Start out I live in Michigan and I only get to drive my car ~2 weeks out of the year due to the weather! After having my 4gc rebuilt and rebuilt and rebuilt, ordered a rebuilt one, I am now going on my 4th of this round the first 2 leaked very badly the 3 is a piece of ^%#&!@. Everyone tells me to go to a Edelbrock, my question is all the linkage getting the switch for the trans right etc if this 4th try is bad. Anyone have any recomidations or better yet photos of a conversion? Thank you for any help, I think we only have another 2 or 3 days above freezing and I want some convertible time. Mike Rochester (sorry)
Get am AFB applicable to your car. You don't mention year, make, moderl or engine. NEED MORE INFO!!!!.
Sorry That is a 1964 Skylark 300 V8 with the Al intake 4 barrel, Rochester 4GC, mostly all original, only variation is when rebuilt went with lower compression pistons and very mild cam from TA performance, I think they refer to it as a "RV" cam just a little more lift and duration. Not sure what else would be applicable. I am mainly interested in seeing what others may have done to address the switch linkage for the switch pitch trans switch. Timing for engagement, length, location etc. Thank you for what ever help that can be offered, a photo can go a long way photo worth 63 words...... Thank you! Mike
I see 183 views for this post isn't there any one out there that can take a photo of their, very photogenic. carb. and able to post it please please please!!!!! The snow is scheduled to fly soooooon.
Explain your rebuild efforts and where you purchased the rebuilt unit. There are many, many poor quality volume builders around. Parts are still available for the 4gc carb, though they are limited. I have built many, and could possibly help out with yours if you are interested. When correct, they run well.
The carbs have tried were from RockAuto they get them from AutoLine. After sending me 3 carb.s, them having my payment for 2 with 2 core charges they seemed to take the position I was doing something wrong and refused to sell me another, talked to AutoLine and they would not deal with me directly. The fist carb worked ok but leaked very badly from upper part where gasket is, second ran the car extremely well but leaked very badly same place, 3rd car did not like at all and the accel pump was not working, but it didn't leak! Orignal was rebuilt locally by a auto parts shop that specializes in old car parts.... Am looking at a shop in Fla that gets some excellent reviews but they want 2 to 3 weeks, but warrantee for life.
My experience with the 4GC is that the needle and seat assemblies tend to leak in most of the cheaper kits that I've bought. Most kits that I seen recently have thes high-precision excellent quality controled parts from China. For some reason they can't seem to machine them to fit, they always either dribble, pee, or just fail. They also include some dumb clips that seem to be more a hinderance than any good. (They looked like a good idea) The key thing with those carbs is getting the floats set up correctly. Here again, the newer needle and seat set-up with gasket changes the entire dynamics of the float set up. And then there's the issue about leaky floats, sticky power piston bores, or badly sealing anti-perc valves. That all said, I hate those carbs; I've rebuilt about a dozen of them and have yet to get one to run perfectly. Always get them "close", but never perfect. They've got to be one of the most finicky carbs out there besides a Holley. I like the AFB or the Q-Jet much more. They're more forgiving. Most jobber rebuilders will use the same crappy kits, except in their case it was installed in a factory setting by people who really have no idea what they're doing, and they're generally set up to run a wide variety of cars. So the demands your car will have on it will probably be different from what it's set up to run. It's been my experience with most jobber-part rebuilds that the initial problem with the cast is never properly identified so never fixed; I once went through 9 jobber rebuilds for a simple Ford 2 barrel before I got one that actually worked well enough. They all had weird problems. And yes, getting a modern acelerator pump will help too; try and check the date of re-manufacture on that rebuild if you can; - if it's more than 5 years old then it'll probably be no good. You're better off getting a couple of original casts from the wrecker and throwing a kit in one yourself. Odds are the reason the car wound up in the wrecker was not because of carb failure, so you might get a good problem free cast out of one that just needs some cleaning and a new kit. The last time I needed a Q-Jet I did this and had moderate sucess, - not to mention I've now got a sizeable collection of original cast late 60s Buick carbs. Avoid any carbs with a rebuilder's tag in place of the original factory ID tag. As stated before, the cast on the jobber part may be clean, but chances are it does have an unknown and undiagnosed problem that will cause you grief.
Thank you for that, my latest adventure is off one of the old posts I found a guy in Lansing, Mi, great guy by the way (Johnson's Speed shop) he has literally thousands of Carb.s most in the box new or rebuilt. I bought one from him, his last one same style as mine, that was an AC Delco rebuild. Here again it runs ok but the accl pump seems to leak and is not giving proper shot because I get a lag. Any thoughts where I can get good parts for this thing? Thank you!!!! Mike Lorang
It is very important that the carb you use is for the application (64 with 300 engine). All these carbs are specific to the application, use the correct carb. I would use something like this and have a reputable rebuilder go through it. I suggest Ken at Everyday Performance or Mark "Carmantx" here on the board: Send him a PM http://www.v8buick.com/member.php?u=13537 Here is a carb that might work for you... Might as well get it sent straight to a rebuilder. http://www.ebay.ca/itm/1964-Buick-S...r_Truck_Parts_Accessories&hash=item1c1de97ee9
Thank you, I am quite certain the one I just got is correct, it matches my original and my original still had the al. tag. The paper inside the box for this thing even mentioned verbiage about the accel pump seal may be dried out and give 24 hours to seal.... Just it never sealed and I think the fuel is getting over the top and coming out the boot, this thing smells like gas all the time. getting very frustrated this is 4th carb. went through 5 if you include my orignal I had rebuilt by a local parts store that specializes in "old car parts".
I also have a 4GC in my Buick Electra 401 cu in. I read that if you have a hesitation when you accelerate from a stop then it could be that the two idle speed air screws located on the front near the bottom of the carb may be set too high. He recommended backing off on these screws one full turn from being lightly seated. My screws had been set at 1.5 turns but after a reset them to 1 turn it seemed to resolve the problem. Almost all hesitations are diagnosed as accelerator pump problems, but if you see gas squirting from the the accelerator pump jets whenever you quickly reve the engine then it isn't the accelerator pump but could be the too high setting on the aforementioned idle speed air screws. I've pasted From the "expert": [FONT='Arial','sans-serif']Bog from a stop is virtually always (and generally erroneously) diagnosed as a faulty accelerator pump (see the section on “accelerator pumps” for testing)[/FONT][FONT='Arial','sans-serif']. Most modern carburetors are designed to function with roughly 0.020 (20 thousanths) clearance between the center of the throttle plate edge, and the throttle body at a point equidistant from the throttle shaft bearing areas. This clearance allows for maximum velocity of idle air past the idle ports. Exceptions to this are GM carburetors with the idle speed air screw, and end carburetors on tripower. Setting the idle for the highest vacuum idle reading will result in too little clearance of the throttle plate; forcing too much of the idle mixture through the lower idle port and too little through the idle transfer slot. This will cause a phenomena called “puddling” where little droplets of gasoline adhere to the intake manifold runners. When the throttle is opened, there is now sufficient velocity of air to sweep all these droplets into the cylinders, creating a mixture which is too rich to burn, hence the bog. As soon as the overrich mixture is pumped out the tailpipe, and a normal mixture is ingested by the cylinders, the bog disappears. A defective advance mechanism can also cause bog; as can a defective accelerator pump. If bog exists only from an idle, not when accelerating from a constant speed, the idle adjustment is probably the culprit.[/FONT] [FONT='Arial','sans-serif']Bog from a cruise RPM may be caused by a defective advance mechanism, but on 4 barrel carburetors is often caused by the secondary side opening too soon[/FONT][FONT='Arial','sans-serif']. Most original equipment 4 barrel carburetors have “on-demand” secondaries (I use this term rather than vacuum, as some early 4 barrels used vacuum to actuate the secondary, while most 4 barrels from about 1960 up used either spring tension or weights to control the secondary). The Carter AFB uses weights, and therefore never goes out of adjustment. Other 4 barrel carburetors such as the Carter AVS, Carter TQ, Rochester 4GC, and Rochester Q-Jet have a tensioned secondary spring. As the spring fatigues, the air valve will open too soon, creating an instantaneous lean condition, and a bog. These units, when rebuilt, should virtually always have the tension spring replaced, and adjusted to factory specifications. A defective accelerator pump will rarely cause bog from cruise.[/FONT]
