PatriYacht

Good idea Russ. Is there a number where I can reach these guys? Rmbuilder, I wasn't recommending that cam for use in a 502. My engines are almost identical to RLW's so it seems to be a good choice for me. Is there a number I could reach you at?

JimV

Thanks Chris
Airflow numbers are very important when choosing a cam. The first thing I look for is where the peak air flow is. There's no reason to lift the valve past that point. Some ports will loose airflow at higher lifts.

mjb

Wags(or others)- Very informative thread-could you help clarify something. I am doing a similar 502(actually 509) but I am using the 308 Dart Iron Eagle heads and my max rpm will be a little lower than yours at about 5200-5300. I think you were looking for 5500 in your original post. After researching this site for weeks and talking to crane, as&m and others, I too ruled out the 741 cam...too big. I thought I had it narrowed down to the 731 or 761. From what I've learned, the 731 is pretty mild in a 502 and better suited to around 5000 rpm where the 761 will be happier at 5200 -5300. The 16HR00065 you seem to be leaning toward has the same intake duration of 226* as the 731 and is actually smaller on the exhaust but yet you are looking for max power at 5500?? This is contrary to what crane told me. I understand that better heads on the exhaust side allows less I/O split...but do the AFR heads flow that much better than the Darts that only 226* intake duration will net 5500rpm's?? I was ready to purchase the 761 but now I am not sure that I am getting good advice from crane and others. Looking forward to all opinions. Thanks-

cstraub69@comcast

MJB,
You really can't compare 2 heads when one is CNC ported and the other is an as cast. Most cylinder head companies leave excess material in the ports so that custom head porters can conture and shape ports to produce more airflow. So the AFR's aren't really better, they have just had additional work done.

Now, it is my school of thought and way of doing things that the better the head flows the less camshaft that is needed. Now this is all relative to rpm and cid and cross section of ports.

Camshafts are dependant on airflow so that the cam "knows how much or how little it has to move through the engine". CNC heads are very consistant when it comes to numbers. As cast heads will vary due to core shift. No 2 as cast heads are alike. So to make this short, to know exactly what you need camshaft wise, it is well worth the $50 or so dollars to get your heads flowed. Now since a BBC has 2 intake ports, you need to get a reference on both ports.
You purchased good heads and they will make fine combo. You just don't need to put 20 year old cam technology in the engine.

Chris

mjb

Thanks Chris- If I understand you right, it sounds like the 761(old technology) might not be such a good match with the Dart heads(new technology)??? I am having some bowl work done and I will flow the dart heads before actually buying the cam. Could you or anyone else in the know steer me in another direction other than the 761 for my application. It needs to be a cam that A,S&M has experience with since they are doing my ecm. My basics are : heavy 38' top gun, 509 MPI, 9:1 comp, exhaust, as&m intake manifold, fuel, ignition, 530-540 HP goal at 5300 max. I thought I had it all figured out...I really appreciate the help on this board. Thanks-

Jmemoli

Guys ,
I have used the following cam in a number of engines - It peaks out at 52-5300 in a 502 and about 5100 RPM in my 540 . This cam has gobs of torque and is perfect in single engine applications . For twin engine apps. , it may be a bit mellow sacrificing top speed for gobs of midrange . this cam also works well without headers ( low overlap) .
CP Performance sells it (www.cpperformance.com) -
It has 224/232 duration @ .050 , around .600 lift , runs mellow valve springs (340 lbs. open ) , 112 ls,.
It has a exhaust valve closing around 41 degrees Atdc , and 4 ATDC(.050).
Therefore , it can be used with wet exhaust no problem .
Torque peak is around 3800 -4000 rpm.
Sorry , I do not have the p/n in front of me but can get the comp cams p/n if you need it .
I have used it in my Pantera 28 race boat for the past year in lieu of the Crane 244/256 , .625" lift cam - The boat turned 5800 rpm with the crane cam , had no lo end/power out of turns , and ran 78 mph. the Comp cam turns a 8 pitch at 5100 rpm , and pulls the boat to 75 mph, with gobs of midrange .

WAGS382

mjb,
I am going through the same thoughts as you, I don't want to over cam, but I want the top end performance to be there. The AFR's I ordered are cnc'd combustion chambers, but the runners are as cast. I built a pair of 9.0:1 454's with oval port merlin heads, 731 cam, rpm airgap intake, gil exhaust. These motors are very mellow at idle with gobs of midrange, but seem to flatten out at approx. 5000 rpm. I built the same motors for my old boat a few years back with an isky cam that had almost the same specs, but was ground 5* in retard compared to the 731. My 454's also had a mellow idle, killer midrange and a better top end, they pulled strong to 5400 rpm. So now I am considering putting a smaller cam in a larger motor. I gues the guestion is how do the AFR's compare to the merlin's, are merlins old technology also? I know the exhaust is better than the chevy heads. here are the results from the 454 with the isky cam:

Queenie

I need some help with my motors. I'm going 68.1mph and want 71.8 What can I do Wags382??

WAGS382

Sell the boat and buy a Formula. I find that speed of 71.8 interesting, it would be one mph faster than what SKRAMER claims.

WAGS382

I plan on running one of the stock motors this saturday and will post results with wet and dry Gil's and dry headers.