S489

i purchased a "rebuilt" q-jet some time ago built for a BBC. After inspection, it seemed mostly ok, but had to adjust about everything to get the engine started. The primary butterfly blades were drilled, one hole each (can't remember diameter-don't have notes in front of me). Running on the engine stand, no load, it seemed to idle just a bit high, maybe about 1000 rpm with the idle screw backed all the way out. I could get it to drop by helping the return springs with my finger. I thought that the drag added by the TH400 tranny would pull the idle down, but that doesn't appear to be the case. So now i'm thinking that the holes drilled in the butterflys must be to large or not required at all.

Can epoxy be used to plug the holes or do the butterfly plates need to be replaced, and if so, where can I get new screws?

Thanks

noonie

I just solder them.

S489

flux core, like used in wire connections, or paste flux with solid wire?

noonie

I use paste with a hot iron and clean holes.

S489

thanks, i'll give it a try

bigbadbowtie

The reason for the holes is that someone at one time had that carb on an engine that had a wild cam in it. What happens with the large cam is they have to crank the idle screw in so far to get it to idle. Instead of running off the idle circuit it idles off the main circuit causing a rich condition. They drill the holes in the main throttle plates so it draws in more air and they can back off the idle screw.

Hope that makes sense.

Im not sure it I would trust solder on it. If that solder joint somes loose, in the engine it goes. I would either tack weld it or replace the blades.


My .02 cents

S489

is there any way to plug the holes temporarily without damage to engine just to see if idle is corrected?

FKING1

Small nut & bolt or silicone.

Fred

S489

great idea! thanks!

The_Dude

A mechanic I know uses pop rivets.

Rdavis

I used 5min epoxy once & it worked fine I never came out.