Garage full of 2.4L junk...what should I put together?

[lbhsbz]

Boat is a 19' mod VP style bahner tunnel. Even though it still twisted a 26P chopper to near 7K and ran right about 80mph, 3 holes were down to 70psi and the cylinders looked like hell so I figured its time...old motor was a '86ish 200hp w/ the black boxes removed, oil injection removed, timing set at 25°, stock WH39 carbs and a set of CCMS reeds. Motor was hurt when I got it, but it ran good for 5 years.

I have a '83 200hp (pre oil injection, 9 ring crank) 2.4 with 5 beautiful holes and one with some scoring...good holes make 118psi, bad one makes 110psi. That's 20 more than my old one ever made. This has a set of WH22 carbs, 5 petal reeds, uncut heads.

I have a '85 200hp, same as the old motor, with perfect holes...I haven't put heads on it to do a comp. test...just picked up the motor.

I have a 1980 early style 2.4L 200hp (head bolt bosses on the cylinder casting, non-finger ported, should have the big rods) that has WH20 carbs, I believe a 7 petal reed setup, but one hole is fubar.

I'd rather not buy much more than gaskets. I have a mill and a lathe, and 3 sets of heads, and a little bit of time.

I was thinking of cutting a set of heads to run on 50/50 AV gas and pump premium (AV gas is available where I boat), but unsure on what carbs to use or whether to use the 5 petal or 7 petal front half. The '83 powerhead is on the boat now as I hadn't acquired the other 2 yet and that was the only other motor I had. Plan was to yank it and get it sleeved after this summer, but now that I've got a good block...might as well use that. Are extra finger port holes (like in the Cherry 2.4 build) of any benefit at this level of "build"? Are any real gains to be made from epoxying up the oil injection void in the case on #2? The "good" block is still assembled, except for the intake, carbs, and heads...I don't mind tearing it down to do more fun stuff, but if gains won't be too significant, I'd rather not.

[outasite]

Well here's my two cents,If you you have a second gen block with six good holes use it! Use your seven petal front(cut .050 off the front) with the wh15 carbs,new set of reeds,if you are going to run the 50/50 fuel,ALL THE TIME, cut the heads for 170 pounds,otherwise 150 will do.put an early bell tuner,and light flywheel on,25 on the timing and go!!! That combo was fairly common for a sport boat hot rod.

[lbhsbz]

Excellent. I've been kicking around the idea of trying to build the Cherry 2fo without touching the block..instead of shortening the whole piston, either mill a small relief or an angle cut to have the same effect of knocking .050" off the whole top but not requiring 5.75ccs be recovered by taking .050 of the block deck. It's getting hard to find clean virgin 2.4 blocks...I'm kinda hesitant to use it or cut on it...not sure why. I'd have to spend a couple weeks building fixtures to do it right. This thing is supposed to be wet in 2 weeks. I'll start with your plan...that should give me a hard-on for this summer, then I'll sleeve another block and use that for the Cherry 2fo next summer. I have 3 sets of second gen heads, so I'll cut 'em a couple different CCs and see where that gets me.

No WH15 carbs though...I have WH20s, WH22s, and WH39s. Which should I use...and why do the WH20s have 74/76 jetting while the WH39s have 80/82 jetting?

[rgsauger]

Pics, man. We gotta see pics!!!

[lbhsbz]

Pics soon...hopefully.

Since I'd already put my '83 powerhead on the boat, I decided to leave that there and use it instead of rushing to put something else together in time for the first trip. I got this mota about 5 years ago and never ran it...it was a bit of a tuning nightmare. I yanked the black boxes and couldn't get the damn thing to time right or idle under 1500 RPMs. Turned out the stator was not indexed correctly when the previous owner had replaced it (was one hole off). Of course, all the limit screws/linkage was incredibly misadjusted I guess in an attempt to make it run with the stator in the wrong position. I got it about right but for whatever reason after snapping the throttle, instead of returning to idle it would just quit. I pulled off the WH22s that were on it and through on a set of WH39s off of my old engine that worked fine...and the problem seems to have subsided...for now. I'll pull the WH22s apart and see if I can find anything wrong tonight.

[outasite]

The wh 15 and 20 are the same carb,and are the best for your application.Dont remember why the smaller jets but seems like 74/78 would cover most all applications around here. And they will flow fuel faster than you will like buying it

[lbhsbz]

I measured up the carbs last night. When searching, I haven't seen much info on the WH20s except that "they're bigger".

...well, here it is.

WH20 - venturi diameter 1.390", 72/74 jets
WH22 - venturi diameter 1.325", 74/76 jets
WH39 - venturi diameter 1.325", 80/82 jets

The larger venturi has 5% more area than the smaller carbs.

Jetting seems pretty far apart....not sure why

[lbhsbz]

Trying to make all the "bolt on" improvements I can without getting too deep. I wanted to cut .050 off the front half, but didn't want to split it, so I made reed block spacers out of some .070" ish aluminum

[UR

And cleaned up the intake a bit

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I cut a .040" off a set of heads to which got me to 140psi cranking (33cc), and cut another set .085" which got me to about 29.5cc. Stock chambers were only 35cc...I thought they were bigger. I may try these on AV gas. I'll try it in a few different configurations

[lbhsbz]

I ran the motor with my ported reed cages, CCMS sport reeds, stock intake, and cut heads (140psi cranking), 25° of timing along with a set of WH39 carbs off of my old motor....couldn't get the idle to come down to anything reasonable with the WH22s that were on it. Also found the stator was clocked wrong (after I changed the carbs..lol).

I also picked up a 4 blade 24P Eagle ET from Ron Hill.

Bottom end is pretty impressive. It'll put you back in the seat when you stab it and still ran 81 (actually 4mph faster than the 26P big ear chopper I have) at 6800rpms.

I think I need more prop.