Mystery of the ZL/X

[markjohnson]

Yeah, I know about those #990 heads. There's also the #188 heads. I've seen several of those heads on LS-6 and LS-7 crate motors all the way up into the '90's. I think the 026's, 990's, and 188's are all VERY similar. I'll tell 'ya, I've had some friends go VERY fast on those 990 heads. How about 8.60's in a 10.5 Shootout-style 72 Nova!? That was around 540 inches with a pretty heavy shot of the juice, but still that's really impressive for an old out-dated cast-iron head when everybody says you have to have the latest, greatest most modern aluminum heads to go fast.