Advice needed from 612 hemi experts

400sforever · Apr 4, 2020

I'm wanting to build this 612 hemi that I have in pieces but I've heard that these particular Indy hemi heads are the full on race version capable of 1000 plus horsepower. I have also heard they are a son of a gun to put into a b body because there is only 1 set of tti headers that will fit them. Anyone used these heads on a motor and have fitment/exhaust issues? I don't want to cut a car up to make these heads work if that's what it would come down too. Thanks for any input

dvw · Apr 5, 2020

If you want to build a 612" the headers are the least of your worries. You're taking a good block (if you can find one) to close to its Maximum bore limit right off the bat. Along with a 4.75" crank. Why? And then run store bought headers? Is this a street car or racecar? Your looking at a $30K engine. Why worry about a $1500 custom set of headers?
Doug

400sforever · Apr 5, 2020

I know what the headers cost. I have the entire engine. .you can't build a 426 to a 612 that would last.this motor has the heavy duty Indy maxx block, crank, cam, everything. .i wanted a street/ strip possibility but I have heard these radical heads may be tricky in s stock car. .also I wanted to be sneaky and run factory valve covers. I have also heard they won't have clearance so I would have to get a fabbed up set that looks anything but stock. This is just hearsay. .im wanting advice from someone who knows or has done it

dvw · Apr 5, 2020

When tall installed height on the springs is used clearance gets close on the exhaust side. We used to "dimple" the stock covers for clearance.
Doug

PRHeads · Apr 5, 2020

Looking at the head specs, two things that stand out with regards to fitting in a stock engine compartment.....
-ex ports are raised .750”
-valve cover rail is raised .500”

Advice needed from 612 hemi experts

400sforever

Well-Known Member

dvw

FBBO Gold Member

400sforever

Well-Known Member

dvw

FBBO Gold Member

PRHeads

Well-Known Member

Similar threads