[QUOTE="Bob Shuman"] The aluminum alloy engine block was nice and light, but the cylinder walls unfortunately did not hold up well over time and the under-designed cooling system caused problems due to the differing coefficients of thermal expansion with the steel head resulting in head gasket sealing problems, coolant loss, overheating and warpage.[/QUOTE] The block was light. The head? Heh. Heavy. I don't get GM at times. Harley had aluminum heads in the 30's, GM had iron heads in the 70's... The cooling system I can vouch for - the thing would overheat in traffic on a 980 degree day. And it wouldn't shut off for a feqw secs most of the time either. Wow, it ran hot. IIRC, the ads in the mid 70's for it actually boasted how the car was more likely to start in the rain, due to the HEI system. It's amazing how far we've come! [QUOTE] I rebuilt several of these engines when I was a lot younger. I eventually learned to use a bored and (steel) sleeved remanufactured short block and replaced the standard (smaller) radiator with the larger HD one used for the AC equipped version.[/QUOTE] There was AC available? Gah. IIRC, the car had maybe 100hp on a good day, and they weren't light cars either. And you couldn't put a tranny cooler on them! Stupid GM had that stupid 350 with the holes in it and no cooler passages. Thank god my dad's had a 350 in it, it was far overengineered for that car's motor. Only gave up once, after 150,000... [QUOTE] With these modifications and several others including an Edelbrock manifold, Holley 4 barrel carburetor, and headers my tiny little 140 cubic inch 2.3 L engine actually ran very well.[/QUOTE] Oh, once the car got tolling, it ran. It was starting it and shutting it off that it never really got down right...