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Icarus · New user Joined: 20 Oct 2009 Posts: 4

Hi

I'm in the process of re-building a pair of 40 DCOE's and 'converting' them to throttle bodies, basically plugging all the holes and adding a TPS

But my question is, with the throttle stop fully un-wound, should the butterlies/throttle plates make a light tight seal? I'm guessing they should.....

Thanks

Pete

dave999 · Posted: Mon Oct 26, 2009 3:42 pm Post subject:

the throttle disks should fit the bore yes but not at a dead 90 degrees
if one does and one doesn't you have a bent throttle shaft.
you would set throttle stop at just closed. otherwise you will wear a groove into the bore.

what ya doing with all the bits you take off??

ideally you would take out everything

and have a perfectoy smooth bore

you really don't need any venturi effect as you don't need any variation in vacuum to pull heavy fuel through any tiny holes

in fact why go for 40s .

you get little benefit from any restriction.....the whole shooting match is going to work on tuned length for a specific rpm range dicated by your cam. so a runner for each cylinder with a throttle disk and a trumpet is all you need

if you are doing a fuel injection setup where are you putting your injectors

in the runners near the valve or somewhere out at the velocity stack?

are you not better picking up some jenveys off ebay? they are at least drilled for idle/starter injector and main injector so you don't have to go and weld in injector bosses to an otherwise good carb manifold.
and have the generic TPS mount
and have drillings to allow balance tube or MAP take off if you feel the need.

use a pulse smoothing module off an alfa if you need MAP signal

www.dellorto.co.uk

do em

Dave

Icarus · New user Joined: 20 Oct 2009 Posts: 4

My engine has a separate fuel rail with injectors which is mounted on the inlet manifold, the throttle body manifold then mounts to that, so the injectors are downstream of the throttle bodies and nearer the valves. If I ever get to build a much higher revving engine, then I shall mount a second set out side of the velocity stacks.

I have used these as they only cost me £10 for the pair! everything has been stripped out, chokes etc and the 'barrels' smoothed on the inside's.

All the bits, of which there was not much, hence the £10 price, are in my toolbox somewhere...........

Jenveys are still quite expensive, even on ebay, and where's the fun in buying ready made stuff 'off the shelf'? Wink

I have already mounted a TPS on a self fabricated bracket and spindle adapter.

Dont need a map take off as my ECU, Emerald, is using throttle angle for airflow mass, and the brakes are sero-less Smile

Max rpm atm is 7500 and we'll see how it performs when it get re-mapped as to weather we need bigger bodies........

The engine curently has Suzuki GSXR750 throttle bodies mounted on a custom manifold, but the linkage is woeful and the availability of propriety linkages and filters for these is non exsistent, Yes I know, where's the fun in that, but some things are just better if they work Smile