Thread: SBC mileage

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Techinspector1,

Thanks for the Elgin Cam address and the other site on lobe separation. The cam you cite has less lift and duration than the stock 350 cam, but I guess 3-5 mpg has to come from somewhere. From the tight lobe separation it might be a mistake to add 1.6 rockers on the intake valves? I am still digesting your claim regarding the squish and 11:1 CR. I have played with the automatic C.R. calculator from Cambellenterprise.com and the PAW catalog and there are several possibilities ranging from flat top pistons to 22 cc dish pistons to use my old 461 double-hump heads and various gaskets to achieve C.R. from 8.8 to 10.7. Then again I could buy a low end crate motor with 9.1 C.R. and replace the cam. I still like the Comp Cams XE-250 which is also marketed by Elgin. However, my first choice would be a Holley-Lunati "Avenger Truck Cam", 253/265 adv. dur., 204/216 @0.050", 112/107 lobe sep. with 0.427"/0.454" at the valve because it has higher lift and the claim is that it will operate with stock springs. You bring up a deep issue in "hot rod philosophy" as to what are we trying to do? I had hoped that I could use a medium range cam with Rhoads lifters to get BOTH mileage at low rpm and occasional "performance" at higher rpm. So far no one says the Rhoads lifters are worth anything but clicking noise, so I am back to the choice of MPG OR PERFORMANCE, not both. Thus I would prefer the Avenger Truck cam or the Elgin 5870 (their second cam). How sure are you that if I were to use 0.025" deck and 0.015" gasket (0.040" squish) with 10.7:1 I would be able to use 92 octane pump gas without detonation? If so I may build up my present block rather than trade it in, otherwise I will just order a crate engine with 9.1 CR and swap in the Holley Avenger Truck cam. You are the expert!

Don Shillady