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I need a rebuild kit for my 4gc carb on my 1965 330. I'm curious as to what makes the differences between the various tag numbered 4 gc carbs. Is jet size the main difference? My tag reads 7025054 or 7035055, the last digit is damaged. Most places I've contacted here in Canada jump from 5053 to 5056. Rock Auto lists a rebuild kit that covers both 5054 and 5055, is that what i should be getting?
I need a rebuild kit for my 4gc carb on my 1965 330. I'm curious as to what makes the differences between the various tag numbered 4 gc carbs. Is jet size the main difference? My tag reads 7025054 or 7035055, the last digit is damaged. Most places I've contacted here in Canada jump from 5053 to 5056. Rock Auto lists a rebuild kit that covers both 5054 and 5055, is that what i should be getting?
Contact Daytona Parts for the very best carb kits available. Their kits are ethanol compatible and their pumps are top shelf. https://www.daytonaparts.com/
Besides what Yellowstatue has already stated, the only difference between the 5054 & the 5055 (aside from application - auto vs. manual) are the primary jets.
I need a rebuild kit for my 4gc carb on my 1965 330. I'm curious as to what makes the differences between the various tag numbered 4 gc carbs. Is jet size the main difference? My tag reads 7025054 or 7035055, the last digit is damaged. Most places I've contacted here in Canada jump from 5053 to 5056. Rock Auto lists a rebuild kit that covers both 5054 and 5055, is that what i should be getting?
The same rebuild kit applies to both the 5054 & the 5055. The only difference between these two carburetors are the primary jets.
Additionally, there are two primary differences between the primary metering rods of the 2653 & the 2654 (employed on the 5054 & 5055 carburetors, respectively):
(1) The 2653 primary metering rod contains a smaller orifice than the 2654 primary metering rod. Therefore, the 2653 metering rod will burn 'leaner'; and,
(2) While the 2653 (OEM) was zinc, the 2654 (OEM) was made of SS.
Before I order a kit I want your opinion on whether or not that is what I need. I've done a tuneup, new points, plugs, wires. The points were set by adjusting until the engine started to miss then back off 1/2 turn. Timing was set to give highest vacuum. I don't have a dwell meter or timing light. I then adjusted idle to max vacuum. The engine idles well and pulls hard except for one thing. When I give it lots of throttle or floor it there is a major bog! It completely dies for a second or so then recovers and pulls hard. I checked the accelerator pump and it gives two strong streams of gas.
What are your ideas on the cause of the bog?
It's your decision on how you tune-up your engine. I would not tune-up your engine in the manner you have chosen. Your tune-up procedure is old-school and not very precise - at all. You can get close to a good tune, but you're guessing on dwell, points & timing - your decision.
(1) Establish Dwell as prescribed specifically for your engine. This can be found in the chassis service manual(s) for your car;
(2) Establish timing. When you set your timing did you disconnect the vacuum hose at the vacuum advance canister at the distributor and plug that hose? You need to disconnect & plug the vacuum advance when establishing initial timing. If not, you're introducing advanced timing at idle which is not what you want to do. Initial timing is set with vacuum advance disconnected and plugged. Regarding your vacuum advance what port are you using for vacuum advance - ported vacuum or manifold vacuum?
(3) Set your A/F mixture (ratio) until you achieve the highest vacuum you can obtain.
I'm suspecting you own a vacuum gauge since you are adjusting everything based upon vacuum alone. The issue the way you're performing the tune-up, IMO - is the fact you're setting idle & initial timing to maximum vacuum. That's like setting the slow idle with the governor wide open. I don't see or understand the utility of tuning the engine in this manner. I'm not going to suggest what your issue is, since tuning the engine in your manner introduces several variables which are difficult to control. Personally, if you have owned this car for some time or plan to own this car for any length of time, you should: (1) Own the chassis service manuals and follow the indicated procedure(s) to tune the engine; (2) Purchase/Own a dwell meter/tachometer meter (they're very reasonable); (3) Use a timing light and disconnect the vacuum advance when setting initial timing. I don't want to sound overbearing in my recommendations or discount how you are performing your tune-up, but use of the proper tools will provide you with a far better tune-up than the method you have chosen.
Your tuneup procedure is old school but worked for years before dwell-tachs became commonplace, especially for DIY guys.
If the accelerator pump is working, make sure the distributor mechanical advance weights move freely and also check vacuum advance for function.
Past that sounds like the secondary air valves which on a 4GC are buried in the carb and require disassembly to get at them.
Some, not all, 4GC have a brass screen strainer for the secondary fuel circuit. It too could be gunked up but again, requires disassembly to service it.
Get a good kit, soak and clean it thoroughly, then reassemble using the shop book specs. IMPORTANT. Use the correct throttle body to float bowl gasket.Wrong one can make a 4GC do crazy things.
While you're at it, scour the web for a good used dwell-tach/engine analyzer and timing light. The things are loads of fun and since they don't work on anything made in the last 25 years, a good one can usually be had cheap. Sears had some nice ones as did Allen, Dixco and the tool truck brands.
Last edited by rocketraider; Jul 21, 2021 at 11:50 AM.
I would suspect the accelerator pump is shot, very common in a 4gc carb especially if it has a older accelerator pump that is not alcohol gas proof. Check if you are getting two good streams of gas with each pump of the throttle if not that is your problem....Tedd
I've ordered a carb kit. I figure if I'm going to disassemble the carb I may as well put in a new kit. I am getting two good streams of gas, but like I said if it's coming apart I may as well install new parts.
I will look for a dwell meter.
I've ordered a carb kit. I figure if I'm going to disassemble the carb I may as well put in a new kit. I am getting two good streams of gas, but like I said if it's coming apart I may as well install new parts.
I will look for a dwell meter.
I use this model , intresting thread because i think i need a tune up to my carb also, the engine can suddenly stop in citydriving
at low rpm / idle and hot temp outside. I bought mine carb rebuilt " Autoline" 4GC from Rockauto .
