3 replies to this topic

[johnR]

My re-built 1293 will only run if one of the twin SU HS2's is blocked off suggesting it needs to be richer? I currently have M needles and red springs, and was thinking of changing to AH2 needles and yellow springs but I can't find a listing for these springs for HS carbs? 

[gazza82]

These are closest I know about ...

Needle order is Normal - Rich - Weak

1275 Sprite IV, Midget III AN GG H6 Light Blue
1275 Cooper S M AH2 EB Red

[carbon]

My re-built 1293 will only run if one of the twin SU HS2's is blocked off suggesting it needs to be richer? I currently have M needles and red springs, and was thinking of changing to AH2 needles and yellow springs but I can't find a listing for these springs for HS carbs? 

Yellow springs on a HS2 is likely to be too strong, the 1275s used either red or blue.

 

As Gazza says, Cooper S 1275 standard spec was M needles with red springs. What spec of engine are you running? There are a couple of richer needles which might be worth considering.

 

PS. If you're using the BMC inlet manifold with locator rings first check the manifold rings are not too deep for the recesses (holds the manifold off the gasket). Then check that the thickness of the exhaust manifold flanges and the inlet manifold flanges are all within 10 thou or chances are it won't seal properly and then lets air in.

Edited by carbon, 07 May 2019 - 07:13 PM.

[johnR]

I'm using the BMC inlet manifold matched to the head with locating rings deleted and using pins to locate.
I did wonder about a disparity between the exhaust and inlet flanges after I'd fitted everything - perhaps I'll go back and check that's not the problem as it seems to want very rich carbs to run. I've ordered AH2 needles as well.