6x heads for 455

Hi poncho fans, I bought a pair of 6x heads 15 years ago when I knew less than now about pontiac head codes, which is still limited. am ready to build a 455 using these heads. codes are  e 11 6  gm 2 and e 20 6 gm 4 . My question is , can they be used together, or are they different cc sizes? Thanks for any info. Tom  

I ran a set from a 77 400 on my 455 for  bunch of years. Great for street with pump gas. Also good for low 11's if the rest of the car is set up right.  

You need to know the secondary stamping on both heads it is located the exhaust side there are 2 rectangular shaped bars one side threaded for a bolt the other has the secondary stamp on it it will be either a 4,8, or 11.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Thanks for the reply !  I did research in this forum about the numbers stamped into the vertical pads and they are both "8", i think i got lucky!! I will have them checked out for soundness, if good, i will follow H.O book on porting. The car its going into is a 67 firebird : 3000 lbs., beefed th350 w/shift kit, 3310 holly, RA111 intake, lunati 00072lk cam kit(Pontiacman8 recommended for my 354ci)bore measures 4.191 , ring to wall is >0075 in. , 8.2 w/ 3:55 posi. I get shaky in anticipation of actually driving this piece of honored history!!!! Been waiting for 19years!!!!! Done with kids,houses, businesses, careers, etc.  MY  TURN !!!!!!!!!!!!!!!LOL  THANKS AGAIN,THIS FORUM IS A GODSEND!!! YOU GUYS ARE THE BEST!!!!!!! This will take awhile,im not as fast as i used to be, but i will post pictures and keep you updated!  TOM67BIRD  

Yep the 6X-8 heads have 101CC chamber and should work well on the 455.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Thanks buddy! Cool!!! What about the cam ?  

That cam should work fine on the 455.  
professional hi-performance engine builder

Horsepower sells engines and torque wins races

Tom, my 68 made it through a marriage, buying a house, dopting my wifes son, a daughter nd a divorce. Then it made it into  second marrige and still runs mid 10's. Takes a while but doesnt' cost to let it sit.  

This really is a great forum, we are all in the same boat with our love of these cars. Nobody tries to make you feel dumb or try to sell you viagra.

Brazil