Cam selection/recomendations

[bottom feeder]

Putting together a new motor for my jet boat and looking for cam recomendations.
Motor details
489 CID BBC
Bore = 4.281"
Stroke = 4.25"
Rod length = 6.385"
Pistions JE/SRP 11.8 on 124 CC chambers.
Heads Casting #343049 intake valve = 2.088" Exaust valve = 1.687"
Dooly 14 quart pan with windage tray.
Melling standard pressure high volume oil pump.
Low tension oil rings.
Moroso vacume pump.
Victor intake with single 1050 dominator.
MSD crank trigger with Digital 6 box.
Crane roller rockers
Stud girdles
I do not have flow numbers for the heads.
This is the cam I have been running.
Crane PN 134781 powermax mechanical
Intake .567 lift
Exhaust .590 lift
Advertised duration
Intake 314
Exhaust 324
I am not opposed to going to a mechanical roller.
Here is a picture just cause (checking block to rod clearance)
http://www2.***boat.com/image_center/data/500/1501New_motor.JPG
Bottom Feeder

[blowngas]

Advertised duration
I used this cam in a flat, and turned it 7200 rpm which worked pretty good, although most jet boat guys turn theirs around 6000 or less unless they are running a C cut impellar----with the intake you have it looks like you plan on spinning the motor on up-----hard to say what the best cam would be without knowing what your intentions are with the boat

[cstraub]

Without flow numbers I can't tell you anything about camshaft but if you want me to critic the build I will. If you want me to post on the thread or on PM either I will do. If you want me to shut up that I can do also.

[bottom feeder]

cstraub69,
It would be great to have you input. Here or PM is fine with me. It may help others if posted here?
Here is what I found for stock unported from Stan Weiss Web site
Flowed@ 28"H2O
Port volume Int 253 Ext 116
Valve size Int 2.06 Ext 1.72
Combustion chamber size 122 CC
.1 lift Int 59 Ext 52
.2 lift Int 124 Ext 98
.3 lift Int 188 Ext 128
.4 lift Int 232 Ext 152
.5 lift Int 250 Ext 177
.6 Lift Int 264 Ext 187
.7 lift Int 264 Ext 192
.8 lift Int 265 Ext 192
blowngas
You are correct. The Operation range is a bit high for a jet boat.
The boat is a 13 foot alloy sprint boat. AMT pump. Most of its use is just lake racing. river running
Thank you for the input

[cstraub]

First we have a bottle neck. You've got intake and carb to run this engine 7500 rpm but heads and intake valve area for 5500. Once you start to get in the rpms with that 489CID, the port signal on the intake track will be so strong that atomization will never happen. You need heads to do what you want to do. I would hold off on the build and see if someone is upgrading over the winter and get a set of 188 take offs. If not the cam in this thing to run say 6500 will be huge to compensate for the bottle neck.
Second, I will pat Steelcomp on the back, note in his build on his engine the piston domes. I would say he has at least 2 hours massaging the dome profiles and getting rid of sharp edges. In a BBC with OEM style heads we have to use a dome to get compression. This interupts flame travel greatly. Ideally in ignition of the chamber we the fuel and air molecules to "meet and mix" so that we get optimum burn. Piston domes that have sharp edges interrupt this "mixing" and make for a less effective burn which results in less power, hot spots that will cause detonation, and more money out of your wallet. So don't be afraid to mask off those pistons with some 200 mph duck tape and go after the top of the piston with some cartridge rolls.
Chris

[bottom feeder]

Thank you for the input thus far.
So what heads and cam. I am not opposed to ordering a set of heads. I figured the heads I have would be less than ideal. Maby Steelcomp would like to prep another set of Canfeilds :D I was going to wait on blending the pistions until I had checked valve clearance. It took me some time just to clearance the block for the .06 rod clearance, deburr and chamfer. It would be great if it only me took two hours to blend the piston heads.
Best regards
Brian

[cstraub]

Brian,
Good to hear this is just a mock up. I know Mahle pistons have a big price tag up front, but when you figure that they are coated, the ring lan tolerance they hold to resist flutter, and that the dome is "profiled" in the long run they are a good deal.
Chris

[396_WAYS_TO_SPIT]

Has the block been decked???

[bottom feeder]

No it has not been decked. I will just do some surface prep. The block was nice and flat.

[steelcomp]

BTW..that's some NICE work on the lifter valley. You're a better man than I am! LOL! I did that once.....a LONG time ago!! :D

[bottom feeder]

BTW..that's some NICE work on the lifter valley. You're a better man than I am! LOL! I did that once.....a LONG time ago!! :D
Yea right Mr 800+. I just love grinding cast and being a human bio filter. Do not see many people polish the lifter valley and timing chain area anymore. Guess it is less time consuming to just paint it. I did it beacuse this block had some scale in the front and back corners.

[TIMINATOR]

Deck the block,bore notch it,unshroud the chambers and put 2.19/1.88 valves in it. It all is worth about 50-70 HP depending on cam. Also port the oiling system.We do all of that on all perf Big Block Chevys we build. I'm done ranting now, but these things are considered basics on a performance deal. I believe in them. Your opinion may vary. TIMINATOR