63super88

I have a 394 with a Rochester 4gc 7023051, and I believe its in need of repair. the top gasket weeps, the inlet fitting weeps, and the accel pump weeps and I don't want to tighten the top plate or inlet fitting to hard, they really need to be fixed. the car idles as if it has a vacuum leak putting and such, and is developing slight hesitation. im sure it needs these repairs but im not so sure about good shops in my area, I had a monojet Rochester once and had a bad experience with a local guy and id hate to get a bad result on this one and was thinking of doing it myself.

I just want to change inlet fitting/gaskets/accel pump and make sure rest is in working order.

where is a good place for the parts I need, rebuild kit and inlet fitting?

Am I in too deep, or can I go by the kits instruction sheet and forum advice? (I understand basics floats, needles/seats, check *****, accel pump, but never actually had one apart)

pogo69

There are a few problems you may have that might be a challenge...the primary and secondary wells might need attention....the inlet threads might need a helicoil and the throttle shaft bushings might be worn and most lijely need bushingsu...you can easily take the carb apart for cleaning/inspection just take you time and keep the the parts organized

63super88

well i think i could getaway with changing the gasket for the inlet fitting its not good but not that bad and im pretty sure the throttle bushings are ok not leaky atleast.. and im sure it needs attention here and there but if i could just change the gaskets and the accel pump i think itd run much better and solve my vacuum leak type problem i hope. the difficult part is taking the linkages off and back on right like the choke system and after i take off the top plate how not to disturb settings on the internals.

pogo69

The 'settings' are pretty straight forward and a rebuild kit will have instructions as to setting float level etc... you wont know for sure the condition of the carb throttle plate etc untill you remove the carb ands take it apart...thats an old carb and probably needs a rebuild,how much of a rebuild depends on the condition once you have it apart

REFORMULATED400

Cliff Ruggles is very helpful and responds to questions on his parts and tech forum quickly. HE makes great kits that stand up to today's ethanol blended fuels and offers jets and rods for just about any application. He helped me sort an off idle flat spot a local pro shop gave up on. All it needed was primary rod and jet change and slight PP adjustment and he showed me a master A/F adjustment they nor I knew about. All the advice was free I just bought his Kit and jets /rods. He helps a lot of Pontiac guys out on the PYyears forum, now I only go to him.

nsnarsk65cutlass

If you never done one then maybe look online for how to videos before you try it.Mikes carburetor in Washington has some pretty good 4GC videos on rebuilding them.He also sells kits for them your local part store does not.Weeping airhorn gasket maybe from too high of float-s level ie leaky needle seat or bad float-s.Nick

mike8162

I am a big believer in putting in a new float. It will not come with your rebuild kit. If you are not changing jets or rods or tuning the rebuild is pretty straight forward. The instruction sheet will give you all the measurements you need and some even include a tag board measuring tool. Use a digital camera when disassembling and you probably will have no problem.
Cheers, Mike

pcard

X2 on going to Cliff Ruggles for help, and also the parts. He has a kit that includes floats, plus everything else you could need. I can also recommend his rebuild service. He will do only what is needed, or you can get the full monty.

Gary M

Check the gasket side, across and front to back under the top plate with a straight edge. You will see if it is warped which may cause bad idle & weeping. Some builders use a hammer and file to straighten them. This ruins the carb because you loose the fine ridges that help seal the gasket. The above recommended guy may be good ,I may try him if he does not fix them that way. I used Barker Gang Garage in Colorado. He uses an oven and a jig to straighten the warp then rebuilds. His is on my car but I haven't driven it yet so its too soon to recommend him. The hood latch part I need prevents me from driving it yet. Will let you know. Good luck but research before you choose any.

Octania

It sounds like you are capable, just hesitant to proceed due to the complicated links and such. In the old days I used to mark em with a paint pen and/or make a hand drawing that made sense to me. Surely you have a camera in your phone, or a digital camera? Take pre-disassembly photos. Special attention to the ends where things connect, which way 'round they go, which tang is outboard vs inboard, etc.

Try to understand why each part is there as you study and remove it, that helps remember how it goes together.

Put in the new parts, set the settings, chances are that will be enough.

As for a new float- this is a pre-QJet carb, which uses brass floats eh?
Brass floats NEVER need to be replaced unless leaky or dented to hell.

Gary M

I missed that. Sorry I thought it was a quadrajet. Don't know if the pre Quadra jet were prone to warp. . The kits usually come with good instructions and measurements. I agree with taking lots of pics.

D. Yaros

Here is a tutorial on doing a carb rebuild, based on eperience; mine!

http://GrayLady.WebNG.com/carbrebuild.htm

Gary M

Very cool that people like you take the time to do those. It helps immensely for someone unsure of trying. That's how I fixed my convert top motor. U-tube video.

63super88

Excellent stuff guys, thanks. I have a great cam in my phone so lots of pics as I work labeled in steps and sent to computer will definitely be helpful. Thanks D.Yaros for the instructional.

As Nsnark65cutlass mentioned, the airhorn gasket could be because of bad floats, is this most likely the case? Octania says they should be brass and pretty durable so I would hope this is the case and the they are good brass ones. The instructional there says to check them in bucket of water.

instructional also says the drift pins/floats come out by hand the the needle/needle seats come out with flathead screwdriver so that doesn't seem to complicated, but I still haven't seen it in person or tried to adjust them so idk.

Ok, as for rebuild kit itself cliff ruggles looks like the best option as you guys say thanks reformulated/pcard. for 45 bucks+ship the basic kit or they call it S/R, it says the kit comes with: "All new gaskets, complete accelerator pump assembly w/springs, Viton needle/seat assembly, float, fuel filter/spring, & small parts." I would assume small parts to be 2 check ball/springs and the pins that hold them in and stuff right?

it also says come with float but as octania mentioned mine should be brass and should be good but idk since nsnark mentioned they are why im leaking up top so im unsure now. I may call them first before ordering and ask about what kind of float and make sure the kits ethanol safe but the website says they are.

63super88

I watched the Mikes carburetor rebuild youtube video, and it was a great visual of the process, not so much breaking it down but putting it back together from the throttle plate up. Im feeling much more confident, and after the visuals the linkages aren't as difficult as they look, and the floats are pretty simple concept too just tricky. mine was a little different than his (his only had 2 tubes on top instead of 4 and his choke was slightly different) but his was a slightly earlier 4gc practically the same. I think im just about ready! maybe ill call in the kit order tomorrow or next day.

Anything else im forgetting?

a couple guys mentioned warping, but someone dismissed that saying the pre-quadrajets are more durable?

I saw the guy in the vid instructional use some sort of paste on his inlet fitting but didn't mention what brand it was, any ideas?

nsnarsk65cutlass

The later 4gcs have the black phenolic floats 7025154 does anyway,make sure you get the blue accelerator pump cup,as the black ones will not last with todays gas.Also the throttle plates housing is cast iron and not as prone to the wear as the qjets alluminum is.Good luck.Nick

Octania

I would definitely use silver or copper anti seize paste on ALL the threads, especially the fuel inlet. Die cast is weak and with dissimilar metals, protection is advised.

As for warping, I once had a QJet that was overtightened ? a LOT on the front two long bolts, and was warped over 1/8"- have photos somewhere- funny thing, the body and air horn were warped the same, and it did not leak, and it ran great. Replaced it anyway, as the number was incorrect to the new purpose.

I did a bit of carb reworking a while back, and I found that it is very much to your benefit to spend a few minutes making tools that fit Just Right.

I went to the buy n sell store and bought a variety of screwdrivers.
Using the new parts and screws as needed from the patient or a similar carb, grind a screwdriver to EXACTLY fit each of the various screws. One thing that helps a LOT, to avoid Seat damage, is to get your VERY wide blade screwdriver, that spans the whole OD of the seat tube, grind it so the fatness is about right, then, with a Dremel or similar, put a notch in each side of the blade tip:

Tip that enters the seat tube

_|-----|_

Main blade of screwdriver

This protruding tang keeps the blade centered in the tube and it goes very smoothly.

Unless you have proper fitting tools, you usually get mangled and marred screw heads.

Not sure if the 4-jet needs such a thing, but with QJETS I found that getting the air horn's protruding tubes into the body was vexing. So, I cut the heads off two of the LOOOOONG carb screws and used them for guide pins which made installing the air horn a breeze.

63super88

it actually wasn't an anti seize, the vid said it was a pipe sealant he liked to use which was fuel resistant and such, then he warned against using Teflon tape. I think it is this gasket which is leaking, and a new one from the kit and a bit of the proper sealer paste would solve the issue, and I would use the same paste on the angled fitting which connects the inlet with the fuel line and I think my inlet problems would be solved. I did notice the inlet filter didn't have a spring on it, I hope I put it back together right the last time, I don't remember it even being there though, is it missing?

As for the needle seats, I will try to be as ginger as possible when changing them, and if I find its difficult to remove them and I chew up the old ones I will get crafty in installing the new seats. Although the guy in the instructional I just watched used normal craftsmans one small one wide one Philips for the whole thing and it looked pretty straight forward.

im not gonna take apart the actual throttle plates, or the choke for that matter because the plate closes/opens as it should and it cold started great until this occasional on/off vacuum leak type problem occurs. im just gonna change the gaskets in between, the needles/seats, the accelerator pump, and make sure the floats rise/drop levels are correct and the power piston piece is working correctly.

63super88

Ok, so cliff ruggles said they only do quadrajets, so they don't carry a 4gc kit. I called ChicagoCarburetor.com, and they have one for $25+ship. Guy said it has all the gaskets, needles/seats, check *****, and accelerator pump. also said its ethanol approved. I was going to order off of ebay, but that said 10 days so ill order it direct and hopefully get it by wedsday next week.

Anyone deal with them before, are their kits good? I had them re-man a monojet for nova 194 once, but sold it soon after buyer says it got damp here/there. For that price its either a great buy OR inferior quality materials. although they seem like a good outfit.

D. Yaros

You are more than welcome. Hope it helps. Lots and lots of pics is indeed the order of the day in the rebuild process. I distinctly recall being glad I had them to refer to when needed, and needed they were!

lilhow

Just to put a screw into all this. I rebuilt my 4gc for my 65 330. I studied and found a lot of info. The problem I found was the power valve. It is actuated by a vacuum operated piston. Piston made of brass and is located in the aluminum air horn. Which would wear faster. From what I read when at idle 18" vacuum the power vale is closed and stays until throttle is opened and vacuum drops to 9". I rigged a refrigeration vacuum pump and gauge to test and found mine to open at approx 13 to 14". This will open power valve to soon over fueling motor. I am assuming because of wear and vacuum leaking around piston. There are replacement pistons available but is the air horn also worn. If that's the case a lighter spring maybe. You will see this when you disassemble the carb. Power valve is at bottom of primary bowl and actuator you will see spring loaded in air horn above. I'm at a loss to fix this was going to quiz this to the card builders at the next swap meet. Also choke pull off work the same way.

63super88

I understand what you mean. I watched in the instructional how to install the valve in the bowl which screws in place and the spring loaded brass rod in the top airhorn has like a sleeve that it sits in and is seated in the slot in bottom on airhorn powered by vacuum. I didn't plan on taking this out, just making sure it stays in place in the slot and the rod moves up and down freely in place without falling out, I think its all operational im mainly gonna change gaskets to cure vacuum/fuel leaks, check the floats, and change the accelerator pump/needles/seats. the cheap kit im getting doesn't include the power valve pieces, but I did call a shop that offered a more expensive kit which did include the valve, rod and spring but for $95 vs $25 Chicago carburetor kit, and I could be opening a can of worms trying to remove/replace those things. I also plan on leaving the choke in place, but im not sure if im gonna take the venture out to replace the gaskets and check acc pump holes on the primary one.