New to tinboats

[Grease Slinger]

Hello everyone , new here but love this jet boat section. Ive literally looked threw all 30 some pages reading any thread that caught my eye. But anyways I have a 1648 Alweld with a 75 evinrude on it and my main problem is speed ( yes you read that right) . It'll only run 30 . My boat is mostly used for fishing for cold cans . Not a fisherman . Motor seems to run fine , everything is set up good , bottom of boat is decent. Over the winter I planned on doing some hotrod stuff to the motor (has a 6 7/8 impeller in it and wouldnt pull a 7 3/16's i bought , thats my goal) and redoing the boat. It's not quite set up how I want and I think I could shed some weight that way = speed. But before I do that , anyone have a idea what a bare 1648 blazer ss goes for ? Like nothing in it but the ribs . Thanks everyone !

 

[Lil' Blue Rude]

If you wanna go fast I'm your guy. lol :mrgreen: Last time I checked on a 16' 48" Blazer ss they were around $2500.
Your 75hp isn't going to pull a 7 3/16, sorry just not gonna happen. You've probably got the 49 cube block since it's 75hp, if you have the 56 cube block you can get it built up to pull the 7 3/16 impeller but your better of just getting a 6 7/8 stainless 3 blade. The 49 cube is better for high rpm the 56 is better for low end torque. jets need low end torque. It's hard to get back the low end torque with a 49 cube because of the port lay out on them. You can put a 56 cube powerhead on your current mid section, just have to swap out the exhaust and the drive shaft or put the 49 crank in the 56 cube block.

 

[Grease Slinger]

Lil blue rude I very much expecteded you to hit this up. Yes your are the guy I'm after , buuuuttt I'm kinda stuck on the 49. I've poured over fast Fred's on brf , read every page twice ( seen ya there and on here in all the right places ) but really I'm stuck on the 49 ( I already own it lol ) the thing with the 56 is isn't there exahuast cast in ? I figure there losing a lot there ( I really don't care bout hole shot more top end cruising) , yes I know your gonna preach the 56 . Spare me lol , I wasn't joking about reading all that. I'm planning new pistons , maybe some finger ports and maybe some laughing gas to prove a point every now and then . It will pull that 7 +by the time I'm done lol . I'm gonna call in a day or two and price some . I almost think over half the batle is my boat . Idk I guess we'll really see come spring

 

[Lil' Blue Rude]

To each there own. Love to see a fast 49 with a pump but have my doubts. Fast freds a big talker, when it comes to a jet pump he don't know squat.
Yes the exhaust runners are cast in but the exhaust tuner isn't cast in and can be replaced. If you don't have enough torque to get up top then having all the hp in the world up top won't do you any good. You have to be able to get over that hump. You want torque with a jet, if you don't have that it's gonna be a sluggish motor that takes forever to get going.
More power to you if you want to build a 49'er. I'm interest in the build and I'd be happy to help with any questions you got and come spring if you got a motor put together you thinks hot and wanna run them I'd be happy to line up and see what it's got.
How fast are you wanting to go?

 

[Grease Slinger]

I know it's a challenge but I figure worse comes to worse I end up right where I started , witha slow boat lol. And yea he does a lot of talkin but lots of good info from others on there too. Just curious did you change your port heights much ? I know we got two different animals but didn't know if you had found what works best or what to stay away from ? And the little support in the pump , can it be removed ? Will it help anything ? I'm gonna polish the insides . Did you put a lightened fly wheel on ? Been around truck pulling a long time and know that's not wise there and jets kinda translate over roughly. And we'll see come spring if it's anything worth talkin bout haha . I'm pretty familiar with 4 strokes ( built a few gassers and more diesels than i can count ) messed around with a banshee I had once but a ob 2 stroke is a whole new ball game to me. Got a few buddies who know all kinds of stuff bout 2 stroke 4 wheelers but no ones ever been in a ob. So I'm trying to soak up all the knowledge I can and appreciate any input.

 

[Grease Slinger]

And if I could run 40 to 45 I'd have the biggest grin on the river. But realistically I'd say upper 30s would be ok

 

[Lil' Blue Rude]

Stay away from changing port height especially on that motor. Finger ports help. Leave the support in the pump. With outboards the lighter rotating assembly helps make the motor more responsive. Look up Gordon Jennings two stroke tuning hand book. A lot of good info on porting and what changes effects what. He talks about high rpm street bikes from the 70's or so but a lot of it still applies to all two strokes.

Your boat can probably make upper 30's but still don't thing it's gonna pull the 7 3/16 impeller. I've hit 50mph with a 6 7/8 3 blade stainless.

 

[Keystone]

opcorn:

All I can do is sit by and read. I know almost next to nothing about the jet stuff.

 

[Grease Slinger]

I'm not looking for responsive , mine will need all the torque it can find and little factor in truck pullin is the more rotating mass the harder it is to fall off the power band but then again thats bbc v-8's . And on the 7 feller collecting dust in the garage , off sound ( never had a tach in it ) I'd say it was doin 2k ish with it , 21mph gpsd with 3 peep . Roughly guessing with the 6 its runnin mid 6k at 30 mph ( sounds healthy don't labor bad at all) . I think it was right on the line of doin something or laying down and it layed down . All guesses , but half decent idea . On port hieght I don't want to raise it but I was thinking of widening it and maybe bringing down the bottom side with a decent curvature and makin the top match. I've read the two stroke tuners handbook and did plenty of math on the side to find out expansion chambers ain't the ticket on out boards unless you want lotsa attention . And in serious moment how do you feel bout the stainless ? Would ya of bought it was plated in gold if ya know what it does ?

 

[Lil' Blue Rude]

Boats and pullers are different when it comes to that. The water has some give to it. So having a lighter rotating assembly doesn't really lose that much inertia vs a puller with a light rotating assembly. Just makes it little easier to get going. Plus it's easier on the top main bearing of a outboard to have a light flywheel.

I run a stainless in every motor I've had and see at least 1mph gain in them. Seem to have a better hole shot. Worth the money if you want to go fast. Just make sure to get a 3 blade and not the 4 blade. 4 blades are slower.

 

[Grease Slinger]

Well 1 mph is worth every cent ! (Never thought I'd say that and be serious lmao) .I guess that does make sense , not a load against a solid surface . So would you suggest having it turned down or search for I think it was the 50hp one ?

 

[Lil' Blue Rude]

Been told the older model flywheels might come apart if there turned down, something about the way they are cast leaves all the strength in the outer skin. Not worth the chance of getting someone hurt to turn one of them down. the 94 and up cast iron ones can be turned down. Not sure how much though. Normal 50hp fly wheel won't work. The mod50 flywheels will work. There's 2 different ones the red ones and the gold ones. Not easy to find and not cheap.

 

[Grease Slinger]

Yea defently not worth risking it , had a old man tell me once he had a fly wheel come apart in his race car and cut the header in half. I don't want no ones head comin off cause I'm huntin speed. I looked it up I guess it's the 65hp that will work and it's 3 pounds heavier than a mod 50 so I'll begin the search I guess . Another random thing I've thought about , buddies got a completely ruined intake foot I thought about playing with , making it into a scoop shape . Your thoughts ? It would be positive pressure against it instead of a suction but didnt know if it might bring in a bunch of drag . And then there's those pesky rocks lol

 

[Lil' Blue Rude]

1972 65hp will work, weights about 7lbs or so. you have to trim on your timer base to make it fit. The radius from the flywheel to the hub isn't enough to clear so you have to trim the timer base at the edge. You can clean up the intake to help water flow but I think making a scoop will create to much drag. You can cut the leading edge of the liner to help water flow.

 

[Grease Slinger]

The one in the center has to be cut down or the stator ? I replaced the stator when I first got this thing and its a lil fuzzy remember what's goin on under there . Once it all gets back together I might try a little scoop ish kinda thing. I've already worked the shoe over pretty good and beveled the liner. I'm actually in the garge yankin the motor right now. So let the fun begin lol

 

[Lil' Blue Rude]

The one in the middle. You'll see what I'm talking about if you get one of those flywheels. Are you going with cast or forged pistons? How high are you planning on getting the compression? What kinda reeds you going with? I like my compression around 140-150psi Can be higher but it's harder on the motor.
Personally I use cast pistons because I don't get compression high enough or turn enough rpms to need the forged pistons. A lot of people on scream and fly like to nickname the wisecos "sticko's". Thinks it's due to the locator pins coming out. The forged pistons expand more then a cast piston when hot and over time the locater pins sometime loosen u and eventually fall out. Also a forged piston needs to come up to operating temp before taking off (guess all motors should be) but with the forged pistons there's extra clearance between the cylinder and pistons to allow the pistons expansion when at operating temp. You probably know all about the cast vs forged piston but figured I'd explain for any one else that's wondering.
When you get the head off take a pic of the ports. might be able to help you out with it. Use to have a 49 block laying around but that's been a few years back.

 

[Grease Slinger]

I planned on using wisecos . Seems like most of the threads I've seen on wisecos going bad where older ones , seen on one someone said they changed they're recipe a little and didn't have as bad of a problem with swelling. I'm assuming your saying they swell some , lose the pin , ring moves to a port , break and everything goes catistrophic. Anyways it seems like with plenty of clearance and a good break in they'll do the trick. I'm planning on keepin a extra 10 pounds on the boat at all times, that's why forged . Got a buddy with a shoal runner I'd like to take down whenever I want hahaha. Comp i was thinkin 155-165 range . Not a lot of info on spray and outboards and I figure that's safe ish . Reeds I was thinking boysen but seen a lot of good things about Carson I think it is. One problem I am having is uploading pictures on here. Guess its a I device problem. And if ya run across that block I might need it sometime , seems like I might be venturing into uncharted water

 

[Grease Slinger]

Also didn't know if studding the head would be a good idea with nos. And what about head gaskets ? Are they known to let go often ? Are there options ? Like copper or a mls ? And maybe not this go around but what you think about a e-85 setup . I kinda think a high comp e85 setup would be pretty bitchen but didn't know if the carbs could be retrofitted

 

[Lil' Blue Rude]

What kind of setup are you gonna run with the nitrous? Are you going to fog it in the air box or plumb it behind the reed in the front half? Are you gonna run a enrichment system? I'd start with 140-150psi especially if your gonna run nitrous. Probably want to back of the timing alteast for the first couple test then play with it when you get to tuning it in.You can always shave a little more of the head. Are you gonna run premium? How big of shot are you planning on running?
A guy around here runs a 50 shot in a 60/40 merc. Think he's set it up for 75 shot and maybe even tried a 100 shot before. Don't think it held together or he was afraid of blowing it with the 100 shot. Can't really remember. I've heard of a couple guys running nitrous around. 2 were 60/40 merc and the other was a 56cube omc. The mercs ran good but a built 56 would still beat them and the 56 had to be detuned enough to keep it from blowing, it didn't gain much so he ditched it.
As far as reeds go I think Chris Carson's are better then Boyseens. From what I've seen and read the boyseens fray at the ends and don't seal well after a little bit of run time. There's a test on scream and fly between Boyseens, Chris Carson's, and TDR's. Carson's and TDR's are about the same the Boyseens made a little more power but they where fraying by the end of testing.
You can have the heads cut for O-rings, studding it probably wouldn't hurt. Don't know of anybody around here doing it. These head gaskes can let go. Always use a new one if you pull the head off.
Think it was on here where a guy converted a 15 or 25hp to a e 85 motor. Might of been another forum but I think it was tinboats.
You might look into Klotz Nitro or Klotz Cozoc (think that's how it's spelled lol) Gasline additive. Don't think it's as hard on the motor as nitrous. Plus it's a power adder that don't run out until the gas tanks empty. Never used it but seen a few guys that have. Think it's good for a couple hundred rpms and better holeshot. I'm more of a all motor guy myself. Don't want someone using that as an excuse for getting beat. :mrgreen:

 

[Grease Slinger]

Wet single stage port plumbed in behind the reeds. Unless there's somethin your thinkin might be better ? Figured I'd start at 75 ( why not try doubling out the gate lol ) and like to work up and see what seems safeish from there . And I always run premium ( non eth) True I could always go further , and I've even thought about buying another one or two off flee bay and have em cut different . I see em cheap enough and deffently if I have orings cut. And always a new HG . And Ill have to check that out , I wonder how seals hold up over time. And I never heard of that stuff I'll have to check it out , I'm just thinking of very upper end of the compression range , e85 , and loads of timing . Only down fall would be shorter fuel range and if it ate up seals. Seams like they have the separation issues fixed these days. And the only excuse I'd bring along is I didn't bring my cubic inches with me today :LOL2: