My rebuilt original 750 quadrajet on my 68 /396 nova has recently developed a few issues.once the car runs for a bit and you shut it off;sometimes it will not crank unless you physically open up the flap at the rear 2 barrels.And now when you really nail the car from a dead stop it fall flat on its face and then it takes off.It doesn;t bog ;it more of a bad hesitation.Maybe the needle and seat are sticking?thanks for any advice.chris
The carburetor should have nothing to do with whether the engine cranks or not. That may be a battery/cable/starter problem. For the hesitation, check the vacuum break at the passenger side front of the carburetor. It should be connected to the secondary air valves(flaps up top) with a link. With the engine running, the vacuum break should pull in and hold the secondary air valves closed. If you can open the air valves with your finger, with the engine running, the vacuum break is bad. Also, with the engine off, you should be able to open the air valves and they should snap back closed by themselves.
http://www.v8buick.com/showthread.php?t=89299 and http://www.v8buick.com/showthread.php?t=62194 IS this the same Buick..er...I mean Nova that you are having the same problems with in 04,05? Just curious if you tried those suggestions too. ElectraJim
Just trying to establish prior issues and solutions applied. This Nova's carb may have multiple issues. Two rebuilds within 3 years. ElectraJim
Yea guys ;it has been a continuing problems.the car idle good now and runs well ,except for the hestitation its has recently developed and the starting issues.Will check the choke pull-off. over the weekend.Between the Quad Shop and Greg Gessler's help we have eliminated most off the problems/except the issues of Starting the car again after it has been ran and set for a few minutes;sometimes it will crank up and 5 or 6 times in a row.Going to change the fuel inlet seat this weekend.I have the Doug Roe book and the cliff ruggles book ;and it has been a great help.Like Barrett had said if he could work on the car he could probably eventually figure out the problem.Anything that pops into you guys head ;let me know and we'll give it a shot.thanks again,Chris
You may be experiencing a condition called a hot soak. What essentially happens is that the hot fuel in the carb vaporizes, causing a flooded condition. Once the engine starts, the hot fuel from the pump also vaproizes, exacerbating the condition. To make matters worse, the cooler fuel from the tank then follows, and vaporizes in the carb as well, until the carb cools. This might be made worse by the winter fuel in many places now. The pressurized fuel systems of fuel injection mitigates this, but further reduces the fuel quality. Just a heads up. Ray
1. Stock intake manifold??? Got a (very thin sheetmetal) stainless-steel plate between the carb base gasket and the carb? If not, you're killing the carb with exhaust gas contamination; just ahead of the primary throttle plates. http://holley.com/108-20.asp 2. Got a heat riser valve? Does it work correctly? 3. Dual exhaust, but maybe one side is all dented and mangled?
