SU HS6 tuning - lifting pin question

[tdskip]

OK guys - what say you on this;

To use the lifting pins or not when adjusting mixture? Lots of writes up say use them, but other say use the screw driver blade method. The lifting pins raise the pistions a LOT more then the screw driver method.

So which one, and how much to raise via the lifting pins?

Tomorrow I'll ask about which oil, what tires, and if I should use DOT5. Grin.

 

[Geo Hahn]

I find the pin handy for a quick check -- yes, it lifts more than that miniscule amount the book mentions but (as I recall) the piston rises much less than the pin travels so it seems like a lot more.

Good thing about the pin is I can check the mixture w/o removing the aircleaners. IMO, the pin-lift is just one of several possible steps in finally getting the mixture right.

 

[poolboy]

With a little finesse can you use the pin to lift the air valve just 1/8 inch ?

 

[hondo402000]

and another reason to use the pin method is when you set the mixture with the airfilters off, it will get richer when you put the airfilters back on

HOndo

 

[tdskip]

and another reason to use the pin method is when you set the mixture with the airfilters off, it will get richer when you put the airfilters back on

HOndo

Bingo - why I'm asking.

Randall, if you could see the pin lift them the same amount then sure, but no way to see the piston with the filters on. Harder to lift exactly same amount with the pin than one would think...

 

[TR3driver]

I'm not sure why my name got mentioned here ... I'm still running H6 carbs (even though there is a new pair of HS6 sitting on the shelf next to the DCOEs).

But with the H6, my experience has been that the air filters don't affect idle mixture enough to worry about; and that it is not difficult to achieve a repeatable measurement by lifting the pistons with the pins. My pins only have about 3/16" or maybe 1/4" of travel before my finger hits the casting, and probably half of that is freeplay, so the actual lift is pretty close to 1/8" and nearly identical from carb to carb. It ain't rocket science anyway; these carbs don't hold the mixture nearly as close as the later 'emissions' carbs do (let alone EFI). So after setting mixture with the "lift the pin" method, I usually wind up making some small adjustment based on how the engine seems to run. (For example, I leaned them out by 1 flat after it seemed to be running a bit rich during a hot mountain run; then later added back 1/2 flat when it didn't like to idle when underhood temps were low.)

But your mileage may vary; if you want to pull the air filters every time and use the screwdriver blade, I don't mind at all. In fact, I recently picked up a wideband O2 gauge (with the primary intention of adjusting needle profiles after I get my "hotrod" motor built and installed).

 

[Geo Hahn]

I'm not sure why my name got mentioned here...

Even when you're not here... you're still here.

 

[DNK]

Randall

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[BillyB62]

Randall,

Because

 

[tdskip]

I'm not sure why my name got mentioned here ...

Because I was on my BB and confused Poolboy's icon and yours Randall. Sorry.

O2 sensor is the trick set up, no doubt.

Thanks guys.

 

[Jerry]

I don't want to get this discussion too far off track, but I have some HD6 SU in addition to the HS6 that came with my TR3A. What are the differences between the two SUs??

Jerry

 

[TR3driver]

I don't want to get this discussion too far off track, but I have some HD6 SU in addition to the HS6 that came with my TR3A. What are the differences between the two SUs??

Here's a web page that briefly describes the differences:
https://www.sucarb.co.uk/TechnicalDetail.aspx?id=89