It would work well in your 555's... With a 4.5" stroke motor you really can't give the motor enough duration or lift. Best thing to do is just leave the intake valves out of the heads.

Hodup now. Let's try something like that in yours first. Should idle very nicely for you. Besides you'll never guess what I'm going with??? Might surprise you. actually kinda close to something you mentioned in a thread a few weeks ago.

On a serious note I have a question for you BB. I realize stroke eats up duration but let's say for same stroke engine how much would .100 larger bore size difference make with same duration cam in regards to peak hp rpm? My gues would be minimal but what's your take on that? Maybe 100 rpm or slightly more? Just wondering.

It's not going to eat up the cam as much with the larger bore. The larger bore help helps the head move more air. Big stroke want a big valve you really can get a big enough valve in a 24 degree head. Then when you put a bigger valve in the head to support the motor now you end up with the valve to close to the bore. So what do you do? bore notch? Not going to happen when the bores are almost touching each other... So you move the cylinder head on the bore. If you want to get everything out of the combination that's how it's done and that is the difference between an engine builder and an engine assembler.

ill dig that card up .marine kenetics specked it .. I know nothing more than it didn't go in the engine .. lol probly why ..im going to hunt it down rite now

I have a nice combo for 598. If you have any questions send me a PM and I'll share specs.

Also, with a bravo and that much cubes I would let it spin some RPM to help it live. 5400 is going to kill it quickly IMHO and I think 5800-6000K is more where it should be.

https://youtu.be/u-5P0vw1UqQ https://youtu.be/Zjxja9AYp00 https://youtu.be/n9cQRzU9jdA

Mine is 110 LSA, Solid roller - 257* .7314 lift intake, 266* .7149 lift exhaust
I run it at 6400 RPM

Thanks for all of the advise. My builder called today. Thought I should either change heads from the BB-2X of do some work on them as they are stock. I'm having them go ahead and work my existing heads, new valves, springs etc. the are boring it to 4.61". Thats all I got today.

Is that lift with 1.7's or 1.8's. I'm assuming 1.7's but thought I'd ask.

I am running Jessel shaft rockers ( stock ratio)

I am running AFR 357 CNC'd heads.
8.6 to 1 ratio JE pistons ( plan on adding a M4 Procharger eventually.
Crower crank, Lunati rods, Big M block, Edelbrock sequential port EFI intake with the Holley 2000 CFM - Hp system.
Idles smooth and has so much torque it is unreal. Accelerates like it's tail got stepped on.