exhaust for bigger cams
 

Went to the crane 741 cams last year when i did my top ends over,, now found indication of reversion with my gill exhaust system. What is a good couple of choices to replace it witout reversion issues.

make it dry then you can use any cam .i beleave there is a guy selling dry pipes for your exhaust

Dry will be alot louder, and would my tips get hot, as my 32 active thunder has pipes above swim platform.

if you go dry you cant run tips, you have to extend your tails all the way through the transom.......the problem with running dry tails is that you cant run tips with a rubber hose, so they have to hit your current holes PERFECT or its time to get your saw out

how hot will the ends of the tails over my swim platform get.

the tails wont be hot, i ran dry tails on my old boat and theyre the same temp as the wet tails im running now. It the actual exhaust gas that is still hot because no water is ever introduced to cool it, that is what would burn a rubber boot.

ya mine are the same the water goes to the end of the pipe and i have the rubber flappers on the end it works for me
the water cool the pipe down i had to do this because of the cam i am runnig

Is it alot louder

yeah, but i never got bothered for it and i went passed many police boats........

My guess is that completely dry tails would trash your swim platform. You really shouldn't need dry tails with a 741 cam. The stock cam is probably more prone to reversion than the 741.

Where do you have the idle rpm set at nuetral and in what rpm while in gear. A 100 rpm bump in the idle rpm could do wonders if you actually have a little reversion.

I did for sure have reversion, i sold my gills to my buddy so i need to get something different now., had idle set around 900 out of gear. i guess either cmi e tops or lightning.

Thats about as high as you would want the idle. I'm still surprised you had reversion.

You could go with a set up like I have on my CMI tails. They are dry all the way through the transom. Basically the tails are just cut off and the water dumps out at the very end. They are significantly louder than standard wet CMI's. I have switchable mufflers on mine though and my platform is above the exhaust. They do not get hot at all.

Why would the dry tails trash his swim platform? The 741 cam has quite a bit more duration than a stock 500 cam. Pretty sure a 741 is like 236/[email protected]

I run this cam in my 454's with 177 blowers and stellings with full dry tails. Also ran that cam in a n/a 540 with stainless marine manifolds with standard bravo risers, no reversion.

You can run mufflers on dry tails, but they need "stingers" at the ends, or at least some holes drilled at the end of the pipes to let some water into the mufflers to keep them cool. I had gaffrig mufflers on the ends of my stellings with stingers, no blueing or anything, and they stayed nice and cool....

My pipes are over my platform that is why griff is saying dry tail may damage it. 741 cam is 236/244 @.50 the stock 500 hp cam was 222/230 @.50. here is the tails i was using below.

Fixx
 

Did yoyu have the turbulator's installed? sure it wasnt moisture from the risers cooling down?

http://www.cpperformance.com/detail.aspx?ID=2586

Yes had the turbulators on them, i had damage to # 3 exhaust valve seat, indication on top of cylinders and pistons of water and oil was some what milky with alot of milky chit in the breather tubes and upper valve covers, all indications were same on both motors. The top ends was all redone last winter, heads and all parts, cams, chain gears, lifters and gaskets. Only put 16 hours on them last summer and have this issue.

My buddy who had the Cigarette Bullet that just sold, had upgraded 500 mercs with 741 cams. He ran CMI with dry tails. No issues.

Personally, I would go with stainless marine or similar and just do the full length tails. I doubt it will cost much more, and reversion wont be a concern. I see where your tips are, and I dont think you would trash the platform as long as the water came out at the end of the tips, and not via separate dumps like the old gil dry tails.

Heres a video of the bullet, with the 500's and 741 cams, with CMI headers, full length tails, and cmi mufflers idling.

http://www.youtube.com/watch?v=unmMQV1m-eg

Don't use the Lightnings if you have reversion issues

Its not necessarily the amount duration that causes reversion. Its the amount of overlap. The carbed HP500 cam is also ground on a 110LSA where the 741 is on a 112LSA.