I was up until 12:15 last night building a "new" set of two-bolt SUs out of parts and jets that I have on hand. The jets and pistons springs are matched pairs as were the carb bodies. The KN needles were brand-new. It took a while to get the jets centered, but it went relatively fast otherwise.

I went with a two-bolt pair because the forward carb has a small vacuum port for use with a vacuum-controlled Dizzy (like my BL33). I have it capped right now and I did test it with a vacuum gauge later.

So, this morning I removed the 68's 3-bolt carbs and installed the 2-bolt carbs. I was immediately faced with significant fuel pouring from the reservoir/jet connections and this took some time to get that correctly sealed up.

Now I know what that sort of problem looks like... scary. The 68 was not previously leaking fuel there. That's for sure.

Anyway, I got the repaired two-bolt carbs on and ran the motor for some time to warm it up. I tried to get them both down to baseline, but found that even using a "Unisyn" it was a chore. The engine was rocking quite a bit when I finally got the mixture and vacuum in sync.


I followed Cam's directions carefully - adjusting the flats as suggested. I think I got these new carbs pretty straight. The mixture is quite a bit "leaner" than when I had the 3-bolt SUs on there, but I'm not so sure about the engine rocking. I'm also not sure if I got the idle down to the grumpy idle that was described. The idle did definitely slow as I leaned it out, but it did seem to plateau after a bit. I was pretty close to the top.

I've had the issue (recurring with most of my carbs) that the one will adjust just fine, but the other usually runs high, even when the throttle screw is all the way out (touching nothing). I've never been able to figure that out.

I took to car for a drive and found that I had plenty of power, but it hesitates somewhat suggesting that it is still not quite right. I strongly suspect that the system is out of sync even after using the unisyn and checking individual mix with the lift pin. It also has this behavior when I rev the engine while tunning. I'm not sure what to do for that.

I also hear some faint pops in the exhaust noise, even when idling. Maybe still too lean... seems different than my other experiences...

I did re-check my timing after adjustments and re-adjusted it after I got the carbs tuned for a test-drive.

This has also been a chore since the cart's Smith Tach ceased to read correctly some time back. I have to sorta go by idle sound and memory of what 900 rpms sounded like. My tach only reads up to about 1500 even at full throttle. It also drops down to almost 0 when the car idles. This makes is hard to really do this right. I have a small 240-gauge on it's way and that should help.

So if any of you can tell me what's probably going on with the engine shaking and the hesitation at initial acceleration, please let me know.

Thanks.

Oh yeah, the 68's 3-bolt carbs had KN needles, but at least one was showing some wear/damage. This was probably a contributor to my problems, but does not seem like enough to explain it all.