[Mgs] Carbs still being nasty

Clayton Kirkwood crk at godblessthe.us
Thu Dec 29 11:22:00 MST 2016


Thanks David for the good info. I needed to order a few more things from
Moss to get above their minimum $10 charge. I have the worthless wrench: my
fingers can move the dang nut most of the time.  Given your description, I
do have HS carbs. I had porpoising like you described once; I was running
low on gas. I think it can also be caused by the float bowls not adjusted
correctly, but that is a guess.

 

Clayton

 

From: Mgs [mailto:mgs-bounces at autox.team.net] On Behalf Of David Ambrose via
Mgs
Sent: Tuesday, December 27, 2016 7:36 PM
To: mgs at autox.team.net
Subject: Re: [Mgs] Carbs still being nasty

 

 

You probably have HS-2s. HS carbs have a separate float bowl assembly. HIF
carbs have the float bowl integral with the carb body. I don't think those
were ever fitted to MGAs. 

If you don't already have one, get an SU tool kit. It will have a couple of
pointers you can attach to the pistons which will let you sync the carbs. It
will have a wrench for the mixture adjustments, and most importantly, it
will have a small tool to center the needle on the HS carbs. 

And, if you get totally frustrated with that MG, I will give it a good home.
:-) Selling *my* '62 MGA is one of the few regrets I have. 

If it's any consolation, my first encounter with those carbs was anything
but encouraging. Sitting there at idle, the engine would rev up to 2000 RPM,
then drop to 900, and keep repeating. 

HTH,
Dave Ambrose



On 12/27/2016 12:52 PM, Clayton Kirkwood via Mgs wrote:

I have no idea which kind of SU's I have. This is on a 62A. How am I to
tell?

 

From: PaulHunt73 [mailto:paulhunt73 at virginmedia.com] 
Sent: Tuesday, December 27, 2016 12:45 AM
To: crk at godblessthe.us <mailto:crk at godblessthe.us> ; mgs at autox.team.net
<mailto:mgs at autox.team.net> 
Subject: Re: [Mgs] Carbs still being nasty

 

OK, twin SUs then, but HS or HIF?

 

Screw both the idle screws in until you can get it to idle, only then can
you really have any chance of adjusting the air-flow balance and mixture.

 

If you still have problems getting it to idle, perhaps the mixtures are way
out.  The starting point is to screw the jets up until the top is flush with
the bridge, then screw back down two full turns.  You will probably also
need some enrichment from the choke.

 

For air-flow balance yes when listening with a tube at the carb intakes if
one carb is quieter than the other the quieter one needs the idle screw to
be screwed in further until the sounds are as equal as you can judge.  This
should speed up the idle, so while doing that the louder carb may well need
its screw unscrewed a little to keep the engine at a reasonable idle speed.

 

Whilst you can adjust for air-flow balance while the engine is warming you
won't be able to adjust properly for mixture until the engine is fully up to
temperature.

 

PaulH.

 

 

----- Original Message ----- 

I can't keep the engine running when tuning for both slow idle, it dies as
soon as I start it. I have had some success listening through the rubber
tube and there is significant difference. I presume the intake which sounds
weaker needs the idle raised??

 






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