Classic/Antique Car Repair: Twin SU carbs on 68 AH Sprite, blue flame, fuel pumps

Question
I have been working on tuning the SU's on my 68 AH Sprite with a mostly stock 1275 (9.0 cr and a AEG567 cam and am experiencing some trouble. I have tuned SU's before (My dad has a 64 sprite) and they worked fine. Mine are 1 1/4 AUD266, I have Grose jets in each carb and they seem to be sealing fine, I also have the plastic floats , stock (AN) needles, new jets ,new throttle shafts and solid throttle plates. My problem is that I am having trouble getting the carbs in tune. I have checked the float level, it's at 3/8 inch. I have set the carbs with a Gunson color tune (blue flame at about 2 flats) but when I drive the car around the neighborhood (It's not on the road yet from it 4 1/2 year resto)it will not take throttle until I return to the house and drop each jet 2 flats. Also if I let the car sit for an hour or so after my run around the neighborhood it spins for 2-3 seconds and when it fires I have to rev it a bit to "clear" it. What have I missed or need to do?

Thank You,
Greg Coryell
Orl, FL

Answer
Greg:

I would suggest you've got to "re-center" the jets. You may have one or both carb jets uncentered so that the carb(s) dashpot is sticking.   A friend of mine wrote the following, so if you've got the time, go over the whole thing using this write-up as a guide.  If the link doesn't work, then let me know.  Also, I assume you're running a stock S.U. fuel pump, but if not, some aftermarket fuel pumps put out too much pressure.  You should have one that puts out about 2-4 psi. Might also want to check that. If you have a replacement high pressure pump- you can buy a regulator for it--or just replace the pump with a correct one.  Here's the link: http://members.core.com/~ckotting/tuning.html

Good luck and let me know how you make out.
Brian