Saturday, February 24, 2007

Bits and bobs.

Found some spangly new DHLA45M's for my K-Series...Ultimate carbs, Turbo spec too, not that I intend to Turbo the car.

Finished off Andy's carbs, bench calibrated and ready for hand delivery tomorrow on my way to pickup some other stuff.

Interestingly I bench tested the old ones. As such I am confident once we have a quick tinker and find the right jetting (should be within 5points anyway) he will be ALOT faster this year! Oh boy were the old ones out of wack!

Actually looking forward to Mallory as I sure he's in for a bit of suprise, thats all I am gonna say!


Jim said...

What makes a DHLA turbo spec Dave?
Is it just uprated seals etc??
Or is there more to it?

David Powell said...

Turbo has numerous differences. However you can use them on normally aspirated engines.

Firstly it has seals on the inside of each barrel to stop leakage from the spindle shaft. The outer spindle simply retains the normal bearing which is air tight anyway.

Also the progression hole caps have an O-ring seal. The venturi retaining screws are a different design and have a fibre washer under them.

The top jet cover is metal and not open to atmosphere as per normal. The fuel bowl and all internals are then sealed at the same pressure as the turbo boost/airbox. The hole in the jet cover feeds the choke with normal air pressure I believe or should do, as you don't want to boost the choke system! As it'll blow the choke open and throttle the engine with fuel.

Seems also some internal drillings are slightly larger to enable a greater flow rate.

The lead plugs are usually covered in epoxy so they don't blow out.

To use them on normal no turbo simply remove the metal jet covers, replace with open flowing plastic ones...

Thats about it :)

David Powell said...

Actually having had a decent look at the Turbo's, never really used or rebuilt any of them! It's obvious the metal jet cover has a hole to blow boost into the top of the choke system, to match the pressure coming from the barrels via the choke feed holes in the lower choke area, as to equalise the pressure either side of the choke system, top and bottom, so it doesn't blow open under load:)

Thats it :)