somenone please come in and help lol

[360demonRT]

dont wanna sign on the dotted line lol just playing. after posting that i found a site that said 58cc, as well as a site that sait 76cc. so i dont really know. i'll CC it when i take it off to make sure. figure at the worst i should be able to trade those heads off to something i can use

 

[DRIVEN]

1993 Lincoln Mark VIII 4.6 DOHC -- 9.8
1996 Camaro LT1 -- 10.5
I have had both of these and run 87 octane (Oregon gas sucks) and almost never heard them rattle. Keep in mind that these both had computers to control timing. Both of these cars are recommended, by their manufacturers, to use premium fuel.
By the time you take into account the thickness of the head gaskets (which can vary greatly by application) and the valve reliefs/dish in the pistons, a jump from 64 to 56cc isn't that huge. I'd be really surprised if it puts you past 9.5:1. The cam profile (specifically overlap) will probably affect the need for specific octane requirements more than anything else. Your new heads should be fine. If you are really concerned you could order thicker head gaskets.

 

[SScamino]

dont wanna sign on the dotted line lol just playing. after posting that i found a site that said 58cc, as well as a site that sait 76cc. so i dont really know. i'll CC it when i take it off to make sure. figure at the worst i should be able to trade those heads off to something i can use

well remeber, there was a 305 available for that truck, so the 58cc you probably read was for a 305, if your truck has 76cc chambers, then id stay away, it'd easily raise your compression 2 points, I think its 1 point for every 10ccs.

 

[custom442]

I disagree, although your compression will likely be fine on 93 octane and breathe well, it's only going to be at certain rpms.

A smaller combustion chamber with large valves like yours will breathe very well but only at the top end. How narrow that band is with a stock bottom end is anyones guess. You'll likely lose a lot of mid range and maybe all low end. You can only run a very radical cam if you want good performance with those heads, and when adding power after you've installed these heads you'll be in a tight spot

The only plus is that they've been ported

I'd really look for a ported 64cc head that has smaller valves for the engine you're building.

 

[SScamino]

I'd be very surprised if your compression doesnt get past 9.5 because youll atleast have 9.5

 

[360demonRT]

well, got the heads for 550 so i'm getting them. worst comes to worst i'll try to trade them to something else. was planning on using a 480/292 109lsa cam (already have it NIB) probably too small on the lift side to take advantage of the port work... or maby the high duration and lower lift would help the heads act a little smaller. dont know. i'd like to run these heads. my combo would be

these heads
750 holley
rpm
2500-3k stall
4.11
th350
1 5/8 lt's

the guy that ported them said he thought they'd flow in the low 300's. a TON of flow lol. these are going to be way overkill. may just try to trade them off. how much power would hte motor make, and how high do you think i'd have to spin it?

 

[custom442]

The problem isn't makin power, you'll have tons of it. It's just to get the most outta those heads you'll need a single plane manifold, the other pieces look good. It'll be a helluva 1/4 mile car but it's street manners... well...

 

[360demonRT]

well scratch that idea :evil: offered the guy 500. he said he'd take 550. between the 3 hours he said he'd take 550 and the time i told him i'd do it someone already offered him 600 . so in my frustration i ordered some parts off summit lol. going the vortec route afterall. ordered a cloyes timing chain. Trans cooler, and a RPM vortec intake . my goal is to run some deep 13's... only thing left to buy is the heads and fluids... and welding my spider gears together. dont really care about streetability with this car lol.