newby with v8 ski boat....

[gaz46]

Hi all!

i would like to start by saying great site!!!

Im currently looking in to converting my mastercraft to lpg, it has a small block ford 351 v8 (5.7l) and 4barrel holley carb. ive been to told to go with the impco 425 gas carb. What are your thoughts on this system? i want to be able to get rid of the petrol tank completely. any info would be greatly appreciated!!!!!!!

cheers in advance. gaz

[Gilbertd]

Impco gas carbs are designed specifically for American V8 engines so you have been given good advice so far. Afraid I can't help with the fuel tank question. I presume an Impco will allow you to start on gas but don't actually know. Hopefully someone that knows more about them than I will be along soon (which on this forum can sometimes be a week or so.....).

[rossko]

That seems reasonable.
You won't be able to thrash it on gas only in freezing conditions until its warmed up a bit, but that may well not bother you!

In a boat install you will need to have a gas alarm in the bilges.

We got a 100L cylinder into Mastercraft 190's but that was leaving room for a reserve petrol tank. That was an injected setup though, haven't done a carb. The customer told us that mixer based systems have a tendency to stall when doing 'emergency stops' that push the exhaust flaps closed, and tested hard for that (terrified me). I dunno if that applies to Impco setups too.

[jayc]

Yes impco 425 if you want to run LPG all the time. If you want dual fuel then impco 300a 50&70 series.

100L tank will fit no problems in most 19ft ski boats. 120L at a push.

You should have no freezing issues if plumbed correctly. I run boats all year round and even with water temps just above freezing I can run WOT by the time i have my drysuit on.

Also no issues with stalling on 'emergency stops' (assume rossko means a 180 powerturn).

[gaz46]

jayc, can you recommend a supplier for the impco stuff????

[jayc]

HKL are the UK disty for impco but i always get my kit from the US as it's loads cheaper. Nashlift on ebay.com are pretty good and have used them in the past.

There are some US ebay sellers that distribute the nolf and woodward range at a slightly cheaper price. These are essentially copys of the impco range which work equally as well and accept genuine impco replacement parts. I have a nolf setup on my maxum, an impco 300a dual fuel setup on the 2001 nautique and an OMVL/sprint gas set up on the ski tique.

The 351w lends it self very well to a straight propane conversion. Bolt the 425 to the holey throttle plate. Use a 1" npt pipe nipple to couple an impco model e vaporiser to that and then use a 1/4npt pipe nipple to connect an impco vf30 to the vaporiser.

For supply lines I always prefer flexible hoses on a boat. Get a 1/4npt to 3/8 flare fitting and then get the required length hose (about 3m should do it) made up from someone like HKL.

As for the gas alarm definately advised and I install them on mine but they are not fitted by the UK dealers as standard.

[gaz46]

Thanks for the info... ive actually emailed nashlift for a price on shipping but they are yet to reply! Im a little confused on the type of tank i will require, ive been looking at around 120 litres but im unsure whether i will need a single hole tank?

[jayc]

Don't get a single hole, choose a 4 hole tank.

[Charlie Renard]

If it is of interest, the supplier I mainly use, Tinley Tech, also stock Impco equipment.

[gaz46]

Can anyone tell me the advantages of a 4 hole tank??? its just that ive been offered a single hole 120 litre that will fit perfectly!!!!!!!

[billynoband]

A 4 hole tank fills a bit quicker at the pump which is why people like them in cars which need tanks that size. In a 40-60 litre tank the filling difference time to a single hole is very small. They are more expensive though and the more someone can sell you the more profit they make.
There may be other reasons 4 hole is good for boats though.

[jayc]

4 hole tanks are good one boats as they lend their self to flexible supply and fill hoses due to the jic/flare fittings.

I wouldn't worry too much about getting the biggest size possible unless you don't have onsite LPG.

[gaz46]

Well ive ordered all the impco parts from nashlift! it came to £315 including shipping. just need to find a tank supplier now, any recommendations? does anyone have any pictures of the installs you have done?

[bikermickyc]

Hi we should have some Dual curve remapp for ignition boxes if you get stuck - we bought somein USA- I run dodge 360 with impco 300e- it is great even runs in snow- no need to warm up on petrol in my experience-Mike

[jayc]

No need for a dual curve in this application as it'll run either points or EI via mechanical advance. I'd bump the timing forward a couple of degrees though.

As for your tank look on ebay. There is no need for certification so you can pick up a 10yr old tank for peanuts.

[gaz46]

ive been given a 100l tank and fitting kit with a single hole set up! is it worth fitting? the tank and valve is three years old.... it also fits perfectly where my petrol tank was!!!!!!!!!

no sign of the parts from the states yet... i wish they would hurry up!

[jayc]

Personally I'd flog the 3yr old tank on ebay as it'll fetch a half decent price and buy a likely cheaper 4 hole jobbie that is over 10 yrs old as they are cheap as chips.

[gaz46]

well the parts have finally arrived from nashlift! unfortunately due to the weather i cant get near the boat.... does anyone have any pictures of an impco 425 install in a boat???