Quote:
Originally Posted by GoldOlds
Thanks, Joe - guess I got a few facts mixed up (maybe it's the #6 W31 heads that I was told were rare?). Anyway, the newfound info brings about another question; what's the difference between #5 and non-W31 #6 heads, aside from the years they were produced?
- GoldOlds
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#6 heads used valve rotators, #5 did not. As a result, the spring pockets in the #6 heads are deeper, requiring a shim if you don't use the rotators or enabling you to run a taller spring with thicker wire (ie, stiffer) without running into coil bind. And just for completeness, the #7 heads used rotators on the exhaust valves only, so they have a deep/shallow combination of spring pockets. Note that 68 Ram Rod 350 motors and 69 W-31s also used #5 heads with the bigger valves.
Quote:
Originally Posted by Redog
I thought I read that 6 was only on Canadain cars, thus making them rare  |
I'm afraid you read wrong. Every single 1970 350 Olds came with #6 heads. The desirability (as opposed to rarity) may be the deep spring pockets as noted above, which allow stiffer springs to be run if you dump the rotators.