
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#11 |
Still plays with trucks
Join Date: Jul 2009
Location: Spokane, WA
Posts: 3,556
|
Re: do I have a Gen IV big block?
Could be either small (peanut) or large passenger car style oval port heads.
__________________
miSSed opportunity - ground up creation of an AWD 1994 454 SS that never was http://67-72chevytrucks.com/vboard/s...d.php?t=795577 69 C10 shortbed stepside 400 small block - built like what a super sport truck could have been 69 K20 lwb TBI 350 4L60E NP208 14-bolt Dana-44 w/disc 68 Camaro SS / RS 500hp 439 inch roller cam big block 4L80E 79 Malibu TPI 350 4L60 w/ Z28 steering & sway bars |
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#12 |
Senior Member
Join Date: May 2004
Location: Binghamton, NY
Posts: 3,460
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Re: do I have a Gen IV big block?
I had one 73 454 with 049s, and the motor in my truck now is out of a 75 and it had 781s. I don't think there is a rhyme or reason why this truck got this head, and that truck got those heads. 049 and 781 are the best "street" head.
__________________
2000 GMC CCSB 454/4L80 6” lift SAS 1999 Chevy CCSB 454/NV4500 6” lift 1999 GMC Yukon 350/4L60 4" SAS |
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#13 |
Account Suspended
Join Date: Jan 2009
Location: galt ca,
Posts: 749
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Re: do I have a Gen IV big block?
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