Quote:
Originally Posted by OE Espo
Helping someone work on a 70 Lemans Originally equipped with 350 2Bbl. Have build-sheet and under 40k original miles.
Doing some research probably (guessing here) has a 254 camshaft .375 int .410 exh. Has No11 heads. Believe its a 2.78 open rear.
Want to wake it up some this winter but probably in stages.
1. Winter plan replace 11 heads with 13 (have them). getting them cleaned up. they dont have springs OR rockets in them. considering keeping cam now and using 1.65 rockers. no port mods. hoping block is chamfered for larger valves and just increasing ratio that we wont have any valve interference.
2. Add 68-72 iron intake (have)
3) Add quadrajet
Thinking these mods alone should get better seat of the pants feel.
Future considering 068 cam, 3.23 rear posi Want something for highway trips
Should i get heads milled to more like 350 HO #48 heads. had one in my car it ran great. if so to what cc?
other camshaft recommendations?
rear gear recommendations?
thanks
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You are correct on your current camshaft. On my 1970 Esprit, while in college I converted the 350 from a 2 barrel to 4 barrel by installing a Torker I intake manifold, Quadrajet, Borg-Warner electronic ignition, dual snorkel air cleaner and dual exhaust. Rear wheel horsepower went from 182@4400 RPM to 212@4400RPM on our chassis dyno at General Motors Institute.
For my restoration of the car, it has been a full rebuild. The 1970 block does have chamfered cylinder walls. I installed 6X-4 heads milled down .010 inches. The deck was given a cleanup pass at .005 inches. The valve spring seats needed various degrees of milling to get correct and even spring pressures across all cylinders, and with the use of Comp Ultragold 1.5 ratio rockers and Johnson hydraulic roller lifters, custom length push rods were necessary for correct valve train geometry.
Other mods included a 4.25" Eagle crank and Eagle H-Beam rods, Ross flat-top pistons, Comp XE275HR cam and MSD billet distributor. Displacement is now 413 cu in with 9.3 cr. I am replacing the 2.78 open diff with a 3.23 posi, and going from the stock converter to a 2800 RPM stall unit.
I had always thought about dropping in a set of 1.65 ratio rockers back in college and my auto engineering professor, Jim Lyons, who later went to Pontiac to head up the Turbo 301 development, cautioned against it without upgrading the rest of the valve train for the added stress. In his estimation, going from the 2 barrel to the 4 barrel was the best bang for the buck.