# Max lift on 092 heads?



## torpedo51 (Sep 8, 2009)

I've got a 1965 389 bored to .040 over (now 396cid) and a stock Tri-power. The stock 092 heads are rated at 10.5::1. With the increased bore, its probably at 10.6::1. I think the pistons were selected to get it all down to 8.5::1. Next, we increased the intake valves to 2.02. I think is the max allowable on these heads because of narrow spacing.

Then, we bored out the valve spring pockets to accommodate a "more exotic than stock cam solution". I don't have lift number in front of me (507?), but its definitely at coil bind and putting 150+ psi on the springs to get there. I'm afraid to bore the pockets out any more than they are.

I'd like to dump all this junk and go with a roller cam solution with an 068-ish grind.

Does anyone know how deep can the valve spring pockets be safely bored from stock?

And, what is the maximum lift recommended for these 092 heads? I didn't think that going up from 488 to about 507 was that nutty.

The cam in the car before I had all this work done was an old school Fireball 234B
234 244
488 508
112


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## geeteeohguy (Feb 2, 2008)

Been running .490 lift in my stock 77 heads on the '65 389 since 1981 with no issues, and with press -in studs and no pushrod guides. No issues whatever with the Sig Erson Hi Flow 1 cam. But I would think that's about max. I run these heads only because that's what was original to the engine, and back in the day, it was as good as it gets. Nowadays, I would simply run better heads. The pre-'68 closed chamber heads are really not optimal for today's fuels and timing curves.


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