mercruiser 5.7 v8 lpg conversion advice?

[badger32]

hi im fitting lpg to a magnum 350 5.7 v8, where do i pick up the water connections from? if its from the thermostat housing what size thread/fitting is it i need?

second quesation is its a weber 4bbl does anybody know what size fitting the fuel pipe unions i will need so i can fit the fuel solenoid isolator?

many thanks for any advice anthony

 

[RogersJetboat454]

Re: mercruiser 5.7 v8 lpg conversion advice?

hi im fitting lpg to a magnum 350 5.7 v8, where do i pick up the water connections from? if its from the thermostat housing what size thread/fitting is it i need?

second quesation is its a weber 4bbl does anybody know what size fitting the fuel pipe unions i will need so i can fit the fuel solenoid isolator?

many thanks for any advice anthony

Where is this happening? Are you in the UK/Europe, or in the U.S.?
If you are in the U.S., as far as I know (and I may be wrong) there are no U.S.C.G. approved LPG conversion kits for enclosed engines.
Secondly, you are probably not going to find a plethora of info on this site about how to do your type of conversion, as the majority of the boaters on this site are from the U.S., and have to follow U.S.C.G. regulations.

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

in the uk

 

[Another retired guy]

Re: mercruiser 5.7 v8 lpg conversion advice?

An LPG powered boat sounds like a very scary scenario
How will you refuel it? Will you use portable tanks? How will you protect against gas leaks?
LOL Why are you doing it?

I just did a quick web search and I see that these installations should be done by a licenced installer!!! I would take heed - propane is a very dangerous fuel.

 

[RogersJetboat454]

Re: mercruiser 5.7 v8 lpg conversion advice?

Good luck in you're endeavor, but it's personally not something I would ever consider unless a certified system were available. Lives are more valuable to me than the thrifty use of a pleasure craft...

 

[MWG2600]

Re: mercruiser 5.7 v8 lpg conversion advice?

you would want to find the hottest water line on the engine, and tap into it somehow. It dose sound scary, just convert it to E85 ethanol and you still have cheep fuel. much safer.

 

[RogersJetboat454]

Re: mercruiser 5.7 v8 lpg conversion advice?

just convert it to E85 ethanol and you still have cheep fuel. much safer.

He's not going to be able to find many (if any) stations that dispense E85 in the UK. Heck, I haven't even seen one up here in the North Eastern U.S.

 

[haulnazz15]

Re: mercruiser 5.7 v8 lpg conversion advice?

He's not going to be able to find many (if any) stations that dispense E85 in the UK. Heck, I haven't even seen one up here in the North Eastern U.S.

e85 would be a terrible fuel to use in a marine environment anyway. Talk about absorbing some water . . . in any case, this LPG idea sounds like an explosion waiting to happen on a boat. One leak, and you have heavy propane building up in the bilge until a spark blows the boat out of the water. Stick with gasoline.

 

[QC]

Re: mercruiser 5.7 v8 lpg conversion advice?

LPG conversions are common in the UK. Even in marine. No less safe than gasoline/petrol. Both are heavier than air. I am not a fan, but those are facts.

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

LPG conversions are common in the UK. Even in marine. No less safe than gasoline/petrol. Both are heavier than air. I am not a fan, but those are facts.

in uk these are common, cost of fuel is double lpg, the lake we use has its own lpg tank for us to use so refuling is easy.
thought the place to pick up the water feeds would be from the thermostat area but dont know the thread size of the housing as its going to need to be heater hose size as in a car heater matrix.

 

[Another retired guy]

Re: mercruiser 5.7 v8 lpg conversion advice?

LPG conversions are common in the UK. Even in marine. No less safe than gasoline/petrol. Both are heavier than air. I am not a fan, but those are facts.

The one difference is that you can see a gas/petrol leak - a LPG leak is invisible. I once bought a house with propane heat/water and installed a propane detector on the basement floor. It immediately sounded the alarm. A technician confirmed the water heater fittings were leaking There was no smell or visible/audible signs of a leak.

 

[Bondo]

Re: mercruiser 5.7 v8 lpg conversion advice?

in uk these are common, cost of fuel is double lpg, the lake we use has its own lpg tank for us to use so refuling is easy.
thought the place to pick up the water feeds would be from the thermostat area but dont know the thread size of the housing as its going to need to be heater hose size as in a car heater matrix.

Ayuh,..... Donno exactly what intake manifold, 'n T-stat housing ya got, pictures might help....

Anyways,... There should be 1/2" pipe threaded pipe plug on the intake manifold, just aft, slightly starboard of the T-stat housing...

There should also be a couple of 1/2" pipe threaded ports in the T-stat housin', under the T-stat...

That's usually where the temp gauge sender lives, 'n temp alarm, if ya got 1...

There's also a couple of ports on the heads, but marine exhaust manifolds block their use...


I just can't see how yer gonna run propane through that Merc/ Weber carb...
It uses a 3/8" inverted flare fittin'....

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

The one difference is that you can see a gas/petrol leak - a LPG leak is invisible. I once bought a house with propane heat/water and installed a propane detector on the basement floor. It immediately sounded the alarm. A technician confirmed the water heater fittings were leaking There was no smell or visible/audible signs of a leak.

i understand which is y u put an alarm in the bilge

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

that sounds like the ones in the thermostat is what i need are they 1/2 npt thread or do u know what thread they are please?
also if i take the temp sensor out of the thermostat and use that hole can the other senser which isnt connected besides that which is screwed into the engine rather than the thermostat is that one ok as a temp sensor?
many thanks anthony

going to use a sprint gas newgen mixer and a r90e convertor

Ayuh,..... Donno exactly what intake manifold, 'n T-stat housing ya got, pictures might help....

Anyways,... There should be 1/2" pipe threaded pipe plug on the intake manifold, just aft, slightly starboard of the T-stat housing...

There should also be a couple of 1/2" pipe threaded ports in the T-stat housin', under the T-stat...

That's usually where the temp gauge sender lives, 'n temp alarm, if ya got 1...

There's also a couple of ports on the heads, but marine exhaust manifolds block their use...


I just can't see how yer gonna run propane through that Merc/ Weber carb...
It uses a 3/8" inverted flare fittin'....

 

[86 century]

Re: mercruiser 5.7 v8 lpg conversion advice?

If you are just needing hot water to warm the lp put a t in the spot for the temp sender then t in at one of the exhaust lines to dump it back in.

Right or wrong I have seen it done this way on some inboards to run the heater.

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

Hi yes this is what I need but needing to find out correct fittings to order before I go to the boat as its about 3 hours drive any pics or fitting advice will b much appreciated.

If you are just needing hot water to warm the lp put a t in the spot for the temp sender then t in at one of the exhaust lines to dump it back in.

Right or wrong I have seen it done this way on some inboards to run the heater.

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

Hi yes this is what I need but needing to find out correct fittings to order before I go to the boat as its about 3 hours drive any pics or fitting advice will b much appreciated.

Hi fitted the kit last weekend just one question I piped into the port side of thermostat housing to the inlet of vaporiser and put the out let of vaporiser back into the water pump lower left if u look at it from front of engine, thing is is this correct as if I disconnect hoses from vaporiser I get water flowing out from both hoses?

 

[Bondo]

Re: mercruiser 5.7 v8 lpg conversion advice?

Hi fitted the kit last weekend just one question I piped into the port side of thermostat housing to the inlet of vaporiser and put the out let of vaporiser back into the water pump lower left if u look at it from front of engine, thing is is this correct as if I disconnect hoses from vaporiser I get water flowing out from both hoses?

Ayuh,.... Pictures man,... Pictures....

Is the line from the T-stat housing, coming from the engine side of the T-stat,..??

Was there a pipe port, on the lower starboard-side of the circulating water pump,..??
That's where ya plumbed the return,..??

If the answers are Yes, it's Right...
Both are somewhat pressurized, but the 1st, is a slightly higher pressure than the latter....
'hence, water flows that way...

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

Yes to both bond cheers for the help can not get pics due to camera faulty sorry

 

[badger32]

Re: mercruiser 5.7 v8 lpg conversion advice?

Does anyone know how many degrees I will have to advance the timing?

Yes to both bond cheers for the help can not get pics due to camera faulty sorry