Bad to the bone

here is my mistres with scoops and pad best of both
worlds.

Monty

I test fitted a couple of different intake manifolds to the cylinder heads, but the Victor Jr provided the best port match. It's the manifold AFR recommends for these heads and the match is perfect. The Performer RPM and Airgap RPM were close, but they would have required a little welding to build up some material for a good seal on the tops of the ports. At that point I figured it would just be easier to raise the hatches somehow.

I've currently got Stainless Marine exhaust. Fred (Too Old) put them on the boat and they are in like-new condition so I'm going to stick with that for now. I will probably have to switch from the short to long risers though, because SM doesn't recommend the short risers with cams that have over 230* duration and I don't want to risk water reversion. The Crane 741's are 234/242.

Monty

Bad to the Bone,

Nice setup, but my wife ain't gonna go for that....I like laying back there too sometimes.

outriggers

Monty, I haven't chosen heads yet. My boats not that heavy so my bravo should live with a little work, so I was kind of thinking of a 731 for a cam. E-tops for exhaust but my silent choice might have to go.( ie reversion again) Thanks, Doug

aTX427

Monty,
If I was to change out my engine from a HP500 to a 540 w/ aluminum AFR heads like yours, would the physical height of the exhaust ports change? I do not have any additional clearance where my tailpipes exit the transom. If the height does not change on the 540, would it change with a tall deck?

Thanks John

Monty

John,

I have height limitation as well, the two middle exhaust risers are within 1/4" of the hatch support that runs down the middle and divides the engine hatch opening. That limited my choice of cylinder heads because most aftermarket heads have the exhuast ports raised .600" or so for improved flow.

If you go with a tall deck block, that will definitely raise the intake and exhaust, and the exhaust will also be spread out wider slightly as well.

aTX427

So, do the AFR heads have the exhuast ports raised .600? If so, what aluminum heads would you recommend that do not raise the ports, or I just stay eith my stock HP heads?

Monty

No, they are in the stock location.

jspeeddemon

Keep in mind that the .600 inch raise of the ports is at an angle so .600 doesn't equal raise .600 on the angle. Someone good in trigonometry can figure the distance. Probably 60% or .360, just a guess.