Jetstar boats

[enginuitytriumph]

Hi Alan, got the old girl on the water at last, still only getting 36 mph when she's running properly ! After changing the carb, ALL electrics & re-setting tappets, won't rev over 4500. After running for 20 mins or so, it starts to missfire, I believe it's a sticky valve where the unleaded conversion has been poorly done / not done at all !!  A Friend has just offered me what he believes to be an RS 3.1, so I think I know my next move.. Do you know if this configuration of engine cover breathed well enough or did it suffer from excessive e engine bay heat? I know the last time I used it was on the hottest day of the year so far, but it's driving me a bit mad !  thanks... Mark

[alanr]

Unless the vents have been moved I don't think there is a breathing problem.
More likely there is fuel starvation and you may want to use an auxilliary tank direct
to the fuel pump and see if there is a difference. 35 mph at 4500 rpm sounds right
to me.
 

[enginuitytriumph]

Hi, put a primer bulb in line to prime it as the fuel runs back after a few hours, tried to pump it when it was full bore & it seemed to make no difference. It picks up better than it did after its tune, but still seems to lack sparkle when reved. It might even be a cam timing or quality issue ?? I think I might have to whip the lump out over winter & hope to get the 3.1.
 how is the engine coupled to the jet drive ??   I will take some more pics this weekend to show the new decals. I let my imagination do some work for me!!  thanks... Mark

[alanr]

Fuel should not flow back to the tank at all. Is the tank breather pipe clear? It is still an idea to eliminate the tank and line by connecting a separate auxilliary tank direct to the lift pump and see if there is any difference. Is the air filter clear and are the two butterflies fully open at full throttle?
To remove the engine...remove engine cover completely, drain coolant from heat exchanger and disconnect top and bottom hoses and oil cooling hoses from exchanger. Remove throttle cable,battery cables and fuel pipe. Remove two coach screws holding rubber front engine mount to hull cross member. Disconnect exhaust hoses from manifold risers. Remove 4 nuts holding " U " clamps on bell housing and taking the weight of the engine with a crane slide it forward until the splines on the shaft have come out of the rubber donut drive then lift unit out of the boat. Alan

[enginuitytriumph]

Hi, I think its a good idea to get the tank out as I've got to replace the sender unit anyway & I'll check the flow out of it. I must admit the fuel pump I thought should have a one way valve in it ? It could probably do with changing anyway!  The carb is new & I checked it for full throttle when I fitted it. Paul (the other Jetstar man) did mention the air intake 'pan' & did it have enough air allowed to get into it? I said that I thought it was the original castoldi cast ally one without a filter, but just a gap all around it & I thought the gap was sufficient ??  I think I'm still plumming for the valves. when it started to missfire at the OSB meeting, it sounded much more 'tappety' & top end 'rattley' which I'm guessing is the valve clearances opening up with the valves not shutting, just a hunch ??  thanks for the info on removing the lump, I'm not looking forward to the intercooler pipes, they look a bit crusty !!  thanks a million... Mark 

[enginuitytriumph]

sorry, forgot the pic!!

[GeoffL]

Hi Mark, sorry to here about the puncture on the way home...that doesn't sound like fun. As a further thought to the air cleaner pan if it's causing a lean condition as we discussed then maybe the plugs would show the classic pale colour....also could the tappety noise be a bit of detonation? I hope this doesn't muddle the issue any further. Hope to see you again soon, Geoff

[enginuitytriumph]

Hi Geoff, no it definitely wasn't pinking, I was thinking of plying with the standard timing to try & get more power out of it !! Plugs look pretty good.  I was lucky to have a spare & my car jack is a simple bottle jack, but I forgot a wheel brace, but managed to get the wheel nuts with an adjustable!! I think I've got myself a winter 'project' (again) .  all the best.. Mark

[alanr]

The air filter should have a s/s mesh in the grooves between top and bottom casings.
The fuel tank is retained by rubber rawlplugs and 8 mm bolts so a 13mm socket is
needed to remove them.
If you do not want to remove the oil cooling pipes the alternative is to remove the oil filter and underneath that the spacer block by removing the large bolt in the middle. Then none
of the oil pipes need to be removed. Make sure not to get any dirt inside and put a freezer bag over it to prevent this.
Just remembered the fuel sender unit is screwed to a ring which on the inside of the tank and held in by a single small csk screw. If you remove this screw the plate will fall into the tank so be careful.
When you initially throttle up do the revs go higher than 4500 then settle back? Alan

[enginuitytriumph]

Hi, the 'air filter' (no filter ) is an aluminium casing in 2 pieces, base & cover. It has 'Castoldi Marine Jet' written on it which looks like the original thing ?? no gauze & no provision to keep a gauze in place ??  I think I'll take the tank out to clean it out as well, just in case!  As for the revs, even without the missfire, it didn't go past 4500 at any time, initially it would go to say 3-4000 & then build eventually to 4500. I'm still not convinced the engines running to full capacity, so I'll probably whip the heads off & check the valves, before the end of the season so I can test it again & see. Then a little transplant over the winter & hopefully.....   

[enginuitytriumph]

Hi Alan, I'm rebuilding another engine to put in the 520. With a little modification, lead free & mildly ported heads matched to the inlet manifold, fast road cam, balance the crank & lighten the flywheel. With that in mind, is the flywheel completely standard to mount the jet drive to ? Or should I take out the original engine first to get the flywheel off of that?  thank you again for your help... Mark

[alanr]

Hi Mark
The flywheel is standard so you should have no problems with
the new engine. A.

[289]

Spotted your mail thread whilst browsing, and saw that you were an ex-employee of Bluebird Marine...
I bought a new Jetstar 520 off your stand at the Earls Court Boat show back in (I think) '76
It was bright red with twin engines (Ford) twin Castoldi jetdrives, with a plaque on the dashboard which clinched the deal...I wonder if you can remember what it said?!
I remember you did a very keen deal as the market was going through another of its flat spots...I think vat was at 25% or something.
I had some great fun with it on the River Orwell based at Levington. It certainly caused quite a stir in those days as there weren't many twin engine speedboats around then.
It seemed quite big in those days...certainly I quickly got a Range Rover to tow it with! Now it doesn't look so big in the photo's.
Funnily enough I never appreciated the Campbell link until about a couple of years ago...either you didn't mention it or I wasn't listening, but I do remember coming down to Bolney to collect it after you had added Nav lights etc to it.
Fun days...I wonder if it has survived?

[alanr]

I remember your boat as we only built two with twin Castoldi 04 jets.
Your boat was fitted with ford 1100 engines which gave about 40 mph.
The other boat was blue and white and was fitted with ford 1600 engines which gave about 46 mph. This boat was exported to the Middle East and I have not
heard of either of them since we built them and it would be interesting if
anyone knows of them today. Alanr

[289]

Hi Alan,

yes I do wonder if it has survived somewhere.
It was amazingly manoeuvrable and had neat tricks like (when moored) soaking a chum walking along the jetty be applying full lock in 'neutral' and zapping the hand throttles.
Also the spin stops were amazing.
It had a plaque on the dash which read "You can tell the men from the boys by the size of their toys" obviously fitted by your team for the show.