The part no. for a mark 4, Gen 5 741 is now 139021. Have to use a cam button in a Gen 6 instead of the retainer plate. Maybe Crane can make one to fit a Gen 6.

Yep, they're wrong or simply misunderstood. I have three Gen6 502s all with 741s

http://www.cranecams.com/?show=brows...tType=camshaft

Its got a good chance of reversion with the 741 and gils. thats a big risk for not much hp.

The 741 will fit a gen 6. Dock holiday is running the 741 in his 500efi's.

But with CMI's

The 731 cam has bin replaced with the new Z-camprofile #139011. This cam act like a "bigger" cam caused to the new grind. Powerrange is 1600-5600 RPM and it pulls very strong al way up and idle is smoote 750-800 rpm

So can I assume that an HP500 with 731 & GIL'S may have less reversion issues than the same set up with a 741? It seems that a lot of reversion discussions are stemming around the 741. Of those who are running 731's vs 741's who's got a bigger reversion problem? And for those experts, in your opinion is the cause of the HP500 reversion issues mainly CAM related or Exhaust related? If you remove the water all together from the tailpipes I guess you'll solve the reversion problem, like cutting the head off a snake, but would a simple "less aggressive" cam change also do the trick?

Bob Lloyd whos opinion I trust and did my engines said the 731 would work with the gils. The 741 would work, but would need to change exhaust. I didnt want to spend the money on the exhaust.

The 731 isnt much of a performance gain over the stock carb'd hp500 cam, but every little bit adds up.

That is good news. I'm staying with the 731 and my GILS. For now. I'm just running out of time to get these engines back in. Adding the Crane HI-6M and a Crane PS92 coil. That combined with the new Dart Heads, Dart intake and upgraded valves, I'm hoping I've nailed the "Best performance for the reliability buck" Only thing left is to find dyno time the week before Memorial day.

I'm with Griff if the carb has not had the metering blocks modified the jet you have is going to be at least 25 hp off to what it has to be the numbers are as Griff mentioned try that you won't regret it we've done a lot of work on those carbs for years since we were racing Factory 1 AND 2 that's the best way to run that carb on that intake don't worry about the two front plugs being darker then the rest . Sincerely Laz Mesa