What HEADS would you select? On a 2K budget.
 

My current setup is 454 stroked to 496 CI
781 Large Ovals with original size small valves.
118 CC chambers. With SRP pistons 9:1 compression ratio
Comp Cam Extreme Marine 226/236 @ .050
BG Sea Demon 750 DP
Edelbrock Performer Intake
I do not want to spin this over 5,500 RPMs
Last year after spinning a bearing(long story, stupid mistake) :( I stroked it to a 496 and only gained 100 RPMs same compressing rato, cam heads etc.
I obviously have a bottle neck somewhere, and I am thinking the heads?

Edelbrock Oval Marine Heads 110CC
290 Intake Runner. What would this raise the compression ratio to?
I am guessing around 9:6.

Dart Iron Eagle. 119CC chambers, 305 Intake runners same size of valves as the Edelbrocks. Probably flows better out of the box. These can be had for about $1,500.

Any other IDEA’s

Thanks in advance for your input, and based on it will determine what I will purchase in the next few days.

Re: What HEADS would you select? On a 2K budget.
 

I'm leaning towards changing the cam. Can you give more info on it, hyd.flat tappet or hyd roller? Since you have small ports and probably good torque, I'd put in a Crane 741 or the Merc 525 efi cam. Also get a Dart or Merlin single plane intake.

Re: What HEADS would you select? On a 2K budget.
 

Bear in mind that 91 octane will be the max pump fuel available from 2007 on, if the new EPA regs go through. I read this in another thread about the 800hp NA 572.

In any case it's worth considering, 9.6-1 should be OK with aluminium heads.

Re: What HEADS would you select? On a 2K budget.
 

How about the new Dart Marine Aluminum heads?
I think they are right at 2K.

Re: What HEADS would you select? On a 2K budget.
 

1BIGJIM, I used Canfield with 119cc chambers and 310cc runners on my 496 stroker. Not sure how they would compare to others since these are the only heads I have run on this engine. I am running 10.2 SRP's and a bit more cam than you and they seem to work great. They are marine version (coated/anodized) and were $2k.

Re: What HEADS would you select? On a 2K budget.
 

The cam is a COMP 270 Extreme Marine
hyd.flat tappet
544 547 Gross Lift
112 center line
Adv Max RPM 5,800

Re: What HEADS would you select? On a 2K budget.
 

That's what I suspected. You don't have enough cam for your cubes. That cam is similar to the Merc 420 cam that was rated for 5200 max on a 454.http://www.cranecams.com/?show=brows...tType=camshaft If you have the money do cam and heads. On a 500 cid engine, my favorites are Canfield 310 rectangular.

Re: What HEADS would you select? On a 2K budget.
 

That cam looks very similar or milder than the one that I have. The duration and lift are almost identical and its on a 114 center line. What am I missing?

Re: What HEADS would you select? On a 2K budget.
 

I'm saying that Merc used that in a 454 with good idle and warrenty and now you're using it in a 500. It's too mild for what you want to do. You need to do a cam change as well as a head change. An engine is a system. All parts have to work together and produce power at the same desired rpm. Look at my first post.

Re: What HEADS would you select? On a 2K budget.
 

TTT :D

Re: What HEADS would you select? On a 2K budget.
 

How many rpms are you turning and what speed. Your engine looks like a torque monster on paper. Maybe you should try going up in pitch on the prop. It might be making more power but at a lower or the same rpms.

Re: What HEADS would you select? On a 2K budget.
 

Its turning a 24 labbed prop at 4,900. Around 68 GPS
in a Pachanga-22. :D

Re: What HEADS would you select? On a 2K budget.
 

Personally I think you have selected cam that should make real good power to 5000rpm in your 496 with better flowing heads. The tighter 112° LSA will extend the rpm range vs. the 114° of the 420cam.
With a good set of heads and an intake to match your engine will make a lot more power. Those heads need lots of work and bigger valves to flow.
Is the engine sit in the boat?
Swapping heads and an intake is doable in the boat, a cam change would be a PIA...

Re: What HEADS would you select? On a 2K budget.
 

Try a 26. It might pull it to 48-4900 rpm.

Re: What HEADS would you select? On a 2K budget.
 

I agree, now way those heads flow enough for 4900rpm.

Re: What HEADS would you select? On a 2K budget.
 

Crane says the 420 cam is 112* lobe

http://www.cranecams.com/?show=brows...61&lvl=2&prt=5

Re: What HEADS would you select? On a 2K budget.
 

Cam Timing: TAPPET @.050
Lift: Opens Closes Max Lift Duration
Intake 5 BTDC 43 ABDC 109 228 °
Exhaust 57 BBDC (1) BTDC 119 236 °

Maybe I'm not doing the math right, but I believe 114°LSA

Re: What HEADS would you select? On a 2K budget.
 

Pat,
You are correct.
109º ICL
119º ECL
114º LSA
Bob

Re: What HEADS would you select? On a 2K budget.
 

With out going to a roller cam
and
my current cam will work,,

Getting back to my original question
What heads would you select?

The engine is in its winter home ENGINE STAND :D

Re: What HEADS would you select? On a 2K budget.
 

Personally, I like the Brodix 3x CNC. They have made great power for me and have been recommended by many engine builders.
You might also look at the PRO 1's from Keith Eikert. They are advertised in the classified's for 2k a set complete, I think.

Re: What HEADS would you select? On a 2K budget.
 

Dart Heads with a matching Dart Intake... :drink:

Re: What HEADS would you select? On a 2K budget.
 

OEM ovals will support this CID to 5500 rpm. We run OEM ovals one several engines in truck pulling engines and turn 470CID to 8500 to 9000 rpm. 2 out of the last 3 champions have had ovals.

The head will work but is not optimum choice. A nice aftermarket 300 CC runner would be a good choice. Low to mid lift airflow on these heads are exceptional so the use of a mild cam would make a nice flat powerband.

Head options would be the Canfield, AFR, Brodix, or the Edelbrock. I would go the route of hard anodizing for longevity.