Lotus Elan

Throttle shafts not countersunk?

PostPost by: oldchieft » Fri Sep 05, 2014 9:09 pm

Hi all
Just got a pair of new steel throttle shafts to replace the brass ones that did not survive the removal process.

Unlike the brass ones they are not countersunk.

IMG_1307.jpg and


My guess is they are intended to have the horrid cheese head type screws.

Are the countersunk ones no longer made or have I been incorrectly supplied?

If I countersink them myself I will need to make a tool for it as they are not normal 90 degree angle.

IMG_1310.jpg and


Anyone know what the correct angle for this would be? To my eye it looks about 60 degrees, but the word of someone who knows would be welcome.

It is a sure thing that the old screws in the new shaft won't fly.

IMG_1311.jpg and


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PostPost by: Elanman99 » Sat Sep 06, 2014 8:52 am

Fairly certain it is 60 degrees which is not an uncommon angle for countersinks so most engineers suppliers stock them.

Its the same angle as a 'centre drill' which will work fine if you are careful.

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PostPost by: AlfaLofa » Sat Sep 06, 2014 11:39 am

Hi Jon,

Good luck with your countersinking.

On (nearly) the same subject:

How do you intend to ensure that the screws securing the butterflies don't work loose and enter your cylinder head?

An Alfa forum I've seen recommends high strength Loctite 270 for butterfly screws - so this is what I intend to use.

But is just using Loctite enough?

I see that Des Hammill in the excellent "How to build & power tune Weber & Dellorto Carburettors" recommends using thread locking plus crimping.

But crimping new steel screws looks to me like a nightmare.

I realize that the originals were crimped in the factory - but I don't have the same kit.
Steve
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PostPost by: Pastapesto » Sat Sep 06, 2014 12:55 pm

Just a question for my benefit really as I don't have a carb to hand & I'm just being curious looking at the photo..

Do the screw heads pass through the butterfies on the spindle & if so, are the butterflies not countersunk & not the spindle?

Please go easy on me if that's a completely dumb question :roll:

Adam
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PostPost by: AlfaLofa » Sat Sep 06, 2014 1:02 pm

Hi Adam,

The butterflies slide into slots in the spindles - so only the spindles are countersunk.
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PostPost by: Pastapesto » Sat Sep 06, 2014 1:56 pm

Thanks Steve, sorry for such a dumb question. It was just in the picture it would appear that the recess where the butterfy sits has the countersinks but surely the countersinking is on the back of the spindle. I have never really had a good look at how they fit together but would assume the butterfly has the thread in it & the spindle part is just a recess with two holes in it with hopefully some countersinking on the other side. Is that correct or have I completely got that wrong?

I must strip a spare one apart one day soon to see exactly how they go together.

Thanks for the answer.

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PostPost by: AlfaLofa » Sat Sep 06, 2014 2:08 pm

The spindle is threaded.

When the butterfly is slid into the slot in the spindle the screws firstly pass through the spindle, then the butterfly and then again through the spindle (i.e. the other side of the slot).

The holes in the butterflies are oversize to enable a bit of jiggling around to ensure best fitment.

At least this is what happens with original Italian Webers.

I do know that when buying new spindles you should specify whether your DCOE40s are Italian or Spanish (which must therefore use different spindles - and definitely different butterfly screws)
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PostPost by: oldchieft » Sat Sep 06, 2014 2:19 pm

I did order the Italian type, that is why I wonder if I have been wrongly supplied.

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PostPost by: Pastapesto » Sat Sep 06, 2014 2:23 pm

Steve

Thanks, I think I understand that completely now. Well explained to me!

Adam
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PostPost by: AlfaLofa » Sat Sep 06, 2014 2:37 pm

Adam - mind you I know not whether the Spanish spindles have a slot.

I presume they do - but all the photos I've seen are so poor that it's impossible to tell.
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PostPost by: ort » Sat Sep 06, 2014 9:11 pm

if the spindles haven't been drilled for the pump cam you'll need to make up a spacer and stop to get the correct pump stroke.
Spanish spindles are slotted just the same but have an opening angle of 78 deg. whereas the early carbs are 79'30" deg
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PostPost by: oldchieft » Sun Sep 07, 2014 7:38 am

Hi ort
The are't drilled and that is a task I will need to address.

If you can give details of how you have done it I would be grateful, and it would be good to have it posted for the help of others.

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PostPost by: Elan45 » Sun Sep 07, 2014 2:51 pm

Weber used to supply jigging tools to drill the spindle for pump lever. I bought a pair of them long ago, but have never used them. They weren't exactly foolproof.

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PostPost by: ort » Sun Sep 07, 2014 4:52 pm

Hi Jon
Assemble the spindle into the body making sure the pump control arm is free to spin on the spindle.
At this point I don't bother putting the leather washers, springs and retainers on.
Lightly nip up the spindle nuts with the lever on one end and the washer on the other to centralise the spindle as I have found there to be a little end float in the replacement spindles.
Slide the butterflies into the spindle and centralise, no need to Loctite or peen the screws at this stage.
Fit return spring to the pump control arm and body.
set alignment stop to pump control rod length less the pump stroke

IMG_0007 copy.jpg and


bolt alignment stop onto the body

IMG_0008.JPG and


assemble spacer and drill bush onto the spindle lining up the drill bush with the roll pin hole

IMG_0009.JPG and


now comes the fun part to hold the jig in place while keeping the butterflies shut and drilling the roll pin hole. I tend to put a tension spring on the lever to keep the butterflies shut otherwise you find you need at least 3 hands!!!
hope it makes sense

Iain
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PostPost by: oldchieft » Sun Sep 07, 2014 6:42 pm

Hi Iain
OK then, I don't have the jigs and if they are a Weber tool they look like the were made with a knife and fork.

I had a few spare moments today, so I played with a set square and the bench grinder to make a 60 degree drill to relieve the holes in the shafts.

Then the slots in the shafts for the discs are a joke, I spent a while with a swiss file easing the fit as I could only get the discs in with a soft hammer.

I can only conclude that the engineering standards for Weber have slipped, if it was as bad as this in the past they would never have been the equipment of choice the were.

I think I will work from the carb that I have not worked on.

I will install the shafts completely, and wire them shut at the control arm.

Then position the pump control arm the same as the one that has not been moved and fix it with a dab of super glue, then use a 2mm drill to mark the shaft.

After that take the whole thing apart and drill it in the vice, the problem would be picking up the line of the back hole.

The way round that might be to plug the back hole with a steel pin silver soldered in so it would not mater, or buy new pump control arms.

That's the start plan, it may need a coat of thinking about before I go with it.

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