After Market Heads?
 

Ok I know this has been talked about. What are the best heads to use on a 522cu.in block. with the following criteria

1. Standard exhaust port location
2. Future build up to 598's
3. Naturally aspirated
4. Fresh water (no salt)
5. 9.75 : 1 Compression
6. Crane 741 Cam
7. Approx. 5200 RPM Max

Thanks
Mark

Re: After Market Heads?
 

Hi Mark, Not trying to exclude anyone, but if you can swing it on the $$$...one of the top aluminum heads out there are the AFR heads---especially their CNC ported heads. According to another member here on OSO he used the Crane 741 cam with the AFR heads on his engines with excellent results, but the engine would make better power with a cam that is more in tune with the cutting edge port/combustion chamber design of the AFR head.

Bob Madara of Marine Kinetics (585-654-8583) can get you some AFR heads and a custom cam to go with them if you desire. He's straight talkin' guy and has helped many on here with head/cam applications. He works with Wesseldyk a lot. Whatever you do, I hope it works out well for you.

Mark

Re: After Market Heads?
 

Hi Mr Cig.
I really liked the looks of KAAMA's heads. I think they're AFR 315cc CNC.
You might want to check with him about a set of heads he has from before. Nice heads, low time.

Re: After Market Heads?
 

THanks Guy for the info. Do the AFR's have raised exhaust ports? I do not have room to move my headers up and out any. I have solid tail pipes all the way thru the transom and my 2 center mufflers touch now.

Re: After Market Heads?
 

I had VERY good results with the AFR 315 CNC'd heads (305 base cnc'd to 315) and the Crane 168741. As far as the exhaust runners, they are in the stock location. The only exhaust modification I did, was upgrade my Gils to CMI elbow tops. All of the tails lined up with the original Bravo exit.

Hope this helps.

Dave

Re: After Market Heads?
 

Mr Cig, are you currently running a talldeck? You seem worried about exhaust location. If you aren't currently running a talldeck, when you swap to one (which you WILL be doing for a 598), you will be moving the exhaust port location up 0.3" and out 0.3"

Just something to keep in mind.
mc

Re: After Market Heads?
 

Yes the motors are Tall decks already.

Mark

Re: After Market Heads?
 

Mark, would you like some help with the engines? I'd be more than happy to come down and lend a hand.

Re: After Market Heads?
 

I have the AFR heads in my mistress. I am running Stainless Marine Manifolds. Tight Fit

Re: After Market Heads?
 

Mark, I don't think you'll need to make any changes if you go with an aftermarket head. The difference in exhaust port height is minimal.

Re: After Market Heads?
 

Dave,

you posted your stuff before I could use you as an example.

The 741 works great with the AFR heads. There is no reason to pay extra for a "special" cam, unless you are looking for an extra 5 or 10 HP which means nothing in a marine motor.

As far as just plain heads go, there are AFR's, and then everything else. (unless you want to go with Pontiac heads). AFR's aren't cheap, but if you want to have your engine set up to make the most possible HP they are the choice.

Re: After Market Heads?
 

DO you have solid pipes straight out the back or a rubber hose connection? With the solid pipes I don't have much movement.

I did read this on the AFR web site

"Also, be aware that our exhaust port location has been raised .300 over stock height to improve flow characteristics.
If you are currently running stock heads and you have a very tight header/exhaust manifold clearance, you might be forced to modify them to fit."

It is raised half the distance of the Brodix and Canfield. But i'm not sure if it will make it still :confused:

Mark

Re: After Market Heads?
 

I'll look for a picture, but I do have about 1" between the end of my tail pipes and my thru bolted transom mufflers which are connected together with rubber. If they were going straight thru, I think they'd be fine. Let me look for the picture.

Dave

Re: After Market Heads?
 

Thanks for the offer Dave. We torn the one motor down today. Found a valve guide disappeared into little pieces and imbedded itself into a few pistons.

Bottom end looked like the day we put them together 350 hours ago.

Looks like it's time to get rid of the old GM Steel Heads.

Mark :drink:

Re: After Market Heads?
 

This is the best I have of what I think you are looking for...

Not a bad thing to upgrade!! :drink:

I'll look on my other computer for a better close-up later this week!

Dave

Re: After Market Heads?
 

Mark/Mr. Cig, my boat eventually went from cast iron Merlin heads, to Dart aluminum Pro-1's to the 315cc AFR's which I now have and are supposed to have a thicker deck. The center to center dimensions were important to me because I have a hatch actuator that is mounted on the center stringer between the engines/headers and I still didn't need to change the cut-outs where my tailpipes go thru the hull with the AFR's. So, if there were any changes I couldn't really see them or notice them on my boat just by eye balling it.

Re: After Market Heads?
 

Same observation for me as well!!

Dave

Re: After Market Heads?
 

Hi Mark, glad to see you're stepping up to the AFR's. With a 522 and a cam that large, your power peak will be about 5800 rpm. A 598 will be a torque monster with the same components. I would think about AFR 335's if you're going to build 598's soon. Custom cams are no big deal. Comp Cams maks them for about 40.00 more than off the shelf. Mine is 236/240 @ .050, .630 lift. AFR's benefit from less exhaust duration because their intake to exhaust flow ratio is so much better than a stock Chevy head. If you want the grind number for my cams call or send a P.M. Good luck with the new build, Ian

Re: After Market Heads?
 

TTT for a friend

Thanks for all the replys

Mark

Re: After Market Heads?
 

You're welcomed.

Re: After Market Heads?
 

Mark, I don't think there's any difference in $$$ from the 315's to the 355's, if so, it's very minimal compared to the expense of upgrading later if you decide to go to a bigger inch engine. Get the 355's right off the bat.

Did you decide not to go with an 4.5" arm???

Also, you will need either a different valve cover to accept the stud girdle, or run the Jessel rocker setup. If you're gonna change the cam and want to stay with a non-custom grind, I would consider the Crane 651 stick. The extra lift and duration will benefit you with the larger ports, and you can run the same spring rate as the 741 cam uses.

Who's gonna do the cylinder heads???

Re: After Market Heads?
 

With a max 5200 rpm and the Crane 741 cam I wouldn't suggest the stud girdle. The Jesel rockers would be nice but roller rockers without the girdle would hold up fine IMO.

Re: After Market Heads?
 

Mark, I ran your numbers through Desktop Dyno. Give me a call for more info.

Re: After Market Heads?
 

I haven't made any decisions yet on what I am doing.

Dave I'll give you a call tommorow. I just got home from work and need to find some food. Sorry I missed your call Saturday we were having a bad day.

Thanks
Mark