BBC heads casting number

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76sierracamper

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Hey I am looking at a set of heads and wondering if you guys can give me any feedback on them. The casting number is 8818840 and it also says gm3t hi perf on them and E1608. I've got a 454 I'm building and I'm still learning so any info would be great! Thanks

Ps the asking price is 1400 cad
 

nvrenuf

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I can’t find any info on the casting number but almost every GM head says “hi perf pass” so that doesn’t mean anything special. Since I can’t find any info I’d bet they are later model peanut port heads which only flow to about 4K rpm.

1400 seems like a lot unless they are freshly rebuilt with receipts.
 

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Are you sure it is 8818840 do you have any pics of them
 

76sierracamper

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I dont have any pics of them. The guy said they are rectangle port heads which makes me think they are 3919840 heads and I can see how they could mistake reading the 3 and 9's for 8's but I'm not sure I gotta go look at them in person. If they are 840 heads are they still worth that money. They have been ported and polished as well
 

1973c10

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I dont have any pics of them. The guy said they are rectangle port heads which makes me think they are 3919840 heads and I can see how they could mistake reading the 3 and 9's for 8's but I'm not sure I gotta go look at them in person. If they are 840 heads are they still worth that money. They have been ported and polished as well

If they are 3919840 67-69 rectangle port Closed chamber 396, 427 107cc
I have seen them go for from $200 to $800 plus
 

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I dont have any pics of them. The guy said they are rectangle port heads which makes me think they are 3919840 heads and I can see how they could mistake reading the 3 and 9's for 8's but I'm not sure I gotta go look at them in person. If they are 840 heads are they still worth that money. They have been ported and polished as well

I would be real careful... first of all, square ports are not as friendly on the street generally speaking. They flow best at higher RPM. The fact they are ported... umm there's room for concern here.
If you're porting Square ports, what are you doing? What are you trying to achieve? You're already dealing with a high rpm design, so what are trying to increase flow and port velocity? This is what is generally the goal. I can tell you this, larger valves(exhaust for sure), open the throat below the valve seats to vertical walls, hog off and/or narrow the valve guide bosses, and match the ports (which are not as bad off as generally speaking sbc heads, any casting).
So what I'm getting at, is usually porting will have the goal of producing more power as rpm increase. So the square port is already a better head for high rpm power (compared to oval port, of course).
Sounds like a lot of $ for heads that may not be the best for your application. Or maybe you actually want to shoot for 6-700 hp beginning around say,
5500 rpm.
I will recommend 781 heads, shaved. Thick solid bronze valve guides, not the cast guides with a bronze liner. If you want to port them, even without hogging out seat for larger valves (exhaust 1st priority), you can still open the throat and grind down as vertically as you can and narrow off the valve guide bosses cast into the ports.
I know these heads even with larger exhaust valves and the recommended porting will produce more torque providing compression and the right cam.
I'm not so sure this can be achieved with square port heads. Flow velocity at lower rpm is just superior with oval port 781s, lending to better street torque.
Hope this helps..
 

AzGeo

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Get some "large oval port heads" (049/781) and when rebuilding them install larger (2.20/1.88) valves in them . This will keep the low end velocity up and make the cam "breath better" at mid, and top RPMs . This combo will work better than running big square ports, unless you are going with an 8-71 + blower . This is exactly what I did with the truck in my avatar, plus an inter-cooled turbo . It's still not completely done, because I've been finishing up a "bracket race flat bottom boat" .
 

76sierracamper

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Well I took your guys advice and passed on those heads. Since then I've done a different take and am going to order up a pair of AFR 265 fully cnc'd heads so hopefully they work nice
 

Rusty Nail

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I would be real careful... first of all, square ports are not as friendly on the street generally speaking. They flow best at higher RPM. The fact they are ported... umm there's room for concern here.
If you're porting Square ports, what are you doing? What are you trying to achieve? You're already dealing with a high rpm design, so what are trying to increase flow and port velocity? This is what is generally the goal. I can tell you this, larger valves(exhaust for sure), open the throat below the valve seats to vertical walls, hog off and/or narrow the valve guide bosses, and match the ports (which are not as bad off as generally speaking sbc heads, any casting).
So what I'm getting at, is usually porting will have the goal of producing more power as rpm increase. So the square port is already a better head for high rpm power (compared to oval port, of course).
Sounds like a lot of $ for heads that may not be the best for your application. Or maybe you actually want to shoot for 6-700 hp beginning around say,
5500 rpm.
I will recommend 781 heads, shaved. Thick solid bronze valve guides, not the cast guides with a bronze liner. If you want to port them, even without hogging out seat for larger valves (exhaust 1st priority), you can still open the throat and grind down as vertically as you can and narrow off the valve guide bosses cast into the ports.
I know these heads even with larger exhaust valves and the recommended porting will produce more torque providing compression and the right cam.
I'm not so sure this can be achieved with square port heads. Flow velocity at lower rpm is just superior with oval port 781s, lending to better street torque.
Hope this helps..

Great post.
 

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Well I took your guys advice and passed on those heads. Since then I've done a different take and am going to order up a pair of AFR 265 fully cnc'd heads so hopefully they work nice

I'm not familiar with AFR heads, but I generally advise to get any aftermarket head inspected before they are installed. Don't just take them out of the box and install them without at least checking the valves are actually sealing and also want to check the valve guides for proper clearances. Oh and also verify the gasket surface is actually flat.
Always check your shorts for bugs before you put them on!
 

bucket

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Never had a set myself, but AFR is supposed to be superb quality.
 

1973c10

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Well I took your guys advice and passed on those heads. Since then I've done a different take and am going to order up a pair of AFR 265 fully cnc'd heads so hopefully they work nice

If I remember right super chevy did a big block build with thous heads
and what I remember right it was a torque monster
I will see if I can find the article and post it
I look at the 265 and the 290 when I was building my big block
and would bought them but got a good deal on a set of Procomp heads
 

shiftpro

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Never had a set myself, but AFR is supposed to be superb quality.
I'm not saying AFR is low quality.
It's just always good to check before your favorite torque wrench goes CLICK!

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This vid is just an example. I'm not a fanboi of this guy, actually I think he's a bit of a jerk. All the same... don't trust anyone with your engine, or at least double and triple check things.
 

shiftpro

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Another example...
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shiftpro

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No shortage of videos on this subject...
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