Does anyone have any detailed close-ups of a HS4 carb? I'm having trouble getting my new carb to run, or even start properly. I've just put a rebuild kit though it. Found out my main problem was the mainfold sucking air not through the carb. So i've sort of blocked those pipes off, I need to drill and tap the holes so i can put a bolt with thread tape in them.

I have a Leyland Marina manual that has great info and detaild pics of an HS6 carb.......not HS4 though.

Well, with my HS2, the needle is hard bolted to the damper (ie no movement, hence the need to center the jet) but the HS4 has a spring loaded needle, and not sure if it should have as much movement as it does. Also, I've had to unscrew the mixture screw an awefull lot (well it seems quite a lot) to get it to idle, and it won't rev yet
Will post some pic's up when I get back from a job.

do you mean turning the nut to lower the 'jet body' ?

I was told that the top of the jet body should be .060" below the SU body. Measured with a vernier and the top off the carb.

I had never rebuilt SU's before, used this principal and new needle/seat and jet body....and my carbs are sweet as!

The spring loaded needle isn't supposed to need centreing.
For an initial setting for the jet, turn the adjusting nut until the jet is flush with the top of the bridge in the intake then lower the jet by 2 full turns of the adjusting nut. This should allow the engine to start and run. Warm it up and adjust from there.
This is for an HS type carb.
Since you mentioned an adjusting screw are you sure it's a HS type and not a HIF type?

Regards
RonR

Thats what I though the spring loaded bit was for.


Well, which bit is which? Which part is the bridge?


Yeh, its got the fuel bowl on the side, has a number too, its FZX1240 or something, will check at lunch. I meant the mixture adjusting nut.

According to Burlen UK's site:
Carburetter: FZX 1240 Total Carbs: 1
Make: Mini Model: 1000
Year: 1976 - 1976 Engine: 1000cc Oz
Set Part No: Type: HS4

(if my number/tag is correct)

The bridge is the SU equivalent of a venturi. The bridge is the flat section in the intake that the piston ALMOST sits on when the engine is not running. ALMOST because there is a tiny plastic rod that sticks out below the bottom of the piston, adjacent to the needle. If this is missing the engine won't idle properly.

Regards
RonR

I think its missing this little peice. Any pics of what it looks like? I had it running fairly smoothly this afternoon, mostly rough because of the manifold leaks, which hopefully I'll have fixed tommorow. Got my reco starter back, spins the engine much quicker, but the positive terminal is now shorting out.

The tiny rod only sticks out about 0.010" to 0.020" approx. Dont know exact amount. Stops the piston from completely resting on the bridge and hence not allowing any air into carb. Could be brass depending on age of carb. It's off to the side of the needle. If it's missing don't confuse the hole for it with the hole/s leading into the suction chamber.

Regards
RonR

Nope, its there, so all is good. I couldn't find a 1/2" welsh plug to plug the big hole in the manifold, so I've now welded an offcut of old floor pan over it

Its just about all good, gonna go try some olive oil for the dashpot.