Power making 2.4 s

[evinrudejohnson]

I'm tossing around a bunch or 2.4 parts and over the winter I want to build a strong 2.4 I have some good parts and want to see what you guys have put together in the past . porting front halves carbs piston mods and so on . thanks Ed.

[evinrudejohnson]

Purpose built 2.4 s something ?

[bobthebuilder]

A 2.4 can make real power.. I have built quite a few and a couple were monsters for a 2.4 What is it going on and what do you expect? I am an outboard machinist and engine builder here and I will help you.. all the info you need..

[evinrudejohnson]

Thanks bobthebuilder I want to build a 2.4 that's spins some high rpms . I have a set of 5250 rods a 7 pedal front half 3 diffrent sets of wh carbs and a couple of other little things .But the main thing is I want to port the block the pistons lighten and balance the rotating assembly . I want to see how you guys hog out the exaust on these 2.4ss ? What stuff people have done to the pistons . it's all been done before im just looking for specs . not trying to reinvent the wheel . I seen a lot of people have build them cherry 2.4s . what rpms do they spin up top ?

[evinrudejohnson]

Basicly I want to break 100 or better on my Allison ss2000 comp with a 2.4 . so far 94 is my best number . with a stock 2.4

[bobthebuilder]

If you are getting 94 already then breaking 100 is right there.. The 2.4 will turn 9K for sure if set up correctly and a light load on it. Hogging out the exhaust isn't so good.. Look up the cherry lil 2.4's that T-Rex posted.. I personally do not like decking the block and pistons as that raises the ring land too high and IMO compromises the pistons. But it keeps chrome in tact.. That is the only reason it was done that way was to not chip chrome.. A iron sleeved block with ports raised is my preference. I have one here I plan to build that way in the future.. Also if you are going to turn such high rpms you need to consider having the pistons top pinned. VIA John Marles.. A 1 inch spacer will help it get more flow.. a long bell tuner will help I turn high rpms too.. as far as the exhaust chest turn ports down and you can mill out the narrow channels down to maybe 1/4 inch left in it under the bit. Also match the dump ports on the bottom of the block to match up to the tuner. If you were in my area I would help you with machining and such but where is Lindenhurst? Not in the USA?

[evinrudejohnson]

OK I will do I am in lindenhurst long island ny .

[evinrudejohnson]

Cool ! I have 3 blocks I can mod one is a finger ported 2oo . the other is a regular 200 . the last one us a Bridgeport I really don't want to build the Bridgeport so I'm leaning towards the finger ported 200 . they all need one hole fixed how much do you charge for a sleve ? On the 2.4 cherry build do you have to cut into the cyl at all ? I'm worried the chrome might peel .

[Michael J Giesler]

You know who was really good at 2.4 Gene Trickel sorry if i missed spelled his name and Dick O'day also

[That's Right]

Bud Conner "hstream1" has built some hell of a 2.4 monsters.

[David]

What gear case are you running? You might get there with the power you have. I bet an XR6 case would get you close to 100. Of course it would also blow up. My suggestion is to find people who have done big numbers in Ally's and pick their brains.

[bobthebuilder]

David, a 2 to 1 gear and depending on the hull maybe a coned housing but on some boats it actually hurts it being coned. The set up means as much as HP does.. height and prop and set back and so on.. but 100mph has to have the right hull for it.. I personally am looking for a Stroker bass boat hull but I want it at my price not high dollar.. They have been officially clocked at well over 100mph with the right set up..

[evinrudejohnson]

David I was running a xr6 case but the problem is I can't get the height out of my setup being that I have a 20 inch mid right now . over the winter I'm gunna have my mid cut and I'm putting a cle with a Bobs cone together also . I would like to find a sporty . I know that's not the fastest case but it beats messing with bondo .

[bobthebuilder]

You set up is most important.. you are on the correct track to what you want.. I have a nice CLE for sale here. Hardly any hours on it even paint is nice and original paint.. 1200 bucks.. it is not bob coned but could be done.. but work on that set up thing.. I have just changed to another prop and gained 5 mph just from changing it to a different one supposedly same pitch..

[Small strokes]

Pretty much in the same situation I recently picked up a 78 200 for cheap it has 2 steel sleeves and the rest chrome I'd like to put all steel in it and bore to .30 over when I do the rebuild. Befor I start into this I'm new to marine engines but have experience with 2 stroke and four stroke atv dirt bike and snowmobile engines I bought a clymer manual and have the power head off and heads off waiting on my flywheel puller to get here befor I try an go any further. Any advice from anyone would be greatly appreciated. I'm not looking to build a race engine just trying to wake it up a little. My goal is to get 75 to 80 out of my 16ft ceebee avenger bubble deck