Carb differences 1098 and 1275?

[radibob]

I think I have a needle issue. Here's the deal. I rebuilt a 1275 for my 66 sprite which had a an early 1098 in it (previous engine swap from PO).

Since both engines used the HS 2 SU carbs I used the same carbs, but I haven't been able to adjust the *&^%$ things.(I have used color tune and a carb balancer) They are OK at idle but it will miss and buck at higher speeds. The 1275 is a late one from which I removed the air pump and plugged the holes etc etc.
The ignition is all brand new with Petronix and the right rotor etc.

Any previous experience with this one? different needles? damper springs I am all ears?

 

[Pythias]

Let me start by saying that I'm not an expert or even very knowledgeable about this stuff, so wait for a real pro to weigh in. I'll await the answer as well,.....but my understanding is that all the bodies are the same, the differences coming from fitting proper springs and needles.

The book shows the spring to be "BLUE" and the needle to be "AN" in all applications from 1098 thru the 1275, EXCEPT for 1275s-12V778F/H101- from very late cars, in which case, needle AAC.

 

[Woblynne]

I have an early 1275 (UK spec) which has the same carbs as the 1098 (tag number AUD 136) so it should run ok with the those carbs, You could try refitting the points/condenser etc to see if theres a problem with the pertronix as it seems to play up when you're asking more from it?

Mark

 

[radibob]

Yeah that's a good idea that I have been trying to avoid but the petronix is the only thing that I haven't touched yet.(long sigh)

 

[Dug]

There are differences in the needles. Figuring all the past owners, who knows what needles you have. But none the less you will need the proper set of number / letter size for the cc displacement. The jets can be different as well. What color band is on the jets now?
Dug

 

[Billm]

Of course you have checked that there is oil in the dash-pots and that the carb pistons move freely?
Bill

 

[texas_bugeye]

ballasted Coil?