hif38 carb

[cadetchris]

having caved and bought yet another hif38 carb, as my other one was not working at all, i got this new one working but its running the engine very rough. it is also running rather fast, i have reduced the throttle adjustment screw so its actually not doing anything and when i reduce the mixutre, it does reduce the revs.
however, if i stop the engine and restart the engine, i have to use full throttle to start then i can reduce it almost immediately.
so, how can i get the carb set up right, so it runs well and i can start it on the key every time (like i could do with the standard carb)

[aupickup]

Is the choke on all the time maybe

[cadetchris]

nope, when the choke is pushed in, its off at the carb

[aupickup]

to lean maybe

[cadetchris]

not sure, it runs ok without the choke, i just have to use the choke to get it going then i can knock it off straight away

[bmcecosse]

You certainly have your adventures Chris! I really don't know what to say - I bolted mine on - started the engine - twiddled the screws slightly - and it's been perfect ever since! Look for air leaks - is the dizzy vacuum pipe connected - is the rocker cover breather connected to the brass inlet on the side of the carb ?

[cadetchris]

yep all connected up correctly. ill go back and check for air leaks and then i am scratching my head. i followed the haynes su carb book and reset it all, but that just maid the carb do nothing. i did fettle with the screws and it works, but alas not fantastically.
ill have a fiddle abit more then report back i think

[bmcecosse]

Usual Qs - does the piston rise/fall easily? What needle is in the carb - and is there some 3 in 1 oil in the damper chamber ?

[cadetchris]

Yes the float moves freely, its got a AAA needle in it, and 3 in 1 in the damper. So all is well on that part.

[bmcecosse]

Take it for a good run - then look at the plugs and report back colour.

[Ratbag]

Most well-used SU carbs will be worn around the throttle spindle, allowing air in. This allows them to run with the throttle butterfly fully closed....

[bmcecosse]

Not so much the HIF - it's return spring is on the shaft - so not the side loading of the earlier carbs on the spindle. Unusual to get any significant leakage there.

[cadetchris]

well i got the carb running sort of.
it still takes full choke to start and then i can pop it straight back in a few seconds later. However, once its started it runs at a nice idle speed but once i set off and have to stop again (junction, traffic lights etc) the engine revs are very high, even though nothing is sticking.
so what could be causing both these abnormalities?

[bmcecosse]

Air leak at the manifold/head joint or manifold/carb joint or do you have a servo intake with a leaking pipe or leaking servo ??

[cadetchris]

strangely, whilst "crossword" was picking up the 8inch brakes, a bloke who has a mini and also a marine engineer said almost the same thing.
so ill go have a fettle with the gaskets, pipes and anything else seal related and hopefully that should fix it

[bmcecosse]

Well it MUST be sucking air somewhere - otherwise it CANNOT run!

[crossword]

Chris ,
The other random thought that occurred to me whilst travelling back , I recall from somewhere , either here or Mr. Vizards book that the HIF38 & 44 carbs prefer the dashpot piston to be vertical & i believe there is an adaptor available for the inline engine that makes the angle correct . I think the Metro transverse engine is at an angle that makes HIF carb pistons vertical . Might be worth trying .

Regards Andy .

[bmcecosse]

That's a new one on me......... Any of mine have/are at an angle and work just fine.

[Ratbag]

Ditto - had a pair of HIFs on a Rover V8 that were both at an angle.... from the factory.

[bmcecosse]

Exactly....... the beauty of the HIF is that it CAN work at an angle !!!!!!!!!!