Rumblefish 360.
I went to that Demon Sizzler website you recommended in order to "get up to speed" on Thermoquads, but didn't learn much except that he has a lot of neat carburetors for sale.
You did not read this from the site? There is more specific tuning info on my site than any other in print or on the net; much of it is not avail at all any where else!
General ThermoQuad info
The Competition Series circa 1969-1972
The ThermoQuad started life in 1969 as a race or competition carb, best know as the Competition Series. Two cfm ratings were available, 850 and 1,000 and an early and later model. The early model circa 1969-1970 had press-in jets that were held in place with an o-ring in a grove in the top end of the jet. The later model circa 1971-1972 used screw-in jets. The early models were # 4846S for the 850 cfm and # 4847S for the 1,000 cfm while the later models were # 4846SA for the 850 cfm and # 4847SA. These four digit #'s can be found on the corner of the base plate. All C.S. carbs used metering rods and an adjustable 2ndary air door much like the oem Mopar, Ford and International Harvestor carbs. These carbs were all air metered carbs and can quickly be identified by the rectangular boss cast into the outside of the top plate over each float and included a foil decal with the Carter T.Q. logo and checkered flag. The main difference between the 850 and 1,000 is the 850 had double boosters and an air ring or wedge in the primary bores while the 1,000 had only one small booster and no wedge in the primary bores for max air flow/less restriction. These carbs are scarce these days as are new jets/metering rods. The good news is that I sell new rebuild kits, brass floats and choke pull-offs. All C.S. carbs have idle mix screws that angle out away from the centerline of the carb base plate.
The 1971 340 model, 1st oem model
The next generation of T.Q.'s was the one year only oem 1971 Mopar 340 carb. It shared features with the C.S. series carbs in the metering rods and piston, floats, choke pull-off, the top bowl gasket and the screw-in jets. This carb is # 4972 for the 4 speed and # 4973 for the automatic cars. These carbs had the idle mix screws similar to the C.S. carbs. It was often replaced by 1972 carbs by Mopar dealerships since the 72' up carbs were improved over the 71' carbs and are relatively scarce carbs today. These are also air metered carbs.
The 72'-74' oem models
The carb was reengineered for 1972 and became a solid metered carb and thus was a much improved carb in both performance and tuneability. This was the first year the carb was used on a big block as an oem unit, a Mopar 400 cu in hp engine. Two different but similar top plates were used on the 72' 340 engines and can be id'd by the # 2007 and 2083 cast into the top plate. All big block carbs were the same casting but were slightly different from the 340 carb and were 850 cfm's while all 340 carbs were 800 cfm's. In 1973, only one carb top was used for for small and big blocks while the mid section and base plates were again 800 and 850 cfm specific parts.This was the first year used on a Mopar 440 engine and the first and only year used on a US manufactured Ford, the 460 cu in engine. It was also the first year used on an International Harvestor engine, the 345 and 392 cu in. In 1974, the top was again slightly revised having an extended accelerator pump arm boss and different pump arm linkage that both remained through 1984. All 1972-1974 carbs were known as the 6000 series carbs. The 74' Ford carb was an 800 cfm with an integral 12 volt choke and special accomodating base plate for the choke. The I.H. carb was an 850 cfm.
The 75'-84' smoger models
In 1975, the carbs tops/bowls were changed. This was the end of the non smoger carbs and the begining of the smoger carbs, the first of the 9000 series. *The acception is the 1974-1977 Mopar Truck 440 cu in carbs which were based on the 1974 carbs. For the first time, very lean circuitry was used for less exhaust emissions, rendering these carbs poor performers on non smoger engines. These carbs have a distinctive vertical flat boss on the front center of the top plate which remained through 1984 and were again available in 800 and 850 cfm's. The 1976 carbs were the same as the 75's but for the first time, used a vacuum solenoid attached to the vertical boss on the front of the top plate. Some of these carbs did not have an idle speed screw or a vacuum port for the distributor vacuum advance on the Mopar lean burn ignition. I.H. used the carbs through 1979. This same design was used through early 1978 and again changed in late 78' through the final run in 84'. Many changes took place on the late 78' to 84' carbs due to smog regulations including electric idle enrichment solenoids added to the vertical flat boss on the front of the top plate and extra ports added to the base plate and even leaner circuitry. In 1979, a final aftermarket T.Q. was available and is known as the SuperQuad, only available as an 800 cfm with the integral 12 volt choke like the 74' Ford carb had. This S.Q. carb was a direct replacement for all oem carbs and was part # 9800/9810, non egr/egr for Ford, GM and I.H. engines and 9801/9811 for Chrysler non egr/egr engines.
Additional info:
The 1975-1984 carbs are decent carbs on the origional respective engines but perform poorly on non origional/emissions engines but the good news is that I convert/modify these carbs for non emission use with excellent results, so don't throw away the smoger carbs; keep them as the jets/metering rods can be used on all 1972-1984 carbs, DAVID.
General ThermoQuad info
The Competition Series circa 1969-1972
The ThermoQuad started life in 1969 as a race or competition carb, best know as the Competition Series. Two cfm ratings were available, 850 and 1,000 and an early and later model. The early model circa 1969-1970 had press-in jets that were held in place with an o-ring in a grove in the top end of the jet. The later model circa 1971-1972 used screw-in jets. The early models were # 4846S for the 850 cfm and # 4847S for the 1,000 cfm while the later models were # 4846SA for the 850 cfm and # 4847SA. These four digit #'s can be found on the corner of the base plate. All C.S. carbs used metering rods and an adjustable 2ndary air door much like the oem Mopar, Ford and International Harvester carbs. These carbs were all air metered carbs and can quickly be identified by the rectangular boss cast into the outside of the top plate over each float and included a foil decal with the Carter T.Q. logo and checkered flag. The main difference between the 850 and 1,000 is the 850 had double boosters and an air ring or wedge in the primary bores while the 1,000 had only one small booster and no wedge in the primary bores for max air flow/less restriction. These carbs are scarce these days as are new jets/metering rods. The good news is that I sell new rebuild kits, brass floats and choke pull-offs. All C.S. carbs have idle mix screws that angle out away from the centerline of the carb base plate.
The 1971 340 model, 1st oem model
The next generation of T.Q.'s was the one year only oem 1971 Mopar 340 carb. It shared features with the C.S. series carbs in the metering rods and piston, floats, choke pull-off, the top bowl gasket and the screw-in jets. This carb is # 4972 for the 4 speed and # 4973 for the automatic cars. These carbs had the idle mix screws similar to the C.S. carbs. It was often replaced by 1972 carbs by Mopar dealerships since the 72' up carbs were improved over the 71' carbs and are relatively scarce carbs today. These are also air metered carbs.
The 72'-74' oem models
The carb was re-engineered for 1972 and became a solid metered carb and thus was a much improved carb in both performance and tune-ability. This was the first year the carb was used on a big block as an oem unit, a Mopar 400 cu in hp engine. Two different but similar top plates were used on the 72' 340 engines and can be id'd by the # 2007 and 2083 cast into the top plate. All big block carbs were the same casting but were slightly different from the 340 carb and were 850 cfm's while all 340 carbs were 800 cfm's. In 1973, only one carb top was used for for small and big blocks while the mid section and base plates were again 800 and 850 cfm specific parts.This was the first year used on a Mopar 440 engine and the first and only year used on a US manufactured Ford, the 460 cu in engine. It was also the first year used on an International Harvester engine, the 345 and 392 cu in. In 1974, the top was again slightly revised having an extended accelerator pump arm boss and different pump arm linkage that both remained through 1984. All 1972-1974 carbs were known as the 6000 series carbs. The 74' Ford carb was an 800 cfm with an integral 12 volt choke and special accommodating base plate for the choke. The I.H. carb was an 850 cfm.
The 75'-84' smogger models
In 1975, the carbs tops/bowls were changed. This was the end of the non smogger carbs and the beginning of the smoger carbs, the first of the 9000 series. *The acception is the 1974-1977 Mopar Truck 440 cu in carbs which were based on the 1974 carbs. For the first time, very lean circuitry was used for less exhaust emissions, rendering these carbs poor performers on non smogger engines. These carbs have a distinctive vertical flat boss on the front center of the top plate which remained through 1984 and were again available in 800 and 850 cfm's. The 1976 carbs were the same as the 75's but for the first time, used a vacuum solenoid attached to the vertical boss on the front of the top plate. Some of these carbs did not have an idle speed screw or a vacuum port for the distributor vacuum advance on the Mopar lean burn ignition. I.H. used the carbs through 1979. This same design was used through early 1978 and again changed in late 78' through the final run in 84'. Many changes took place on the late 78' to 84' carbs due to smog regulations including electric idle enrichment solenoids added to the vertical flat boss on the front of the top plate and extra ports added to the base plate and even leaner circuitry. In 1979, a final after-market T.Q. was available and is known as the SuperQuad, only available as an 800 cfm with the integral 12 volt choke like the 74' Ford carb had. This S.Q. carb was a direct replacement for all oem carbs and was part # 9800/9810, non egr/egr for Ford, GM and I.H. engines and 9801/9811 for Chrysler non egr/egr engines.
Additional info:
The 1975-1984 carbs are decent carbs on the origonal respective engines but perform poorly on non origonal/emissions engines but the good news is that I convert/modify these carbs for non emission use with excellent results, so don't throw away the smogger carbs; keep them as the jets/metering rods can be used on all 1972-1984 carbs, DAVID.
If you take a few min and read this info, you will gain useful knowledge that will help you understand how a T.Q. works and its simplicity, David.
