Dhadley, V-4 mods

[R.Johnson]

Some time back you gave directions on milling out the intake manifold. Do you recall about where you were with jetting? Did you make any mods to the exhaust system?

 

[Dhadley]

Re: Dhadley, V-4 mods

On mine the exhaust was open but the motor was on a race boat. We did put on a recreational boat but the noise drove me nuts. Opening the exhaust wont normally do anything unless you dry stack the motor too. And unless you are turning over 6500, you may not see an difference anyway. I have seen cases that the rig slowed slightly if it wasnt dry stacked.<br /><br />Usually the stock jetting, for which ever carbs youre running, is good thru about 6500 rpm on a crossflow. You might have to play with it after that.<br /><br />Are you running the "bubble back" block? Is it together yet?

 

[R.Johnson]

Re: Dhadley, V-4 mods

I just picked up a complete 1973, 135. I also have a complete powerhead of the same size, and year. I intend to take the best of the two block's , and have it rebored just enough to clean up. I will be running it on a 15.5 ft Checkmate with 5 inchs of set-back with the jack plate. The prop is a OMC Raker repitched to 25 inch's. The rear seat, and built in gas tank has been removed, and front seat's replaced with lighter units. I have been running a 1972, 125, it has the mid-section, and mounting bracket's replaced with later unit's so that I have dual tilt tube steering, and tilt & trim. I'm really curious what this old 135 will give me. The 125 will break 6000 with this set up. What do you think would be a realistic figure for the 135. I have heard that Dah propeller's can work some magic with these Raker props.

 

[Dhadley]

Re: Dhadley, V-4 mods

Neat rig! Keep an eye on Bass & Walleye Boats and Trailer Boat Magazine. John Tiger Jr wrote an article on his daughters boat with a V4 OMV CF. Its a checkmate too -- the same one I believe. You'll love it. He redid the motor but its all stock. Should give you some great info and baselines.<br /><br />With stock reeds the 135 should start to give up somewhere in the low to mid 6000 range. Boyesens should take you past that. The stock port timing configuration will probably give up somewhere just shy of 7000.<br /><br />DAH has always done a good job with props. Hold off spending money on a prop until youve ran yours. Then you can compare the 135 to the 125. Watch for Johns article. Theres a whole deal on props.

 

[R.Johnson]

Re: Dhadley, V-4 mods

I have Boyesen reed's in the 125, and they will be installed in the 135 also. Those thing's are a cheap investment. Where will the milled out plenum manifold take me? Thank's for all the help.

 

[R.Johnson]

Re: Dhadley, V-4 mods

I have Boyesen reed's in the 125, and they will be installed in the 135 also. Those thing's are a cheap investment. Where will the milled out plenum manifold take me? Would there be anything to be gained by removing the pump impellers out of the hydro-assist oil pump and running just forward gear. This boat is a personal project, we have a fishing boat for family use, or as my wife say's, reasonable use.

 

[Dhadley]

Re: Dhadley, V-4 mods

I think the milled intake will definately help you get to these rpms. I had my cf on a 15 Allison so I cant say exactly what it will do on a Checkmate. Conventional bottom vs a pad bottom.<br /><br />To be honest we ran the later model intake but yours is shorter so in theory it should work better. Same with the gearcase. We ran the later model which was longer. A longer gearcase will blowout at a higher speed. I'm not sure where the small one like yours blows out (without a nosecone) but I would suspect somewhere in the mid 60's. Maybe higher, I dont know. <br /><br />We had to run a shifting gearcase -- class rules -- so I never fooled with the gearcase internals. I know one guy who ran a V4 looper like I was (after the CF) and he had this tube running from the gearcase up under the hood. Their theory was that at speed the oil was thrown away from the moving gears and it went up the tube thus reduced friction. Beats me. He was turning 7800 rpm. I didnt have any "vent tube" and was turning 8200. I guess the bottom line is that your theory sounds correct. Try it and see. Stranger things have happened.