Su carb P


Active Member
There is a big silver nut directly under the carb it’s self winding it in or out will adjust the jet you might have to take off the air filter unless you can get in there with a small tool.


Well-Known Member
Which car are you working on?

if it’s a 2000 cylinder single carb or early V8 then the large nut under the carb directly below the jet.

If it’s a 2000tc there’s a screw beside the vacuum bell that lowers the adjusts the jet via a linkage and lever.

if it’s V8 or 2200sc or 2200tc it’ll be a HIF6 and you’ll have screws going into the body at a 40° angle from the side
Still having problems with plugs shooting up, I know pressure is down on one cylinder but why are th other three plugssooty. Spent a lotofmoney with a so called garage in Bristol to sort it and made it worse. Any ideas please.?


Well-Known Member
Following sdibbers reply above, follow the linkage up from the jet to the adjusting screw on the side of the carb and set the jets around 1.3mm below the bridge using the tang on a vernier caliper as a depth gauge and see how you get on then.
Run the car on a decent fast run and pull up and remove a plug, adjust screw according to plug colour. Jet going down = richer darker colour, jet coming up = leaner lighter colour. Aim for mid grey.
The adjusting means taking the top bell off the carb and removing the piston, adjust both evenly. Dashpots need SAE 20 oil filled to just down from the damper rod tube top.
Make sure both jets are returning right up after the choke is pulled, and check this before adjusting. This applies to HS8 carbs
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Well-Known Member
Couple of things I thought of that may not be obvious. It is only the initial set up that you need to take the top off the carbs, mark them so they go back in the same place. Subsequent adjustments can be made 1/4 turn at a time on both carbs. When adjusting put a finger under the jet and push up to keep the jet tight up to the adjusting linkage.
After all this I hope you have HS8 :)