CAV Fuel pumps.

[burgundyben]

Following the broken prop incident I have fitted a pair of props that I got with the boat, she was under prop'd with 16 by 17's that should have been fitted to a huntsman with 130's, mine is fitted with 145's (should be 16.75 by 17.75), cept the props I have fitted are for 165 (16.75 by 18.5), to make my engines 165 you have to up the fuel pumps by 15% I beleive.

Question - if under prop'd will the engines over rev or will the guvnor hold them back?

Question - how do you measure the out put of a fuel pump, is it something to do with "shots" and cc's of fuel per 1000 shots?

Question - a CAV rotary pump fitted to a Perkins T6.354 should be set at what? is it a matter of winding back the throttle stop (I think not)?

Question - cant find this info on the web, can anyone point me to it?

TA

Fitting the shaft tonight, shud be launching 2mora

<hr width=100% size=1>Sod the Healey - I think I'll buy an E-Type.

 

[aztec]

Question - if under prop'd will the engines over rev or will the guvnor hold them back?

A, the governor will prevent overrevving. untill such time as the size and pitch on the prop will take over..then it'll black smoke. (overload)

Question - how do you measure the out put of a fuel pump, is it something to do with "shots" and cc's of fuel per 1000 shots?

A. yep, you need to mount the pump in a test rig and measure the amount of fuel over revs/time. lucas service can do this for you.

Question - a CAV rotary pump fitted to a Perkins T6.354 should be set at what? is it a matter of winding back the throttle stop (I think not)?

A. dunno 'bout the settings, are you setting max revs?, if so the governor operated onto the rack which controls the maximum fuel stop, so setting the throttle lower will lower the revs but only to the point of reducing the maximum travel.

hope this helps, give lucas service a ring. they should have all the settings for the cav pumps.

regards, steve.



<hr width=100% size=1>

 

[Freebee]

There used to be a fuel injection place down west quay road in southampton that set up fuel pumps dunno if they are still there. I can give you a clue how the pump works tho, fuel is incompressible and therefore your fuel pump has a measured volume cylinder that fills with fuel and empties on demand passing this measured amount to the injectors, therefore to uprate you need a larger volume cylinder, I think.

<hr width=100% size=1>

 

[tr7v8]

If the guvnor is set properly then yes it should rev limit the engines but I wouldn't guarantee it. If the pump hsn't been serviced for a while then it will need doing anyway and I'd take the injectors to be serviced at the same time.
The diesel pump in simple terms uses a small piston in a bore, one for each cylinder, these pump fuel in very small metered amounts. As the diesel pump is rotated by the engine each piston is moved by a cam which moves all the pistons in sequence (like a petrol engine distributor) the travel of each piston is governed by the cam. The cams lift is controlled by the throttle and at any given throttle postion all the pistons travel an equal amount. Moving the throttle further open increases the travel of each piston and increases the amount of fuel injected. Diesels are NOT throttled in the same way that petrols are, in a diesel the speed is controlled by the amount of fuel injected, not by strangling the air intake as a petrol engine is.
Setting diesel pump calibration needs specialist equipment and fiddling will make it worse. A new pump is probably £ 900ish so thats a good incentive to leave it to the specialist. Settig it all up shouldn't be a fortune, injector service about £ 15-20 each, pump around 70 although its a few years since I had one done.




<hr width=100% size=1>Jim

Draco 2500

 

[boatone]

OK, the governor is supposed to limit engine speed? SO what caused the spasmodic increase in revs I was experiencing and which seems to have been cured with successive changes of filters? The inference is that the surges(around 200-300 revs for a few seconds at indeterminate intervals) were due to dirty fuel and clooged filters restrictinbg fuel flow. Other suggestions included air being sucked into the fuel system.
Anyone got any other ideas?

<hr width=100% size=1><A target="_blank" HREF=http://www.boatsontheweb.com/> Website, Photo Gallery, Chat Room, Burgees</A>

 

[tr7v8]

Surging in revs could be either the stop starting of the fuel flow confusing the govenor, eg. it limits the revs and then the fuel suddenly flows easier increasing the revs.
The other possbility is if the return is getting clogged, this means that the pump is seeing a variation in fuel flow and again can't regulate it.
Air leaks would normally result in the engine dieing, then picking back up or sometimes they are a pig to start but OK once running.

<hr width=100% size=1>Jim

Draco 2500