Hi,
Maybe I should have done this long ago, like two decades ago, but I tried to replace the throttle plates on my carbs, as during the last MOT the float in my rear H4 carb started to sink and I removed the carbs from the car.
I had replaced all seals and the jets about 14 years ago and IMO they were running nicely, but lately, after the engine rebuild I could not really get the idle to stay below 600 rpm when fully warmed up, even with the throttle plates supposedly fully closed. So i thought Iâd check them and replace the throttle plates and see if there was any extra clearance in the shafts etc.
Is there any special trick to get the throttle plate locking screws loose?
I tried soaking with penetrating oil for a couple of days, giving them as much heat as I could, but still, in the end I had to drill out both screws from the front carb. Now I am afraid I will have to do the same for the rear carb. The screws are all black and the look like they are rusted solid with the brass shaft.
Anything else I could do? Anyways I had a new float and all the seals etc.
What do you think, should the shafts be machined a bit so they could accept some kind of seals? Now it looks like there is only a brass bush in one end and nothing in the other end of the shaft on the carb body, right?
Burlen UK says on their website: "Throttle Spindles are now made from manganese bronze as this material is more resistant to alcohol Fuels than Brass. All SU Spindles are precision ground to size and slotted to mate with the appropriate Throttle Disc . "
So is that true? Could 5000+ miles on ethanol fuel eat up the brass parts enough to produce too much clearance and too high idle?
Also the new throttle plate locking screws look as it they are now stainless or plated, the old ones were round slotted head mild steel and black, so the six years in England and 14 years in Finland have the screws rusted solid in the shafts I guess?
So I was hoping just to replace the plates, but now it looks like I would have to order two of these as I am likely going to have to replace also both shafts etc.
Cheers!