Took the Skylark out for a spin this afternoon and it started up and idled fine. Backed out of the driveway then put in in drive and pulled away slowly, gave it a little more gas and I got a major stumble. I let off on the gas a little and it was fine, but put a little pressure on the pedal and stu...stu...stu...stumble. I brought it back home and checked for loose or damaged wires and found the wire going to the positive side of the coil needed attention so I rewired it, but I still get a stumble with any amount of gas. The coil was just replaced a few months ago, could it be bad already, or maybe something else? Carb was rebuilt a year ago so I hope that is not the problem. It ran perfectly last week, so this is really annoying :af: What do you all think? -Chris
I think you and I are the only ones who have chronic bog problems. When was the last time you checked the timing? Check to see if the choke plate is sticking at all. I've had to advance my timing to compensate for a stretched timing chain...seems to help.
Yeah, it's in the 30's here today. But I have driven it in cold weather in the past without problems. -Chris
ic oh i c cause im in canada and sometimes when its cold it will start up fine but when you drive off it still start ti give way and try to die.i just floor it and it quits when the engine warms up.i got a 71 skylark
I just drove my GS to work today and had the same problem. My stumble is more noticeable after the choke is off. It stumbles mostly between the 1-2 shift. The temp outside was 6 degrees, and this is the first time driving it in the cold (due to the gas tank of my Bronco developing a leak, with 25 gallons in it!) I think the problem is the vacumn advance, where it should not get full vacumn until the engine is warm. This was originally controlled by a thermal switch on the intake, which is missing from mine (1973 350 2bbl engine)
Octane Rating Hey Chris this is Brett. This to me sounds like the octane rating in the gas you have chosen is to low. When ever I owned the Buick I put 91 or higher. I put 87 in it once and I could only about rest my foot on the gas or it would pop or back fire what ever you want to call it. Hey maybe some day I could come down and look at your new toy. Maybe Friday? I dunno. I would just like to see how nice it is. Give me a ring. Later. __________________
Make sure you or someone else don't have 12 volts going to the coil. I've owned two vehicles now that someone had rewired and made this error. ( ok, I did one) You should only have about 8 volts, HEIs use 12. 12 will fry your points in as little as 100 miles. Check it out. Good luck, Dan
Hey Brett, how's it going? I'll give you a call later. And I always use premium gas (91 or higher), it just seems to run better with it. Now a couple of things. Thanks to everyone for all the ideas by the way! My stumble is more pronounced and practically doesn't show up until the engine is fully warmed up, so what does this mean? o No: When the choke is still on, it revs out fine, but later begins the annoying stumble. What is the easiest way to check to see if I'm running 8 or 12 volts. I am considering swapping on an HEI anyway. I have a 455 HEI that I just need to swap the bottom gear on if I understand correctly. Can I simply take the gear from the points distributor and put it on the HEI? What have others done? Can I buy just the gear somewhere? How about wiring, what do I need to do here? I am also going to replace the fuel filter, plugs and wires soon. Anything else I should check? Does anyone think this could be a carb problem? -Chris
Chris - It still sounds to me that it's a fuel starvation problem, i.e. plugged fuel filter, low fuel pressure, carb out of whack, etc. Good luck and keep us posted. Mike
455 to 350 Distributor Chris, When you go to swap the drive gear on the distributor. The gears use different size roll pin to hold the gear to the distributor so when you swap the 455 HEI to the 350's drive gear you will need to drill out the 350' s gear. Normal most of us do the opposite and need to oversize the hole in the shaft. Maybe you should consider offering a swap to someone for a 350 HEI. Because it would save yourself and the other person the trouble of have to recurve the distributors too. I have a fresh NAPA remanufactured 350 HEI if your 455 HEI is in good shape I would consider an even swap. Let me know Jake
Chris, I permantly borrowed a voltmeter from my brother to test volts. It prints out volts on an LED screen. I'd say you need to use a similar device. Also check to see if your vacuum advance failed. Check your vacuum source. It shouldnt suck at idle, only when throttle is applied. If you have vacuum at idle, when you throttle it, it could stumble cause the timing isnt advancing properly. I think you are on the right track putting in an HEI. My 72 Skylark started running really crappy one day, so I yanked the points and put in an HEI. Problem solved. The points distributor had an initial timing of 4 degrees before, and a max of 12. With my HEI I'm running 15 degrees before, and a total thats off the balancer.(I'm guessing 28?) I'm using 87 octane and theres no ping. If your engine was a factory 4 barrel, your compression is higher than mine, so you probably won't get away with as much timing as me. Maybe if you run super unleaded. If you do the HEI, remember it uses 12 volts and you'll have to open up the spark plug gap. Hope this helps. Dan
