.75,135 exhaust chamber porting,diverter

[dzoolk]

i did a complete rebuild onmy 1975,135 ,evinrude.<br />i noticed there is alot of casting flaws in the intake areas ,, exhaust ports,just cleaning up so air and exhaust will flow ,trimming gaskets that block flow, not changing port heights or anything crazy.good thing i dont have any specs,,lol.just want her to gain some free h.p. while keeping her dependable.anyway when they went from a flat back to a bubble back they left a thick flat wall for the exhaust flow to slam rt into on its way out the block..so in the pix you can see i grinded and molded a diverter to split the exhaust flow path. has anyone done this b4? noticed much diff? theres got to be a great benefit .and also i wonder what jetting i should use on my mains.on brp calls for 61c mains.im sure i have to go bigger.did anyone try any bigger jets on stockers? im am going from an 85 crysler junk to big h.p 135 evinrude,on a 17 foot whaler the tri hull should suck in lots of air for lift,this 135 should fly..can't wait to g.p.s. it.thanks much,dz titusville fl.http://i39.photobucket.com/albums/e189/dzoolk/divter300.jpg<br /><br /> http://i39.photobucket.com/albums/e189/dzoolk/diveretafter.jpg <br /><br /> http://i39.photobucket.com/albums/e189/dzoolk/0c29b4b7.jpg <br /><br /> http://i39.photobucket.com/albums/e189/dzoolk/sideramp50.jpg

 

[Dhadley]

Re: .75,135 exhaust chamber porting,diverter

That section is cut on the 140 crossflows. Unless you're turning some good r's it won't make any difference. What will help, if you're close to 6000 rpm, is to leave out those exhaust stuffers. Depending on the hull configuration you'll gain a few rpm.

 

[dzoolk]

Re: .75,135 exhaust chamber porting,diverter

thansk dhadley. where are these exhaust stuffers? i dont remember seeing them when i put the 135 rude back together.. do you mean under the bubleback? one of the 2 bubbles?<br />and how high a jetting could i go onmains? thanks, dz,,=]

 

[Dhadley]

Re: .75,135 exhaust chamber porting,diverter

The exhaust deflectors are those 2 things bolted in the exhaust cavity of the block.<br /><br />The jetting depends on the rpm you're at. Stock jets on stock porting is usually good to about 6500 or so.

 

[dzoolk]

Re: .75,135 exhaust chamber porting,diverter

[The exhaust deflectors are those 2 things bolted in the exhaust cavity of the block.]<br /><br />ohhhhhhhhhhhhh those things!<br />i dont know, they sure seem like a good idea, like headers directing the flow right out.how could not have that do any good? seems like the flow would just crowd up.wouldtn they be part of the tuned exhaust system?<br />any reviews of any one removing them?<br /> many thansk d z

 

[Dhadley]

Re: .75,135 exhaust chamber porting,diverter

On a ski boat (no step or pad) the motor will pick up almost 200 rpm. From 5600 to almost 5800. At higher rpm removing them helps a little more. <br /><br />What rpm are you set up at now?

 

[dzoolk]

Re: .75,135 exhaust chamber porting,diverter

that sounds great!i may take them stuffers out then, i dont no the r.p.m. yet as i have to break her in first..all new evrything complete rebuild ,i havent even set the timing yet on w.o.t. i am close on the 5 dgree pickup timing however..local dealer mechanic said cdi brand timing bases go bad alot.what do u think/?anything oem seems to ooze potting varnish,, lol<br /> http://i39.photobucket.com/albums/e189/dzoolk/powerhead.jpg

 

[Dhadley]

Re: .75,135 exhaust chamber porting,diverter

Actually I've think the CDI stuff is better than OE as far as Evin/John stuff goes. None of the race motors use OE stators, we all use CDI stuff.<br /><br />Don't kill yourself trying to get it to idle at 5*. Just set the idle in the water to whatever makes it idle the best.