Thread: BBC head question...Pat or Erik?

Tweet

I am building a 1970 LS6 454 which is a brand new short block (purchased 30 years ago & never used). I had the BBC originally professionally built but never fired the motor nor put it in anything. My problem is I DO NOT KNOW what heads were installed, but they are supposedly open chambered, street ported, with 1.7 Crane gold rollers & a Jomar stud girdle. My question is what heads would be BEST to run with the 11 1/2 to 1 forged pistons in the LS6? I would like to run 10 to 1 compression or as high as possible mixing premium with octane booster. Would you suggest aluminum heads or iron heads? I've seen many on ebay, but don't have a clue as to what I should be seeking. My engine is being professionally torn down now so in a week or so I will know for sure what heads I currently have. If they are not the RIGHT ONES, I want to make sure I purchase what will work best. Weight is not an issue because the BBC is going in a 30 A-bone roadster. Thanks for your input!

What size of combustion chamber should I be looking for and also what runner size too? The hyd roller cam is 231/239 @ .050 with 626 lift across the board. The transmission is a built turbo 400 with a 2600 - 2800 stall. No serious drag racing at tracks...just power & torque with tire spin...Hossier Pro Street radials.

with the alum heads you can run one point more cr with them .i think i talk to you about this before. you may cut the dome down some on the pistons if need or just buy a set of pistons for cr you want with the heads you have hard to say. if you look in side of the heads there will be numbers that will tell you what they may have been? why do i say this older engine hard to say if they have had been cut ALOT on heads this would be up to you them 800.alum heads new on e-bay i do not know any thing about them so if you want to throw 2300+ on a good set of alum heads then go for it but the heads you have may be good it will not take any thing to move your car and the alum heads will help on the front end weight but that is up to you

Originally Posted by stylingZ

What size of combustion chamber should I be looking for and also what runner size too? The hyd roller cam is 231/239 @ .050 with 626 lift across the board. The transmission is a built turbo 400 with a 2600 - 2800 stall. No serious drag racing at tracks...just power & torque with tire spin...Hossier Pro Street radials.

big O ports or small rect ports

Originally Posted by stylingZ

What size of combustion chamber should I be looking for and also what runner size too? The hyd roller cam is 231/239 @ .050 with 626 lift across the board. The transmission is a built turbo 400 with a 2600 - 2800 stall. No serious drag racing at tracks...just power & torque with tire spin...Hossier Pro Street radials.

With that size cam I would guess the engine would be done making power by 6,200 rpm's.
If you wanted to get by on the cheap and had a set of the 781's you could do some bowl work, gasket match and install 2.19/1.88 valves and call it good.
My first choice would be the Brodix 270 cc oval's or a set of the Edelbrock's 290 cc oval ports.
The Edelbrock heads also have a 110 cc combustion chamber size which might raise your comp. ratio to much.

if it is a real ls6 it should have rect ports .that is why i said rect ports so if you have them use them and i would think a O port would work good but the TQ with your car will move it out or spin allover so the rect ports may kill some of that but i would not bet on that

When I purchased this new from the Chevy dealership I purchased the 1970 LS6 454 short block (without the rectangular port heads). I was originally planning on using it for 100 yd. sand drags. So I went with oval port heads which were street ported and supposedly the valves were changed to 2.19 intake and 1.88 exhaust.

Erik are those Brodix 270 cc ovals aluminum or iron? I am leaning toward oval port heads because my new air gap manifold is for oval ports and I am not using the brand new open plenum Torker II. Once the heads are removed I will know for sure exactly what I have and probably will have to go with hardened seats.

Originally Posted by stylingZ

When I purchased this new from the Chevy dealership I purchased the 1970 LS6 454 short block (without the rectangular port heads). I was originally planning on using it for 100 yd. sand drags. So I went with oval port heads which were street ported and supposedly the valves were changed to 2.19 intake and 1.88 exhaust.

Erik are those Brodix 270 cc ovals aluminum or iron? I am leaning toward oval port heads because my new air gap manifold is for oval ports and I am not using the brand new open plenum Torker II. Once the heads are removed I will know for sure exactly what I have and probably will have to go with hardened seats.

Yes,the Brodix heads are aluminum.

When you have the heads off, you can see exactly what pistons you have...this will dictate your head choice, and chamber size. The original LS6 used a closed chamber head, it was about 106cc to yield that c/r... to drop it down to 10/1, the calculator I used said 118cc should do it, which would be those 781's. You'll probably be fine. This is assuming the LS6 pistons are in there. You'll be OK at 10/1 with iron heads, just use good gas. Dont waste your money on octane boosters, you would need gallons of it to raise the octane. You wont need it anyway if you dont get too high in c/r. And you wont need the hardened seats unless you're driving this thing 20K plus miles a year...what is it used for? John

hey 1JONNYO he told me he is going hunting for them 67 chevelles with it and drive it to church THAT IS IT

Hey Pat, he can hunt 67 chevelles all he wants.....mine is a 71!! The 67 is a Camaro. I'll forgive you this time, Im sure you just mis-placed your glasses John

Originally Posted by 1JohnnyO

Hey Pat, he can hunt 67 chevelles all he wants.....mine is a 71!! The 67 is a Camaro. I'll forgive you this time, Im sure you just mis-placed your glasses John

well i was thinking it was older than that i guess i will have to look harder at the screen

Thanks for hooking me back up with UDHarold for my roller cam. It should be installed sometime this week or next. I am anxious to see how this runs in my BBC in my light A-bone. Also the egnima of which heads were originally installed on the brand NEW LS6 short block will be solved. Hopefully my current unknown heads will be the RIGHT ones. Don't worry I am not going to be out hunting Chevelles or Camaros...I am just using the BBC in the A-bone to help dry it off quickly after I wash it