It could also be a carbon track on your coil tower.........I've seen that before. Also loose distributor shaft bushings can cause backfiring. :bglasses:
I'm having a very similar problem since a few days back. The car runs fine, but under load it bogs and hesitates. When it's in park it runs fine while idling and at higher rpm's. I'll go through this post to see if I can do anything about it. It isn't bad, I can drive it, but if I floor it, it starts to act up. I'll go out and have a look at it now. Back later.
My new 72 lark is bogging when starting out also... HI all! my first post! have been reading this forum for months and have finally got my new(used) 350/350t 72 skylark WEWT! Ive driven it alot in the last 2 weeks (ALL GOOD) and yesterday, finally found an open road & ran it upto 90mph and tested the new brakes ((drum )) and shocks...since speeding it yeterday, my carb has been bogging at launch ( seems like its lean in that i dont smell gas and it lights right back up....)... I can always just coax the peddle and get the rpms up and "power through the bog" but it seems inapropriate to bark my tires at EVERy red light* ... (notice the happiness in my typing from thoughts of a V8) -should i spray it down with cleaner? (im a NewB so dont laff) -I dont want to tear it down.. ill prolly change plugs/fuel filter/air filter/dist cap/ adjust timing with a friend before even considering playing with my carb .... Any help is appreciated....thanks in advance..& also please use somewhat common terms inthat im real green but wanto learn... thnx again -leetlark
Another thing....Im in the tacoma/seattle Wa area 98465 & would love it if anyone had the time / inclination to sow me how to rebuild my carb - \ thanks again- eleetlark
irratic cut out Guys there is one possibility that no one has mentioned. The old original type ign. coil will go bad and run fine untill the engine heat gets it good and hot then it will begin to break down and misfire. It will get progressively worse untill it finally goes out, then you will find it for shure. Other than that I would check the vacume advance and make shure it was not leaking down and clean and lube the mechanical advance to make it work correctly. :Brow:
It seems that we have 2-3 people with this problem, including me. I have the bogging at slow acceleration, and bad bogging, like almost about to stall if I want to accerate quicly (ex. 20-50mph). I just rebuilt the carb. The carb was from a 455, but its on a SP350, I was told to set the float level according to the 455 setting, thats what I did, was I suppose to set it according to 350 setting? Thanks Slawek
bog Well, I typed for an hour and then hit the wrong blasted key and lost all of it. I will return later and do it again. :af: :af: :af: :af: :af:
secondary valve spring O K Slawek, in the pic You sent the screw with the allen head on it that comes in from toward the bottom of the carb is the screw that holds the spring tension locked in place. The spring tension screw comes IN FROM THE SIDE of the carb. Loosen the allen screw first and turn the side tension screw to the right untill you reach the desired tension,then lock the side tension screw in place by tightening the allen screw. :laugh: :3gears:
One addition to this. Have a screwdriver in the side, spring tension screw, as you loosen the allen screw. Otherwise it will spin itself back once the pressure is relieved. Try tightening in 1/4 turn increments. If you get rid of the bog, then back off an 1/8th of a turn and see if it bogs again. If not, that's a good place to lock it in.
Regarding the hesitations, that sounds very similar to what happened to me when my coil went out in my 71 GS455. I managed to limp it home. After trying a few things, I put in my 30 yr old coil (was running a Petronix setup in those days) and it ran just fine. I eventually threw out the Pertronix and went back to points in it.
Thanks for replies, since mine bogs only when i get to the secondaries, ( not even under full throttle) it seems to me that it is to tight and wont open, am I correct? Slawek
Ok, I did the secondary spring adjusting. Didn't help. The car still sputters, grr. Sometimes it dies, sometimes it recovers. When I accelrate hard I can hear the valves knock, could this mean that my timing advance was not working, I wish someone that knows Buicks could just see this. What should the timing be set at? (degree's?) Thanks Slawek
Hesitation O K Lets go to the next possibility, You may be getting secondary ign. breakdown. This occurs when the eng. is loaded. make shure the rotor , dist. cap and wires are in good condition, no cracks in the cap or rotor and no carbon tracks. check each tower in the dist cap for corrosion. and check each wire for broken or burned places. dont forget the coil and coil wire . set the ign timing WITH THE VAC ADVANCE DISCONNECTED, I think at or about 0 deg. on that eng. and after tightening the dist hold down then reconnect the vac advance. While you have the vac advance line in hand suck it down and hold it with your tongue to see if it leaks and wont hold vacume. if it leaks down replace it. Check the spark plugs, eaven if you recently replaced them, all plugs are not created equal. Personally I would go with Motorcraft gapped to about .035. Finally try switching ign coils with some one who has a known good coil and see how the car runs. :blast:
Ok, Today I replaced the cap, rotor, wires, and plugs, still sputters. Changed the coil (with a different one,not new), did'nt help. Then, I went to the gas station and filled up my almost empty tank with a full tank of 89 octane gas. Still sputters. What could be the next possibility? Could the Timing still be off? When I have the timing light flashing at the degree marks, What should the nick be at? I haven't checked if the vacuum advance hose is good, I'll do that tommorow. Thanks Slawek
Actually that's more the opposite - it would be too loose and they're flapping open. I would try tightening them. On my 71 GS455, I went to an aluminum intake and started getting this bog. I had to tighten the secondary air valve up just a little bit to get rid of it.
REALLY? :eek2: Crap, I did it the wrong way then, crap again. lol, I'll see if that works. THANKS! Slawek
