Pontiac Owners Club UK

Update, after fitting yet another base gasket, I turned the choke cover so the choke was fully open, started the car and after a couple of minutes of holding throttle open a bit it idled at 6 or 700 rpm, after 8 minutes the idle jumped to 1200, sprayed wd40 around the base of carb and idle shot up when I sprayed around the back between the large brake vacuum bolt and rear corner.
The carb was bought new ( reconditioned) from i5 automotive in the states, is it possible that the base of the carb is warped in some way, the car hasn't been driven yet. But the carb has been on and off 5 or six times, always with the same results?

If the rpm increases when you spray around the base of the carb then there is a problem with leakage somewhere there. Quadrajets are known to become warped if they are tightened down too much but it usually affects the air horn part of the carb. The hold down bolts really only need to be finger tight and then nipped down to slight crush the base gasket. Anymore than that and you risk warpage.

If the base of the carb is warped would a machine shop be able to skim it flat or is it more complicated than that?

I think it's more complex than that. First of all you could check to see if it's square or not by testing with a straight edge. Another method would be to blow smoke into the carburettor somehow and see where it's leaking out to pinpoint the exact leak point.

I had a quick look tonight with a metal rule, seemed to be straight , I am taking it to a mechanic friend on Thursday to properly check if the base is square, if the whole thing is warped, is it viable to have work done o to fix it or buy a different carb?

i would buy a replacement if it is warped although i do know of people having them repaired in the past. weigh up the costs when you get to that point!

Had it checked over by a mechanic friend of mine, definitely warped, concave on the base, it was also noted that the throttle shafts had play in them, this was a remanufactured carb, bought from the states costing £300 with postage and import duty, last October, it's been on and off the car about 6 times and never been driven , too late to complain to them about it, not a happy bunny, have a couple of people who have proper workshops who could try and save it but as you say there is a possibility that the airhorn is warped too, booooh.

Carb is now on again and there are now no leaks from the base of the carb but the idle is still jumping up after 5 to 10 minutes, I am stumped!

I'd get it to somebody who can fault find the fuel control side of things. Sounds like the electronic control of the idle is out of soecification somehow.

When the idle goes high if you blip the throttle and snap it closed fast does the idle go back down for a time?