428 CJ Dyno Results....Inquiring Minds...

[bubbaf100]

To get more mpg using the volumetric efficentcy formula in for example say you have 427 FE standard bore with solid lifters,my preference ship the standard solid lifter and get solid rollers and solid roller cam it gets you another 20HP using the identical lift and duration as a standard solid cam that is the same except its a roller cam because of less friction and don't have to adjust lash as often as long as you son't go in the upper 580's with fat duration. And pick up mpg as long as you don't go too big of a cam but why not go bigger if you can in racing, for the street I can understand a Street beast with great power and torque that can kick ass and won't break your wallet from the gas pump and higher octane. Back to the volumetric efficentcy formula same 427 FE with solid lifters running say 6500 rpm's multiply your DISPLACEMENT X MAX RPM DIVIDE IT ALL BY 3456. In this case you'll get a recommended Carb CFM with 100% VE it would be 803 cfm to able to achieve 100 VE it would be an all out race engine asuuming that this motor is a modified street engine multiply 803CFM by 90% and will get 722CFM. And the secret is what do you round you cfm rating up or down? If have the cash to spend on fuel on the 722cfm get a 750carb 4150HP or equivalent because the choke tower all it does is restrict power and won't get a better air fuel ratio mixture. Put a percy block on the primaries and secondaries and jet the primary a little lean and the secondaries 15%-25% more. say you have a size 70 jet in the primary and the secondary would be 87.5 with 25% more jet in the pecry blocks all you have to do is make turns and not jet changes which is the best carb invention since the 4500 Carb was made. And if you want a great gas milage like my 412FE the 722cfm figure round down to a 700cfm carb again use a 4150HP with a Percy blocks on primaries and secondaries but set it up as a spreadbore make the primaries lean but not too lean where it's going to screw up the air fuel mixture and make the secondaries 30-35 % more the reason why I say for a street engine mpg to go down in cfm so you won't flood out in the big end and readjust the mechanical secondary linkage on the carb so at 70-75 percent throttle you get all of the secondaries
and not partial at 50% percent throttle and be wasting gas and you'll see the difference in mpg and still get great power with your foot in. Another good aspect of the 4150HP you'll get more and mpg changing to it out of the box usually it's 10-15HP and 2-3mpg. My truck was a street engine that is a destroked 428 and a destroker motor interestingly enough will act like a small engine reving quicker and higher and has great torque and in a destroker it be a like a larger displacement engine, like a 377sbc that is almost unstreetable to be able to use it properly but in a FE a destroker is great because you'll have an extended lifetime on the engine more HP and hold torque forever. And in a single plane intake you'll get more power and mpg crusing than a dual plane intake as well ad a 1inch spacer and will see more power and better on fuel. It will take some time to get your combo right it took me 30 plus years playing with these FE motors and found what they like and hate. They love single plane intakes especially high rise air gaps with carb spacers if desired,headers is a must collector pipe size is a must don't use reducers for you'll lose power gain torque but not enought to make it worth it when you can get it back in the air fuel department they like large intake ports big valves is a must and use a slightly smaller exhaust valve for more torque and another secret use a Chevy 454 rod conversion for more torque and engine life-H-beams rods. Got cash only get the Dove or DSC motorsports heads or port the edelbrock heads heavy. On a budget get the C8AE-H heads and have the runners gasket matched to Edelbrock Gasket 7129 for power and especially sealing quality. The C8AE-H are cheap heads that have the small kidney chambers for more compression. Best of Luck