Carburettor Float Adjustment Question

[ke70dave]

Right so this isnt a corolla carb, its actually a Suzuki Sierra carby...but hey a carby is a carby.

 

I'm half way through putting a carby kit through it, and i have a question about setting the float level.

 

I think the needle valve is actually a tad longer than one I pulled out, due to the fact that the adjustment is miles out.

 

The manual gives me photo of the float with a measurement of 7mm from the bottom of the float to the gasket case of the casting (with the float/top of carby upside down and the weight of the float on the needle valve). And the float is parallel to the gasket face.

 

In order to get this distance of 7mm I have to bend the bit of metal that attaches to the float qutie significantly (as far as it will bend), but with it bent like this the float is now on a mean angle, not parellel to the gasket face at all.

 

So I am thinking, am I supposed to also bend the tab of metal that attaches to the needle valve itself, and hopefully bending this tab i shoudl be able to achieve my 7mm as well as keeping the float parallel to the gasket face?

 

Thinking about it more and more I think its obvious i need to bend this tab, but just want to make sure as its not mentioned in my workshop manual here.

 

Sorry for long winded post, but best to get all the details down...

Edited March 17, 2014 by ke70dave

[Taz_Rx]

Will it work if you just bend the tab under the needle and seat?

[GJM85]

Just bend the tab.

In 32/36 webers you bend the tab which the needle attaches to.

[altezzaclub]

In order to get this distance of 7mm I have to bend the bit of metal that attaches to the float qutie significantly

 

I'm not sure which bit you mean, but you only bend the tab that touches the neele base. Same with DCOEs.

 

There's a second tab that limits the drop of the float, but that's not important really.

[ke70dave]

Thanks for all your replies, i think its fair to say i should be bending the tab as well.

 

Here is a little photo for future reference, this is slightly different to mine (photo found on internet).

 

The workshop manual is quite specific about bending it along the red dotted line. Ill give the orange line a go this arvo.

 

 

Edited March 17, 2014 by ke70dave

[ke70dave]

All right so i got the carby all back together, started first go, and runs/drives well so i must have done something right. I also replaced all of the vacuum lines (all 50 thousand of them)

 

However i have a question for you carby nuts.

 

The engine is standard except for a set of extractors and about a 2" exhaust. However I am currently running a haltech E8 ecu to run the ignition side of things.

 

If I'm at say 1500rpm in first gear just cruising along and i slam open the throttle (ie 10-100% throttle in less than 1/2 second), I get a reasonably large hesitation. If i just slow the throttle application a little bit (say roll onto the throttle to 50% then slam it open over say 1 second) it picks up perfectly fine.

 

This does not appear to be an issue in higher revs (say 3000 +).

 

As for the igntion tuning, I think the igntion map is pretty good. i based it off a 4age map of all things, but just dialed it back a bit at maximum advance. maximum advance at wide open throttle is around 28 deg. Howeever the above hesitation was present when i was just running the distributer, so i think its carby/fuel related, as opposed to ignition.

 

The carby runs a vacuum operated seconday, would this have something to do with the hesitation? (i have proved the vacuum widget that operates the secondary works by sucking on the vac tube and i saw it moving)

 

Or am i just asking too much of the carby to go to wide open throttle so quickly? or should i be looking at different jet sizes? (ive never actually changed jets)

 

One theory i had was that the bigger exhaust was moving more air, so the hesitation i am feeling is a lean spot. I actually put a spacer under the accelerator pump spring on the carby so that the accelerator pump was actuator more, I think this helped, but i still get some hesitation.

Edited March 23, 2014 by ke70dave

[GJM85]

I think its a combination of timing and fuel delivery coupled with low engine speed and a sudden loss of manifold vacuum when the throttle goes wide open.

Having vacuum secondaries is likely the source of the issue because there is a momentary delay between when your foot hits the floor and the secondary throttle opens.

Fuel delivery from the accelerator pump is instantaneous so it could be overly rich for a moment.

[ke70dave]

hmm that makes sense. I wonder if i can convert it to mechanical secondaries...tis an aisin carb after all, and some of them had mechanical secondaries.

 

I will alter the timing around the 1500rpm @ ~0kpa and see if it makes it better/worse.

 

I might also shove my Gopro under the bonnet with a torch and see if i can see the delay in the secondaries opening..