Pro Systems Carb Users.

[greg schroeder]

Originally Posted by jhv48

Was the Street Avenger that far off what this engine needs? And if so, why does Roush install it at the factory?

So, what specs did you guys end up with on your carbs and what size engines are you running. Just give me your engine size, carb size, squirter size, main jet sizes and your altitude please.

Just want to make sure this thing is not too much for my engine.

My engine was the 427R with single plane intake, TKO 600 .64 5th, 3.73 rear gear and usually 28 inch tall rear tires. I had the 1060 CFM mechanical secondary from Pro-Systems. Absolutly not too big for the engine I had. Out of the box with stock Superformance side pipes it hammered perfect. When I bought new 3" ID side pipes I went up 2 jet sizes all the way around for summer and 3 jet sizes all the way around for winter. I forgot the jet sizes, but they were in the 90s. The car hammered from just about any RPM or drove like a cream puff farting around too. There were zero street drivablity issues and power was like a light switch when desired.

Here's my air fuel, HP and TQ at the rear tires


You could drop down one jet size for both primaries and secondaries. You'll know if you're to lean if the top RPM of 3rd or 4th gear stumbles on hard acceleration before your rev limit.

Vacuum secondary carbs and dual plane intakes are are nice for heavy cars with auto transmisions and lug around rear gears. That Avenger 770 is sort of goofy for a stick shift 2450 lb car with driver in my opinion, but hey the Superformance dealer here talked me into one so I could find out it didn't work too.