need a carb.

need a carb.

Home
»
Keeping The Dream Alive!
»
Technical

http://209.208.111.198/Topic51638.aspx

Print Topic | Close Window

By F250RED - 15 Years Ago

I have a 292 Y with a 56 4v manifold,I am currently running a Rochester quadrajet,probably off about a 56 buick.it was rebuilt about 5 years ago,ran great,hasn't run in about 5 years,was drained but now it does not run good.I don't know if I should have it rebuilt or replace it. The block is 62-64 era 292 with ECZ-G heads,reds headers,was originally a dearborn marine interceptor conversion,I put it in a 54 F250 with a t98 4 spd.Its stock and I just want a daily driver.need some advice on a good choice for a replacement carb,want to stay with a 4 bbl.with the small bolt pattern.looking for something in a reasonable price range or maybe someone has a good used one they would sell thanks F250 RED

By pcmenten - 15 Years Ago

I'll bet that's a Rochester 4G, not a quadrajet.

Carter made a carburetor with that bolt pattern. But if that were mine, I'd go ahead and clean the Rochester 4G and keep using that.

By Ted - 15 Years Ago

Another option is use an adapter on the intake you have so a later model Holley or Carter carb can be used. For a daily driver, a 390cfm or 450cfm Holley carb works out well when using the adapter on the earlier intakes.

By ejstith - 15 Years Ago

Ted (11/8/2010)

Ted, I've got a brand new Holly 390 on my 272 and it has give me fits ever since I've had it. When I push down the accelerator it hesitates, falls on it's face then takes off. If I push it down real slow it is OK. I've looked down the carb while giving it gas and it seems to squirt fine. The cam was set in the #2 hole from the factory but I'm not sure I understand that 1-2 hole anyway. Back when I messed with Carbs I always used AFB Carters. Back in the 60's they were the hot item.

By oldcarmark - 15 Years Ago

Re problem with 390 Holley.I have one on mine and am very happy with it.If you are getting good fuel feed from the accelerator pump it should not be the problem.Is the pump arm adjusted so the pump moves right away when the throttle is moved?That is adjustable using the screw and locknut.The pump should return fully when the accelerator is at idle but should move instantly when the throttle is opened.I assume you are using the later distributor with this carb?I would suggest checking the advance to be sure it is working properly.These are a fairly simple carb and unless you have defective unit(which is possible) I would be doing some more checking of other causes.One complaint I do recall is the base to body screws were loose from the factory.One other item to check is the float level.Hope these ideas help.

By rick55 - 15 Years Ago

What you are describing is a poorly adjusted accelerator pump. Setting it up as per manual instructions should fix it. As mentioned Holley carbs are very basic and easily fixed.

Regards

By speedpro56 - 15 Years Ago

E.J. If everything checks out you may be alittle too lean on the front jets, remember one size does not always fit all. Move the fronts jets up two numbers which should be 56s and see if that helps, it worked on my 292. The 54s are just to small on some engines and not on others?? go figure.

By ejstith - 15 Years Ago

Thanks guys. No I have done nothing to it at all. I have a late model distributor with a Mallory electronic unit. Timing is at 8 degrees I think. Like I said it squirts as soon as you move the linkage. Maybe I'll try those 56's. I'm going to Turkey Run, I'll go by Holly's booth. Thanks again.

By paul2748 - 15 Years Ago

Try a little more advance - push it up to 10 degrees.

By oldcarmark - 15 Years Ago

I swapped my jets for #56 and works well.Mine is a stock 292 with the later distributor and "B" manifold with the 390 Holley.The jets that come in these from the factory are #512 which are way too small.If you havent done anything thats a good place to start and is a good bet to solve your problem.Just re-reading my Holley catalogue.The holes in the pump cam controls how quickly the cam activates the accelerator pump.#1 activates the pump a little "early" using the full capacity of the pump.This setting is usually used for engines that idle at low RPM-600-700.The #2 and sometimes #3 settings delay the pump action slightly and are used in engines that idle at around 1000 RPM and higher.Try setting yours on #1 and replace the jets.Resetting the cam just requires loosening the screw and moving it and retightening the screw.Each size increase in the jets gives about 4 1/2% increase in flow and you really need to jump 2 sizes each time you change jets to notice a difference.The above info is from the Holley catalogue which gives more than just parts info.

By junkyardjeff - 15 Years Ago

I have a 56 merc carter carb I probably wont use,its been sitting in a garage for many years and needs rebuilt.

By Ted - 15 Years Ago

ejstith (11/8/2010)Ted, I've got a brand new Holly 390 on my 272 and it has give me fits ever since I've had it. When I push down the accelerator it hesitates, falls on it's face then takes off. If I push it down real slow it is OK. I've looked down the carb while giving it gas and it seems to squirt fine. The cam was set in the #2 hole from the factory but I'm not sure I understand that 1-2 hole anyway. Back when I messed with Carbs I always used AFB Carters. Back in the 60's they were the hot item.

There’s a myriad of items that can cause a ‘hesitation’ and several aren’t even carb related. But on the model 4150/4160 Holley carbs, proper accelerator pump linkage adjustment is at the top of the list before going any further. With the throttle wide open (WOT), the pump arm intersecting with the diaphram lever arm should only have ~0.015” clearance between them when the diaphram arm itself is fully depressed; or stated differently, the diaphram should be just a tad shy of being bottomed out. After that, pump cams and accelerator pump shooters may have to be changed assuming of course that the engine itself is in good mechanical condition (no leaky valves), and vacuum leaks and retarded ignition timing have been ruled out as possibilities.

By ejstith - 15 Years Ago

Thanks Mark. I'll try all of that. On the cam thing there is 2 holes one marked 1 & the other 2. My screw now is in the 2 hole & 1 hole is empty. What do you do just move the 2 hole in the plastic cam to the 1 hole & put the screw in there? I'll get some of those 56 jets when I go to Turkey Run or may look at Moultrie next week when I go there. Holley will have a booth @ Turkey Run, don't know if they will at Moultrie or not.

By F250RED - 15 Years Ago

thanks for the replys, pcmenten was right it is a Roch.4GC.Am going to rebuild it.Ran good but it sat for 5years , was plugged up,had what looked like tan mud inside,maybe mud wasps,ordered a kit,$90.00,but I think it is a good carb,only 54 years old.wondered if anyone knows how many CFMs it is. thanks F250 RED

By ejstith - 15 Years Ago

Where can one buy carburetor jets? I didn't see any at Turkey Run.

By joey - 15 Years Ago

ejstith (11/11/2010)

On the cam thing there is 2 holes one marked 1 & the other 2. My screw now is in the 2 hole & 1 hole is empty. What do you do just move the 2 hole in the plastic cam to the 1 hole & put the screw in there?

Yes. It's pretty simple--just don't drop the little screw!

ejstith (11/11/2010)

Where can one buy carburetor jets?

If you don't have a speed/performance shop near where you live...you can get them at any number of places on the internet. I've bought them from jegs.com in the past because they're pretty fast at getting orders out. I think a pair is about $7.