Sacrilege or sense?

[starman]

A couple of fellow 'vintage engine' boaters have recently suggested the benefits of taking out the Blackstone that comes with our JP3 and substituting a suitable hydraulic box. (The chief benefit being ease of gearchanging, plus in our case being able to improve the present poor access through to the engine room from the back cabin.)

Given that we have to make up new controls anyway owing to changing things around, would it be sacrilegious to ditch the Blackstone?

[MoominPapa]

I think it would be a wrong thing to do. But I secretly look down on people with converted generator engines and PRM gearboxes. Sorry.

 

MP.

[rrt2]

A couple of fellow 'vintage engine' boaters have recently suggested the benefits of taking out the Blackstone that comes with our JP3 and substituting a suitable hydraulic box. (The chief benefit being ease of gearchanging, plus in our case being able to improve the present poor access through to the engine room from the back cabin.)

Given that we have to make up new controls anyway owing to changing things around, would it be sacrilegious to ditch the Blackstone?

 

Having had a JP2 with the blackstone gearbox and a wheel gear change (that combination if high geared is a real wrist wrecker) may I suggest as you are going to change the linkage etc, going down the route of a lever gear change.

[cereal tiller]

fit the p.r.m. it is a classic british design(circa 1962).

i do believe that there is no such thing as "tradition "with regard to canal boats,just evolution and sensible enhancement.

a working boatman/person would have sold his soul for a p.r.m.,or get a horse!

[starman]

fit the p.r.m. it is a classic british design(circa 1962).

i do believe that there is no such thing as "tradition "with regard to canal boats,just evolution and sensible enhancement.

a working boatman/person would have sold his soul for a p.r.m.,or get a horse!

 

I'm tempted to agree with that - so which PRM would handle the JP3's output?

[tom_c]

according to the prm website the 260 should handle a JP3 even on a heavy commercial rating. i would be more tempted to fit the 500 though, especially if the engine is worked hard or a lot of river work is likely. the prm 160, which was replaced by the 260, in wyrd has been rebuilt 3 times in 20 years and still has a habit of dumping all of its oil into the drip tray under the engine with a compete loss of drive!! not good on rivers. the other thing to be careful of , is the minimum engine speed that prm recommend for the gearbox, a JP3 might have to run a bit more quickly than you may like for the gearbox to work correctly. hope this helps

Tom

[cereal tiller]

the prm does enjoy being cooled,my 260 does 8 hours at 80% load somewhat frequently.i would suggest that the examples you mention have been "cooked"due to improper ol cooler(S)

[steamraiser2]

JP3s run happily with a PRM260 , no problem at all. We have taken a couple of Blackstone's off and replaced with PRMs recently, it seems that more customers want a modern box on a vintage engine these days.

[frangar]

If anyone has a spare take off Blackstone 3G box as fitted to JP2 and JP3 then I will gladly look after it for them!!

 

Cheers

 

Gareth

[Proper Job]

according to the prm website the 260 should handle a JP3 even on a heavy commercial rating. i would be more tempted to fit the 500 though, especially if the engine is worked hard or a lot of river work is likely. the prm 160, which was replaced by the 260, in wyrd has been rebuilt 3 times in 20 years and still has a habit of dumping all of its oil into the drip tray under the engine with a compete loss of drive!! not good on rivers. the other thing to be careful of , is the minimum engine speed that prm recommend for the gearbox, a JP3 might have to run a bit more quickly than you may like for the gearbox to work correctly. hope this helps

Tom

My PRM 260 works well on my JP3. Tickover is very low (around 280 - 300 rpm) and the box functions normally.

 

Mine also spends a lot of time doing river work (800 rpm'ish) and has never been a problem.

 

Annual oil changes and good cooling are the key things.

[starman]

Next follow-up question: how difficult a job would it be to do the swap? Does the PRM260 fit to the engine via an adaptor plate and the propshaft suitably resized or is the answer more complicated than that?

[steamraiser2]

Fitting the PRM in a proper close coupled manner needs an adapter kit and some machining. So it is not a quick job , nor cheap. There are quite a few boxes mounted on a stand alone plate which works but looks very agricultural.Its a matter of choice of course.