Big block heads on a small block?

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Big&Rich$

n00b
Jan 22, 2017
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I've read it can be done in several different articles. My question is which intake do you use when you make the head swap? My 86 Cutlass Supreme has a 71' 350 in it. So 455 big block intake or small block intake when you do a big block set of heads on a small block olds.
 

JAMCAR223

Royal Smart Person
Jun 6, 2014
1,853
5,507
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Houston, TX.
You use the small block intake and port it to correct the mismatched port alignment of the 455 heads.
 

Bar50

Royal Smart Person
Jan 1, 2009
1,180
870
113
Tulsa, OK
You really need an intake that has enough meat to port to big block Olds size...some of the Edelbrock intakes are made that way.
 

565bbchevy

Geezer
Aug 8, 2011
9,591
12,612
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Michigan
If you use the cast iron 455 heads the Edelbrock Performer RPM #7111 has enough material to port match but being that your name is "Big&Rich$" why not just spring for the Edelbrock aluminum heads and save some weight and have a better flowing head.
 
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Kennybill

Master Mechanic
Mar 17, 2010
286
401
63
Braceville, Ohio
Do you have the big block heads and if you do, what is the letter on the corner before #1 spark plug hole? What "number" are on the small block heads on the engine presently? Stay away of J big block heads. You may lose a little compression unless your your small block heads are#8's which are around 80ccs like BB heads.
 
Oct 14, 2008
8,806
7,746
113
Melville,Saskatchewan
Either Procomp or Edelbrock heads with 10 cc's removed and the #7111 intake. Your 71 350 has huge dish pistons and will need replaced. Your #7 heads are good heads to start with and unless 10 to 1 compression and a big cam is used, I would just open the bowls and add 2.07"/1.625" valves on the factory heads.
 
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