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I am experimenting with my SU H6 settings and I need a second hand fast idle cam. I can  not understand why my cam will not fit in the correct place. The adjusting screw and the lever prevent it fitting. 

I plan to use my file and hacksaw but would like a used part to experiment with. Is there more than one cam. My carbs were rebuilt a few years ago and otherwise work really well.

Please see the wanted section where I have posted.

Thanks

Richard & B.

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Haven`t got a spare cam, but I thought a picture of mine might help with fitment etc.

Ralph

20210120_133922.jpg

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Hmmm. The one on my car is similar Ralph except the actuating rod fits in the middle hole so the cam is further ccw than that, which I think brings the fast-idle in sooner. 

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Thanks for the picture.My cam will not fit under the adjusting screw. So I want to file it down and make it work with the pin in the second hole. But I am planning to try the modifications on a second hand part, by way of an experiment.

Thanks

Richard & B

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2 hours ago, RobH said:

Hmmm. The one on my car is similar Ralph except the actuating rod fits in the middle hole so the cam is further ccw than that, which I think brings the fast-idle in sooner. 

You are right, mine was in the middle hole originaly and had worn it quite a lot, I am experimenting with it in the top hole mainly because in the middle hole I had to have the adjusting screw so far out it lost the tension on the spring, where it is I have been able to screw the adjuster in further. Seems to be working OK.

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7 hours ago, Richardtr3a said:

I am experimenting with my SU H6 settings and I need a second hand fast idle cam. I can  not understand why my cam will not fit in the correct place. The adjusting screw and the lever prevent it fitting. 

I plan to use my file and hacksaw but would like a used part to experiment with. Is there more than one cam. My carbs were rebuilt a few years ago and otherwise work really well.

Please see the wanted section where I have posted.

Thanks

Richard & B.

Richard, 

   I don't have a spare because I've filed down the one I had doing something similar to you. I'm actually on the look out for a original as well. However they are quite easy to make, I have a few home made ones. I'm more than happy to make you one and send it to you and you can file it to match your original or into any other shape you want. Having gone down this route I found that the issue was with the position the arm had been connected to the butterfiy spindle. The hole was drilled in the wrong position and the arm was lower than it was meant to be. I ended up rebuilding the carbs and filling new butterfly spindles and fitting the arm at ther right angle and then all works, apart from I filled down the cam, so made one myself. 

Let me know if you want me to send you a home made one which you can use for experiments. But it's worth looking at the angle of the arm coming of the butterfly spindle. 

Note I'm not an expert, just a self taught mechanic so my solution may not be fit for thr problem you have. 

Neil

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This is a very useful reply. Someone else has my problem. My carbs were rebuilt by a specialist about three years ago.  I have considered sending this one back to him but after some email chat I have decided not to progress in that direction.

I found the spindle kit on the Burlen site and spoke to them . I have a instructions on fitting the spindle and it involves drilling a new hole for the tapered pin.  This needs to be on the bench. I am not confident in being able to drill accurately with a hand held drill. I can see the hole correct at the start and exiting at an angle. I did buy the correct size bit, 3mm. There used to be a workshop near me who could carry out small jobs but he suddenly packed up and left.

So I seem to have two options.

1. Leave the spindle alone and try and customise the fast idle cam so that it works.

2. Send the carb off to Burlen which will cost a lot and maybe have a new jet and needle as well,  which would mean new jet and needle for the other carb. After the original overhaul I had it set up by a specialist carb man who works for a local sports car business and used to be with Southern Carburettors in Wimbledon, who were very good. They looked after my tuning for many years when I lived nearby. Since that set up , Bob (tr forum) checked it over with his Colourtune at the International in Lincoln, and  afterwards it was giving near 30 mpg on long runs. The sports garage cost £275.00 and I looked on it as am investment for many years. I only do low mileage anyway and in lockdown, no miles at all.

So it looks like some mods to the fast idle would be the safer route.

Any advice welcome.

Richard & B

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There is a third option Richard, buy yourself a cheap bench drill.

I bought one a few years ago on a whim (a late night bid on ebay!) and have found it to be one of the most useful tools in my workshop.

Rgds Ian

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11 hours ago, Ian Vincent said:

There is a third option Richard, buy yourself a cheap bench drill.

I bought one a few years ago on a whim (a late night bid on ebay!) and have found it to be one of the most useful tools in my workshop.

Rgds Ian

Just really to add, I did it on a cheap bench drill. I also soldered in the pins, which I'm sure some would frown on but it's a belt and braces approach. One way on understanding if this is the issue is by looking at how much play there is with the idle adjuster. If the screw is nearly all the way out then it's going to mean the arm is lower (closer to the cam) than it could be. If I'm honest, Ralfs photo shows this to some degree. In my case it was slightly worse than this on one of them. I really would try to get this bit right and then work from there. It made the car so much easier to get right, idle speed and mixture. I always struggled with this. But the offer to make and send some cams is there if you want to see if there is just enough room to make work at the agle you already have.

   Oh and if someone has more experience please feel free to contradict me and give the best advise. I'm happy to learn also. 

Neil

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  • 3 weeks later...

I have been in touch with Burlen and I suggested that I could bring my H6 carb in to their workshop. I would be passing on the way to my son in Devon. I offered to fit the spindle and leave the pin and drilling to Burlen. They wanted to charge me £80.00 and suggested that I find a local shop. There are not many SU specialists in Sussex.

So I am taking the easy route and will be modifying the cam when the weather improves. I have some good files in the garage.

Richard & B

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