Building my first Big Block
Thread Starter
Drifting
Joined: Nov 2005
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From: Downriver Mi.
Building my first Big Block
need some help on this i have a 10114182 gen v block just found out gen iv heads wont work?anyone know if i can use 990 or 188 rectangle heads on this motor?thanks for any help or advise,i have a gen 4 motor dont know if its a 4 bolt yet,would rather use newer 1 piece seal block if possible?
Instructor
Joined: Sep 2009
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From: Hiawatha Iowa
Have you seen this article yet: http://www.chevyhiperformance.com/te...ons/index.html
At a high level it talks about the differences of Mark IV Gen V and Gen VI BBC
At a high level it talks about the differences of Mark IV Gen V and Gen VI BBC
Race Director
Joined: Jan 2000
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From: Corsicana, Tx
2020 C2 of the Year - Modified Winner
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Most aftermarket heads work fine on GenV blocks. There are iron GM rectangular ports that fit them with the correct coolant passages that they used on the 454/425 and 502/450 versions.
*SOME* Mark IV heads will work on *SOME* Gen V blocks but it's a case by case deal. You have to look real close at those upper coolant passages. There were some gaskets made by Fel Pro that helped a lot that you can do a search on.
See if you can swing some aftermarket heads because that's what a 502 needs to wake up....or a REALLY nice set of professionally ported GM iron oval ports if you want to keep RPM under 6500.
JIM
*SOME* Mark IV heads will work on *SOME* Gen V blocks but it's a case by case deal. You have to look real close at those upper coolant passages. There were some gaskets made by Fel Pro that helped a lot that you can do a search on.
See if you can swing some aftermarket heads because that's what a 502 needs to wake up....or a REALLY nice set of professionally ported GM iron oval ports if you want to keep RPM under 6500.
JIM
Le Mans Master
Joined: Dec 2006
Posts: 5,557
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From: Oquirrh Mountains
St. Jude Donor '09
That's a 454 gen 5 block. If you have Mk4 heads and another Mk4 block why not use them together? There's nothing special about the gen 5 block. The gen 5 502's are thin cylinder wall castings (can't remember on the 454's). A two piece seal rear main works just fine as long as it's installed correctly.
Thread Starter
Drifting
Joined: Nov 2005
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From: Downriver Mi.
going with a 445 block,gen 4,just picked up a set of 990 heads,forged crank,rods and pistons,from a 454 mag mercuriser,will go with crank and rods looking for different pistons, 12 to 1 forged,comp 294 solid flat tappet,1050carb, going to run e 85,guess my HP
Last edited by MR NICE; Apr 20, 2012 at 11:09 PM.
