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HS2 question

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Luke_Healey

Luke_Healey

Jedi Trainee
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I bought one of those carb tool kits on ebay last year, but the jet centering tool is too large for the application.

Where can I order one that actually works right?

SPM-018_1.gif


Also, the part in this diagram (item #9) called the Jet Bearing Kit is problematic on my back carb.

It seems as if there is no way to tighten it without throwing the jet off of center, such that the needle bumps it and the dashpot piston binds up. However, I don't have this jet centering tool to aid me in my seemingly fruitless endeavour.

Any tips or tricks? My car runs, but not well. I've purchased a few sets of HS2 carbs on ebay, but they are all for different years and have differing emissions controls, needles, etc... I just want to use what I have, but I am at my wit's end with getting the rear carb set up correctly. Even when using the Colortune tool to set lean and rich, things never work out right. The car seems to run very rich at all times, regardless of how I get it set at idle. Most likely due to needles touching jets and other general badness.

Thanks for any tips or tricks.

I know I've posted about this 40 different times in the past, but I just can't get things adjusted right. I know how to adjust the carbs. It just doesn't seem possible with the situation I'm presented with.
 
Yes, He will/can fix you up.

Steve
 
OK, cool. I am more than willing to unbolt and send the carbs away for a tune up, but I don't want to pay the minimum 300 dollars people seem to charge for complete overhauls. My carbs are 97% OK. It seems to be that one issue that is the root of my problems.

But if anyone knows where to get HS2 jet centering plugs, I'm all ears.
 
Peter C has the proper tool for centering your HS2 Jets!!!

Contact Him.

Steve
 
You can get someone else to do it once, but sooner or later you'll need to service the carbs, and then you'll be right back where you started. So, it's worthwhile figuring out how to do this.

This is actually a fairly common problem with SU carburetors. The needle stays aligned until you give the jet assembly a final tightening, then everything shifts and it binds. I dunno exactly why this happens, but I suspect it's caused by things not being quite perfectly machined. Bumps fall into dents as the thing is tightened. Then everything shifts just a smigeon, but that's enough.

One cure is to take the jet apart, move the washers and other parts, then put it back together. This may take a few tries, but eventually you'll get things into position where they don't shift. When you tighten it, creep up on the tightness SLOWLY, checking the centering as you do it, and if it starts to bind, back off just a little, get it centered again, and continue.

I suppose you could put a little oil on the parts, too; might help. I've never tried this. Just don't go nuts with it; use only a little.

There is some info on this in the Wiki under Spridgets. Scroll down to Tech Tips.
 
Lubricating the jet bearing assembly might be a good thing to try. That's exactly what happens. It's centered fine until you go for the final tightening, at which point everything shifts.

Is there a chance that replacing the jet itself would fix the problem? I haven't ever actually pulled everything all the way apart to examine for wear and tear.
 
I got the jet centering tool to fit. It turns out the part that was too large was the skinny piece that fits in where the needle normally goes. I had to put the tool in a drill and use emery cloth to sand away at the top part. Eventually I got it snug in there. Lo and behold, for the first time ever, the jet is actually centered and my dashpot comes down with a legitimate clunk.

I haven't adjusted the carbs, or gone for a drive yet, but we shall see if things have changed.
 
Too "big" is waaay better'n "too small". To have center'd th' #9 part is the key here.


Well done, L_H!!!

It'll run fine. Start with the "12 flats" setting and work thru th' rest of th' process.


You're on your way!!! :cheers:
 
I'll tune it tomorrow using my colortune. The car started about 5 times easier and was operating smoothly. I still have about the same power, but I might still be running too rich. The main thing I noticed is that the car is a lot quieter. When I go under bridges, the exhaust is much quieter. A nice even burble rather than a harsh spitting sound.

Tomorrow my new front shocks arrive, so I'm hoping to start driving it daily. It was getting about 45mpg in town running badly. Who needs a Prius?
 
Luke_Healey said:
I got the jet centering tool to fit. It turns out the part that was too large was the skinny piece that fits in where the needle normally goes. I had to put the tool in a drill and use emery cloth to sand away at the top part. Eventually I got it snug in there. Lo and behold, for the first time ever, the jet is actually centered and my dashpot comes down with a legitimate clunk.

I haven't adjusted the carbs, or gone for a drive yet, but we shall see if things have changed.
Click to expand...
The problem was that the tool was made for a larger jet. H2 & H4 use .090" jets. H6 use .100" jets. H8 use .125" jets.
D
 
I have never used a jet centering tube on my HS2s. I have simply used the needle itself. I have had occasions where the final tightening of the nut causes things to bind a bit. However, when you move the jet down just a tiny fraction of a turn (less than one flat) it often is enough to release the binding. The amount you're off-center should be minuscule at that point.
 
My other carb worked fine this way, but the stubborn one moved the jet upon that last 8th turn of final tightening every time, without fail, right to the same spot. I think it was seated that way for so many years in storage that it just wanted to remain that way.

The jet centering tool did the trick, not to mention, it seemed to leave a space in all directions. I might pull the front carb apart and center it in the same manner.

OK, here's a really dumb question:

I have solid AN needles I have them seated in the pistons such that they are flush with the piston face. I thought I read somewhere that it was the correct way to seat them.

However, on this Jag page about SU carbs, they show this image:

sucarb2a.jpg


Am I supposed to seat the needles as far back as possible, like shown in the righthand diagram?
 
Dave, the jet centering tool is actually for centering the jet holder, so its OD is the same as a jet. Jet ID doesn't matter.

Doug and Luke, the very last tightening can bind the needle. I've found a trick that works for me is to use the wrench on the opposite side of the nut. (Badly written) Let's say your tightening from the front side of the carb. The last turn should be done from the backside, if you can. It just seems to help to not always be torquing from the same point, if that makes sense. Try it next time. It works.

Peter C
 
I was using a 3/4" craftsman wrench (the only one I had that worked for the job) and it's too big to really swing from anywhere but one spot when the carbs are on the car.

I think I'm all set though! That little tool really does work. And yes, it centers the jet holder. You use it with the choke engaged in order to pull the actual jet out of the way.
 
Peter I think I understand what you're saying about which side of the carb to come at when making the final tightening.

Luke, there are nice sets of stubby SU and Stromberg carb wrenches available from most suppliers. Those wrenches are tiny and very, very usefull for reaching under the carbs in tight spaces.

From memory, aren't the jets sandwiched in place by the jam nut (bearing nut?) and a thin aluminium thrust washer? Perhaps it would help to lap the aluminum washer flat on some sandpaper to minimize surface problems kicking the jet tube to the side.
 
PeterC said:
Dave, the jet centering tool is actually for centering the jet holder, so its OD is the same as a jet. Jet ID doesn't matter. Peter C
Click to expand...
OK, that explains it. The ones that I have seen fit into the jet center. I've never really needed a "tool" to center the jet though. Seems like cranking the jet up & bottoming the needle while tightening the jet holder does the job.
Thanks,
D
 
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