SoCal Jet Boats

Tech Talk => Engine Mechanical / Electrical => Topic started by: SoonerFan on January 25, 2009, 05:15:16 PM

Title: MPH ???
Post by: SoonerFan on January 25, 2009, 05:15:16 PM
Hey Guys !! Well I got the starter issue taken care of....thank god !! So I took the boat out to Silverwood today ( I also head the carb rebuilt ) and I took my GPS and I had the go pedal to the floor and could only get her to 32 MPH ??? the motor ( BBC 454 ) sounded fine but thats all I could get from her....does this sound right?? the boat is a 21 footer...any thoughts ?? and dont say get a ford !!  ;D  Just a thought from a rookie wrench turner....can I adjust the go pedal at the carb??
Title: Re: MPH ???
Post by: 76 Bonneville on January 25, 2009, 05:21:01 PM
What kind of rpm's.
Most 21's should get to at least 50 mph.
What hull is it again?
Whats the altitude of Silverwood?
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 05:25:52 PM
it was pushing 4500rpm , its a daycruiser ( hawaiian ) silverwood lake is around 3350 ft I believe
Title: Re: MPH ???
Post by: GT Jets on January 25, 2009, 05:30:16 PM
Here's a check list for ya. Not neccisarily in any order...

Ignition timing.  ;)

Carb. linkage (wot?)  ;)

Secondaries in the carb working fuel wise?  :-\

Cam timing.  :-\

Dead cat or something in the pump?  :P

Gonna be something fairly easy to find IMO, our Spectra 20 did just a tick over 60 with a 455 Olds, Berkeley pump and a diverter.

GT

Title: Re: MPH ???
Post by: GT Jets on January 25, 2009, 05:32:56 PM
Hey Guys !! Well I got the starter issue taken care of....thank god !! So I took the boat out to Silverwood today ( I also head the carb rebuilt ) and I took my GPS and I had the go pedal to the floor and could only get her to 32 MPH ??? the motor ( BBC 454 ) sounded fine but thats all I could get from her....does this sound right?? the boat is a 21 footer...any thoughts ?? and dont say get a ford !!  ;D  Just a thought from a rookie wrench turner....can I adjust the go pedal at the carb??

You need to lower the floor LOL. ;D

Reverse gate opening 100% ?

It almost sounds like the boat is heavy, Water?

GT
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 05:41:16 PM
I had the engine timed and the carb rebuilt we ran it and to check if everything was working correctly....the dead cat could be an issue !!  ;D  also I just had a droop and diverter put on !! reverse gate?? whats this?? I didnt take on any water hardly at all on this run water was like glass I assume because it was 50 degrees  :sly:
Title: Re: MPH ???
Post by: GT Jets on January 25, 2009, 05:46:23 PM
I had the engine timed and the carb rebuilt we ran it and to check if everything was working correctly....the dead cat could be an issue !!  ;D  also I just had a droop and diverter put on !! reverse gate?? whats this?? I didnt take on any water hardly at all on this run water was like glass I assume because it was 50 degrees  :sly:

Soonerfan, don't take this the wrong way, but not sure a droop will help on a 21' boat, maybe...
The reverse gate is the cover over the diverter, if it hangs below the outlet it will hamper the boats speed....Big Time...

How high was the rooster? too much diverter will do goofy stuff too. I would think the boat should be in the high 40's at 3500+/- feet altitude...

GT
Title: Re: MPH ???
Post by: BOOST on January 25, 2009, 05:48:03 PM
 Testing at silver wood is not the best test and tune because of the altitude less air,between silver wood and Elsinore gained 7mph@ Elsinore if the boat is not trimmed right you will lose mph, just my o2.
Title: Re: MPH ???
Post by: FORKEDUP on January 25, 2009, 06:39:52 PM
dumb question but have you verified you are actually getting full throttle, i know when i put mine together everything seemed fine working the carbs by hand, but as soon as i used the gas pedal i was only getting about 75% throttle. quick adjustment and problem solved.
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 07:34:48 PM
Soonerfan, don't take this the wrong way, but not sure a droop will help on a 21' boat, maybe...
The reverse gate is the cover over the diverter, if it hangs below the outlet it will hamper the boats speed....Big Time...

How high was the rooster? too much diverter will do goofy stuff too. I would think the boat should be in the high 40's at 3500+/- feet altitude...

GT
GT thanks not how I roll ! ;D I wouldnt take anything the wrong way!! Im asking the questions and you my friend are giving me great info !! I wanted the diverter put on and the guy put on the droop and diverter for the same price .. I will DEFINETLY check the reverse gate and see if Im getting full throttle!! The rooster was a good 25 feet high and about 100 feet long Id say  ;D
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 07:37:12 PM
Testing at silver wood is not the best test and tune because of the altitude less air,between silver wood and Elsinore gained 7mph@ Elsinore if the boat is not trimmed right you will lose mph, just my o2.
Thats good to know but that would stiil only put it at around say 40 mph...there has to be something I'm overlooking...but thanks for all the great info!!
Title: Re: MPH ???
Post by: crewchief22 on January 25, 2009, 07:44:48 PM

It almost sounds like the boat is heavy, Water?

GT

What GT is talking about here is if the boat is heavy due to excessive water saturation of the foam or wood under the floor. 

There is a thread with a bunch of pics showing the crap that can be wet under the floor (if I can find it I'll post the link)

Title: Re: MPH ???
Post by: GT Jets on January 25, 2009, 07:47:58 PM
GT thanks not how I roll ! ;D I wouldnt take anything the wrong way!! Im asking the questions and you my friend are giving me great info !! I wanted the diverter put on and the guy put on the droop and diverter for the same price .. I will DEFINETLY check the reverse gate and see if Im getting full throttle!! The rooster was a good 25 feet high and about 100 feet long Id say  ;D

If the roost was more than say 6' high, the rest is not real conducive to top speed, especially on a 21' boat...with the droop, you're trying to lift too much ass end (where have I heard that before?  :sly: ) out of the water...it makes the hull "plow" and will really lower the performance, luckily it's not difficult to change stuff around, I would see if you could borrow some different attatchments and play around with the setup..


I'd like to see a pic of the pump if not too much of a pain in the arse. :-\

GT



Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 08:00:02 PM
do you need exterior or interior ?  :sly:
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 08:02:15 PM
What GT is talking about here is if the boat is heavy due to excessive water saturation of the foam or wood under the floor. 

There is a thread with a bunch of pics showing the crap that can be wet under the floor (if I can find it I'll post the link)


How can you tell if the under floor is wet ?? and how do you stop it if thats the issue??  :sly:
Title: Re: MPH ???
Post by: Stevecat on January 25, 2009, 08:25:15 PM
How can you tell if the under floor is wet ?? and how do you stop it if thats the issue??  :sly:

One day many, many years ago I was puttering around on my boat in the driveway and looked closely at the floor (I have a false floor over the top of the stringers). I noticed what seemed like white spidery mold under the resin and cloth. So I took either a spade wood drill bit or a small hole saw and made a small "core sample" of the floor. Soppin wet with little critters crawlin around (boat aliens I guess).  :screwy:

I probably should have yanked anything I could off the boat and hauled the hull to the dump. But instead I decided to "redo" everything. When I cut out the stringers they weighed about 100lbs each (full of water) and the flotation foam was another 200lbs of water. Tearin out was fast and easy. Putting it back together just took another 11 years.... :banghead:  :banghead:

Most likely your slow speed is something other than evil water in the hull. GT's got a good list of the likely suspects for you. He's even got a great story about some ski rope instead of a dead cat in the pump...
Title: Re: MPH ???
Post by: GT Jets on January 25, 2009, 08:49:41 PM
SoonerFan, I like that "half snoot", not sure if it's a good fit for a 21 though, looks like a pretty sweet setup. Tom (JBP) will probably chime in soon, but I'm thinking that snoot may be hurting you, I have only had good luck with snoots on really light "flighty" hulls, on the other hand I have heard folks having good luck on larger boats, just not me..

I would do some more testing and maybe as a shot in the dark have it weighed. Also as Stevecat says, make sure there isn't 200' of rope around the impeller shaft LMAO.

GT
Title: Re: MPH ???
Post by: GlassCutter on January 25, 2009, 08:59:41 PM
It has been my experience (but never my fault) that even 6 feet of rope will result in an engine speed of 4 grand and a forward speed of appox. 1 mph.    Gotta luv the usually easy fix.
Title: Re: MPH ???
Post by: SoonerFan on January 25, 2009, 09:07:51 PM
So what your saying is that if I see a piece of rope hanging out my water intake like a tampon string I know what the prob is huh  :sly: On another note I went out and tested the reverse gate and its completely clear of the outlet !! I have this weird feeling its the carb linkage... I'll take a look at it tomorrow
Title: Re: MPH ???
Post by: Stevecat on January 25, 2009, 09:30:36 PM
It has been my experience (but never my fault) that even 6 feet of rope will result in an engine speed of 4 grand and a forward speed of appox. 1 mph.    Gotta luv the usually easy fix.

Ya, Glasscutter is right, even a duck turd in the impeller will drop the boat speed to nuthin. You probably don't have anything inside the pump that's not supposed to be there.
Title: Re: MPH ???
Post by: beerjet on January 25, 2009, 10:44:21 PM
I had a fist full of weeds in the pump and my Hallett 21 (which is a tank) and it didnt want to do a thing .
Mashed the gas and it felt like it was in neutral .
Idled around fine.
Maybe rocks in the bowl too.

-beerjet-
Title: Re: MPH ???
Post by: crewchief22 on January 26, 2009, 05:54:45 AM
I had a fist full of weeds in the pump and my Hallett 21 (which is a tank) and it didnt want to do a thing .
Mashed the gas and it felt like it was in neutral .
Idled around fine.
Maybe rocks in the bowl too.

-beerjet-

With only one rock inside the grate it would idle and move around great with no throttle but as soon as it hit 3000 rpm it would start to vibrate.
Title: Re: MPH ???
Post by: Nordie on January 26, 2009, 06:19:46 AM
atleast this is all good future reference stuff as soon as you get the problem worked out
Title: Re: MPH ???
Post by: Legal Chemistry on January 26, 2009, 10:14:36 AM
There is NO WAY you should see only 30mph!  Check your throttle linkage and make sure the primary/secondaries are opening.  If your primary isn't opening all the way and not enough vacuum for the secondaries -you're at less than half throttle.   With just your primaries you should see more than 30 or 40.  Look under your intake, maybe there a rope.  Check the weep hole -maybe there's a elephant jammed in the there???   

A little perspective:  My 25 Euro, stock 454, ,4 people and easily another 400# of gear and gas will do 50.
Title: Re: MPH ???
Post by: Legal Chemistry on January 26, 2009, 10:17:01 AM
BTW, when my secondaries aren't open I'll see ~4200rpm.
Title: Re: MPH ???
Post by: electrowoman on January 27, 2009, 04:24:06 PM
You may have way to small jets in your carb.   What size are they?  We put a 750 on my 460 out of the
box for break in day and it wouldn't even pull up on plane.  Between the dinky jets and the way heavy seconday spring it was really dead.
 
We putted around for half hour and went back to change oil.  Put on the 850 with 80's all the way around and off she went! 

I'm wondering if your jet doesn't need rebuilt.  Mine is a 23' day cruiser and pulled 4500 rpm's bone stock.  The speed was 51 mph.
Title: Re: MPH ???
Post by: SoonerFan on January 27, 2009, 07:21:37 PM
Hey Electrowoman this is good stuff  ;D   Im not sure on the carb I'll check it when the boat comes back from getting the trailer brakes redone  :banghead:  between this and the go pedal linkage Im pretty sure you all narrowed it WAY down..thanks so much to all...Oh and about the "Boat Aliens" Stevecat we'll just forget that whole post  ;D 
Title: Re: MPH ???
Post by: SoonerFan on January 30, 2009, 11:52:30 PM
Well so far Ive checked the carb linkage ( looks good ) Checked the intake ( no rope ) checked the weep hole ( No elephant )  ;D   Still need to check the primaries/secondaries/jets
Title: Re: MPH ???
Post by: crewchief22 on January 31, 2009, 07:26:29 AM
This is some good information from another thread.

Hey Mike
I remember your boat now that I can see it. I met you up at Berryessa a few years ago with the Laid Back Boaters. I was driving the orange Nordic minicruiser, sitting under the bridge with Cas. I thought your boat ran really well with that panther.

I just read through this thread. My question would be what did the motor sound like at the 4200 rpms? Did it run strong right up to the 4200, or kind of "starve out" ? I had a similar experience in a sleekcraft that I put a good BBC (from another boat) into. Started right up, ran great on the trailer, but when I got to the lake, it wouldn't go above 4000 rpms. I fiddled with the timing, fuel filter, carb, an figured it needed a tune up. Took it home and it ran perfect on the trailer, but I changed the points (yes it was that long ago) and plugs. Went back to the lake and its back at 4000 rpms. I was about ready to pull the plug, when I decided to disconnect the fuel line from the tank and poke it down the fuel fill--whoa, all of a sudden I was getting 5200 rpms out of that little race boat. Turns out the screens in both tanks were clogged, and restricting the fuel flow. Fuel flow was fine at idle, and with no load on the pump, but not enough to feed the motor past the 4000 rpms in the water. All I had to do is take the sending tubes out of the tanks and replace the screens. Maybe you've already figured it out, but I thought I'd relate my experience.

Mark--"Sanger Pete"

Title: Re: MPH ???
Post by: Sanger Pete on January 31, 2009, 12:51:12 PM
Hey Soonerfan
Saw your boat in a previous thread--looks good. You mentioned there that you took the boat to Perris. How did it run there? Similar rpms? Did it seem alot faster?
Title: Re: MPH ???
Post by: pw_Tony on January 31, 2009, 01:22:13 PM
Something I couldn't see when I took the pump apart in my Spectra. It looked like somebody decided to throw a bunch a rocks into the bowl from the back.... totally trashed my impeller..... don't know how or why.

I wish I had a picture.... I'll have to see if I can find one.... Looking from my intake side of the boat, the impeller looked fine.... but when I took it apart the back half of the blades on the impeller were GONE... broken off.... I couldn't beleive it even moved when I took it apart.... Just a thought

Tony
Title: Re: MPH ???
Post by: SoonerFan on January 31, 2009, 01:34:31 PM
Hey Soonerfan
Saw your boat in a previous thread--looks good. You mentioned there that you took the boat to Perris. How did it run there? Similar rpms? Did it seem alot faster?
yea it ran great, was hitting 50 mph now it just doesnt have the speed..still runs good though
Title: Re: MPH ???
Post by: SoonerFan on January 31, 2009, 03:31:47 PM
Hey Guys.... Ok I have a question for you all...this still concerns my MPH..I was talking to my dad and he asked me what octane gas I was running?? does the octane of the gas have anything to do with the MPH ?? I told you all I was a newb to this jet boat thing !!  ;D
Title: Re: MPH ???
Post by: Sanger Pete on January 31, 2009, 04:15:43 PM
Hmm, a real puzzle. Essentially you've lost approx 20 mph by adding a droop and PD. It seems to me that (1) the motor is OK--4500rpms @ 3500' elevation in a 21' boat sounds about right. (2) the pump is loading OK if you re getting a 100' roost 20' high. If the pump was cavitating, I think your rpms would be higher, and your speed even lower. I've had junk in my pump and had a very loose pump before, and the problem isn't from 30mph to 50 mph, it's from 0 to 15. (3) I'm not sure your boat could hold enough water to slow its speed by approx 20 mph unless it was more than ankle depth--and then it would be pretty noticable.

It sounds to me like something must be dragging in the water--maybe the droop, the box anchor, or like I read one time, "A guy went to the lake for the first time to run his new boat. He launched the boat , idled out and proceeded to run it around the lake. However, he was very disapponted with the top speed which was much lower than he had expected. Back at the ramp he found out that most people disconnect the boat from the trailer when they go boating." That old trailer was just causing too much drag.

I think I would take off the droop, although I've never seen one cause this much of a loss of speed.



Title: Re: MPH ???
Post by: SoonerFan on January 31, 2009, 04:23:57 PM
LMAO !!  Ok I feel beeter now !! Im that THAT Newb  ;D  yea this is a puzzle well I'll pull the droop off and see if i helps..I can always put it back on  :banghead: but losing 20mph from that is it possible ?? :sly:
Title: Re: MPH ???
Post by: GT Jets on January 31, 2009, 05:08:06 PM
LMAO !!  Ok I feel beeter now !! Im that THAT Newb  ;D  yea this is a puzzle well I'll pull the droop off and see if i helps..I can always put it back on  :banghead: but losing 20mph from that is it possible ?? :sly:

I don't know about 20 mph, but definately 5 or even 10, it may be and probably is more than one thing....Removing the snoot is inexpensive and reversable, definately worth a shot...

GT
Title: Re: MPH ???
Post by: SoonerFan on February 03, 2009, 07:18:41 PM
Hmm, a real puzzle. Essentially you've lost approx 20 mph by adding a droop and PD. It seems to me that (1) the motor is OK--4500rpms @ 3500' elevation in a 21' boat sounds about right. (2) the pump is loading OK if you re getting a 100' roost 20' high. If the pump was cavitating, I think your rpms would be higher, and your speed even lower. I've had junk in my pump and had a very loose pump before, and the problem isn't from 30mph to 50 mph, it's from 0 to 15. (3) I'm not sure your boat could hold enough water to slow its speed by approx 20 mph unless it was more than ankle depth--and then it would be pretty noticable.

It sounds to me like something must be dragging in the water--maybe the droop, the box anchor, or like I read one time, "A guy went to the lake for the first time to run his new boat. He launched the boat , idled out and proceeded to run it around the lake. However, he was very disapponted with the top speed which was much lower than he had expected. Back at the ramp he found out that most people disconnect the boat from the trailer when they go boating." That old trailer was just causing too much drag.

I think I would take off the droop, although I've never seen one cause this much of a loss of speed.




I was looking at the droop before I pull it off and it doesnt hang below the boat?? so would that slow it down at all?? Could running 87 compaerd to 91 octane have that much affect on MPH ?? and there was no anchor OR TRAILER dragging  :sly:
Title: Re: MPH ???
Post by: Stevecat on February 06, 2009, 03:55:23 PM
  also I just had a droop and diverter put on !! reverse gate?? whats this??
Quote

Wild idea. What kind of reverser lever do you have? Is it by itself or part of a combo gas/reverser lever?

You said you had a diverter installed, right? That means the reverser bucket/linkage is new to the boat (even if it's used equip). The Place diverter bucket geometry and travel is "different" from what the boat had before. If you have a combo throttle/reverser control lever then maybe the reverser bucket is opening all the way but stopping the throttle cam/linkage in the control lever from going further an letting your motor rev higher.

Ask me why I suspect this and what I've been doing for 45 minutes!  :sly:
Title: Re: MPH ???
Post by: SoonerFan on February 07, 2009, 01:11:39 PM
  also I just had a droop and diverter put on !! reverse gate?? whats this??
Quote
My forward/reverse/throttle is not a combo...I have a foot pedal and a l ever for forward/reverse. what kind it is im not sure...I pushed the pedal to the floor and it had WOT...this is so weird..I had it all timed and the carb rebuilt..i took it out and from GPS it would hit about 32mph and when I use the diverter which is way cool by the way  ;D  I got down to about 28 mph  :banghead:

Wild idea. What kind of reverser lever do you have? Is it by itself or part of a combo gas/reverser lever?

You said you had a diverter installed, right? That means the reverser bucket/linkage is new to the boat (even if it's used equip). The Place diverter bucket geometry and travel is "different" from what the boat had before. If you have a combo throttle/reverser control lever then maybe the reverser bucket is opening all the way but stopping the throttle cam/linkage in the control lever from going further an letting your motor rev higher.

Ask me why I suspect this and what I've been doing for 45 minutes!  :sly:
Title: Re: MPH ???
Post by: GT Jets on February 09, 2009, 11:53:24 PM
Hey sonnerfan,

I think I have an idea that will help your top speed out, taking a closer look at your picture of the back of the boat I noticed you have a set of trim tabs on the transom....yank em', or otherwise raise them up as high as they will go, it looks as though they are in quite a down setting and creating a big fiberglass barge, the idea is to get the bow up a bit to get some boat out of the water, the tabs will make the ride quality most exellent, but at the cost of performance, could be wrong, but worth a shot...

GT
Title: Re: MPH ???
Post by: SoonerFan on February 11, 2009, 01:48:44 PM
GT, sounds like a good thought I'll raise them and see what happens..Im about ready to just rebuild the Jet !! Now my gas gauges and tach went out...ohhhh the life of the jet boat  :sly:
Title: Re: MPH ???
Post by: SoonerFan on February 12, 2009, 10:23:36 AM
Hey GT,  I havent yet tried out your idea yet weather here has not been very nice to me....you were right the tabs were all the way down though ..Good Eye !! Im just going to pull them off....but as I was looking at them I was wondering ...why are there trim tabs on here at all ??
Title: Re: MPH ???
Post by: GT Jets on February 12, 2009, 05:43:42 PM
Hey GT,  I havent yet tried out your idea yet weather here has not been very nice to me....you were right the tabs were all the way down though ..Good Eye !! Im just going to pull them off....but as I was looking at them I was wondering ...why are there trim tabs on here at all ??

Like I said before, they are typically used on hulls that have a porpoising problem or that list (lean to one side while under way), they basically work like an adjustable hook. let me know what that does for the performance of the boat. Should make a difference...

Don't forget to put the screws back in the holes with a little sealant.  ;)
Title: Re: MPH ???
Post by: SoonerFan on February 13, 2009, 12:08:35 PM
sweet..will do !! Hey I was reading that the trim tabs should be mounted 1/2 inch above the bottom of the boat ?? not flush with the bottom as that will cause alot of drag ?? any thoughts or clarification on this?? and by the way mine are flush with the bottom !!  :sly:
Title: Re: MPH ???
Post by: GT Jets on February 13, 2009, 04:34:14 PM
sweet..will do !! Hey I was reading that the trim tabs should be mounted 1/2 inch above the bottom of the boat ?? not flush with the bottom as that will cause alot of drag ?? any thoughts or clarification on this?? and by the way mine are flush with the bottom !!  :sly:

Flush with the botton is correctomundo!  8)

GT
Title: Re: MPH ???
Post by: SoonerFan on February 21, 2009, 01:39:51 PM
Ok all.... i raised up the trim tabs...and got another 2 mph  :banghead: but the boat was porposing..didnt do this when the tabs were down LOL But at 3600 rpms I was hitting 34MPH and 3600 was WOT ??  Im wondering if my pump needs an overhaul or if this ia a motor issue ?? The motor sounded strong didnt cut out at 3600 just wouldnt go any higher  :sly:
Title: Re: MPH ???
Post by: GT Jets on February 21, 2009, 01:54:26 PM
Ok all.... i raised up the trim tabs...and got another 2 mph  :banghead: but the boat was porposing..didnt do this when the tabs were down LOL But at 3600 rpms I was hitting 34MPH and 3600 was WOT ??  Im wondering if my pump needs an overhaul or if this ia a motor issue ?? The motor sounded strong didnt cut out at 3600 just wouldnt go any higher  :sly:

Unless the pump main bearing is locking up the pump is not the issue, 3600 RPM is pitifull, there is something keeping the motor from running, or the tach is full of shiat...

How low are you running the nozzle when it porpoises?

GT
Title: Re: MPH ???
Post by: SoonerFan on February 21, 2009, 01:58:23 PM
I had it all the way down..then played with it awhile....it seemed worse when the rooster started to fly !  I just dont get the 3600 thats crazy... the pump seems to be fine I think its a carb issue maybe to small ?? what do you think ??
Title: Re: MPH ???
Post by: GT Jets on February 21, 2009, 02:00:50 PM
I had it all the way down..then played with it awhile....it seemed worse when the rooster started to fly !  I just dont get the 3600 thats crazy... the pump seems to be fine I think its a carb issue maybe to small ?? what do you think ??

Hard to tell without a vacuum gauge, what carb is on it?

GT
Title: Re: MPH ???
Post by: SoonerFan on February 22, 2009, 06:21:32 PM
I believe its a Holley 600.....I may switch it out with a 850...maybe it needs more air ??
Title: Re: MPH ???
Post by: GT Jets on February 22, 2009, 06:44:00 PM
I believe its a Holley 600.....I may switch it out with a 850...maybe it needs more air ??

Yeah I agree to a point, I think it still should have pulled 4k.. :-\

GT
Title: Re: MPH ???
Post by: povertyjet on February 22, 2009, 08:03:48 PM
I think I am still leaning to a timing issue, either the cam timing or the total advance is not right.  What is the initial timing + what have you got left in the distributor.  To setup your mechanical advance you first need to disconnect your vacuum advance line. Next you should hook up a tach and timing light and see what your timing is set at. Watch the timing marks with the light. The reading at idle is your initial advance. Rev the motor up until the distributor stops advancing and note what speed it maxes out. This is your total advance.  I think most BBC like about 10* initial and about another 20*-24* in the can.  Most engines will have all timing in by 2,500 to 3,000 rpm. 

If that does not work, I would drop the pan, pop off the timing cover and check how the cam timing is set up with a degree wheel, alot of work but...

p-jet
 
Title: Re: MPH ???
Post by: GT Jets on February 22, 2009, 08:13:23 PM
I think I am still leaning to a timing issue, either the cam timing or the total advance is not right.  What is the initial timing + what have you got left in the distributor.  To setup your mechanical advance you first need to disconnect your vacuum advance line. Next you should hook up a tach and timing light and see what your timing is set at. Watch the timing marks with the light. The reading at idle is your initial advance. Rev the motor up until the distributor stops advancing and note what speed it maxes out. This is your total advance.  I think most BBC like about 10* initial and about another 20*-24* in the can.  Most engines will have all timing in by 2,500 to 3,000 rpm. 

If that does not work, I would drop the pan, pop off the timing cover and check how the cam timing is set up with a degree wheel, alot of work but...

p-jet
 

FYI Vacuum advances do not work on a boat engine, the motor wont make enough vacuum to pull it in, the load is too great.

You dont need to pull the timing cover to "check" the valve timing, all you need is a cam spec card, a degree wheel and a dial indicator.  ;)

GT
Title: Re: MPH ???
Post by: povertyjet on February 22, 2009, 08:21:49 PM
FYI Vacuum advances do not work on a boat engine, the motor wont make enough vacuum to pull it in, the load is too great.

You dont need to pull the timing cover to "check" the valve timing, all you need is a cam spec card, a degree wheel and a dial indicator.  ;)

GT

Even vac. dists have a mechanical advance as well, because when you open the throttle vacuum goes to zero.  Also, any performance mechanical dist will have modules or  bushings to set up a specific advance.

true, but pull the timing cover to see if any cam sprocket eccentrics were installed...
Title: Re: MPH ???
Post by: SoonerFan on February 22, 2009, 09:42:18 PM
Even vac. dists have a mechanical advance as well, because when you open the throttle vacuum goes to zero.  Also, any performance mechanical dist will have modules or  bushings to set up a specific advance.

true, but pull the timing cover to see if any cam sprocket eccentrics were installed...
  HOLY CRAP !! all I heard was wha wha wha ... LOL   that was all greek to me.... I put that damn boat in the shop today...Im gonna pay out my ass but hopefully it will be good to go !!! This is from someone who is mechanically challenged  ;D

Ill let you all know what their prognosis is !!!   :banghead:

Title: Re: MPH ???
Post by: povertyjet on February 23, 2009, 04:17:34 AM
Sooner don't interrupt, the adults are talking here...
Title: Re: MPH ???
Post by: SoonerFan on February 23, 2009, 09:59:26 AM
LOL.....I'll just listen quietly !!   :D
Title: Re: MPH ???
Post by: SoonerFan on February 25, 2009, 11:58:15 AM
Just an Update... put the beast in the shop and gave it the once through....all timing is good , no vacuum issues, said the motor is running really strong and got it running to 5K RPM's by hand....tomorrow all three of us are going to take it out and see why it only hits 3600 Rpms from the go pedal ( I know theres a "How many morons does it take to fix a Jet Boat" joke lurking out there somewhere )  ;D  there has to be an issue with the throttle linkage.....hopefully tomorrow this will all be history !!
Title: Re: MPH ???
Post by: beerjet on February 25, 2009, 01:55:58 PM
The Punchline is.........

It's not Jet Boat !
It's the loose nut behind the wheel !

-beerjet-
Title: Re: MPH ???
Post by: SoonerFan on February 25, 2009, 02:19:07 PM
HAHAHAHAHA........wait a second !!! HEY !!!!!     :D
Title: Re: MPH ???
Post by: povertyjet on February 25, 2009, 05:35:16 PM
Great job Sooner!
Title: Re: MPH ???
Post by: SoonerFan on March 02, 2009, 09:56:10 AM
Hey Guys.... well we took it out and al I can say is .... live and learn!! this is what we found.. 1) Bad exhaust leak left side, minor leak right side ( replacing all gaskets as we speak )  2) water leak from the bottom of the housing that the bowl connects to ( not sure what thats called ) pulled bowl cleaned and resealed unit 3) was looking at the Carb and saw the vacuum advance line which was kinda hidden....looked CLOSER and saw black electrical tape on the hose...pulled the hose off and blew through it..NOTHING !! the hose had melted and had a hole in it and who ever decided to wrap it with the tape and completely closed off the line so of course the carb could not advance which in turn kept me at 3600 rpms..... any thoughts on this does this sound right ?!?!  so were gonna take it out again this weekend and Im hopeful we have found the problem or problems !! God I love this boat !!  ;D
Title: Re: MPH ???
Post by: GT Jets on March 02, 2009, 08:55:17 PM
FYI again, vacuum advances are a no go on a boat, I would recommend locking it out and disconnecting the vacuum advance and running around 34* total advanced at 2500 RPM, should be good to go....

GT
Title: Re: MPH ???
Post by: crewchief22 on March 02, 2009, 09:19:40 PM
I can't tell if he is talking about a vacuum advance distributor or a vacuum secondary carb.

Post some pics so we can help you get it straighened out.
Title: Re: MPH ???
Post by: SoonerFan on March 03, 2009, 12:44:18 PM
Well since the boat is still at the shop Ill try to explain it the best I can.... bear with me !! the hose connects to the dist on one end and the front of the carb on the other, the hose was completely plugged.... and when I took it off the motor idle changed so something was going on ...GT Im not sure how to "lock out" the vacuum advance ?? and when you say 34* that little* refers to degrees?? LOL Im trying to learn this mechanical talk.....guess I should have listen to the old man when he tried to teach me instead of chasing skirts  >:D
Title: Re: MPH ???
Post by: SLCKREG on March 03, 2009, 12:54:44 PM
The vac line was probably plugged on pourpose, to lock the vac. mechanism out. However it can still move around on you. Depending on what dist. you have petronix sells a lock out that bolts in place of the vacuum can. It was back ordered when I did mine so I just tack welded mine in place.
Title: Re: MPH ???
Post by: SoonerFan on March 03, 2009, 07:11:08 PM
yea GT I remember you saying that !! Im going to talk to the mech and see what he can do....Im kinda at his mercy !! he seems to know what hes doing... but we'll get the exhaust gaskets all changed out first...more updates to come  :D
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