Malpassi adjustable fpr on c1j

[Brigsy]

Ok ive decided to finally crack on and fit the malpassi fpr onto the van to try and cure the emptying the float problem in higher gears.

I have refitted a stock size needle jet in place of the 2.1mm i had fitted. Carb was working fine with the original regulator fitted (by fine i mean no overspilling the bowl).

I have fitted the reg, with base pressure set at 4psi the carb is dribbling fuel down the aux venturi fuel level too high in float chamber??

When fitting the reg i have upgraded the fuel line from the reg to the carb to 8mm, i changed the fitting on the carb to 8mm fitting off the original reg. Could this be the problem?

[Alastair]

Ok ive decided to finally crack on and fit the malpassi fpr onto the van to try and cure the emptying the float problem in higher gears.

I have refitted a stock size needle jet in place of the 2.1mm i had fitted. Carb was working fine with the original regulator fitted (by fine i mean no overspilling the bowl).

I have fitted the reg, with base pressure set at 4psi the carb is dribbling fuel down the aux venturi fuel level too high in float chamber??

When fitting the reg i have upgraded the fuel line from the reg to the carb to 8mm, i changed the fitting on the carb to 8mm fitting off the original reg. Could this be the problem?

Brigsy, I had loads of trouble when i upped the fuel pressure (but does work nicely ). Try another needle valve m8. I think i got a 2mm to seal with upped pressure, but it was trial and error with various needles... I don't think the fitting changes will make any difference to it sealing, the top part of the valve won't see any higher pressure because off it. Good luck mate!

[fishead]

i have had nothing but trouble with this mate, tried all sorts inc max fuel pressure an a smaller valve. no sucsess what so ever, cured all lackage of fuel but floods an dies every gear change, mines goin in the bin asap unless of course you find somethin good. but ive wasted nearly 2 yrs of my life dickin around with that piece of ****

good luck mate

[Adey aka Ewok]

ive got a 12v solonoid i was going to use to feed the fuel bowl extra juice but only on boost, for sale if anyone wants to try it out?

[Brigsy]

Pm adey

Ill try changing the needle jet again and see what happens. It is an old 1.7mm i found in a spare carb so might not be that clever. It shouldnt be flooding with 4psi on idle i checked fuel pressure with standard & that was 4psi so nowt has changed too much.

Ive been having a fair few carb probs lately, first of all my needle jet fell to pieces then the new one wouldnt seal, im going to pull the carb apart & check it out thoroughly!

Super rich on gearchange is nowt new to me fishhead with my old 2.1mm needle i had to flat shift to stop it bogging down

[GTphil]

I have myself a rising rate reg to fit on my raider, it's not ajustable but supplies the fuel at 1.7/1.0 fuel to air as opposed to the solex (standard reg) 1.0/1.0.

I had lots of trouble finding a "rising rate" regulator for a carb'ed engine even the fse web documents don't describe the regulator i have properly.

I'm yet to see if it works as i still need to build the engine

[Alastair]

i think mine is an FSE Brigsy.

[Matt Cole]

Briggsy,

If it was me i would maybe start to look at introducing a secondary fuel supply. The carb was designed to only flow so much (flow through an orifice calc) and the problem now is your trying to get it fuel sensibly (low boost etc) and ridiculously (high boost etc) which it will only do within its design range. All or nothing scenario i think!! Maybe look at filling the bowl as already discussed, or a couple of injectors boost activated.

[5teve L]

Maybe one of those MF2 controllers ?

[Brigsy]

i think mine is an FSE Brigsy.

Mine is fse/malpassi Al

After a bit of pissing about i have got it on & working on idle, changed the needle jet and it seems to be sealing ok.

Still getting an occasional drip from the aux venturi, i personally think the carb body has seen better days so may need to be changed. Need to get out there and do some road testing now.

I will build a setup for filling the bowl from the base if this doesnt work matt, it would have to be a pukka job though. Its easy to throw something together but i want it to be 100% suitable/reliable as i dont want any risk of leaks! Agreed i do seem to be at the point where its an all or nothing in the fuelling scenario

[Matt Cole]

Mine is fse/malpassi Al

After a bit of pissing about i have got it on & working on idle, changed the needle jet and it seems to be sealing ok.

Still getting an occasional drip from the aux venturi, i personally think the carb body has seen better days so may need to be changed. Need to get out there and do some road testing now.

I will build a setup for filling the bowl from the base if this doesnt work matt, it would have to be a pukka job though. Its easy to throw something together but i want it to be 100% suitable/reliable as i dont want any risk of leaks! Agreed i do seem to be at the point where its an all or nothing in the fuelling scenario

Awesome matey! Pop over to trimdon on your test run and we can discuss if you want. I'll also show you me new turbo!

[Brigsy]

Will pop over at some point mate i could do with a sniff round your 225 setup as i fancy swapping to a 'modern' engine soon

Reet have done a bit of testing, first run out didnt go too well as the carb base was playing up, but have changed it and rebuilt another carb and all seems good. With a base pressure of 5 psi on idle and 1.7mm needle the carb bowl seems to be staying full @1.3bar boost. The fuelling seems better all round with no bogging between gearchanges that i had with my old 2.1mm needle.

I plan on upping the fuel pressure to 6 psi idle and up the boost a bit, well i intend to up the boost until it dets then back it off a bit (25psi on std comp??)

The question is where to go with the carb jetting.

My current jetting is - 135 main, .9a/c, .8 1st stage & 1.4 2nd stage 1.4 2nd stage.

Stock 25mm venturi...With my current jetting the afr's are bordering on lean at 1.5bar manifold.

I dont really want to go up on the main jet really as it is on the large side at the moment. Will reducing the air corrector furthur i.e .8 or .7 richen the fuelling up any more??

[Mart]

Work the 2nd stage mate. You know the score

No reason why you can't run any amount of boost, yet still retain o.e size main & a/c jets. In fact, I've always ran a v slightly smaller main to lean off the cruising/motorway/off-boost fuelling.

As for 6psi fuel pressure @ idle, you might struggle keeping the float closed (when chamber full) at that pressure.

I found ~5psi was about the happy limit on my old Raider's 32dis.

[markey b]

slight hijack, but would it be worth having a level sensor in the bowl that cuts ignition if bowl empties, potentially saving engine from det

[Brigsy]

Not worth the hassle mate, if the chamber emptys when setting up you need to make adjustments to fill it up.

I cant get away with standard main/air corrector mart, its far too lean on my setup. Will there be any gain from going bigger on the 2nd stage? from what i read before going any bigger than 1.4mm doesnt do a lot.

[Markey Mark (BD)]

If you got spare body then i say give it a go on going bigger on the 2nd stage mate.

Its interesting to see you say it feels better with 1.7mm needle valve in there but with higher fuel pressure, i feel new routes being embarked on to keep the fuel bowl full now other then going stupidly big needle valve
I always thought about a Nos soleniod tapped into the fuel feed pipe then opperated via a boost pressure switch to feed the carb bowl at the base (through the 12mm nut).

[markey b]

If you got spare body then i say give it a go on going bigger on the 2nd stage mate.

Its interesting to see you say it feels better with 1.7mm needle valve in there but with higher fuel pressure, i feel new routes being embarked on to keep the fuel bowl full now other then going stupidly big needle valve
I always thought about a Nos soleniod tapped into the fuel feed pipe then opperated via a boost pressure switch to feed the carb bowl at the base (through the 12mm nut).

like an aquamist boot switch?

[Sparkie]

I always thought about a Nos soleniod tapped into the fuel feed pipe then opperated via a boost pressure switch to feed the carb bowl at the base (through the 12mm nut).

you wouldnt need the solenoid.
a PRV valve (or even an aquamist one way valve - 15psi opening pressuree) would do. - set the pressure to open the ball valve about 10-15psi fuel pressure.

[Brigsy]

Ive still got all the bits i got off you here sparkie, just thought id give the reg a go first

I might take the 2nd stage out a bit more mark, i can see the fuelling being way too rich across the boards with a smaller air corrector. If it al goes tits up ill tap it and fit an air corrector.

[Matt Cole]

I guess a large needle valve will have an affect on the pressure drop and also regulation of the fuel level in the bowl. If you overcome the float resistance, there would be no regulation of fuel level within the bowl, so you may aswell do away with the float!! As another idea, how about a secondary fuel resevoir with a greater pressure behind it than that within the main bowl?

[Brigsy]

OK have been out doing some tuning tonight, base pressure is up to 6psi on idle & working superb with the 1.7mm needle, no overspilling or bogging on gearchanges. So much better to drive on the road compared to the bigger needles.

Boost pressure is up to 1.6bar @ the manifold, the float is staying full on a long pull in 4th gear to 7.5k...i have changed the air corrector to .8mm and the afr's are back to 11.5 @ wot/full boost. Id like to up the boost a couple more psi as its not detting at all but am unsure how far i can go without knocking. Still it feels quick once again thats all that matters

[Tony Walker]

Good work... sounds promising

[Matt Cole]

OK have been out doing some tuning tonight, base pressure is up to 6psi on idle & working superb with the 1.7mm needle, no overspilling or bogging on gearchanges. So much better to drive on the road compared to the bigger needles.

Boost pressure is up to 1.6bar @ the manifold, the float is staying full on a long pull in 4th gear to 7.5k...i have changed the air corrector to .8mm and the afr's are back to 11.5 @ wot/full boost. Id like to up the boost a couple more psi as its not detting at all but am unsure how far i can go without knocking. Still it feels quick once again thats all that matters

Ala my post previous Brigsy!! Glad its getting there, so what you have found out is the standard needle jet is sufficient to flow for your setup at an increased working pressure and not overcome the float!

Awesome