SU carbs oil level

[Rootes1725cc]

Hi, I have a Humber Sceptre Mk1 with MGB tiwn SUs retro fitted.
As I don't have a manual for the B, could you tell me what oil level should be in the carbs when you take the damper out.
The dampers have oil on them when I remove them but when I look inside the "tube" I cannot see an oil level. There is a restriction about 2 inches down so the oil level must be below this.

PS should I be using ordinary 20/50 for topping up if necessary?

Thanks

[Luxobarge]

Around 1/2" from the top is about the right level, theyre' not critical.

20/50 will work OK but maybe a little thick. You can get the "official" SU damper oil from various suppliers, or mix 20/50 with 3-in1 or something else thinner.

Burlen Fuel systems are the experts on this area, here: http://www.sucarb.co.uk/

[Rootes1725cc]

Thanks, I ahve the MOT this morning and car has not really been used for a couple of years. Fingers crossed it gets there....

[Rootes1725cc]

We she passed which is great as I can now legally legally run her while I'm trying to get to the bottom of what I think is a carb issue.

The car ticks over fine but when I get going there seems to be little power in any of the gears and when the throttle is depressed there seems to be hesitation. I'm no expert on setting carbs up but would like to have a go before I take it to a "professional". Any thoughts?

Cheers

Nige

[outdoorjoe]

Im having a very similar issue wih my triumph spitfire atm with twin SU carbs, ive been told time again 90% of carb issues are in the igniton system so

1. set your tappet gaps
2. set your points gap
3. spark plug gaps
4. timing
5. clean rotor arm and dizzy cap

then if it persists first thing to check with the carbs is for any blockages, does it have an inline filter fitted? if so change it. As you mentioned top up the dashpots level and check that when you raise the damper it falls easily and freely and lands on the bridge with a solid 'clunk' .

Im yet to sort my issue out so will be following this thread with interest

joe

[JPB]

ATF for the carb dampers. Not engine oil unless you want to break down and have to use carbon tetrachloride to clear them by the side of the road some dark night.
Film strength of ATF makes it the perfect stuff for the job, make sure it's non-Dexron. Regular Shell Donax from your local forecourt shop is as cheap and as good at it as anything else.

[Seth]

The car ticks over fine but when I get going there seems to be little power in any of the gears and when the throttle is depressed there seems to be hesitation. I'm no expert on setting carbs up but would like to have a go before I take it to a "professional". Any thoughts?

I can thoroughly recommend this book.

http://www.amazon.co.uk/Carburettor-Hig ... =8-1-spell



Very good info and step by step guides to setting up SUs, particularly in odd applications. Saved me quite a bit of rolling road time with the MX5-Herald

Also, people will tell you all sorts of different things about what oils to use. Every original owners handbook and workshop manual (factory or otherwise) I've ever read has always referred to using engine oil. I tend to use 10/40. There's no point filling above the level of the piston top (probably the 'restriction' you can see) as all it will do there is become more likely to get sucked down into the carb or squirted out the breather hole in the top of the cap.

[Rootes1725cc]

Thanks guys. That book looks like its worth a look.

Cheers

Nige

[JPB]

(Factories') Service bulletins back in the day invariably told us to stick with the ATF and the difference in response, plus the fact that it stays in place far longer, makes it the better choice.

[MidgetSaab]

I've been using motorcycle fork oil for the last few years, my carb dampers are fine on both bump and rebound.
( I do genuinely use it, it wasn't just for a cheap joke)