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Hey, just want to touch base back with everybody about my 4bbl conversion that I was having some issues with some time ago. I had a shoddy 2bbl Rochester that got my truck 14mpg or less regardless of how you drove it or where you drove it. 14 flat. The truck took almost 24 seconds to achieve 60mph. I received this response from another member
Well, I did change the secondary spring to the next stiffest one, and might go to the stiffest one yet, tuned up the truck and replaced every ignition part except the distributor itself. I now get 16 in town delivering food and approach 20mpg on the highway. Hmm. that's a 43% increase on the highway and 14.3% increase around town improvement and it hauls a** to boot!!! Let's see, I took off a 2 barrel and put on a 4bbl and expect to get better gas mileage? Now that I'm done laughing......
INF
The truck achieves 60mph now in about 15 seconds which is a huge improvement in perfromance.Let's see, you took off a 2 barrel and put on a 4 barrel and expect better gas mileage? Now that I'm done laughing, try slightly smaller jets, but if it starts pinging go back up. Run a heavier spring in the secondaries. Run the idle stop as low as possiable, even if it means opening up the secondary stop a little. Make sure your fuel pressure isn't too high and you have a good inline fuel filter, it doesn't take much dirt to get the fuel to bleed past the needle and seat and make the fuel level in the bowls too high. Make sure you have a good tuneup and some extra spark will help, be it, a better coil or if you can swing it an ignion box
Well, I did change the secondary spring to the next stiffest one, and might go to the stiffest one yet, tuned up the truck and replaced every ignition part except the distributor itself. I now get 16 in town delivering food and approach 20mpg on the highway. Hmm. that's a 43% increase on the highway and 14.3% increase around town improvement and it hauls a** to boot!!! Let's see, I took off a 2 barrel and put on a 4bbl and expect to get better gas mileage? Now that I'm done laughing......