Electrical/Mechanical

« **on:** September 28, 2018, 08:22:01 AM »

I recently 4 months ago bought my first jet boat. Restored to my best ability and got it on water, an off I go I can't get past 3200rpm. Upon buying this boat was to be scary fast... Yet it doesn't make me think... I like to think not think on repairs or fixes... I did manage to squeeze 3500rpm yesterday at 50mph, I want another 1500rpm... As it's not in the water I can slap 6500rpm on the hose... Yes I'm sorry I it's bad, yes I did make an intail whack at the throttle, learn one way or another in a state that doesn't have a jet boat mech or dealer... As lonesome as you can imangine, just trying to go fast! Has a Mallory unilite dist., 429 FOMOCO, Wriedt Executive 1974. I'm capable of learning or figuring this out with help or I wouldn't be asking. This is my first jet boat and marine application. Any input or help is appericated... As all the work I have done myself, this was a learning experience, yet she has more to teach me... Thanks

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« **Reply #1 on:** September 28, 2018, 09:11:32 AM »

My guess is ingintion system... Than again the out of water in water lack of rpm has me baffled... As from day one to yesterday night and day difference. It comes out hard and planes quickly, trim all up or plane out sleek, whack the throttle and she lunges and on top. Power isn't a issue it's moreless there is power not getting used in water. I figure this should make 5000 rpm or bang the rev limiter... Or maybe not, I drive shit and I drive it hard. Doesn't matter what I own, I've drove one way since I was 3 WFO! Carb opens up fully, Holley 750 double pumper front jets 86 rear set at 84, altitude 5300, engine temp 160, pop off valve installed off jet set at 16psi, Berkely drive,
place diverter hyd. trim, cast cj intake, exhaust logs with snail's. I haven't messed with the motor as it was turn key and fired when I bought it. Something is robbing power or I'm not getting it's full potential, I'm mentally self taught that if it's not running 100% it will be! Doing what I enjoy, is making money. To do what I love, is going fast! I understand this probably isn't the flat bottom or your typical shallow hull jet boat, it's deep has a V cut and is a bigger boat I'm starting somewhere and wouldn't mind a 2 seater when I don't have to take the kids with me for a project as well.

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« **Reply #2 on:** September 28, 2018, 12:18:16 PM »

Two things that are glaring at me-

1. 3500 rpm out of a big block Ford. Seems quite low. With an 'A' impeller, you should probably see 4800 rpm or so. Need to verify tach is accurate.

2. 50 mph (@3500 rpm) seems fast for the rpm. But a lil on the slow side for 4800 rpm. What was used to verify mph? GPS is the only way to go. Boat speedo's are generous at best..

Also, check for standing water under the floor boards, or saturated foam. A hundred gallons is 8 hundred lbs.

What impeller do you have?

Dan'l

« **Reply #3 on:** September 28, 2018, 12:19:35 PM »

Oh, and welcome to the boards.

Dan'l

« **Reply #4 on:** September 28, 2018, 03:36:52 PM »

Quote from: mash on it on September 28, 2018, 12:18:16 PM

Two things that are glaring at me-

1. 3500 rpm out of a big block Ford. Seems quite low. With an 'A' impeller, you should probably see 4800 rpm or so. Need to verify tach is accurate.

2. 50 mph (@3500 rpm) seems fast for the rpm. But a lil on the slow side for 4800 rpm. What was used to verify mph? GPS is the only way to go. Boat speedo's are generous at best..

Also, check for standing water under the floor boards, or saturated foam. A hundred gallons is 8 hundred lbs.

What impeller do you have?

Dan'l

I have no idea man, I hate to say I'm that green but let's get that out if the way. I talked to the owner as the guy I git it from didn't know where the dip stick was... At any rate if you can let me know how to identify I'll do so. Also the boat is not lacking power by any means an I'm not sure what one of these should go mph wise I'm just looking to correct this issue...

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« **Reply #5 on:** September 28, 2018, 03:43:14 PM »

Quote from: Hall198 on September 28, 2018, 03:36:52 PM

I have no idea man, I hate to say I'm that green but let's get that out if the way. I talked to the owner as the guy I git it from didn't know where the dip stick was... At any rate if you can let me know how to identify I'll do so. Also the boat is not lacking power by any means an I'm not sure what one of these should go mph wise I'm just looking to correct this issue...

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I just went and bought a new distributor, my plan was to re wire from the board on the back of the motor to starter, alternator, coil, ballast resistor, and was wondering what is a good reference chart as this has been hacked on and correcting it. Any correct diagram will do to help me. An as for speed was cal. off speed in boat. I'll pull a gps next run and update. As for tach I set it with a meter based off engine running an cali. an set tach corresponding to meter. I used a fluke meter...

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« **Reply #6 on:** September 28, 2018, 03:43:44 PM »

Thanks for the welcoming and picking up with me on this matter, I appericate it.

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« **Reply #7 on:** September 28, 2018, 03:46:10 PM »

No water in the boat, as it doesn't take on water.... Only water is what splashed in from playing. I tore the boat down to the hull in my overhaul and from where I have my transform of seating to engine bay there is no water and it is dry as sand in dunes...

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« **Reply #8 on:** September 28, 2018, 03:48:52 PM »

Is this boat of any value as I can't find shit on it I bought it for a grand and my work is free have only bought material an hookers time, lol

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« **Reply #9 on:** September 28, 2018, 05:20:42 PM »

Am I hearing 6500 rpm on trailer...3500 in water...?

Have to say jet drive issues.....or the motor cant handle the load.....

And welcome to the boards!

« **Reply #10 on:** September 28, 2018, 05:38:28 PM »

Follow up, read second post...5300' altitude...?

Huge motor losses at that height! We're are you boating?

« **Reply #11 on:** September 28, 2018, 07:04:13 PM »

I pulled 46-4700, 'A' impeller, sbc, about 325 hp at ~500 feet elevation, and 55 mph.

A Marine Power 460 was about the same.

A 'tickled' 429 should easily be 375
-ish hp. Even at 5300 feet.

The housing tag should be marked with the 'original' impeller. That was 40+ years ago. The impeller is marked also, as long as it hasn't been machined. Then ya measure it.

Sounds like speed vs hp is in the ballpark, rpm is outa whack. (Tach)

3200 rpm in my 21' Eliminator Day Cruiser is just on plane. Wide open is a blistering fast 57 mph, GPS'd @4900 rpm , lol (AA impeller) at 500 feet elevation.

Dan'l

« **Reply #12 on:** September 28, 2018, 11:10:55 PM »

Quote from: laveyjoel on September 28, 2018, 05:20:42 PM

Am I hearing 6500 rpm on trailer...3500 in water...?

Have to say jet drive issues.....or the motor cant handle the load.....

And welcome to the boards!

Yes as it tops rpm or speed the throttle is wide open, yet there isn't a thing that says it's being pushed or under heavy load... So after some research and talking with a owner 7 years ago the boat is still epuipped with the same motor. The guy before me says it went out 7 times I'm the last 5yrs. Considering he didn't know where the dip stick was, a. He didn't give 2 shits on what it went threw took in or spit out... The check cover that opens up into the prop does have some dings. Mild little imperfections as much as this is an affect I'm gonna say after reading minor details cut fast and performance fades fast. It's a rough cut not smooth. As reading on props and going for speed an that's what I'm after, I can run a comp test on 8 and from there divide my stack of endless dollars and rebuild an rebuild or dump some money in the jet... So it's true racing on street isn't shit to when you wanna be a racer go for water... Well I see a new field of and I'll say this to the ones and the tried tested and proben and countless hours hats off, I'll join and I have learned the last 4 months but will breach a new tap into physics! So if I wanna go fast I need bowl work... Maybe one good thing about wyoming are long fucking winter's...I suppose any one have and tech tips for great polishing tools, compounds and honestly I want to crack some ass not be the fastest boat but at least respected when it comes to this deep ass v cut boat lol... Maybe not the best choice for a racer but I know it can be achieved. I'll rip the whole drive out strip it down and inside and out begin polishing the as all in all that's my biggest hold up of speed maybe some issue with the jet as well but right now jet needs more attention than anything. My physics of drag racing motocross an whiskey throttle wont get her faster.... Life is good!

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« **Reply #13 on:** September 28, 2018, 11:11:33 PM »

Quote from: laveyjoel on September 28, 2018, 05:38:28 PM

Follow up, read second post...5300' altitude...?

Huge motor losses at that height! We're are you boating?

Wyoming

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« **Reply #14 on:** September 28, 2018, 11:19:18 PM »

Quote from: Hall198 on September 28, 2018, 11:11:33 PM

Wyoming

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Is it hard to to make 75mph on the water or cost just the biggest problem... I'm set at that as a too speed as I'm lost to what it takes. I'm ready for a potion and to smash it threw the punch bowl of mine an make rooster tails

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« **Reply #15 on:** September 28, 2018, 11:23:28 PM »

Quote from: Hall198 on September 28, 2018, 11:11:33 PM

Wyoming

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Sea level what's that...?

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« **Reply #16 on:** September 29, 2018, 07:16:50 AM »

An carb motor loses 3% power for every 1000'. @ 5300, your 16% under power to start.

That is not a 75mph jet hull with the deep vee, thats ok...

Understand, jets are the most inefficient drive out there...you need a streamline hull and serious power/pump to hit 75+, at sea level...

First boat, enjoy...learn...dont sink in yo much $....then purchase up!!

« **Reply #17 on:** September 29, 2018, 01:21:18 PM »

Alright well shit I hate to sell the boat an upgrade but I'll look around for another one. The motor isn't under power or at least from my stand point and allittude. Though I have rewired this boat last night and today I found a few problems and I think that most of it or some of it was wiring to coil and voltage not up to par, alternator not wired correctly as I have kept my mallory and got a new photo cell an ballast I'm gonna load up do some testing an lern to be happy with what I got an do some work over the winter and get some speed out of her... All aside yeah I get the truth as it's not a fast ass boat but this is a good start and eventually that will come.

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« **Reply #18 on:** September 29, 2018, 01:23:44 PM »

Does anyone have a subject stand point if value possibly as I can't find much but it's got a new floor carpet new interior new paint pinstrip and my blood an sweat but I put alot of work in this in 4 months and I'll get pics of the motor as it's all been cleaned up as well... I just need to finish the rear section as winter was coming I will have that all done.

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« **Reply #19 on:** September 29, 2018, 01:52:38 PM »

As for it being what I dream I completely understand it'll never be what I imagined. Though great to take the kids and family out it can be the ladies boat she likes it enough that I bet a fund another build for keeping it lololololol.... Though I appericate everyone and the help and in lightening me on somethings I was about to throw some money at.

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« **Reply #20 on:** October 01, 2018, 08:19:39 AM »

After all wiring cleaned up landing in correct places, photo cell working as well as a supplied 12+ volts everything came together... For the most part. 3800rpm Max at a solid 50mph gps and speedo, I am only yet certain the impeller an intake or any other corresponding component is where my lack of rpm is going and if I'm correct air cavity of loading is my culprit of lost performance... My jet stream or tail isn't clean and tight more like a garden hose spray... Seems I'm losing or have something creating air and it being a factor... Thanks for the general help yet I took it all in and read alot learned alot and you guys are awesome thanks for the general advice. I'm happy with what it show cased I only now what to make it efficient and clean up some loose ends in the jet system. It's time for a new hull/boat... I just want to hall-ass an crack some ass...

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« **Reply #21 on:** October 02, 2018, 02:00:51 PM »

My sons jet boat had a rock the size of a golf ball stuck in one of the bowl veins. Surprisingly the impeller didn't look that bad for having a large rock pass through it. If you pull the bowl off you might find something going on there.

« **Reply #22 on:** October 02, 2018, 04:09:34 PM »

Quote from: spectralen on October 02, 2018, 02:00:51 PM

My sons jet boat had a rock the size of a golf ball stuck in one of the bowl veins. Surprisingly the impeller didn't look that bad for having a large rock pass through it. If you pull the bowl off you might find something going on there.

^^^this.

If the rpm are accurate, as well as speed, either the impeller is waaaay to large, or there is an obstruction in the pump.

A seal leaking air, a bad wear ring, a messed up impeller (cavitation), all would INCREASE rpm.

Time to pull apart the pump.

Dan'l