Primary throttle shaft allowable play?

[daveo76]

I'm finally getting around to putting together my Edelbrock 1903 Q-Jet.  I bought the basic rebuild kit from Cliff's about 6 (or more) months ago.  I was planning on not bushing the shaft, but now I am not so sure.  There is about .01-.02" side to side play, will bushings be tighter than that?  Is it worth it for this carb?  If I buy the bushing kit sold here is it fairly idiot proof?  Do you need a drill press or can I do it safely with a hand drill?  Would hate to screw up my base plate.  Also how hard is it to put the throttle plates back together?  Thanks, Dave.

[73 Z28]

With .010 to .020 of play , you should install bushings to prevent vacuum leakage at the throttle shaft.  Make sure to use a vernier caliper to get an accurate measurement of the bushing o.d. before drilling. Be sure to grind off the staked ends of the throttle blade screws before trying to remove them or you'll break them off in the throttle shaft. It really is not too hard but if it's your first time doing one, find a junk carb baseplate to practice on, then do your carb.
Good Luck!!
Paul

[daveo76]

Thanks, Paul.  I'm thinking about buying the rebuild kit from Cliff that comes with the drill bit I'd need.  Only problem is it's a lot of money for the one carb I need to do.  Good tip about the grinding off the staked part of the screws.  Dremel tool work pretty well for that? 

[73 Z28]

The dremel tool with a small cutoff wheel works great for removing the staked part of the throttle blade screws.  Oh and if your from the metro detroit area, let me know and I'll give you a baseplate to practice on first.

Paul

[motorvation2go]

  Hi Dave,
       Just read your inquiry (re bushed throttle shafts).
I would strongly advise against using a regular drill bit for sizing shaft bores in prep for bushing install.
Get Cliff's kit for this purpose (includes self guiding drill bit)... otherwise you run a very good chance of messing up your baseplate with misaligned holes.
Just a word of caution.
Good luck with your Q-jet... great carbs!

[daveo76]

Thanks, guys. 

Paul, I live near Portland, OR so borrowing your old baseplate probably won't work for me!  Thanks for the offer, though.  (I actually have an old Q-jet I can use to practice on)

motorvation2go - thanks.  I think I'll either buy the kit or take the base plate to a carb shop and have them do it for me.   Since I'm only doing one carb for now it might be a wash.

Dave

[redman76]

You can do yourself.  I bought the kit from Cliff and it is pretty rookie proof; the self guiding drill bit is the key to ease and success here.  I just did mine for first time with no problems and now there is no play anymore.  You can just use a hand drill.  As careful as I was, I did manage to break off one of the shaft screw heads on the secondary shaft.  Tried to drill out, but I ended up tapping for next size screws.  Cliff has the correct size screws and you can buy the tap at the hardware store ($5) if you do not have one.  I found that if I carefully remove the screws just like you are retapping (screw out a little, screw in a little, screw out a little more, screw in, etc. that I did not break any screws.  I went ahead and retapped the screws on the primary shaft while I was at it.

[Cliff Ruggles]

Good advise to avoid drilling for bushings with a standard drill bit.  It will NOT follow the original hole, and the holes will end up to large to effectively hold the bushings.  We see a LOT of baseplates ruined in this manner.....Cliff

[daveo76]

Thanks all for the good advice.  I ended up using a reaming bit in reverse.  Shank of the bit through the base plate holes and then attach the drill to the cutting portion of the bit and run the drill in reverse.  Worked pretty well.  Bushings and shaft are installed and everything seems to operate tight  and smooth. 

I used new screws with red loctite on the throttle plates.  Is that good enough or should I stake the screws as they did from the factory?  I don't want to damage anything in the staking operation, but I also don't want a screw falling down into my intake.  That would probably be pretty bad....

Dave