SU hs4 carbs and my frightened neighbors

[XJRpilot]

i've got my neighbors running scared while i'm trying to tune my carbs. i've got my new handy dandy unisyn in hand and am ready to use it. problem is when i try to adjust the idle on the carbs i cant get it to idle around 8-900 rpm. it seems to rise quickly to around 3000rpm and then about a 1/2 a minute or less later it falls back down to 500rpm or a little less. sometimes i have to shut of the engine because it idles 3000-3500rpm and wont drop back down. something sticking?

 

[Gary Lloyd]

Are you adjusting the throat?? You have to adjust the indicator to the middle, and then you start! GOOD LUCK!!!

 

[XJRpilot]

gary,
can you elaborate a little further. i started
with the dashpot mixture full lean and backed down
12 flats(approx. 2 full turns). i disconnected the choke cable and the throttle cable.
i then set the top idle screws just barely touching the throttle shaft. i then turned the top idle adj screws the same amount till it idled ok, and checked flow with the unisyn to balance it. what did i do wrong?

 

[Gary Lloyd]

This may help!! https://www.mgbexperience.com/service/su-tune.html
What I was referring to, is the proper use of the Unisync tool!! Anyway, read this article, and it will help!!

 

[Bruce74B]

ummmmm...I hate to ask, and forgive me for being prsumptious, but is this the B? If so, doesn't it have HIF4's? I don't know what the difference is as far a balancing them, but some of the settings may be different than the HS's.

Bruce

 

[XJRpilot]

it should have the hif 4's, but the previous owner replaced them with hs4's.

 

[kmcormick9]

my friend had a similar issue with his b and it was as simple as unscrewing the daspot and putting a bead of gun oil around the flared part at the top of the piston. it has those oil tracks in it, use them. his piston was sticking in the up position, but only on 1 of the carbs so you can imagine how smoothly it idled

 

[XJRpilot]

i ordered a pair of grose jets, i'm waiting for them to get here. i'll try the tuning thing as soon as they get here. anybody have any comments on grose jets?

 

[XJRpilot]

oh i forgot to mention that the rearmost carb (closest to the bulkhead) seems to flood once in awhile.

 

[Gary Pope]

Hi,

You can screw out the center part of the Unisyn to allow more air through so you carb won't starve. Usually you would have the red float about half way up the tube.

I have been using Grose jets in my HS-6's and have been pleased with them. This will probably cure the flooding problem too.

Take off the float bowl lid and see if the passageway is blocked at the bottom where the tube goes into the jet body. This area tends to accumulate debris after a while.