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~~EVIL LAUGH~~~
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I forget exactly who on this site has that 'hybrid' setup, but I know it can be done. So, yes I concur :-D Ah, man tony, sounds like you're trying to make your monster into an even bigger monster. :-D
 

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i had thread on this....but i cant remember the outcome cause i decided just to use a b21 head on a b21 motor and soforth
 

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Aren;t the heads the same? So it would be whatever block you have for the head gasket, right?

Are the heads the same from b21-b20a5? I am pretty sure...

Pete
 

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The combustion chamber on the b21a1 head is larger than the b20a chamber, how the b21a1 get's it's compression from the higher hight pistons and the larger bore. I dont know for a fact if the chamber on the b21a1 is wider in diameter than the b20a and that probably helps unshroud the valves, probably a good thing with such a wild engine like yours, Tony. You should use the b21a1 head gasket, the b20 gasket I believe will get in the way of the combustion chamber and cause problems.
 

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I would take the B20 head gasket and place it on the B21 head, with the dowels in it, and see if the steel ring, that seals the gasket from the combustion chamber, sits on the flat portion of the head and does not overhang the edge of the combustion chamber. A head gasket that is bigger than the bore will cause a "dead area" encouraging incomplete combustion........not to mention what it does to the quench effect (good) created by the top outer edge of the piston coming close to the head surface......3gdude
 

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no mo mod
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he's already got one....the head is ported and polished....thats why he wants it :p

3gdude...I am using a b21 head and b21 head gasket...I dont see anything wrong with using the larger bore gasket to match the larger combustion chamber...if you think about it...it doesnt seem wise to use a b20 gasket that has the 81mm bore and have a head with a combustion chamber that is 83mm
 

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I thought you were supposed to use the gasket for which block you had. If you are using a B21 block with a B20 head you use the B21 gasket so the bore is big enough. If you use a B21 head on a B2o block you use the B20 gasket so you get a good seal. Maybe I am wrong but i thougt thats what came of it in other threads.
 

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*shrug*
Im still going with my 'match the larger bore' theory....
 

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tsiah said:
*shrug*
Im still going with my 'match the larger bore' theory....
Well that means you use the B21 period. You don't have to worry about the valves hitting the gasket they don't go that far down. If they did they would hit the block regardless which gasket you use. If you used a B20 head and gasket on the B21 block the pistons would destroy the gasket in no time due it's bore being bigger and it hanging over into the combustion chamber.
 

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you do use the b2 1gasket anytime you use the bore from a b21. the head does have a larger diameter at the deck surface. so does the block so it would make sense to use a bigger bore gasket to prevent the combustion process from burning the gasket or overlaying the combustion chamber in anyway shape or form. hey guys i am running a b20a with a b21 head and i'm running the b21 gasket without any problems.
 

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Slipslap said:
tsiah said:
*shrug*
Im still going with my 'match the larger bore' theory....
Well that means you use the B21 period. You don't have to worry about the valves hitting the gasket they don't go that far down. If they did they would hit the block regardless which gasket you use. If you used a B20 head and gasket on the B21 block the pistons would destroy the gasket in no time due it's bore being bigger and it hanging over into the combustion chamber.
makes sense. wtf do i know im bored and should be getting to work but reading threads like this makes me late
 
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