Author Topic: Replacing Rochester Q-jet 4MV Well Plugs with Set Screws  (Read 3458 times)

Offline 68442Convertible

  • Newbie
  • *
  • Posts: 3
Replacing Rochester Q-jet 4MV Well Plugs with Set Screws
« on: September 13, 2014, 08:21:08 AM »
I am considering drilling out the well plugs and replacing them with set screws. 1968 Rochester Q-jet 4MV.
Can someone tell me what size/type/length set screws I should use, and where to get them?
What is the best stuff to use on the set screw threads?
Is there anything that I need to replace while I have the carb out and the throttle plate off - as a part of normal maintenance?
The carb works OK, other than the float bowl going dry.

Offline 68442Convertible

  • Newbie
  • *
  • Posts: 3
Re: Replacing Rochester Q-jet 4MV Well Plugs with Set Screws
« Reply #1 on: September 13, 2014, 09:04:17 AM »
I found the bottom plug kit in the Parts section. It appears to almost be what I need, except that it is for 69 and later. Apparently my 68 needs a different solution for the rear plugs, but I don't know what it is. I need to be able to fix this myself - so that the car is not disabled for more than a couple of days. Have to be able to move it out of the way. At least that is the case near term. I may be able to leave it parked for a longer period next year.

Offline 429bbf

  • Qjet Hero
  • *****
  • Posts: 539
Re: Replacing Rochester Q-jet 4MV Well Plugs with Set Screws
« Reply #2 on: September 13, 2014, 11:13:25 AM »
your carb should have brass plugs . what i did was lightly screw a bottom tap into the brass and spin them out. then i cleaned up the holes and the plugs with crocus cloth and coated the outside of the plug and the inside of the housing with marine tex. don't use to much it will settle down in your fuel hole. after i had the plugs in i covered the plug the rest of the way with the marine tex.i had to use a slight bit of heat on 1 it was a little stubborn  . be careful them old housings are very thin and fragile.do you have cliffs book? i think he says to use a drill bit (can't remember the size)basically your trying to get the bit to grab and spin the plug so it comes loose. they are not threaded.i tried tapping on of them older carbs and it didn't work very well because the casting was so fragile. fwiw

Offline 68442Convertible

  • Newbie
  • *
  • Posts: 3
Re: Replacing Rochester Q-jet 4MV Well Plugs with Set Screws
« Reply #3 on: September 13, 2014, 07:28:39 PM »
Thanks! Did you do this for the front plugs as well? Or were you able to tap them?

I don't have the book. Maybe I will get it and do a full carb rebuild at some point.


Offline 429bbf

  • Qjet Hero
  • *****
  • Posts: 539
Re: Replacing Rochester Q-jet 4MV Well Plugs with Set Screws
« Reply #4 on: September 27, 2014, 08:59:08 PM »
sorry for the slow reply . no i did not do anything to the front plugs they did not leak so i left them alone. fwiw