HS2 on and Running, but no throttle return

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Nikki&Austin
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HS2 on and Running, but no throttle return

Post by Nikki&Austin »

As previously recommended, we bent the throttle lever towards the block (and up a bit) so that the linkage rises vertically up from the carb.

However, we seem to have lost any throttle return spring function.

To help bend the lever in the engine bay we put a wood block under the throttle pedal.

Could it be that we still need to bend the lever back towards the bulkead to allow for the longer linkage (which currently requires the lever to be raised an inch or two before screwing to the linkage), fit the original (shorter linkage) or is it necessary to fit a stronger spring on either pedal or carb end ? (there seems to be no way to do the latter ?)

Also annoyingly, have cut the new choke cable to length, i note that rge carb didnt come with anything to link to the choke cable and nothing from the zenith seems trasferable. I assume burlen will sell ?

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Alan
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Re: HS2 on and Running, but no throttle return

Post by Alan »

judging by the picture and comparing it to mine, I think the throttle rod needs bending more towards the centre of the engine more. mine is closer to the manifold
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Edosan
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Re: HS2 on and Running, but no throttle return

Post by Edosan »

Hi It all looks great but understand your frustration. I'm sure you've found the throttle spring which is on the linkage just above your foot where the linkage does a right angle. This should be strong enough on its own, I've certainly never needed anything else. Is it possible that this has come out of position on the linkage whilst you've been altering in. Easy way to test is to disconnect the linkage and let it drop to its lowest point. If you then raise it you should be able to feel good spring pressure. If not there is something amiss with the spring and its location on the linkage. There should also be room to keep lifting it until the throttle is wide open. Yours looks very similar to mine and the height of the connecting rod puts the throttle pedal at the right height. I've been in cars with a shorter connection where the accelerator pedal is uncomfortably high for me anyway. If you want a picture of how the spring should look and what height the pedal is at I'll happily post this for you. The best choke connection in my opinion is a very simple one, here it is on the Minispares website but sure you'll find it on others eg SU. http://minispares.com/product/Classic/F ... o%20search
I'd pop one in the post for you if I had a spare lying around but others might be able to help.
Would also be happy to discuss/compare set ups further over phone, skype etc if you wish, simply PM your details.
All Best Ed
Nikki&Austin
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Re: HS2 on and Running, but no throttle return

Post by Nikki&Austin »

Thanks

This is where the throttle lever rests before being pulled up to fasten onto the linkage.

The movement seems to be free, i.e., no stiffness resisting it returning.

Maybe we will try to bend it up a little in case it is taking up much of the spring movement ?

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However, I also prefer the slightly lower pedal position that this provides and it still allows the throttle to open / close fully

Will have another look at the spring when we go back out this morning.
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Re: HS2 on and Running, but no throttle return

Post by earthhist »

Nikki&Austin wrote: However, I also prefer the slightly lower pedal position that this provides and it still allows the throttle to open / close fully
That is not the only consideration - if the angle isn't right engine mounting movement can result in the throttle opening varying, creating "kangaroo petrol" at low speeds.
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Nikki&Austin
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Re: HS2 on and Running, but no throttle return

Post by Nikki&Austin »

Played around with the angles and arcs and with a combination of old and new linkages we seem to have it returning satisfactorily.

I think the linkage to the carb is still a little too short as the pedal is still a little high and it almost starts to kangaroo.

Although we did put a wooden block under the pedal when bending the arm, I wonder if we strained the spring - as to get a decent strength of return, I had to place some packing beneath the spring to get some extra tension, so will order a replacement (how the **** do you get the new one on without removing the entire assembly ?)

Must say it runs so much better with the HS2, even though it isn't fine tuned (just a quick fiddle with a colortune), that rasp of the air intake makes it sound like is has nearly 984 cc, not just 948 !

Thanks all.

Maybe next week it will get off the estate !


ps, this is the linkage love-in that worked in the end !
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Neil Evans
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Re: HS2 on and Running, but no throttle return

Post by Neil Evans »

I can't work out why you've lengthened the link rod, then bent the mechanism higher to suit the longer link. Austin managed on the late A35 vans with the same length link as the Zenith used. Why reinvent the wheel?

The reason the late vans need the mechanism bent towards the engine is because the SU throttle spindle rotates in the opposite direction... Where it was in your earlier photo is not near enough to the engine...
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Re: HS2 on and Running, but no throttle return

Post by A40FARINAGURU »

it is the link arm at fault, the SU fitted to the later vans had a different arm which the angle was different to the cable type arm

this is a 'cable type' arm (like yours)

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this is a 'rod type' arm as fitted to AV6 & AV8 vans

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as you can see the pivot point is higher on the A35 Van type to stop the 'locking' of the cable type arm
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Nikki&Austin
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Re: HS2 on and Running, but no throttle return

Post by Nikki&Austin »

Neil Evans wrote:I can't work out why you've lengthened the link rod, then bent the mechanism higher to suit the longer link. Austin managed on the late A35 vans with the same length link as the Zenith used. Why reinvent the wheel?

The reason the late vans need the mechanism bent towards the engine is because the SU throttle spindle rotates in the opposite direction... Where it was in your earlier photo is not near enough to the engine...
With the original link it didnt move v well at all ! Also the angle of the flange meant that you couldnt attach the link to the arm.
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Re: HS2 on and Running, but no throttle return

Post by Dave Clark »

Whilst there is no doubt that the original arm can be made to work with the SU (as Neil says, the factory did it) I have always just modified the throttle pedal inside the car and used a cable. This will almost always solve any kangaroo problems too !
Nikki&Austin
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Re: HS2 on and Running, but no throttle return

Post by Nikki&Austin »

I did wonder if i could simply replace the fixed linkage to the carb with a cable attached by two of the trunnions suggested by ed above, but for this to work presumably there would need to be a return spring on the carb as tgere is with a twin set up ?
Dave Clark
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Re: HS2 on and Running, but no throttle return

Post by Dave Clark »

Of course, but all it needs is tension spring hooked on to the throttle arm on the carb and a location below the carb to secure it (a self tapper would do)
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Re: HS2 on and Running, but no throttle return

Post by Bill »

Never favoured bending the throttle pedal. Extend the link rod by 127mm and job's done. See the previous correspondence on this.
Nikki&Austin
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Re: HS2 on and Running, but no throttle return

Post by Nikki&Austin »

Hi Bill, that was the first option tried, sadly it would return fully, maybe a PO had already bent something.
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Re: HS2 on and Running, but no throttle return

Post by gazza82 »

Dave Clark wrote:Of course, but all it needs is tension spring hooked on to the throttle arm on the carb and a location below the carb to secure it (a self tapper would do)
Or the Mini way .. I'm sure all I did was to put a small bracket on the exhaust manifold clamp and hook the spring onto that. My SU carb/manifolds came off a written-off Riley Elf.
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