1stGrumpy

I have been battling multiple issues with the '51 Olds 88A that I purchased last fall! When I bought it, I knew that it had an over fueling issue by the black smoke coming out of the exhaust and the black soot on the rear bumper. I figured that it would need an adjustment or at the worst, the carb would need rebuilding. After trying to adjust the carb, turning the idle screws made no difference, and that I had already replaced the plugs, wires and checked the timing but all of this had made no difference I took the carb, a Rochester BB, off and had it professionally rebuilt. Now, I have used this guy for a number of years, he specializes in carburetors and knows his stuff. He does a thorough job, not just a clean and throw in a gasket kit type of rebuild. At the time that I picked it back up, he said that he found that someone had been messing with it and put in part of a gasket kit and had replaced the carburetor base, with a new one, and that he found a lot of dirt in it. After cleaning and installing a new rebuild kit in it and checking it over for worn shafts and such, it checked out good and was ready to go!
I put the rebuilt carb back on, at initial start-up it seemed to run good but not long afterwards it went right back to missing and blowing out black smoke. I called the rebuilder and told him the problems I was having, I also mentioned that someone had recently replaced the fuel pump. Because it is a 100 mile round trip to his shop, he suggested that I check the fuel pressure first. Turns out that it had about 8 pounds of pressure at the carb so I installed a inline fuel regulator ( a Mr. Gasket cheapie) but while adjusting the pressure the starter hung up and came apart!
This is getting pretty long winded so I'm not going to go into all the starter problems that ensued, eventually I got the starter issues straightened out and the car actually seemed to run pretty good for awhile but once again it started over fueling and, now, it wouldn't start at all. At this point, I had had enough! I didn't touch it for quite awhile! Fast forward to a few weeks ago, because of all the electrical issues that I had been having, I converted the 6 volt system over to 12 volt.
Now, back to the fuel problems, I replaced the fuel regulator and got it to start. It ran but it barely ran! It wouldn't idle, puked out gobs of black smoke and when I tried to accelerate, it would miss and backfire. Still suspecting a problem with the fuel pump, I hooked up a gravity fed tank and low and behold it started up and ran pretty good. It still had a noticeable miss at idle that seems to go away when accelerating and still has a bit of black smoke coming out of the pipes.
So now the question ( bet you thought that I would never get here), is it the fuel pump or is it the carburetor? Turning the idle adjustment screws still doesn't seem to make any difference. Or could I have a problem with both the fuel pump and the carb? Anybody got any suggestions or idea's? Thanks...

oldcutlass

Have you checked your float level? Also with engine idling (if you can get it to), look down into the carb and see if there are big drops of fuel and/or dribbling of fuel. Be careful and keep your face from being over it in case it decides to backfire through the carb.

1stGrumpy

Yes, I did check the floats. The float level, I believe, if incorrectly set would cause it to flood whether the fuel pump was hooked up or not, wouldn't it? I am wondering if, when it was running with the high fuel pressure, that something could have been damaged inside of the carburetor. It's got me stumped, that's for sure!
Thanks for your response.

oldcutlass

Look down into the carb with the engine running, it will be pretty evident if its running really rich.

Tedd Thompson

Did you put a ballast resistor in when you changed to 12 volts. Check your points they could be smoked. How about the glass filter at the bottom of the fuel pump is it clean? Tank clean? What do the plugs look like ? are they greasy/ carboned up? ...Tedd

1stGrumpy

No ballast resistor and no points, it has a Pertronix ignition. I don't think that a dirty fuel pump or tank will make it over fuel/ Not sure about the plugs, I haven't pulled them out.

Ozzie

I don't have the spec on the fuel pump PSI for the '51; slightly newer models were in the 4 to 5-1/4 range. The float level for the BB is 1-1/8 to 1-5/32 inch. The drop is 1-3/4 inch. Be sure that when the float is up the fuel is completely stopped off at the needle. Be sure the float is not leaking or dragging on the wall in the float bowl. I'm assuming that this is not a choke problem. The butterfly should be open when checking things.

1stGrumpy

Thank you, Ozzie. Your assumption is correct, the butterfly is completely open.

1stGrumpy

O.k., took the carburetor back off and didn't find any dirt. Checked the float for holes/seepage, didn't find anything wrong there. Reinstalled the float and checked adjustment and, again, found nothing wrong. Reinstalled the carburetor, still hooked to the gravity tank, and it ran worse than it did before I removed it. Back firing, both through the exhaust and carb. Also with the engine shut off, I looked down into the throat and could see that gas was still running out.
According to my 1950 - '51 Oldsmobile Shop Manual, it talks about making sure, when adjusting the float, that the "float tang" is properly resting against the balance spring. I found a picture, in my 1957 Motor's manual, of the float rod and balance spring but my carburetor doesn't have a balance spring! I remember seeing the holes where it was supposed to be but... it's not there. Nor is the fuel strainer that goes into the fuel inlet.
Can anybody tell me, for certain, whether this is going to matter or not? If the float level and amount of drop is set correctly, does it matter what the tang is resting against? Also, does it matter if there isn't a "fuel strainer" present? This is just a filter, right? Or does it meter the amount of fuel entering the bowl as well?

Ozzie

The part where you say "Also with the engine shut off, I looked down into the throat and could see that gas was still running out" doesn't sound good to me. When the engine isn't running, there shouldn't be any gas running out. This is at least part of the problem.
I'm at a bit of a disadvantage since I've never worked on a model BB; nor do I have an exploded view of one. My Rochester carburetor book shows only the basic adjustments for a BB. My comments are based on my experiences with the 2GCs and the 4GCs.
The "float tang" might be the end of the float arm that controls the float drop.(?) The BB might have had a spring to balance the movement of the float.(?) I don't know what a float rod is. Usually there is a pin that the float pivots on. On newer models, the fuel strainer is a cylindrical screen that goes on the end of the needle/seat assembly. It's absence would not cause your problem.
Often a carburetor rebuild kit includes an exploded view of the carburetor. It should answer some of the terminology questions. Possibly someone who rebuilt the carburetor omitted some parts. The person who did the rebuild for you should be able to answer some of your questions.
Try to get an understanding of the terminology, and try to get all the parts needed for a complete carburetor.

1stGrumpy

Thanks for the reply, Ozzie. I talked to Carbking, over on the hamb, he manufactures carburetor rebuild kits and used to do carburetor rebuilding. As I expected, the balance spring helped to hold pressure on the float when closed. He said that it was necessary to have and that was most likely the cause of my flooding. Apparently, the balance spring has been missing for quite some time, I have been able to find conversations from the past 2 owners about the over fueling. Now, if I can only find someone willing to sell me the missing part and not have to buy a complete carburetor! Thanks again for your reply....

1stGrumpy

I guess that I should supply an update to this thread...

I contacted Tim at Custom Carburetor, he was the one that rebuilt it for me last year, he took the carb and took care of the missing tension/balance spring for me at no charge! Said he should of caught it when he had it the first time.

Thanks to all that took time to answer my post...

Jonathan0000

So, is it running like a champ now?

I have a 1951 98 Coupe that has been sitting in the garage for 5 years since I bought it, and I'm just starting to dig into it now. I had the carb rebuilt last year, and haven't tried to run it since (I did run it a few times before, but it definitely needed the rebuild).

I'm very interested in the struggles and successes of other 303/324 Olds owners!

1stGrumpy

Yes, it is running great!

I should clarify that after all the problems that I ran into with it overfueling, I did not use the Rochester BB 2 barrel. During the time that the rebuilder had my carb, I ran across a smokin' deal on a n.o.s. Carter WCFB 4 bbl with a '53 intake and batwing air cleaner. Wow, what a difference that made! So now, I have the complete 2 bbl setup for sale.

I wound up doing a lot more to the car than I had originally expected I would have to do in this past year, isn't that always the case, but it has all proven out to be very good decisions. The wiring was a total mess and the 6 volt system was less than perfect! Now with the rewiring and 12 volt conversion plus the 4 bbl it is a real pleasure to drive. Still I have a few more items to take care of but at least it is able to be driven.