Petrol Carb's

[richardandtracy]

Petrol Carb\'s

When marinizing a petrol engine, what has to be done to the carb?

I've got a Citroen 2CV petrol engine spare which I want to put in my boat, but the snag is that the carb leaks like the devil on starting.

Should I chuck the carb, and make one without floats? If so... where can I get advice? If not.. then how do I stop it over filling and leaking?

I can make almost anything with my lathe/mill, so that doesn't frighten me - but money's the problem. Does anyone know of a free design guide or similar?

I don't want to get involved in the petrol/ diesel debate again - I have an engine that cost me £25, so I'm going to use it. I won't use it often, just once in a while. I have a SAILING YACHT not a gas guzzler, and not using petrol is cheaper than actually using diesel. I don't intend to fry my petrol fumes or anything like that - I like living and will take reasonable safety measures (my definition of reasonable, not anybody else's).

 

[BarryH]

Re: Petrol Carb\'s

Ummm 2cv marinized, sounds err.... interesting. Why not change the carb to a downdraught type. Then any over fueling will go into the engine. If you had no floats in it, as you said about removing them, what will close the float valve and stop the petrol pump flooding the thing. Also what about the fuel return and/or overflow, where are you going to route that too.

For the power output and the drive problems that will arise, would it not be easier to use a small outboard for your auxillary. Yoy can get secondhand seaguls for next to nothing!

OK, to hell with it. Unbolt it and we'll use it as an anchor!

 

[richardandtracy]

Re: Petrol Carb\'s

I want the engine as an inboard on my Bruce Roberts Spray 36 - The design says 23-33 Hp inboard. The 2CV is 29Hp... Purfect for an auxilliary rather than a motor-sailer.

I was thinking, if necessary, of getting rid of the entire carb and replacing with a spring/nozzel type, not getting rid of the floats. The carb on the 2CV is already a downdraft type with a float to one side.

 

[BarryH]

Re: Petrol Carb\'s

Well, er, in that case the only other thing I can think of is the old Fisch carbs from days of old. Apparently you can still get them. Simplest form of fuel metering around. Tupe with a jet and a butterfly. I would consider some sort of flametrap as well tho. What about the cooling side of things, and the drive coupling?

OK, to hell with it. Unbolt it and we'll use it as an anchor!

 

[steve_cronin]

Another saving would be....

your insurance premium for no company would cover this boat with such a Heath-Robinson installation unless you could prove that it was properly marinised by an accepted expert. Also (I may be wrong here) the RCD might have some relevance with regard to re-engining.

I have concocted some "unusual" schemes on boats in the past and therefore wouldn't wish to discourage you but just think of the ramifications of your boat being set on fire by another alongside in a crowded harbour. You might find yourself with a hefty damages claim to settle.

A dripping float chamber will cause all sorts of problems and the Amal type won't work in the constantly upheaving environment of a yacht plus you will need to turn off the fuel tap near to the carb AND have a gravity fed system which means the tank above the engine. What about re-selling the beast too? A marine surveyor will run a mile from it.

Steve Cronin

 

[mtb]

Re:Oh dear

Are you sure , I mean realy sure !!.

Ok then the sloex 34 pics is a basic carburetter but you need to ( from what you've said renew the needle valve , check the float is not leaking,and finaly check the float level.
You will need to fit flash back arrester gauze and renew all rubber hoses with correct marine grade plus the actual fittings also.

Your carburetter has an accelerater pump fitted this will pump more fuel than required so will cause further risks of fire.
RE the air breather hole in the float chamber !!!!!!!!!
The heat will sink into the carb causing the fuel to expand , then flooding again more risk.
To combat this you could fit a drip tray again it must have the correct gauze or yet again !!!!!!!!!!!!!!.

One final thought although not the solution I have in stock early Wal Philips fuel injectors these are the simple fuel and throttle butterfly, but you will find the engine will rev like crazy again !!!!!!!!!!!!!!.



Finaly No I dont have any flame trap gauze

http://www.carburetterspecialists.fsnet.co.uk

cheers and have a nice boat barby !!
MIck

http://homepage.ntlworld.com/boats
I want a big steel ex trawler / tug v / cheap or swap for tug

 

[brianrunyard]

Re: Petrol Carb\'s

First question, why not overhaul the carb so it dosen't leak? It's a downdraft anyway so should be ok for marine use.
Second question, what about cooling? Are you going to fit a water colled manifold and raw water cool, or fit a "Water Cooled manifold/Heat exchanger/Header tank"? Where are you going to obtain the parts.
What about the starter motor, is it spark proof? Otherwise any petrol that leaks from your carb will be ignited when you operate the starter motor.
For the size engine you want, why not look for a cheap second hand marinised engine?
Last question, where do you do your boating?

Brian
http://homepage.ntlworld.com/brunyard

 

[richardandtracy]

Re: Another saving would be....

Insurance in harbour...

I'm not a good enough sailor to be allowed near any other vessels (100 yards being the nearest safe distance!) - that might change a little when I have an engine, because I won't have to kedge all over the place. Mud moorings for me wherever possible.

Resale value is only important to those who wish to sell. I don't. This vessel's been built by me, & it'll rot with me.

Anyway I way already planning on having a 1 gallon (max) gravity feed to the engine + fuel tap next to the carb (want it to run dry to stop the engine).

The engine's cooling air will be used, ducted into the cabin or exhausted through closable vents in the cabintop. I'll also use the 2CV's exhaust manifold heat exchangers to warm the cabin. Drive to the prop shaft may be via chain (works well on motorcycles with much more power and torque) - it won't be messy, because modern "O"-Ring chains need minimal oil.

As I understand it, the RCD doesn't apply to home builds - correct me if I'm wrong.

Oh, and "Heath Robinson" to describe the setup - I don't think it'll be too bad, in real life I pretend to be a Professional Mechanical Engineer - and I've convinced lots of people for the last 17 years...

Richard Williams

 

[dickh]

Re: Petrol Carb\'s

Don't forget that 29HP is an automotive rating and you will probably only get 20hp at say 3000RPM.
Petrol leak - repair/replace the carb - this is potentially VERY DANGEROUS!!
Air cooled so will be noisy and you will have to get rid of the excess heat...
You will have to fit a marine gearbox to take the prop thrust or fit a thrust bearing somewhere before the engine.
What about the exhaust? if not watercooled will need to be well lagged and will inevitably get hot...` - but could try a water cooled exhaust with water injected into an exhaust elbow with a separately engine driven or electric pump.

Will you get insurance? - they will inevitably insist that all relevant safety bits are fitted if a petrol engine or insist on a survey.
Where do you sail?
Try and get a cheap marinised petrol engine from someone who has changed to diesel - there must be loads around - try the Broads area.

dickh
I'd rather be sailing...

 

[richardandtracy]

Re:Oh dear

Yep, I'm sure, really sure. Really, really sure.

Thanks for the information, I'll check it out. By the way, 2CV engines need to rev like crazy (driving style on the road is "If you can hear your passenger's screams of fear, you're not trying hard enough.").

Big tug? Try home build steel. It's fun, good exercise, keeps you from sinking (until it gets into the water at least...) and keeps you too poor to worry about anything else.

Regards,
Richard.

 

[richardandtracy]

Re: Petrol Carb\'s

Must admit, I hadn't considered the starter motor sparking, but I will be complying with the US Coastguard's recommendations on petrol engines in their publication "Safety Standards for Backyard Boat Builders" COMDTPUB P16761.3B, where venting is incorporated and fans are turned on for 4 minutes before starting, and continue for 2 minutes after stopping. If the starter can't be made safe, there's always the starting handle! It's a 1 handed job for me... There have been many occasions when I was saved from a dud battery by the starting handle.

2CV's are air cooled, and I want to minimise the number of holes in the hull. There is 1 at the moment (blanked off prop tube), and that's the way it's going to stay.

Final answer - I generally sail around the Medway/ North Kent coast. Just because you want to avoid me... Well, I try hard to avoid everybody else too. If you're never nearer that 100 yards, then crashes are impossible.

Regards,
Richard

 

[richardandtracy]

Re: Petrol Carb\'s

The 2CV red lines at 6000 rpm. It'll go all day at 5500 rpm, and as it gets hotter & hotter the power increases (I've had one fully loaded through Germany and at the start of the day it could get up to 70 mph, by the end of a long day's driving we were going off the clock [approaching 90mph] under similar conditions).

To be honest, I expect to use the engine for 15 minutes at at time max. I'm such a cheapskate that it hurts too much to go any longer, especially if there's a puff of wind.

Bearings & the lot, thanks - but I'm not going to apply any thrust to the engine. The engine'll be horizontal, and offset by 24" from the prop shaft. I haven't sorted the details of the drive train, but it won't be too bad. However, I'm not ever going to use anything so antiquated as a stuffing box. I'm going to use a properly engineered solution - talk about Heath Robinson... Fancy letting something on your vessel that's designed to leak. Never!

Regards
Richard

 

[dickh]

Re: Petrol Carb\'s

You will go deaf with you 2CV screaming at 6000 RPM and your exhaust and manifold will be red hot... unless you water cool it... Although you say you will only use the engine for 15 min at a time - I bet you won't - been there, done that!

You will still have to use a 3.3:1 gearbox or a similar reduction chain drive to get your prop revs down to about 1800 Max. Get a Renold otr TD Cros catalogue for chain drive calculations. And with a chain drive reduction of 3.3:1 it will be a large chain wheel on the propshaft. Yes there are specialised chains which will transmit lots of HP as on a motorbike for a relatively short period, but on a boat you want reliability so has to be conservatively rated using BS chain which you can get anywhere in the world. Again the gearbox will have to rated for a sideways force as from a chain drive, I dought wether the 2CV gearbox would stand up to this treatment for long.
Stern Glands - how are you going to achieve this "properly engineered solution" - there are lots of variants on the traditional stuffing box on the market some of which don't leak like the Deep Sea Seal and PSS seal.
One advantage of the traditional stuffing box is that if you had a PETROL fire on board the traditional gland will survive this with minimul damage - with all of the other seals which rely on a rubber bellows/oil seal to prevent water ingress they will be destroyed very quickly and you then have a hole in your boat...
One thing I've just thought of, petrol engines rely on a spark so if your engine gets damp you might have problems...
A blower is an essential with petrol engines and if you rely on the ABYC rules you should be OK - Look at the www.boatered.com forums which have a lot of info on petrol engined boats.
Anyway, good luck with your project and keep us posted of your final solution,

PS - another thought, if you have to start your engine in an emergency, are you going to wait 4 minutes for the blower? I think not!

dickh
I'd rather be sailing...<P ID="edit"><FONT SIZE=-1>Edited by dickh on 28/08/2002 13:55 (server time).</FONT></P>

 

[brianrunyard]

Re: Petrol Carb\'s

You're going to need a large air intake and outlet, possibly fan assisted to air cool the engine, as there is no air flow over it to keep it cool as in a car. The exhaust manifold will glow cherry red in no time.

Brian
http://homepage.ntlworld.com/brunyard

 

[oldgit]

Re: Petrol Carb\'s....and I thought I was Mad NM.

NM.

Just lets say the best boat in the known universe starts with the letter P

 

[richardandtracy]

Re: Petrol Carb\'s

I'm getting the feeling it's too difficult. I'll stay without my engine - like for the last 4 years.

Anybody know any designs for an Ulu? (I thinks that's what it's called, the chinese bent oar off the stern...)

Regards
Richard.

 

[richardandtracy]

Re: Petrol Carb\'s....and I thought I was Mad NM.

OK, I'm stupid. What are you aluding to?

Richard.

 

[richardandtracy]

Re: Petrol Carb\'s

Hot water at last!

Seriously though, the manifolds are actively cooled by the engine fan, and all the cylinder head cooling air is ducted over the manifolds.

Regards
Richard.

 

[richardandtracy]

Re: Petrol Carb\'s

That's more like it. Useful, helpful comments. Thanks!

Regards
Richard.

 

[dickh]

Re: Petrol Carb\'s

Not too difficult - just needs a lot of careful thought, the comments on this posting suggest this. As I suggested before try the option of an already marinised petrol engine which should have all the various safety features fitted - there should be lots around cheaply but check it's been properly marinised and insist on seeing it running and that it complies with the latest regs, otherwise it will cost more money.
Regarding the 'ULU' there was an article many years ago in PBO I believe, but no idea when. Why not try a large sweep over the stern? this can work well when dead calm.
Happy Sailing,

dickh
I'd rather be sailing...