Speedmaster head milling
#1
Speedmaster head milling
I picked up some speed master heads on black Friday I plan to put on my 455, replacing C heads, I would like to get them milled down to have 69cc chambers, how much should I tell my machinist to take off? They come 77cc as cast.
also are their any other modifications to these heads you can recommend?
it's a street driven car, shooting for 10:1, comp 292h cam: 292/292 244/244 518/518 on 110.
also are their any other modifications to these heads you can recommend?
it's a street driven car, shooting for 10:1, comp 292h cam: 292/292 244/244 518/518 on 110.
#3
I'm sure Mark will chime in. I believe they are actually 81-83cc as cast. I believe 1cc is a .006" cut on an Olds head. That means a .072 to .084", so a lot. They also need port work to even flow as much as Gen 1 Edelbrock heads.
Last edited by olds 307 and 403; December 17th, 2021 at 10:55 AM.
#5
As you can all see, out of the box they’re not any better than a good set of C, E or almost any other big block iron head. Chambers are normally 81-83cc as cast, they were never 77 as advertised. To get them to 69 you’ll need to take about .070-.075 off. And yes as mentioned, you’ll need to cut the intake to match. I wouldn’t cut the intake side of the head that much though as it’ll make the valve cover rail kinda thin.
I offer various stages of porting as well if you’re interested.
Thanks.
I offer various stages of porting as well if you’re interested.
Thanks.
Last edited by cutlassefi; December 17th, 2021 at 10:49 AM.
#6
As you can all see, out of the box they’re not any better than a good set of C, E or almost any other big block iron head. Chambers are normally 81-83cc as cast, they were never 77 as advertised. To get them to 69 you’ll need to take about .070-.075 off. And yes as mentioned, you’ll need to cut the intake to match. I wouldn’t cut the intake side of the head that much though as it’ll make the valve cover rail kinda thin.
I offer various stages of porting as well if you’re interested.
Thanks.
I offer various stages of porting as well if you’re interested.
Thanks.
#7
Old Joe Mondello formula. That worked out real close for Intake milling on my first build. Was a SBO with 7a heads and 7111 manifold.
Amount cut from Cylinder Head X 1.3 = Intake Manifold Cut.
His example .050 milled from Cylinder Head X 1.3 = .065 to mill from Intake Manifold
You would need to be sure the heads have not been mill before. For this to work.
Amount cut from Cylinder Head X 1.3 = Intake Manifold Cut.
His example .050 milled from Cylinder Head X 1.3 = .065 to mill from Intake Manifold
You would need to be sure the heads have not been mill before. For this to work.
Last edited by HighwayStar 442; December 17th, 2021 at 11:05 AM.
Thread
Thread Starter
Forum
Replies
Last Post
Hotrod-Youngster
Racing and High Performance
9
April 10th, 2014 06:00 PM