vegas daytona

I could use some suggestions. I am about to take the next steo in building up my 540. The bottom end is complete and I have one season on it. Everything is fine but it is time to upgrade the heads and carb. Currently I have standard cast iron rect. port heads from my old 454, a dart midrise sigle plane intake and a Holley 800cfm carb. Cam is ISKY model RR-275/284. Hyd Roller. Adv. 275/[email protected] 228/238. .553"/.578", 108ICL, 114LSA. Currently have 9:1 compression with flat top forged pistons.

Max power is 575 at 5400rpm with max torque of 650 below 3700rpm. Torque is falling off after 3700rpm and is down to 560 at 5400rpm.

The motor is in the boat and I don't want to pull it so please no cam suggestions for now.

What heads would you recommend? What carb would you recommend? Would you suggest going to a higher ratio rocker to get a little extra lift with the same cam?

The boat is a 24' eliminator daytona. I want to get good power while maintaining a good idle and low end torque.

Thanks for your suggestions

Vinny P

I built a 540 last winter. Below is my combination and dyno results.

Dart Big "M" Block
Callies dragon slayer crank
Lunati Pro Mod rods 6.385"
JE Pistons 9.23 final compression
A.F.R. 315 cnc heads, Ferrea 2.25 intakes, 1.88 inconel exhaust
Dart single plane oval port intake, gasket matched to heads
Isky hydraulic roller
intake .578 lift--- 238* @ .050
exhaust .608 lift---248* @ .050
114* lobe seperation
Nickerson prepped 1050 dominator
Wilson tapered 1" spacer





RPM Horsepower Torque
3300 381 607
3400 394 609
3500 407 610
3600 416 608
3700 427 606
3800 438 606
3900 450 606
4000 464 610
4100 479 613
4200 503 629
4300 518 633
4400 539 643
4500 558 651
4600 575 657
4700 590 660
4800 603 659
4900 616 661
5000 627 658
5100 638 657
5200 648 654
5300 657 651
5400 665 646
5500 670 639
5600 672 630
5700 674 621
5800 678 613
5900 679 608

KAAMA

iTrader: (1)

Head, and cam combinations can be a pretty controversial subject. Actually, I kind of like the cam you have now for your cubic inches, and would NOT change it----but hey, that's just me as I tend to "errr" on the smaller side of things. You can go with something like a Holley 850cfm carb. Any good flowing aluminum aftermarket heads would help---there are several brands out there that would get you in the ball park, but I would say that AFR is one of the top flowing heads out there if you have the $$$ for them. An AFR 305cc head would give you a wider torque band, and would be a good choice for your 540 marine.

Here's some info you might be able to use in comparison. I use the 315cc AFR cnc ported heads on my natuarlly aspirated 565cid engines with a Dart single plane intake, and a 950cfm Holley. I suppose I could have went with some larger volume/cc sized heads like some AFR 335cc heads and I still would have been fine, but the smaller 315cc heads on my size CID engines are a real kick in the pants!

vegas daytona

Thanks for the input. Kaama, I went through a few of your old posts and got alot of good information on the AFR heads. It looks like the AFR heads might give the best results. The 305cc heads should be a great improvement over the GM heads under 5000rpm. The 315's might add a few HP after 5000rpm but I'm most interested in cruise and short top end bursts. Would you upgrade to an 850 Holley or just stay with the 800 I already have? I can live without a mile or two on the top end and put the $$ into my other toys. Would I see any improvement with a higher ratio rocker setup?

Thanks

RLW

I also joined the 540 club back in 2004. I have 40 hours total on my motor in two seasons.
I short list of components (very much like Checkmate's).

Dart Big M Block
Callies Dragonslayer crank
Lunati Pro Mod rods
9.2:1 CR
AFR 305 CNC'd Chambers
Merlin Single Plane with Nickerson 1050
Custom Comp Cam 236/240 @.050 .630/.635 lift 112 LSA
Keith Eickert Exhaust withh GGB mufflers.
All of this in a 1989 27' Activator with Bravo XR/ IMCO -2 Shortie.
Runs 82.7 (GPS) at 5600 rpm with 26" Bravo (stock).

KAAMA

iTrader: (1)

Well, am not an expert, but from what I have seen I would think the AFR 305cc heads would be a great improvement over the GM heads period---even up to 5800rpm or so on your 540cid engine. There are too many variables, scenarios to list, but there is a member on here "RLW" or something like that---he's using some AFR 305cc heads with the cnc'd combustion chamber on a 540cid with a larger hydraulic roller cam of something like 236*/240* and his engine dyno tested I think past 675+ HP range @5800rpm or there about---I can't quite remember, but I thought it was quite impressive. Also, with my 565's I wanted a smoother idle than what I really needed , excellent midrange/throttle response without killing it too much on top. With the cams I have, I am turning my 565's to about 5400-5500rpm with the 315 AFR cnc ported heads. So, contrarey to what you're thinking, the 315's aren't necessary because 305's will KILL the GM heads way beyond 5000rpm.

Also, I need to clearify something here----the cam you have now is okay for the GM heads you now have, but too low of a lift, and a bit too wide on the I/E split if you were to use it with the AFR heads. A 305cc AFR head that flows real well to .600" lift doesn't need a wide I/E split cam like a GM head would. So, contrary to what I posted previously, I would definately go with a different cam profile more suited for the better flow characteristics of the AFR head. This where I believe a custom cam profile would be more beneficial vs just an "off the shelf" cam. "rmbuilder"/Bob would be a knowledgable cam tech guy to ask---his prices are fair/competitive. A custom cam is not that much more than a quality off the shelf cam. The cam is the brain, and is the final, most important part to consider with the heads you have selected. If you want to optimize the flow characteristics of the heads you are using then, proper cam selection is the key. That's why one cam doesn't fit all. Send Bob a PM, I am quite positive that he can explain it much better than most.

Unless you have a ton of $$$ to spend on gas then I would assume that cruising is where you'll spend most of your time. If you plan on dyno testing your engine(s), then see if you can borrow a friend's 850 carb or even a 950cfm carb first to see what the difference would be compared to the 800 carb you now have, and if it would be worth buying. I would think you'd get better results out of a larger carb than an 800 for your application/cid. That's one reason why dyno testing an engine is a very beneficial tool to use to help narrow down all the variables there are or may be---and find problems or potential problems if you can afford it.

RLW

Just for clarification.
718 HP @ 5900 RPM
700 FT/LBS @ 5000 RPM
I personally would liked to have seen the RPM peaks shifted down about 500 RPM. Cam is probably a little long on duration but when you have one shot to get it right and limited funds, you only have one cam ground.
My engine builder (who is quite capable at performance builds) said we would have given up the peak numbers with less cam. In hindsight, that would have been okay. Even a mild 540 has enough power to break outdrives.
I second the call to Rmbuilder. The man knows his stuff. Fortunately for me, we have become good friends. He has been in my boat (several times) and can confirm the performance attributes.

hondatv

RLW : If you had to do it again what cam would you use

RLW

I don't know much about cams.
I would let my Cam Guru come up with that information.
Seriously, PM Rmbuilder.