TQ DIFFERENCES
Not sure how that translates to performance, reliability etc. Thanks.
Use the later solid fuel metering TQ's. The difference is the use of emulsion vs solid fuel metering.
I posted this a long time here:
"Holley and Carter/Eddie are similar designs in the sense of how they overcome the inherent design issues related with a plain tube Carburetor.
As airflow increases with rpm the fuel delivery increases at a faster rate which means the carb will have tendency to become richer.
One way to overcome this problem is to introduce air into the system (air bleeding) to lean it out to maintain a steady AFR. So emulsion was born. Both Holley and Carter afb's use emulsion to overcome this problem.
Holley and Carter both use emulsion but they also do it differently. Carter uses a tube style which allows an infinite amount of options of bleeding arrangement and emulsion where as Holley gives you 5 possible locations. In my view the tube design is far superior to the Holley design. Weber also use the tubular emulsion design.
Carter Thermoquads (Quadrajet also)are a different animal all together . They don't use emulsion to overcome the issue with different flow rates instead they use the internal passage sizing to restrict the flow to control afrs Thermoquads are deemed to be solid fuel metering carbs. Whats easier changing air bleeds or sizing internal passages to accomplish the required afr? OEMs have the time and resources to do the solid fuel metering.
Its my understanding that solid fuel metering carbs provide a more consistent afr spread between cylinders because air does not interrupt the fuel flow exiting the booster. Also the triple booster venturi design aids atomisation. A win win!"
This ties into cycle to cycle variation in early flame development. When cylinders receive similar amounts of fuel and air then the burn should proceed smoothly from one cycle to the next but when one cylinder gets more air or more fuel than the previous cycle then it will be inconsistent.
There is quantity of mixture (AFR) that the cylinder receives and then there is quality of mixture the cylinder receives in relation to how well the mixture is spread within the cylinder. You can give a cylinder an AFR of 12.5 and the cylinder can still be lean at the time of ignition. Just because you give a cylinder fuel doesn't mean it will use it.
