Headers and Silent Choice on HP500 Carbs?
 

Have a 2000 38' Fountain w/ twin HP 500 Carbs and stock silent choice exhaust. Are there any headers on the market that will allow me to keep the slient choice exhaust or do I have to go thru hull only? Added slightly hotter cams and am going to add AFR heads and bigger carbs over the winter, but think I need better exhaust to take full advantage of the additions. Unfortunately the lake I boat on requires thru prop exhaust after dark. Thanks in advance for any suggestions.

Re: Headers and Silent Choice on HP500 Carbs?
 

Anyone?

Re: Headers and Silent Choice on HP500 Carbs?
 

Both Lightning and CMI have header setups with Captain's call. But I don't believe you will be able to use the same diverters as with your Gil/Merc.
Also, be careful with your new cam selection. "Big" cams with lots of overlap are a no no with captain's call...

Re: Headers and Silent Choice on HP500 Carbs?
 

i would post your cam specs if you have them.
i ran a similar setup as the hp500 but a little bigger cam with same overlap.
i used the emi thunder exhaust with corsa diverters (came on the boat) and had reversion pretty bad. i since switch to no silent choice and went straight out the back with water exiting at the end of the pipe and it STILL reverted water, not nearly as bad though!! i think ill have to change cams this winter to correct the problem....however, i was told that if my cam was a degree or two off during install(which i did not do myself) it would totally change things as far as rpm range of power and reversion!!

good luck but look into the cams to see what you have, i was able to pull the exhaust after idle on the hose and had water just sitting in the exhaust manifold. :mad:

kevin

Re: Headers and Silent Choice on HP500 Carbs?
 

Thanks Pat, boatn and Fred. I appreciate the advice. I'll get the cam specs from my engine builder and then post here. I'll also give CMI a call with the specs.

Boatn - sorry to hear about your reversion problems. That sucks. Seems to me there are lots of reversion problems, but not a lot of reversion solutions.

Fred - how much for the CMI's you have in mind? Just trying to get an idea on cost.

Thanks,
Brad

Re: Headers and Silent Choice on HP500 Carbs?
 

I am running Lightning headers with silent choice and big cams.
Get the reduced water option and dump the excess water overboard not out the exhaust.

Re: Headers and Silent Choice on HP500 Carbs?
 

My 35' Fountain came with 525SC, CMI headers, and Silent Choice. My guess is that the same setup would fit you boat and motor. (Yep, some of the later 525SC's came set up this way.)

Re: Headers and Silent Choice on HP500 Carbs?
 

Like this?

Re: Headers and Silent Choice on HP500 Carbs?
 

1stfntn, when choosing exhaust, especially in a twin application, you need to know what your engine spacing is. Measure the centerline of the leading and trailing edges of your drives, and split the difference.

Some exhaust types will fit engines on a 33 CL, some require 34", 34 1/2, or even more. Some will do custom sets to fit "tight" spaces, like 33". This is good info to have available when talking to exhaust manufacturers or parts shops that sell them.

Good luck,
Brian

Re: Headers and Silent Choice on HP500 Carbs?
 

rjcardinal - are those the CMI's from a 525SC that Joel is talking about? If not, what brand/model are your headers? They look sweeeet!

Joel - thanks for the info. Can you post a pic?

P4-33 - GREAT suggestion. I know my Gil exhaust is pretty darn tight since the engines aren't staggered. I will measure the CL when I get back from Vega$$ on Mon. Hope they aren't 33".