9 replies to this topic

[joyce1bro]

Hi,

I know this has probably been asked a million times but I've only seen one post that has a similar setup and I want to know if this sounds about right.

As stated 1330 with 276 Kent cam, 1.5 rockers, extractors, extensive porting etc.

Currently I'm on about 24 flats which seems excessive but anything below 22 and it struggles to run. It does over run on shut down when it's hot or been running for a while especially in warm weather. Anything more than 24 flats and its rich so I'm picking the needles for a start are wrong.

I did read someone saying a number 3 or 4 needles with red springs. If that's a good starting point what sort of flats would I be looking at as a starting point.

Currently I have AAM needles with red springs.

Heaps of questions so thanks for the help.

Edited by joyce1bro, 12 September 2017 - 07:56 AM.

[panky]

Can't help with your choice of needles but have you tried this site. Choose you carb and select from the drop downs to compare.

 

http://www.mintylamb.co.uk/suneedle/

 

I've used it on singles with great results.

[joyce1bro]

Can't help with your choice of needles but have you tried this site. Choose you carb and select from the drop downs to compare.
 
http://www.mintylamb.co.uk/suneedle/
 
I've used it on singles with great results.

Must admit I don't even know how to read or use that chart dang it!! Lol

[panky]

Quick run down. The length of each needle is divided into eight 'stations' (bottom scale) where the thickness is measured vertical scale. The thinner the needle at any station the richer it is at that point. Try selecting the needle you have already got fitted in the first box and then select a few more just to see what they look like - the higher the graph is on the chart the richer the needle is.

[joyce1bro]

Quick run down. The length of each needle is divided into eight 'stations' (bottom scale) where the thickness is measured vertical scale. The thinner the needle at any station the richer it is at that point. Try selecting the needle you have already got fitted in the first box and then select a few more just to see what they look like - the higher the graph is on the chart the richer the needle is.

Ok cool. Would you say at 24 flats to start the needle is to lean?

[nicklouse]

 

Quick run down. The length of each needle is divided into eight 'stations' (bottom scale) where the thickness is measured vertical scale. The thinner the needle at any station the richer it is at that point. Try selecting the needle you have already got fitted in the first box and then select a few more just to see what they look like - the higher the graph is on the chart the richer the needle is.

Ok cool. Would you say at 24 flats to start the needle is to lean?

 

sounds like you are talking cross purposes.

 

read the set up info on Burlens web site or in your manual.  that gives a suitable measurement for the jet in the housing. anything much different to that means your needle is wrong. there is also the lift test to check mixture when you may have a good needle.

 

without knowing what needles you have now and what symptoms you have always make guessing a needle harder than it needs to be.

 

http://sucarb.co.uk/...ion-adjustments

 

1

(a) Remove the air cleaner(s).
(b) Check the throttle for correct operation and signs of sticking.
© Unscrew the throttle adjusting screw (each screw on multi-carburetters) until it is just clear of the throttle lever with the throttle closed, then turn the screw clockwise 1.5 full turns (single), one turn on each (multi carburetters) (1).
(d) Raise the piston of each carburetter with the lifting pin (2) and check that it falls freely onto the bridge when the pin is released. If the piston shows any tendency to stick, the carburetter must be serviced.

2

(a) Lift and support the piston clear of the bridge so that the jet is visible; if this is not possible due to the installed position of the carburetter, remove the suction chamber assembly.
(b) Turn the jet adjusting nut/screw up/anti-clockwise, until the jet is flush with the bridge or as high as possible without exceeding the bridge height (3). Ensure that the jets on multi-carburetters are in the same relative position to the bridge of their respective carburetters.
© Check that the sintered needle guide is flush with the underside face of the piston (4).
(d) Turn the jet adjusting nut/screw (3) two turns down/clockwise (each nut/screw on multi carburetters).
(e) Turn the fast-idle adjusting screw anti-clockwise (each screw multi-carburetters) until it is well clear of the cam (5).

3

 

etc

[carbon]

Joyce,

 

Number of flats depends on the thread type on main jet bearing. There are two types used on HS4:

- early type 26tpi, recommended starting point is 2.5 turns down (15 flats) = jet 2.4mm below bridge

- later finer 40tpi, recommended starting point is 4 turns down (24 flats) = jet 2.5mm below bridge

When you make this adjustment you need to be sure you start from point where main jet is flush with the level of the bridge, and moves down as soon as you turn the adjuster nut. Worth double-checking the jet height with vernier caliper once you have set the correct number of turns.

 

As Nick says, what needles and springs are you using at present?

 

You also need to be sure the main jets are in excellent condition. If these are swing needle carbs the main jets (and the needles) are often well worn.

[joyce1bro]

Joyce,
 
Number of flats depends on the thread type on main jet bearing. There are two types used on HS4:
- early type 26tpi, recommended starting point is 2.5 turns down (15 flats) = jet 2.4mm below bridge
- later finer 40tpi, recommended starting point is 4 turns down (24 flats) = jet 2.5mm below bridge
When you make this adjustment you need to be sure you start from point where main jet is flush with the level of the bridge, and moves down as soon as you turn the adjuster nut. Worth double-checking the jet height with vernier caliper once you have set the correct number of turns.
 
As Nick says, what needles and springs are you using at present?
 
You also need to be sure the main jets are in excellent condition. If these are swing needle carbs the main jets (and the needles) are often well worn.

Awesome. I'll have a look at the needles today. I bought the carbs brand new about 2 years ago and the car doesn't get used much maybe once every couple of months. So I would hope the carbs are still in good condition.

[joyce1bro]

👍🏽

Edited by joyce1bro, 11 September 2017 - 09:37 PM.

[joyce1bro]

Ok so I just had a look and I'm running a red spring with AAM needles. What's your thoughts people???