I'm thinking about just doing alot of port work to my iron L98 heads I have. How much better are the vette alum ones? I'm going to be running the LT4 hot cam, siamesed base, SLP runners, headers, exhaust, custom PROM, T56, 3.42s, 3" cutout, Holley 255lph, Holley AFPR, and all the little stuff on my website. I'm wanting at least high 12's out of it. I think thats possible. Are these heads worth it or should I get some vette ones? If so, how much would that swap cost me?? THANKS

 

1st thing is weight....the cast iron heads are heavy as H#!! and the vettes are very light... and 2nd is the combustion chamber sizes.... the cast irons have 64cc chambers and the vette heads have 58cc heads and d shape exhaust ports

 

The aluminum heads also have quite a bit more low lift flow. Here's the flow #'s

Corvette Aluminum # 113
Lift/Intake/Exhaust
.100 62 49
.200 116 98
.300 161 130
.400 185 152
.500 195 159

350 Cast Iron # 083
Lift/Intake/Exhaust
.100 44 41
.200 101 82
.300 155 125
.400 182 137
.500 196 140

 

Thanks guys. I knew they were 58cc, lighter and d-ports, but I wasn't sure exactly how much better they flowed. To me that doesn't look like that much difference. I plan on porting the hell out of these iron heads... I think they'll be fine until I can afford AFR's and a LT1 intake. Thanks

 

No one else has any thoughts??? I'm just wondering how they will do with that LT4hot cam. Thanks

 

I dunno... how does 12.80 sound with Corvette L98 heads and an LT4 HOT cam?

 

Thanks Kevin. Thats a pretty good time for ya I'd say. I was wondering how much I'll lose (if anything) by running fully ported iron heads? Thanks

 

Kevin,

did you have a piston to valve clearance problem with the hot cam due to the extra lift? how thick are your head gaskets?

 

Nope, no problem with the valves hitting the pistons. I'm using 1.52 roller rockers so only .498" lift. I think I used a .040" thick head gasket.

 

how much did you mill your valve guides?

 

Yeah, if I use 1:6's on the iron heads with the hot cam... will they clear or will I have to mill the guides down or what? Thanks for all this help Kevin. I'm getting closer!

 

you'll have to mill them even if you use 1.5 rockers. i have the hot cam and had my guides milled .050 but i think it should have been more like .080.

 

Thats cool. I was wondering what I would have to mill down. So how much do you think I'd have to go with 1:6's on iron heads? I think I'm gonna get the LT4 spring kit from SDPC. Where's Kevin at on this issue. lol Thanks again

 

in david vizard's "How to build and modify small block chevy cylinder heads", it states there is absolutely no power gain difference in a set of fully ported corvette alum L98 heads and a fully ported iron head. he says to only pick them up if you can get them for a good price. it even goes on to state that if you plan on making more than 400hp, the corvette head is too questionable at this leve because it is too fragile.

 

thanks man. I still need to know how much to mill my guides down for clearance. Thanks!!