intake mod advice

[cdoliver]

After optimizing my setup on my boat, I'm still a few hundred rpm's away from where I want to be. I've decided to do the intake mod and install Boyesen reeds. All the parts have arrived and I'm going to start putting it all together today. I few questions: There is a small hole that is in the middle of the top intake plenum that goes all the way through to the back of the intake. Do I leave it or plug it? Where should I look to purchase the required/ recommended idle air jets? What is the best way to service the check valves in the recirc hoses? Someone recommended using locktite somewhere when installing the new reeds. Is it on the plate that holds the reeds down?

Sorry for all the questions, I just don't want to have to do anything again. Heres a pic of my progress

Thanks

 

[Faztbullet]

Re: intake mod advice

Hope you have a light boat as milling the dividers kill a lot of bottom end torque on a heavy boat. The recirc valves are cleaned with alcohol and do not used compressed air on them. You may have to drop several sizes to even get a close to a idle, you will not get a good idle with this mod and may pick up a couple of hundred on top end, and rejet high speed also. The merc mod-vp uses a 3/8 holes in intake and recirc valves dump to a common container. You use loctite on reed screws.

 

[Dhadley]

Re: intake mod advice

That hole stays open. We've had real good luck with that mod and have never had to rejet unless you're going for over 7000 or so. Just don't forget to seal the hole in the back of the carbs.

 

[cdoliver]

Re: intake mod advice

My boat is a 16ft skeeter wrangler. approx 950lbs. 6in man jack pl. 14.5 X 20p raker. I'm at 55.4mph @5500RPMs (looking for 5800). The jack plate is as high as it will go without losing mph. I have to say I'm a little concerned with the idle now after reading your post faztbullet. I have the 1 5/16th carbs (the powerhead is from a 155 comm. compression is 85 throughout. I'm looking for some GT heads. the intake that I cut is an extra from another 155 so I still have the original. Should I just put the boyesen's in the uncut intake? Thanks for the help. I'm having fun doing all this.

 

[Dhadley]

Re: intake mod advice

On every one we've done the idle is fine, never been an issue. I think you'll really like the results. You'll also need the old style carb gaskets.

 

[cdoliver]

Re: intake mod advice

I've read where you have said to use the old style gaskets many times, but can you explain why cutting the centers of the standard gasket wouldn't work. Not disputing, just want to understand. I've looked several places for the old style gaskets, and have come up short on finding them. I'd be fine with making my own if I knew exactly what line to follow. Or lead me in the right direction in finding the old ones. Thanks again.

 

[Dhadley]

Re: intake mod advice

Take a look at the new style. On the ones we cut there wasnt enough material left to make a good seal in the middle. I suppose it depends on how much was cut. If the new style will work on yours, that's good.

 

[cdoliver]

Re: intake mod advice

got it all put together. Had to make some gaskets as you had stated. The problem is on the carb side with the gasket. I was just looking at the intake side. I can't believe the idle. It is fantastic. It runs great. Loads of midrange punch and I'm just a hair over 5700RPM's a 200rpm improvement. Thanks for the help.