Metering Needle - 519055

[sujitroy]

Did all regions use the same metering needle part no. through the life of the Stag? I have a few broken sets and would like to make one good set.
Sujit

[DJT]

Burlen list a range of carbs for the Stag covering production years and markets:

http://zenithcarb.co.uk/cf/vehicle/list/?manufacturer=Triumph&vehicle=Stag

[richardthestag]

start with a standard needle, check emissions and rolling road output, adjust needle as appropriate.

Needle chart is also available from Burlen and if you search on this site another chappy has very kindly scanned the relevant pages

[marshman]

According to my Zenith applications book there were only 2 different ones on Stags between 1970 and 1976 (includes UK, European and USA cars with "emission carbs")

They were B1AQ and B1BF - these are the letters stamped at the top of the needle itself, you have to pull it down against the spring to see them.

They are very similar in profile but the B1BF is very slightly richer at idle.

[richardthestag]

'merican TR6/250 that had 175cd 2se, v and vx used the b1af for lower performance

[trunt]

Sujit, My 71 carbs had the B1BF in them when I got the car, I suspect that they were original.. The B1BF is indeed slightly richer at idle, just a little, I would say about 1 turn richer, and the same elsewhere, so in fact it makes it slightly leaner everywhere else..(if you set it leaner at idle then everywhere else is leaner as well.. ) I am using an O2 sensor so have a pretty good handle on the mixture. The new B1BF I have now are fine, idle is OK and within range, cruise could be a little leaner, I like to see AFR 16 its running nearer 15. The only area I am still working on is the acceleration enrichment which although is not leaning out, I would like to see a little richer, I tried 30wt oil with little effect, still pondering.

I do have B1AQ and have tried them but they were too lean at idle, I only just got the mixture correct at idle but it was fully screwed in and there was no leeway.. HOWEVER My engine is at 9.2 Compression so a low compression engine would probably act differently, (plus I suspect my compensators may have been leaking at the time) I would say the B1AQ were certainly worth a try.. I still have them if you wanted to borrow them.. ohh plus one used B1BF, the other one is no good.
Terry

[trunt]

Just went for a run in the Stag with ATF in the dashpots.. when compared to 20 wt and 30 wt it made very little difference in the acceleration enrichment, which surprises me, If anything its a little better.. opposite to the theory. Therefore its staying there with ATF for now. I guess the needle profile has a limit and no end of thickness of oil will make that any better.., I do need to reassess this when the weather gets hotter.

Terry

[sujitroy]

Thanks all. The parts I have in a box are from a '71 and 73 Fed. Stag. I'd assume they would both have the B1BF. However as mentioned above, without taking the needles out, I won't be able to know for sure.

Sujit

[trunt]

You don’t have to take the needles out as such.. just pull the pistons and leave the needles in place inside the pistons, you should be able to see the number if you pull on the needle itself and not mess with the adjustment