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MG MGA - Carb needles

Last week I finally trailered my 1958 roadster home to Alaska from Oregon where it has been stored for 30-plus years; I'll probably be posting more frequently now than I have in the past. I recently installed an 1800 MGB engine with rebuilt "A" carbs and standard needles. Does anyone have thoughts as to whether different needles might be more appropriate?

Ken
k v morton

Ken,

I did the same thing and had to put in leaner needles. It still burns rich but a lot better. Let me know how you make out.

David....
David Honness

Interesting... My instinct would have been to go to a richer needle. It runs pretty good at low speed with the standard needles once it warms up. I probably won't test it out on the highway until I get some new seatbelts installed and get the sponginess out of the brake pedal.

Ken
k v morton

For what it's worth I also have an 1800 engine (3 main) with 'A' carbs and exhaust. When I rebuilt the carbs I went with an MB needle. That's the standard needle used on the 3 main 1800 engine with the normal MGB carbs, etc.

I picked up that recommendation from an article in A-Antics that suggested using that needle when combining standard A carbs with the 1800.

However, I've not quite finished with the rebuild. I do have around 150 miles on the car as I can't resist driving it, but I'm still driving around on the initial carb settings so I haven't really set them up properly yet. It does seem to run OK up to around 60 mph (the fastest I've had it so far), but it also smells of excess gas when I leave it idling in the garage. I suspect it's running a little rich, but I can't say for sure until I tune the carbs properly.

Larry
LP Pittman

I just retuned with the same needle, H6 I think. The car has always run very well but I have always felt that I could run leaner than but have been unable to adjust it any more. MPG has always been a bit on the poor side

Following this thread with interest.

Steve
Steve Gyles

How often should needles be changed and how do you know if they need changing? I assume that as they wear the engine will tend to run rich but this gets compensated, at least at idle speed, by adjusting the jet setting on the carb.

I would guess that mine could have been in for about 50,000 miles.

Malcolm
Malcolm Asquith

We looked at the needles in the 1588cc MGA I posted about before today, they are marked No 6 but I know they were changed recentley for new ones. They look a lot thinner than the 6 from an MGB race car that I have in the garage and both will be measured with vernier calipers through the week. Maybe a Chinese 6 is a lot less brass for your money than a UK one? I am very puzzled by this, the original 6 came out of my MGB because they were far too rich, and that is a car with a larger swept volume (it's bored to 1950cc so thats 22% more air going in!) fast road cam K+N filters etc etc. Now the Bently manual gives no 6 as the correct needle for the 1588 and 1622 engine and it's all over the web as well which would seem to indicate that 1600 MGAs really ran very rich when you were nailing them, maybe deliberate to cool the valves and piston crowns?
Fot the MGB no 5 is standard and 6 is rich, No 21 weak.
Stan Best

Malcolm,
You generally don't have to change needles as a maintainence item unless they show unusual wear.
This will be obvious when you remove the carb pistons and examine the needles. Look for shiny areas of wear on the needles. Generally the needles aren't changed unless you are doing a carb rebuild or have made serious changes to your motor which call for richer/leaner needles.

Rich
Rich McKIe

HI, I run a 1950 cc in my A , with standard A carbs with a No 6 needle it seems to run fine at about 25 MPG


gordon
g c pugh

Thanks to everyone for your help. I'll have to pull a needle and see if I have the GS needle for the 1500 or the #6 for the 1600 before I do any further adjusting. Looks like our driving season may be over anyway; we got our first snowfall Sunday and it's still on the ground as of Tuesday.

Ken
k v morton

Maybe I was a bit hasty in writing off the driving season this morning. Most of the snow is gone for now. The photo is at Steamboat Pass on my drive home to Alaska from Oregon a week and a half ago.

Ken


k v morton

This thread was discussed between 03/10/2007 and 10/10/2007

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