Biggest Valve Size in Stock Aluminum Hemi Head

Posted By: Husker1

Biggest Valve Size in Stock Aluminum Hemi Head - 02/14/13 06:41 AM

What is the biggest valve size that I can put in a new set of Mopar aluminum hemi (gen 2) heads? I am building a 572 pump gas engine (4.500 bore) and thought if possible going larger than the stock 2.25 would help some with the air flow requirement. I don't have the cam picked out yet but will be running a solid roller.

Thanks

Posted By: astjp2

Re: Biggest Valve Size in Stock Aluminum Hemi Head - 02/14/13 09:25 AM

My stageV have 2.3I and 1.9E with the 4.5 bore

Posted By: Dragula

Re: Biggest Valve Size in Stock Aluminum Hemi Head - 02/14/13 02:40 PM

There are heads out there that run 2.4" intake valves...On the heads you have, you will have to measure them. The bore size you are running will not limit you. Are the exhaust valves rotated out of the way? If not, 2.30 is probably the limit..

Posted By: LaRoy Engines

Re: Biggest Valve Size in Stock Aluminum Hemi Head - 02/14/13 07:09 PM

Should the question be, What is the biggest valve/camshaft combination I can run? Playing with tappet lift, times the rocker arm ratio, during the overlap phase, was very interesting.

Posted By: Dragula

Re: Biggest Valve Size in Stock Aluminum Hemi Head - 02/14/13 07:49 PM

Quote:

Should the question be, What is the biggest valve/camshaft combination I can run? Playing with tappet lift, times the rocker arm ratio, during the overlap phase, was very interesting.

Cam selection is cam selection...Bigger valve is more flow at lower lift regardless of cam. He will need as much flow as he can get with that many cubes, and I would suggest the full CNC port on the heads. Saved the money up front by buying stock heads, now its time to pony up for the flow the engine will need.

My experince on playing the cam game, got me a ton of worn out parts...Valve guides, the seats, lash caps, push rod tips, all kinds of stuff wears out rather quickly with high lift cams and some street miles on them...I should know!

Big cams and overlap are great, but it all depends on your intended purpose. Seems like Bullet cams is the way to go these days, I would call them with all the flow numbers.

Posted By: quickd100

Re: Biggest Valve Size in Stock Aluminum Hemi Head - 02/15/13 02:09 AM

Quote:

Quote:

Should the question be, What is the biggest valve/camshaft combination I can run? Playing with tappet lift, times the rocker arm ratio, during the overlap phase, was very interesting.

Cam selection is cam selection...Bigger valve is more flow at lower lift regardless of cam. He will need as much flow as he can get with that many cubes, and I would suggest the full CNC port on the heads. Saved the money up front by buying stock heads, now its time to pony up for the flow the engine will need.

My experince on playing the cam game, got me a ton of worn out parts...Valve guides, the seats, lash caps, push rod tips, all kinds of stuff wears out rather quickly with high lift cams and some street miles on them...I should know!

Big cams and overlap are great, but it all depends on your intended purpose. Seems like Bullet cams is the way to go these days, I would call them with all the flow numbers.

I agree, I called Bullet cams gave them all the engine/head flow info. I also told them I wanted some gentle lobes that wouldn't beat the valve train to death. They ground me a great cam, haven't had ANY problems and the motor make fantastic power and torque.Dave