Hi guys, this is a last resort as I normally muddle through things on my own . I have recently fitted an HS4 carb and all the associated gubbins and have the idle set just right but as the revs build up it starts to stutter. I have had a play with the mixture but it is the same whether it is rich or lean. I can't remember what needle is in it but will check later. Any thoughts on what to try?
Cheers
Ben
You say HS4 - 'and all the gubbins' - so what does that include ? If the air filter is not appropriate - that will cause problems - and of course the needle must be correct for the engine spec. So - what spec is the engine ! ?
bmc, the engine is a standard 1098 with the HS4 carb, alloy inlet manifold, maniflow small bore lcb manifold and k&n pancake filter. I have just checked the needle and it is marked ADE.
roger, how much oil should be in the damper? Mine is almost full to the top.<br><br>
Looks a nice installation - not the best air filter (face is slightly too close to carb inlet) but not the worst either.
ADE 890 855 832 807 787 765 725 715 708 691 674 657 640 623 606
AAA 890 850 814 785 755 720 674 630 600 580 560 540 520 500 480
As you can see - the ADE is VERY weak compared to the 'normal' starting point of using an AAA needle - however some have used AAU needle - but it is very similar to the AAA - so you may as well try AAA first! That ADE will be so weak - the pistons may be at risk - so get the AAA asap!!
Cheers for that bmc. The ADE needle that I have at the moment is the 'swinging' type and the AAA is 'fixed'. Is it a straight swap or is there something else I need to do?
Thanks again
can't see an open vac port. That tube to the left of the dashpot screw is for a choke cable IIRC. The tubes on the inlet manifold are for water heating.
Andrew
Maggie, 1969, 4 door, Almond Green.
And Project "Traveller"...
[sig]4253[/sig]
AAA should fit - it should be swing needle. Don't see any ports either - connecting the water 'may' slightly help fuel consumption - but reduces top power. The other little 'cup' is for a cable connection - other than the manifold mounted connection shown in the pic.
Yes the tube above the choke linkage is for a different cable set up. I do actually have an open vac port on the other side of the dashpot but I'm not sure were this links up to.
Ahh - well that should be connected to the rocker cover breather (or any breather really) to take away the nasty crankcase fumes - and save the engine blowing oil out of it's rear bearing! It won't make much odds lying open - the flow is restricted - and when connected to the breather it will still pull air into the carb - except it will be oily air!
Ok thanks bmc. I don't have a rocker breather so I will try it open for a bit and see how it goes. With regards to the AAA needle being the swing type I could only find this, although it says swing type it looks fixed to me?? http://www.minisport.com/acatalog/info_CUD1000.html
Or am I looking at the wrong thing
It's just their picture is wrong! In fact - the 'swing' nedle assembly contains the older standard needle inside the swing holder! But I think Minisport will send you a complete 'swing' needle - all 3 digit SU needles are swing design. Older 2 digit needles are fixed type.
You really should connect a breather to that carb inlet!
I assume the vacuum pipe to the dizzy is connected up - can't see in the picture - and have you checked the vacuum advance in the dizzy is working ? Most are not !!
. I have recently fitted an HS4 carb and all the associated gubbins and have the idle set just right but as the revs build up it starts to stutter. I have had a play with the mixture but it is the same whether it is rich or lean. I can't remember what needle is in it but will check later. Any thoughts on what to try?
