My car runs great around town and in normal driving. I take it for a hard pass it will sometimes miss right before redline or shiftpoint, any clue as to what could cause this? I think the first logical thing to do would be to change Points, cap, condensor or coil any other suggestions. It does not due this all of the time, tends to be worse if the car is running hotter. Not a huge deal since I really don't get on the car too often, but when I want to it is nice to have it pull through the entire power band and not break up before I upshift. Any help is always be appretiated
Ever think you might be running out of fuel? What's your fuel pressure/system like? If you still have points, check to see if the dwell remains fairly constant. If it doesn't, might be worn distributor bushings. Whenever you have a problem like this, the more info you post, the better. Carb, fuel pump, cam, exhaust, ignition?
Not sure I have had the same issue with the carb as many other buicks it takes a lot of cranks to start the engine when it has been sitting for a while. Once it has been started no problems, but it does seem to smell rich. I spoke to Jim @ tri shield and he said this is a common problem and could be fixed but not critical. the car has a carb off of a 350-4 on a 455 but I was told they can be interchanged. The engine is a 1973 455 built to stage one specs with stock ignition, fuel pump and dual exhaust. As I mentioned above the car does not have a stage one spec carb on it. So maybe fuel starvation could be an issue.
The "takes much cranking before it will start" problem is because the carb either leaks fuel down the manifold while it sits or the fuel evaporates over time. Mine does this and always has (at least since I've owned it). Thought I fixed it by sealing the plugs in the bottom of the carb - but Nooooooooooo! I hit the carb with starting fluid if the car sits for more than two days after the last drive. I'd rather not crank and crank until the carb fills with fuel. That just wears out your engine, especially if the fuel has washed down your cylinders. Regarding your high speed miss, I've seen a miss that only showed up at high speed be nothing more than a marginal plug wire. IMO, replacing a bunch of parts before you actually diagnose the problem is a waste of money. I suggest putting an ohm-meter on your plug wires before you do anything else. That is a cheap checkup and will take about ten minutes. Eliminate all of the easiest to check or repair things first.
That is most certainly not true. 455 carbs have a bigger idle system among other differences. You can run a 455 carb on a Hot 350, but not the other way around. While I don't think that has anything to do with your problem, you want to put a big block carb on your Stage1. Do you have the Stage1 fuel pump? I agree with Brad, start with the simple stuff. Ohming out your wires is an easy thing to do. Do a complete tune up. If you are using carbon core wires, dump them and get a set of spiral core wires. Like I said before, check the dwell as you increase RPM. Dwell affects timing. If it is varying all over the place as you rev, your timing will vary also.
I had the eaxct same problem on my 350 a few years ago. It turned out to be the distributor. I went with an HEI unit to test it, and it ran great......so I left the HEI unit in and never looked back. If you have another dist., you might drop it in to see if it clears up.
Thanks Larry I did not build the car brought from another board member, it is a nice car just has a few minor things that could be upgraded
Why starve your 455 with a 350 carb? o No: Just asking for problems right from the get go. Too rich will never cause problems at high rpm but lean will cause popping like missing. What year is your carb and what jets do you run?
Still a mechanical novice Car looks runs and drives great with the exception of this small intermittant issue. So I drive and enjoy it, I have not taken the time to look at what I have interms of partson the engine. I have went by feedback from the seller and board member here. The car is a tribute car (1972 Stage 1 convert 4spd), so it was created from a lot of parts from other cars. Some of those cars I have found out about on this board. If I was to swtich carbs, what would you suggest? keeping in mind I want to use the stock air cleaner? I do not want to shell out the money for a real stage one carb. I also have thought about using the flamethower kit to convert the ignition to electronic. What are your thoughts on that kit? I have heard good and bad about it. The car is basically a cruiser and show car so performance is secondary to reliability and driveability. I have lot's of other stuff going on in my life like all of us, and it cut's into the time I would love to spend tinkering. So I just tend to drive and enjoy. :beer You know the story
Converting to electronic ignition is fine, but if the distributor is worn, your problem may still be there. Also, you don't need a numbers matching Stage1 carb. All you need is a Q-jet that belongs on a 455 not the 350. You can then jet it to what you want. If you look at swap meets, you may be able to find a Buick 455 carb. The 71 and up 455 carbs were 800 CFM. 7041540, 7042240, 7043240, 7044240. Those are just a few of the numbers to look for. You may even be able to get a carb by advertising in "Parts Wanted" on this BB. Just ask for a Buick 455 carb.
Thanks for the information One more question, I was on a couple of the carb rebuild and sales sites yesterday and they also show a common Qjet that can be used on a 350 or 455. Is this a common misconception? seems like the carb rebuilders perpetuate the same belief that it is an interchangable item. If the car is better off with a different carb it seems like a cheap upgrade to make things right. Anyways, I am lucky to have Jiw W. 4 miles fom my house so he might be able to help me if I need assistance. First thing I will do is check exactly what is on the car for a carb now, using the numbers you gave me. Thanks for your patience I am kind of a rookie when it comes to all of this but I am learning fast out of necessity and also enjoyment of working on these cars. Thanks again,
A 455 needs more air at idle than a 350. Big Block carbs have extra passages that lead from the air horn down to the bottom of the carb. They allow more air at idle. It's called a fixed idle air bypass and all 455 carbs have them. Rebuilders may not know or care. They want to sell you a carb. What I am talking about is described in the Buick Chassis manuals. This fixed idle air bypass was designed to prevent nozzle drip.
Carb numbers Larry, Finally got around to the numbers on the carb, I had written 7042204. Is there an 2204 carb? or maybe I transposed the last 2 digits, If so the car could have the correct carb on it already (I hope so). Not sure why the seller would tell me it was a 350 carb (when I did not even ask), maybe I was hallucinating or something. Anyways was busy buying another GS, an all original 42,000 mile 1974 455 GS (super cool car). Anyways I finally got back to this, I know I could probably look this up, but I like to hear any additional feedback from "The Wizard". If this carb is corrct I am going to move on focus on the Distributor and other electrical components as you mentioned in previous responses. Thanks in advance for all of the technical advise you provide to the board. I am up to 2 GS's and this is starting to turn into an obscession.:TU: Thanks,
That solves that thanks, I think we may have an electrical issue. By the way how can you tell a distibutor is worn out or bad. Pull it out an measure it? and does it need to be within specific tollerances. By the way what would you reccomend for a good shop manual or guide book for me to start learning on my own?
If there is any noticeable shaft wobble side to side, the bushings are worn. Withn a dwell meter attached, the dwell would vary wildly as the engine is revved.
