540 cam selection ???
 

i could use some good advice on cam selection..
here is what i have...

dart 9.8" deck block bored to 4.5
4340 steel crank 4.25 stroke
6.385 4340 H beam rods
je srp pistons 8.7:1 or 9:1 comp
GM 049 large ovals exh inconel 1.88" intake stain 2.25"
performer intake
850 holly carb
merc/gil hp 500 exhaust
DUI ignitions

like to run on pump gas,and idle

top rpm 5500

would like to go hyd roller cam

thx in advance
X

XCAV8,
If you haven't already bought your intake I would go with the Dart single plane for oval port heads! Trust me on this! I would also go with the Holley 800CFM carb, it will be more than enough for that motor in that RPM range.
As far as the cam, I would go with a Comp Cam hydraulic roller, custom Grind! Somewhere in the 240- [email protected] lift on the intake and [email protected] on the exhaust side! You don't need to go crazy with the lift around .600 to .625 range. Have it ground with a 112 lobe seperation angle and install it around 110 degrees intake lobe centerline. This combo will make tons of torque and allow you to turn a lot of prop for good top end! Keep in minfd that you will need to have almost dry, if not dry exhaust to avoid reversion!
You are going to love the DUI ignition.

thx tomR

i'm really looking for a cam i can run wet and not worry about reversion... well yes i already have the intakes..
i always thought the single plane was more for higher rpm.. ??? and i already have the carbs...

Crane 741 seems like it should work fine. 234/242, .610.632

ttt

i'm curious as to to cam merc used on the hp 500 bulldog? and did they ever have a roller verison?

No. That engine was way under cammed. It was also a flat tappet cam. If you really don't want a reversion issue, just pick one size smaller, the 731.

Those heads are going to run out of poop at .550 lift I wouldn't run much more lift than that. 540ci requires a lot of air to feed it. You may need more duration than you think to make any power at 5000 rpm. my 2

I have a new Crane #721 that I will make someone an excellent deal on.

Todd

Keep in mind i plan on upgrading the heads next year...also the 049's will be worked a bit to helped increase flow... what do you suggest for a cam with the the big picture in mind ???

For my 540, my engine builder went with a custom grind from Comp.
He opted for 236/[email protected] with .630/.635 lift and a 112LSA.
I am running AFR 305 heads with CNC porting. 9:1cr. Merlin single plane with Nickerson 1050. Stainless Marine Exhaust with long wet pipes that dump just inside the transom, at the tip. Hopefully dyno next week.
Russ

Re: 540 cam selection ???
 

RLW thx for the info... is that cam considered mild or wild for your application? i'm really leaning toward reliability i 'd be happy with 500 hp.... or maybe even alittle less... something that has a good idle,and built to last...

Re: 540 cam selection ???
 

You need to talk to RMBuilder who is a member of OSO. Send him an e-mail at
[email protected]
His name is Bob Madara. He has developed a business that specializes in Marine Valvetrain Components. He is quite brilliant in that aspect of engine technology.
The key to good reliability is to install quality parts and to have a qualified engine builder that knows the difference between a marine engine and automotive applications. It is worth the added expense on both fronts.
Russ Withiam

Re: 540 cam selection ???
 

XCAV8,
Depending on the head upgrade you are planning, we have a cam/spring package designed for the 540. This particular grind was designed around the CNC AFR head combination which has a very good I/E ratio in the range of 77%-81%, hence the short split duration. Because these are custom grinds, adjustments can be made depending upon the flow numbers of the head package you choose. With the premium springs it is very durable, reversion free and will exceed your target power.
Max RPM 5500-5600
Cruise RPM 3300-3500
Dur @ .050 233 intake and 235 exhaust
Lift 600 intake and 612 exhaust
Lobe separation 112
intake centerline 108
Bob

Re: 540 cam selection ???
 

thx bob , not sure which heads i will go with when that time comes, question is will that custom grind work well with the 049's i have now???

Re: 540 cam selection ???
 

Xcav8
I could not suggest that particular grind with your 049 heads. Custom grinds are designed specifically with the particular airflow package you are currently using. As Jim V correctly pointed out the 049 heads need to be crutched with additional duration due to the less efficient ports. Also the short I/E duration split is designed around a very high I/E ratio that is not available in the 049 head. There are custom grinds that will work with your current package, but they will then be less than optimum when you upgrade your heads. The advantage of going with a custom cam package over a shelf grind is that it optimizes your individual combination.
Bob

Re: 540 cam selection ???
 

I totally agree with Bob 100%. A well planned combination is the way to go.

Chris

Re: 540 cam selection ???
 

I use a Lunati 54899 RRBI 240-245
valve lift .612 intake .612 exh.
.050 duration 240 intake 245 exh.
lobe centre 110 intake 118 exh.
lobe lift 360

use the imco power flow plus with custom risers as a wet system no problem with reversion is a comfortable cam at the dock