12 replies to this topic

[Ashslights]

Hi all, got a complicated one I cant get my head round, have a 1380 hi torque engine i use for autotesting, I have rebuilt the carb from a 1275 I had kicking around, set the float height etc and on anything going right hand lock is borks, going left hand lock it wont have a problem at all, I made an alloy tank that fits under the scuttle on the passenger side, I thought it was fuel surge in there tank, so filled it, still happened, thought it was the mech pump, swapped it to a facet cube rated 2.5/3psi, still had the problem, modified the pick up in the float chamber, still had a problem, checked the flow rate which was more than ample, car runs amazing and goes like stink going straight and left hand... Any ideas?

[Icey]

This might seem an obvious questions - but are you sure it's fuel?

[nicklouse]

so the problems are only happening when turning away from the tank?

 

where is the tank pick up?

[Ashslights]

Icey- cant think of what else it could be as everything is fresh

Nicklouse- pickup is on the side closest to the tank, thought it was a problem there to start until I filled it full of fuel,

[nicklouse]

Icey- cant think of what else it could be as everything is fresh

Nicklouse- pickup is on the side closest to the tank, thought it was a problem there to start until I filled it full of fuel,

no the pick up on the tank? could you be pushing the fuel away from it in the tank.

 

other things to think of is a fuel pressure display you can record.

[Ashslights]

Sorry brain wasnt working, pickup is on the side closest to the carb

[Icey]

Icey- cant think of what else it could be as everything is fresh

You've not really described why you think it's fuel, are you seeing it suddenly run lean?

[Ashslights]

Mainly think its fuel as its sounds exactly as its done previously when its run out of fuel, could be going down the wrong path completely but there not a lot else it could be if its a surge problem

[cal844]

Does it miss due to lack of fuel then shoot off with a tug of choke? Mine used to... Richen it a bit

[panky]

Have you tried raising the float level a bit more? When you corner hard the fuel in the float chamber will swish to one side and hold the float up so no matter how good the supply is no more fuel will pass the float valve, by raising the float level this should give a bit more of a reservoir to draw on when cornering hard - that's my theory anyway. Is there such a thing as a float chamber extension? If there is then that coupled with a longer pick up pipe could also cure the problem.

 

There is

 

http://www.minimania...amber-Extension

Edited by panky, 09 October 2017 - 10:19 AM.

[Wim Fournier]

"going right hand lock is borks"

Is there a part of the fuel line going -horizontal- from the right to the left?

When -at speed- you turn the steering wheel to the 'lock' you get a fierce centrifugal power on the fuel in a horizontal fuel line that runs parallel with the crank. Have you thought of that?

[Ashslights]

Cal844- makes you think its fuel surge but choke makes it worse

Panky- yes I lifted the float level to its maximum tolerance to nonprevail 😭 Im going to have the carb in bits as the piston had a sticking point yesterday when I tried lifting it from the back, its probably worth me getting a chamber extension but no one else has had to use them?

Wim- orgionally I had the pump above the tank as they have a foot of lift and the tank is one 5 inch tall, thought it was struggling to pull it up so moved pump to drivers side which didnt change anything, I used to run a 998 and ran that for 14 years without a problem with the fuelling setup, there has to be a problem with the carb so going to get it in bits again shortly and get head scratching

Thanks everyone for the help/advise by the way... first post on TMF 👍🏼

[panky]

Would a HS carb be any improvement over the HIF? There seems to be more depth to the float chamber, and maybe easier to fit a baffle in there.