82' 244 - B21A Stromberg Idle

[Clifford Pope]

I think before fiddling with mixture screws there are some basic checks worth doing:

1) Obviously the ignition side - points, condenser, plugs, HT etc
2) Diaphram not holed
3) Piston rises and falls with a nice clunk, without the needle fouling the jet
4) Float chamber needle valve seating properly and not causing internal flooding
5) temperature compensator not functioning or out of adjustment

In my experience needles don't wear out unless the jet is not centralised and they are worn through metal to metal friction. The very long term effects of erosion by petrol alone I suspect is very much a secondary issue, and only worth bothering with after eliminating all other possibilities.

This Triumph site gives an excellent description of the carburettor:
http://www.buckeyetriumphs.org/technical/technical.htm

The carbs have small differences, but the features are all basically the same.

[Clan]

Originally Posted by Clifford Pope

I think before fiddling with mixture screws there are some basic checks worth doing:

1) Obviously the ignition side - points, condenser, plugs, HT etc
2) Diaphram not holed
3) Piston rises and falls with a nice clunk, without the needle fouling the jet
4) Float chamber needle valve seating properly and not causing internal flooding
5) temperature compensator not functioning or out of adjustment

In my experience needles don't wear out unless the jet is not centralised and they are worn through metal to metal friction. The very long term effects of erosion by petrol alone I suspect is very much a secondary issue, and only worth bothering with after eliminating all other possibilities.
This Triumph site gives an excellent description of the carburettor:
http://www.buckeyetriumphs.org/technical/technical.htm

The carbs have small differences, but the features are all basically the same.

all volvos with stromberg / pierberg variants from 1967 have had the emission versions with biased needles which are spring loaded to rub on the jet , this gives better atomisation for emissions apparantly so they will wear, especialy with inleaded fuel or LPG ..

[athilla]

Thanks guys. I did some more digging and found out that I have a setup with an independent idle circuit. I was able to adjust the idle to be at about 1100rpm in P and 750 in D. What is the normal idle diff bet P and D? The idle is a bit shaky in D, and I have been unable to get it adjusted better with the idle timing screw. I think I prob have to get less novice eyes to look at this to check the diaphragm, needle and temp compensator. The distributor points, condenser, wires etc are good (just changed this year). Maybe I do need to start with ignition timing…

[Clifford Pope]

Originally Posted by Clan

all volvos with stromberg / pierberg variants from 1967 have had the emission versions with biased needles which are spring loaded to rub on the jet , this gives better atomisation for emissions apparantly so they will wear, especialy with inleaded fuel or LPG ..

I'm always wary of statements like "all Volvos have ..." because sure enough someone comes along and says, well I have a ... and it doesn't!

Well I have a Stromberg from a c 1972 Volvo 240 and it doesn't have spring loaded biased needle, nor any kind of external needle adjustment. The only way to adjust the needle is to take the dashpot out, release the grubscrew holding the needle, and then push the needle in or out by guesswork.
The jet can be loosened from underneath, and then moved so that the needle centres but never touches the jet.

But of course you never know what previous owners have fitted, perhaps even a similar carb from a totally different car.

[Clan]

I should have said "All volvos have as standard "

Yes someone has fitted a stromberg from some other car , before the bias needle type came out , The ones with the fixed needles were around from about 1966 to 1972 after that , stromberg changed to the Bias needle type as emission regulations changed then , they also fitted seals to the throttle spindles which yours wont have . It makes you wonder which needle you have fitted and if it is optimal for power and economy ...