Caburetor Repair - Carb Rescue, Part 1

Sucp 1208 99 Caburetor Repair Carb Rescue

For all the good technology has done for the performance world (namely electronic fuel injection), there are some downsides--namely, the fact that carburetor rebuilding (and tuning) is quickly becoming a lost art. Where it was once common for any decent repair shop to have the ability for rebuilding the old mixers of fuel and air, today you'd be lucky to find anyone in a shop who's ever driven a carb-equipped car in their life.

So, what do you do when your classic Bow Tie starts having issues, and the carb is at the heart of the problem? You call the guys who still make it their business to keep carbs going--Holley.

Brothers George and Earl Holley started their company back in 1903, with the goal of building horseless carriages. After Henry Ford approached them about just building carburetors for his cars, they moved from Pennsylvania to Detroit, and one of the oldest companies in the automotive industry was born. And while Holley offers a full array of fuel injection products today, it has never lost sight of its roots, still manufacturing brand new carbs in Bowling Green, Kentucky.

Along with new carbs, Holley also offers a complete restoration/rebuilding service through their custom shop. Even if you've got a non-Holley piece (Rochester Q-Jet, Rochester 4-Jet, Motorcraft, Webber, you name it), your ailing carburetor will gladly be welcomed into the workshop of Holley's main carb rebuilder, Greg House. Greg does 99 percent of all the carb rebuilds that come through the custom shop by hand. A typical four-barrel carb that sees a similar rebuild like the one pictured here will cost a customer about $426, including the di-chromating, if needed.

To show just how good Greg is, we sent him an old 750 Double Pumper we had sitting on the shelf that hadn't seen use in over 20 years. We've got plans for this carb, and needed it back in fighting trim. Even though brand new Double Pumpers are readily available, we felt it worth the money to have it restored.

One thing we would recommend if you have a carb to send in is don't touch it! Let Holley handle all of the disassembly process, even seemingly simple stuff like small screws and other things. You could end up doing more harm than good.

Here's 750 our double pumper before it went into rehab. The last time it saw fuel was around the year Regan was inaugurated for his first term. Since then it had been sitting in a box rotting away.
Here's 750 our double pumper before it went into rehab. The last time it saw fuel was arou
1 The first step is removal of the float bowls and metering blocks, then disassembling the accelerator pump mechanism from both bowls.
1 The first step is removal of the float bowls and metering blocks, then disassembling th
2 Next up is gasket removal. Getting all the old gasket material removed is critical for the rebuild. Leftover small particles could easily get clogged in the metering block passages during cleaning, and create headaches later on. Scraping away the old material is a process that requires care and patience. The soft zinc material carbs are made from can easily be galled along mating surfaces by aggressive scraping, leading to sealing issues later on.
2 Next up is gasket removal. Getting all the old gasket material removed is critical for

3a Here you can see both sides of the metering block...
3b...cleaned of gasket material and other loose debris.
4 For vent tube removal and cleaning, Greg uses this homemade tool that lets him grab hold of the tube (pressed in from the factory) and remove it without crushing it.
4 For vent tube removal and cleaning, Greg uses this homemade tool that lets him grab hol

5 With that done, the baseplate is removed from the main body, and the throttle and choke linkages disassembled.
5 With that done, the baseplate is removed from the main body, and the throttle and choke
6 The throttle plates/butterflies are attached to the throttle shafts with special brads/rivets that can't fall out from vibration or heat cycling. To remove these correctly, the non-Phillips head end must be ground down. After that, the brads can be removed and the plates detached so the throttle shaft can be pulled out.
6 The throttle plates/butterflies are attached to the throttle shafts with special brads/
7a After all the linkages, small parts, and other pieces are removed, the main components of the carb are ready to be blasted clean. Greg takes his time in the blast cabinet with each piece, making sure everything is totally clean.
7a After all the linkages, small parts, and other pieces are removed, the main components

7b The amount of time it takes for the custom shop to rehab a carb depends on several factors, including missing parts, parts availability, condition of the carb, and other factors.
7b The amount of time it takes for the custom shop to rehab a carb depends on several fac
8 After everything is clean and rinsed of all blasting media, all parts except the baseplate are sent to the in-house plating department, for a fresh electro-plating treatment. The baseplate will be tumble polished. If your carb wasn't originally electro-plated, or you don't feel like paying for the service, Greg will skip this step and go straight to rebuilding.
8 After everything is clean and rinsed of all blasting media, all parts except the basepl
9 The cleaned throttle plates are reattached to the freshly plated shafts using new brads. One advantage to sending in an original Holley carb to its original maker is the same parts used to build it originally will be used again. If original style parts aren't available, Holley will contact the customer, explain the situation, and offer all possible options to make sure the carb gets rebuilt and working properly.
9 The cleaned throttle plates are reattached to the freshly plated shafts using new brads

10a One of the biggest issues rebuilt carbs face is a lack of sealing around the mating surfaces. All the years of heat cycling causes the carburetor's flat surfaces to warp slightly.
10a One of the biggest issues rebuilt carbs face is a lack of sealing around the mating s
10b Greg takes a file and levels the high spots down (the areas of different color in the second photo) so all the main body's mating surfaces are smooth and level.
10b Greg takes a file and levels the high spots down (the areas of different color in the
11 After the baseplate is reattached to the main body, Greg begins reinstalling the throttle and choke linkages.
11 After the baseplate is reattached to the main body, Greg begins reinstalling the throt

12 The fuel squirters are also reinstalled with brand new screws.
13 To aid in reassembly, Greg uses this specially made fixture to stand the carb on end, making installation of the float bowls much easier. New, factory spec jets are installed in the metering blocks, and TK "blue" gaskets are used when a carb is rebuilt, their sealing far superior to the old cork gaskets. During this part of the rebuild, the float levels are also set, obviously with the carb laying flat again. Also note that new brass floats, not plastic, are installed.
13 To aid in reassembly, Greg uses this specially made fixture to stand the carb on end,
14 Next, the fuel fittings are reinstalled in the float bowls, along with the choke plat and shaft.
14 Next, the fuel fittings are reinstalled in the float bowls, along with the choke plat

15 After that, the rest of the throttle/choke linkage assembly is installed on the main body.
15 After that, the rest of the throttle/choke linkage assembly is installed on the main b
16a Just like the main body, the accelerator pump plate is filed down to make sure the surface is smooth and even.
16a Just like the main body, the accelerator pump plate is filed down to make sure the su
16b Judging from the color difference of the zinc surface, this one had really warped over the years.
16b Judging from the color difference of the zinc surface, this one had really warped ove

17 Once everything is back together, the rebuilt carb is bolted the custom shop's veteran flow bench (we say veteran because this bench has been around since at least the 'Nam era) and "wet tested" to make sure the flow characteristics are correct, the fuel squirters, floats, jets, and accelerator pumps are working properly, and there are no leaks. Greg will also check to make sure the throttle linkage is working properly and the throttle plates are opening all the way at full throttle.
17 Once everything is back together, the rebuilt carb is bolted the custom shop's veteran
18 Here she is, good as new and ready to help make some horsepower! All the carbs that go through the shop carry a TK warranty. They're all hand rebuilt by Greg, painstakingly and one at a time. This means every aspect of a carb's rebuild gets the maximum amount of attention possible, and nothing can be missed. An average of about 30 carburetors go through the custom shop every month for rebuilding, and they'll work on anything, not just Holleys. To find out more about sending your carb in for repair, call (270) 781 9741 to get things rolling before sending in your part. Stay tuned for part II of our series, where we follow along as a venereal Rochester Q-Jet is given the rehab treatment.
18 Here she is, good as new and ready to help make some horsepower! All the carbs that go