Packard Forum Index » V-8 (1955-56)

I'm thinking about replacing my 4GC carb with an Edelbrock. I would rather keep it original with the 4GC but I really like driving my car and I'm having lots of issues with my 4GC. One of the problems is the 4GC that was on the car when I got it was incorrect. It is supposed to be a 7007230 according to this websight. My engine had a 7007327 when I got it and it ran really rich and leaked so I rebuilt it. The jets were the correct size and I set the float levels. It still ran rich, you could see the fuel dumping out the venturies when you sped up the rpms, not much atomization of fuel and air. After a year I purchased another 4GC. I was told it came off a 1955 400. It didn't. The number on the tag was 7008610. I just pulled the carb off the engine and the number on the bottom of the bowl was 7009111. The tag didn't match the carb. This carb also runs super rich and I can't lean it out. I'm going to spend some money on carburation, I'm just not sure what road I'm going down, stay original or modernize with an Edelbrock. Is the 4GC a good carb and are you 4GC owners happy with it's performance? All opinions are welcome. Thanks, Brian

More than happy, no problems whatsoever with my dual 4GCs on my 56 Caribbean. They were professionally rebuilt by Daytona quite some years ago. My friends with similarly equipped Packards also report no issues with their 4GC. I hope you find the problem with yours.

I was able to purchase a new 4GC several years ago at the Maryland meet. After adjusting the idle screws it has performed flawlessly. Have a pro (Daytona) rebuild yours. You won't be disappointed.

Dunno why I see so many cases, in recent years, where carbs have been replaced by incorrect units, instead of fixing the correct one that was one the car - and not just 4GCs - when new, repro kits are available.

I have no problems with the four 4GCs on my three running 56 V8s: two Patrciians and one Caribbean H/T. They were all OE and, for the most part, unmolested. I rebuilt the 4GC on each of the Pats years ago. I just needed to stretch the leather cups of the accelerator pumps a bit to get the Carib running well enough to drive, but will be rebuilding those as well.

However, the original 4GC on one of my Patricians was so badly mickey-moused by the previous owner that I had to buy a 56 Four Hundred parts car just to get another carb for an air horn and a float. The carb on the Pat must have never been rebuilt, as the throttle body (to fuel bowl) to gasket in the rebuild kit didn't quite match; I decided to cut my own, using the original as pattern. Then, the idle mixture screws provided in the kit that I purchased from Kanter were a lousy reproduction - couldn't get a satisfactory idle adjustment until I re-installed the old, original screws. Still, the car had a bit of an off-idle stumble - even after replacing the (leaky) distributor vacuum advance. A few years later, I learned that the throttle body gasket design had been changed during production; the carb ran better than new after I installed the gasket from the kit, in favor of the one that I had cut.

Mind you, that was my first experience with 4GCs, and 25+ years ago. Otherwise, they are are comparatively easy rebuild. Yet, one thing I found in each rebuild or autopsy was that the power piston assembly was loose in, if not falling out of, its mounting in the air horn - simply need to be cleaned up and re-staked.

For a used correct carb, you might wanna check with V8-specialist Mike Dulinski. Used on the 5560 and 5580 chassis, I bet he has at least a few left from the dzoens of cars that he has parted out.

The Rochester 4GC is an excellent carburetor design. When everything is correct, it will perform and operate flawlessly.

FWIW, I've been turning screws on carburetors for fifty years. Until I got a wideband O2 sensor and real-time display, I didn't know how much I didn't know. A good ear is rare but being able to see what is going on makes it possible for most to diagnose and correct carb problems.

The only problem I've had with my 2x4 Rochesters is getting the secondaries to return to full seated positions after a brisk run.

jack vines

If you don't have access to the equipment Jack uses, at the very least use a vacuum gauge to set the idle mixtures; they are cheap, you'll probably get years of diagnostic use from it, and generally lead to a better adjustment than you can get with your ear.

In my experience the 4GC is an excellent carb and behaves well under any temperature/humidity condition. The aftermarket carbs like Edelbrocks and (aftermarket) Holleys are made for the hot rod set, who are only interested in dumping the maximum amount of fuel possible into a performance engine. The Rochester 4GC is a fine piece of carbueration, and is engineered to compenstate for ambient conditions in a way that the hot rod carbs don't consider, due to their intended market.
Get the right numbered 4GC and have Daytona rebuild it and life will be great.

It all sounds good to me, I will stick with original equipment. BH, you mentioned Mike Dulinski might have one. I searched this websight using his name with no results. Do you have a contact phone number for him? Thanks.

He's in the Packard Directory over in the lefthand column under Main Menu.

Click on the directory then click 'M' as in Mike.

Mike is listed in the Packard Club yellow pages

packardclub.org/download/yellow_pages_2013.pdf