Idle

[F250 Restorer]

I have a 78 APT type QJ.  I spent a couple of weeks very carefully rebuilding it.  It is off a sbc van, and is going on a hp Ford 300 I6, in a p/u.  The head is highly modified with larger sbc valves, porting. 

When I ordered my kit from Cliff I told him I had 71 mains with 44 m.rods.  He sent replacements with air bleed restrictions to richen it up.  But actually, on reexamination of the m.rods, it had 41 rods, so that is what I used and removed the ab restrictions.

With the carb installed I can't get the idle to come down.  With the adjustment backed all the way out it idles at 1200 rpm.  Flaps closed.  Mix screws had no affect so I snipped off one ring and now they just make the engine shutter when all the way in.

Any help is appreciated.

[73 Z28]

If the idle will not go below 1200 rpm with the curb idle screw backed out all the way, it's only one of two problems. Either the base timing of the engine is too far advanced or the carb is stuck on the fast idle cam.
When you said flaps closed were you refering to the choke flaps, because the choke, as it begins to open, pulls the carb off of the fast idle cam to the curb idle setting which should be about 600-750 rpms.

Good Luck

[F250 Restorer]

I was referring to the throttle plates.  I have had difficulty installing the choke linkages correctly and can't find any photos or illustrations of how it all sits.

Thx

[F250 Restorer]

I have 19 hg vacuum with my Eddy on, and when I drop on the QJ it surges from 14-17 hg.  No, it is not stuck on the fast idle cam.  Yes, the idle adj. screw is backed out all the way.  Still, there is very little response when I turn mix screws all the way in.  However, turned out about 4 turns the idle speeds up and and v. jumps to 19 and steady.

I would certainly appreciate any help offered.

I noticed when I pulled off the fuel line that there was pressure, and sprayed out.  I wonder if I should remove the oe in housing filter.  I have two filters inline anyway. 

[F250 Restorer]

Really?  Not a single person can chime in here? 

[Cliff Ruggles]

As mentioned on the phone, got to figure out why you can't get below 1200rpm's at idle speed.  The extra air has to be coming from someplace.  Either a vacuum leak, throttle plate(s) not fully seated at idle, too much idle bypass air, or combinations of the above.

If the carb was placed on the engine, with all 4 throttle plates fully seated, it would not idle at all.  Being at 1200rpm's at idle with the idle speed screw all the way backed out, the air is coming from someplace?......Cliff

[jamesF]

Check to see that the plates are closing ALL THE WAY. Could be a very small burr or piece of debris... Pull the carb and blow some air on the plates and some carb cleaner as you work the throttle.

[Frank400]

you said you had an edelbrock carb before, so I suppose you must have some sort of adaptor to run a spread bore QJ ?  Could this be "leaking" somehow ?