Cam Suggestions. Help me pick a cam.
 

Ok heres what I have so far. Looking for Cam spec and why. Pros and cons.

468 CI
Forged Crank
JE 9.5 : 1 Forged Pistons
Callies Rods ARP Bolts
Merlin Oval Port Heads
2.19 and 1.88 Pocket Ported
Crane Roller Rockers
Edelbrock Air Gap Intake
Holly carb 800 830 850?????
Stainless Marine Exhaust.
Thunderbolt for now.

I'm going Hydraulic Roller for sure. I will be spending most of my time at 3500 to 4k crusing. Max RPM will be around 5300 or so depending.

The boat is a 27ft 84 monza single pretty heavy I'd guess 7k loaded. TRS Drive.

Hoping for around 500 hp at 5300.


Thanks Rob

Yes thats great information.

I'm running a stainless marine wet. It dumps pretty far back. It's their racing series. I'm not sure how big a cam I can run without reversion.

Any ideas if that cam would work with a wet system? Its a 240 246 112 lsa on a 110 centerline seems like that would still work with a good wet system???

Also why would you shy away from roller? I thought motors will make more power with roller due to the faster ramps. Easy break in and less friction, seems to be better overall..

Thanks Rob

240/246 is too big for a max rpm of 5300 on a 468.
Why: The torque and hp curve is far to high with those cubes.
I would suggest something down in the 226/234 range on a 112 centerline with the oval port heads. The lift will be somewhere around .600 With that size cam your peak torque should be around 32-3500 and the hp should peak around 5500.

Use the 800 holley mechanical double pumper.
Why: At 100% VE you can only use 718 cfm @ 5300. I wouldn't be afraid to spin it up to 5500 and even then you need 745cfm.

With that combination you'll have great torque and accelaration.

But hey, that's just my opinion.

DAVE

The set up Dave F has described is the Crane "731". I have the same set up and it works really well. I only have a 750 Holley, but the throtle response is impressive. I am pulling 5300 if my tach is acurate. Would I gain anything going to an 800 given that the formula seems to indicate even at 100% VE that 750 is enough?

Thanks Dave thats very helpful..

A couple of questions for you.

How much if any HP will I gain by going with a roller cam, or would I be just as good with a standard hydraulic.

Would going with a 110 instead of a 112 help I could live with the rough idle. My other boat has a 110 in it and its not that bad still idles at 800 and 700 in gear.

I'm trying to get 500hp out of this motor what are my best odds for getting there.

Thanks Rob

Pick the cam behind door #1. Wait, door #3. No, you better go with door #2,,,,,,:D

Anyone else? Someone has to have some more input on this.

How about Hyd Roller vs. just Hyd. Is there enough gain to make it worth the $400.00 extra.

Thanks Rob

The 731 would be a acceptable choice. Maybe a tad big. A little less cam would give you some more low end torque. I'm more concerned about your exhaust choice. You'd be better off with a long primary header. Cmi sport tubes, Stellings, Lightning, or Keith Eickert heads would work good. Your manifolds would be a good choice if you are going to add a blower later on. As a matter of fact, so would that cam.

I stayed away from a roller cam because of my Mark 4 block. I have heard of enough problems using the "adapted" roller lifters on these blocks that I chickened out. Im sure plenty of people have had success with them though. You can get 30 or so more hp out of them but Im not so sure about reliability. My machine shop guy said Mark 4 blocks should have the lifter bores bored true to the cam and sleeved. He said many are not perfectly perpendicular to the cam and thats where the problems come in. The later Gen blocks that are built for roller cams are fine.

Sledge what kind of speeds are you seeing on what boat how heavy? prop and at what rpm? Have you ever had it dynoed? Looks to me the benifit of roller seems to be higher lifts at the same duration. I wonder how much HP that extra lift is good for. So many people say lift doesnt matter.

If I go roller I think this will be the 731 cam. Just wondering if I would gain much hp in roller vs the 134241 its just hyd almost the same duration as the 731 but way less lift.


134241
Int./Exh
226/236
534/553
LSA 112

139731
Int/Exh
226/234
587/610
LSA 112

Anybody know if the more lift would be good for more HP? If so how much? 5? 15? 30? Would it be worth the extra $400?