Took another road trip in the El Camino. First one since changing out the mechanical fuel pump for an electric.
Drove to a small town in Kansas to pick up a complete 3.31 12 bolt rear end. Not worried about numbers matching on this vehicle, but it is even dated correctly for my car. Probably don't need the upgrade from the 10 bolt, but may tow heavy loads from time to time, and will appreciate the peace of mind. Besides, I have some 11 inch backing plates, and plan to change out the rear brakes to 11 inch drums from a full size Chevy to match up better with my Cheap Big Brake upgrade that I already did on the front using modified original drum brake spindles, modified 69 and up brake caliper mounting brackets, Corvette rotors, Chevy truck calipers and pads. Not sure if I posted the link on that, but just in case I didn't:
http://www.camaros.net/forums/16-bra...e-upgrade.html
I can gather parts and get the 12 bolt all done and ready to install. That way the car won't be "down" while I am doing the brake conversion.
Drove about 550 miles all together. Driving mostly 70 mph, achieved and overall mileage of 23.5 mpg. Better than I expected in an open bed carbed El Camino that is about as aerodynamic as a shoe box.
Specs
Engine:
350, .020 over, flat top pistons, decked block to achieve about .036 quench, 186 heads, with 1.94 valves and very little work. I don't remember the final number, but static cr is around 10.2. Crane hydraulic roller cam that makes torque starting at 1500 rpm (thanks Eric, for the cam) stock 68 Q-jet rebuilt by me on a stock 68 cast iron intake, and jetted down one size on the primaries. Has a cheapo Accell HEI distributor (came with the vehicle... uses stock GM coil, pick up and module) which I dialed in on my Sun distributor machine. 10 degrees initial, 36 total of mechanical and initial, all in by 3200 rpm, with an additional 10 to 12 degrees of vac, hooked to manifold vac. Normally use 89 octane. It will run on 87 without pinging if not pulling a load. So far, have been able to get 100% gas. Not sure how it would run on the ethanol stuff, and would rather not find out. Fuel pump, carb and lines are all supposed to be ethanol compliant.
Trans:
4l60E with a stand alone controller (.0696 OD, and converter programmed to lock up after 52 mph).
Rear:
3.36 10 bolt rear spinning 275 60 BFG tires on 10 inch vintage Centerlines.
Puts my rpm at 70 mph at 1973, right in the torque curve, which is why the good mileage. The 3.31 will only bring that down to 1939 rpm. Maybe I will speed up two mph just to keep it in the sweet spot.
Anyone need a complete, drum to drum 3.36 10 bolt out of a 68 El Camino? Would fit other A body cars as well, I believe from 68 - 72.