I have a 73 Dart Sport with worn out slant six. I want to get another engine and build it as a milage engine. I have access to a drool tube solid lifter engine, a peanut plug solid lifter engine and a later year hydraulic lifter engine. They are all in about the same rebuildable condition and all for the same price. Given my goal of maxim milage with good driveability would either of these engines be preferable. It will be paired with an A833OD transmission and 3.55 gears. If not, I would pick the hydraulic engine for ease of maintainance. Suggestions??
Thanks
Steve

Sold lifter cam would be my choice as it would have a better variety of lobes to choose from and not have the extra preload steps to set up after you machine the block and head. I agree that maintenance afterward would be easier not to have to set the lash at the rockers later, though...

The '73 is going to be a heavy car, so optimizing the engine to the torque curve's sweet spot will be the key here.

DI hit the nail on the head. I like playing with the later hydraulic engines just because they are a little different than the average slant, but I still would stick with a solid lifter valve train, especially if you are going to be changing this for economy and are considering a custom cam.

One other thing to consider is that the later hydraulic lifter engines were lighter than the earlier solid lifter engines. Lighter weight components (crnak, timing set) were used and the block is lighter. However, the later heads with the exhaust injeciton passages were heavier than the earlier heads. You might want to consider using the hydraulic lifter engine block with the earlier drool tube head and installing a solid lifter cam. Less weight = better handling and faster spooling of the motor.

Appreciate your views.
Thank you
Steve

well,, working the preload is not a big deal,,,

the oe lifters in the 83 slant motor had around .180 of overall pre load travel. that is a bunch to work with.
in the oe condition the preload was .090 to .085
the after market new lifters also had .180 of overall pre load travel.

after cutting the head .040 and the block around .005 and having the cam ground,, with the motor assembled, the pre load on the lifters was at .90 to .080,,, within reason, at stock conditions.

it should also be considered, that in getting the valve off the seat,, a hydraulic lifter cam does not have to deal with lash take up like a solid lifter cam,, with the right grind, you can get the valve off the seat quicker, hydraulics are better technology and there are plently of grind options available.

call me a sentimental fool but I still like the sound of a solid valve train slant.