Hello all,

my first post here. I own a 1964 Ninetyeight Sedan, mostly in original condition, found it by the roadside about 10 years ago and bought it right away. Here in California, rust isn't that much of a problem so despite the fact that it had no major body job done, it's still in good condition. Had to do some repairs like exhaust, generator, etc, but everything mostly fine. I use it several times the week to do short trips around the city and it runs nicely.

There is one problem though and me and my mechanic have been struggling with that forever. Every half year or so it starts to stall and dies. We did nearly everything on the fuel side, cleaned and re coated the tank, replaced the fuel pump and filter with new models (even moved the fuel pump under the car by the tank because modern fuel pumps are supposed to push, not pull apparently, and a few years ago I had the carburetor rebuilt.

Now these past few times, it was obviously so that the floater got stuck and he had to fix that, but the verdict is that the carburetor is really in bad shape. This guy is well known around here, he has a lot of classic car customers and is an old guy himself so I trust his verdict there.

He told me there might be ways of replacing the carburetor with a factory new model with a conversion kit, but also said he wouldn't recommend it out of fear that the old screws might break and essentially leave the car stranded.

So I wanted to ask here, does anybody have experience with this? Are there kits out there, where would I get them from? Are there any particular vendors/manufacturers I should contact? Any advice in this matter is appreciated.

Thanks

 

First, welcome to our site. I hope you can get a more complete answer than this. I know that the carb was a square bore pattern and that the linkage to the transmission can be difficult. I think there are some solutions which involve getting a new carburetor and I believe this might be a good one for you. With an old carb you can always have a worn throttle plate bushing allowing air to leak regardless of having new gaskets, I know this has been a problem with quadrajets of later years so that might be the problem you have. Good luck.

 

The problem with your 1964 98 is that your transmission uses a throttle valve rod that is operated off the carb. An aftermarket Edelbrcck carb will bolt to your intake, but it does not have the proper provisions to connect the throttle valve linkage. Later model transmissions that use a throttle vavle (like the 200-4R) use a cable, but yours uses a rigid rod. There are no kits to convert your car, since it is not a particularly popular model to modify.

 

Pull the carb and sent it to Daytona Parts Co. for a complete rebuild.

Daytona Parts

 

You can also find those Rochester 4G carbs for sale on eBay pretty often.

I tend to disagree on his diagnosis however. Carbs themselves rarely wear out but the parts inside can. The float should have a pivot pin and that could be hanging the float up.

But...not everyone knows that the Rochester 4G carbs like yours have two separate float chambers..one for the front(primaries) and one for the rear(secondaries).

If you drive it around and never open the secondary side up(punching it) then the gas back there can start going bad and gum up the carb.

I'd overhaul it, put in a new float pivot pin and then make sure to floor it(safely) at least once a month or so to get fresh gas circulating in the secondary float bowl.

 

I had a 64 98 and had similar problems. As Joe mentioned, the Slim Jim transmission prevents you from installing an aftermarket carburetor. Maybe if you rebuilt the carburetor that would help...

 

All good points mentioned here by Joe (Issue with the newer carbs and the trans hook up) and by Tyler on the problems with the Rochester 4GC.

There were two different square bore carbs used in these years, the Rochester 4GC and the Carter AFB. Not sure which one you have, but if it is the Rochester, then I would try what Tyler stated.

I have found that the 4GC's are very fickle. I have had mine apart a few times just resetting the float heights. I have had to lower the float about 1/32" below speck on mine due to flooding issues. The other problem with the 4GC's is the newer gas eats the accelerator pumps. You need to find an old NOS leather one. I have that in mine now and it works as it should.

The old AFB's seem to be behave much better, and you can get the newer accelerator pumps that resist today's ethanol. If you can find one of these, get it rebuilt and also get the metal plate that goes between the carb and intake. (It will have the provision for your transmission too, just make sure you check the carb #'s in a reference book for your year)

 

Oldsmobile never used an AFB and no OEM or aftermarket version has the correct throttle valve provisions. Olds DID use the older Carter WCFB carb in the 1950s but these are not suitable replacements nor do they have the correct TV connections for a 64 394.

 

Doesn't prevent it, just makes it more difficult. You have to fabricate some rods and then set the TV rod for the new carb linkage. Having the HMT linkage adjusting tool makes it ever so much easier.

4GC kits should still be available. You need to pay particular attention to the gaskets as installing the wrong one for the application can create all kinds of poor idle, off-line stumble and vacuum leak conditions.

Should you decide to get a reman instead of rebuilding it yourself, I'd send a 4GC to Don Monroe out in Washington before I'd fool much with Daytona. They rebuild 4GC for Fusick and I got two different bad ones. One of them leaked worse than the one it replaced. Granted, Fusick made it good as they always do, but for what you pay for that rebuilding service it should be a plug-n-play.

And, having fooled with more 4GC than most people on here have, I am convinced that some of them are just bad. I had one on a 64 Starfire (original to the car) that I fooled with for two years trying to tweak out all the issues it had. When I threw it in the dumpster and put a Holley Pro Shop rebuild on the car, ALL the carburetion problems went away. Every damn one of them.

*edit* Pontiac used AFB's on Slim Jim cars (Catalina/Grand Prix) and you will find that some of the Pontiac linkage can be used to adapt an AFB to the Oldsmobile.

 

Thanks alot everyone, this at least kept me from going in the wrong direction. Looks like there is nothing much I can do at this point then. I was considering an engine rebuild since its also smoking from the oil filler funnel sometimes and we were talking about replacing the carburetor then, but alas thats not in my budget right now. I really like that car and put some money in it over the years to get it form a bad condition to one where it's mostly running fine, so I wont give up. My hope is still to be able to replace the engine and transmission one day with a modern one in a custom job

This time it turned out the carburetor was even innocent. It was the gas pump, which is particlarly mysterious since it is the 3rd or 4th gas pump in 5 years. These are brand new Delco fuelpumps and I have no idea why that car is eating them like that. Like I said the tank has been recoated so it cant be rust particles or debris.

Anyway, I'm glad I found this forum and will be following it