Hi,if anyone's interested

http://cgi.ebay.com/ebaymotors/GM-Chevy-...sQ5fAccessories

Can you provide a pic of the chamber and tell how thick the deck is through a water port hole?

I have been told those castings are thin & light & crack alot.

Harry blew out the complete chamber on his new Brazillian head.


MBHD

Took some pics, hope this is what you were talking about. If not, let me know exactly what you are wanting and I can take more.

I believe the deck is 1/4 in.

Sorry, did not know it was your head you are selling.

MBHD

no biggy,deck looks to be 1/4 of an inch thick,too thin?

Well, just historically speaking, the Brazilian head isn't known to be a really good choice for these engines(even in Brazil,they use the siamese head from here in the US) for the reasons Hank mentioned above. Then add just mild porting on top of that and you have a really thin head.

the combustion chambers are 57.5 and if i did my math right the compression ratio would be 11.8.any optoins to lower the compression ratio enough to safely run five pounds of boost or is boost a bad idea?more than likely this head aint goin any where.is having a high compression ratio the main thing that causes the cracked heads?

if the comp.ratio was lower would the thinness of the head still be an issue on a daily driver,na or boosted?

Your going to have to use a huge dished piston to drop that much compression. 8-1/2:1 is usually the most you can get by with boosted(in most peoples opinion that used forced induction). What intake are you planning to use. Only the Brazilian intake matches the ports enough to use. A Clifford or Offy for the siamese heads have or course the siamese ports and would be a very large mismatch to the head.

i have looked on brazilian ebay,mercado livre,for an intake and have found plenty but even with the translater some of it is still confusing.i also wonder if it might be cheaper to weld one from aluminum.

Probably so. What engine are you going to build.

i dont really want an na motor would rather go boosted.your point about the pistons is a good one,if they could be made they would be really exspensive.on one hand i'd love to keep this head and make a go of it but on the other it might cost me more time and money than i have and the end result may be a head that wont last long.i supose if its still mine at the end of the week ill make a go of it and hope for the best.i appreciate the info any more options or ideas would be appreciated

I would consider which build would be the more economical and still provide the best/most bang for the buck. Using the Brazilian head will require custom pistons to tailor the compression to be suitable for boost, as well as the added cost and expense of a sheetmetal intake. Those two items alone will make the cost of using that head considerably more than using a siamese head which will probably be the better head to start with anyway and allow you to use lesser expensive pistons and more intake choices. I don't think the Brazilian head will really give you any advantage over the siamese head as far as HP output, just cost more money for less gain.

What was your main reason for selecting the Brazilian head over the siamese head to begin with.

i just had to have a 12 port,i had read the 12 port was better

I think it was most likely referring to the Kirby/Sissell 12 port aluminum head and not the Brazilian head. When 12 port is mentioned in reference to these engines, thats the head(Kirby/Sissell) it is meaning.

i've seen his website,nice head,pricey though.must be worth the wait though.

does sissell still make the 12 port aluminum head? i read they dont anymore but they do still have a website

Yes, he's working on a batch right now to get finish machined.

thats awesome. is it more benificial to run that head or 2 welded heads?

Run the Kirby head, much easier install, flows great.

MBHD