custom throttle shafts?

[Janspeedcapri]

Does anyone know who/where I can get some made to my own spec? I'm guessing its requires particular tooling? I can't imagine my local machine shop could make the slots and tap and countersink the the little holes...?

[capri v8 driver]

I can't imagine my local machine shop could make the slots and tap and countersink the the little holes...?

a good machine shop can do this. maybe you should ask them.

[Leebay]

Yeah most good engineering/machine shops should be able to produce and mill out the slot and countersink the shafts. 

[Janspeedcapri]

oh right well I'll ask them then
another thing... is there any reason throttle butterflies are often made of brass? would stainless be better if I'm making my own?
and another... the little holes in the butterflies are for idle are they? why do they not just adjust the linkage so the butterfly doesn't completely shut?
cheers

[capri v8 driver]

and another... the little holes in the butterflies are for idle are they? why do they not just adjust the linkage so the butterfly doesn't completely shut?
cheers

sometimes the idle bypass is not big enough, witch can result in a sloppy or to low idle. in that case they drill a little hole. if you open the trottle blade to far, this would 'bypass" the idle bypass again. this would cause a bad metering signal, certainly with a carb or k injection (no decent vacuum signal) or with efi , the position off the tps sensor.

the idle bypass is there for a reason.

stainless blade that open and closes in a aluminum housing could cause wear in the housing. but there are trottle body's that use a (stainless) steel butterfly. thes are made in such a way that they dont tough the housing.

[Janspeedcapri]

O.k, I see then mine can be stainless too - before I drill any holes, I will see how the clearance around the butterfly lets it idle... just a few thou. I found a really helpful company just 15mins down the road who are going to cad design and waterjet cut them out from my measurments and sketch. Cheers for the info

[Mikey J]

I'm patterning up ls7 and 24v throttle bodies so have similar issues to consider.  Find a source for needle rollers to support the shafts and then get the shafts made up.  As for the butterflies, I'm probably going to go for laser cutting and then some precision engineering around the diameter to make them perfect but I've not quite decided yet.

[Janspeedcapri]

I'm patterning up ls7 and 24v throttle bodies so have similar issues to consider.  Find a source for needle rollers to support the shafts and then get the shafts made up.  As for the butterflies, I'm probably going to go for laser cutting and then some precision engineering around the diameter to make them perfect but I've not quite decided yet.

I was going for teflon bushing - my plan was to machine the throttle housings out of aluminium, one for each bank/side of the 2.8 EFI intake manifold. Each would have a blnd hole bored from the back end that intersects the 3 throttles. The shaft would be sleeved between each throttle with the teflon to support the shaft and seal each throttle. The butterfly discs were to be waterjet cut and the shaft flatted. It worked out really expensive to do so Ive recently ditched the idea

[Mikey J]

^ Spark erosion has also been mentioned to me for the butterflies but I'll probably just stick with laser cutting and machining.  I had a set of Kinslers here for an Ls1 and I never actually removed the butterflies but when they were closed shut they weren't at 90 degrees to the bore. Least I don't think they were.  I am wondering if they were manufactured slightly oval.  The needle rollers for the throttle shafts are quite cheap and dust seals can be bought for them.

[Janspeedcapri]

I had a set of Kinslers here for an Ls1 and I never actually removed the butterflies but when they were closed shut they weren't at 90 degrees to the bore. Least I don't think they were.  I am wondering if they were manufactured slightly oval.  

Ive noticed this on throttles I have here. wasn't sure if the bore was oval - none of them are machined so could easily be cast that way. Either way, the edges of the butterflies must angled accordingly to mate more complication

Ive decided to stick with the 2.8 EFI plenum as is more or less - only with two single or a twin modern actuated "fly by wire" throttle bodies. Haven't decided what off of yet but they aren't crazy money new. I looked them up when planning the ITBs because i wanted to be able to actuate them with emerald for idle, cruise, and traction control - all of which I'll still have with twin throttles. Shame tho, I would have loved to have got those throttle closer to the valves.

edit - a couple of these maybe - http://www.google.co.uk/products/catalog?q=throttle+body&hl=en&bav=on.2,or.r_gc.r_pw.&biw=2559&bih=1109&um=1&ie=UTF-8&tbm=shop&cid=408067377210312518&sa=X&ei=AmglTsuLO5CXhQeW-eiJCg&ved=0CJoBEPMCMAk#ps-sellers
Having two would mean the ECU can actually balance the throttles even if that means having to open one more than the other

[tabetha]

I was going for teflon bushing - my plan was to machine the throttle housings out of aluminium, one for each bank/side of the 2.8 EFI intake manifold. Each would have a blnd hole bored from the back end that intersects the 3 throttles. The shaft would be sleeved between each throttle with the teflon to support the shaft and seal each throttle. The butterfly discs were to be waterjet cut and the shaft flatted. It worked out really expensive to do so Ive recently ditched the idea
[/quote]
Teflon is ok, but not hard wearing, just slippery, DELRIN(a form of acetel) would be much better, and cheaper easier to use.
tabetha