I've never had so much trouble with SUs before, please help!

[Burdekin]

Originally Posted by Bork Volvo

Thanks, Ron, I always love your tips.

Yes, when compared to one another, if I push them up at the same time, they have the same amount of resistance and they fall together when I release them.

My initial setting was at 12 flats, but I believe they are currently sitting at 14 flats. That's right about where they were when I set up my 1800S with the identical engine and carb setup.

The air cleaners are currently off, but I have a set of CNC machined aluminum velocity stacks that allow me to quickly remove a modern conical air cleaner for carb service. Removing the velocity stacks makes no change in behavior.

(For those interested, these velocity stacks were made by namvet6970 on eBay.)

To set idle mixture wind down the jet increasing fuel mixture until revs stop increasing then just back up one flat is the best and most accurate without using a O2 wideband sensor and gauge. A SU should idle rich, about 13.2:1. A wideband O2 sensor and gauge is ideal for checking driving mixture.

I have velocity stacks as well and found they definitely weakened the mixture when under load and had to fit a richer needle. The car was slower with them with the standard needle. I experimented with the O2 sensor and timed runs to get it right.

One other thing is check the direction of the fuel filter and have you got the spacer behind the fuel pump?