Chevy Impala SS Forum banner

Cast iron B body heads

874 Views 26 Replies 13 Participants Last post by  shakenfake
Hey guys so I found someone who can rebuild my old cast iron heads to hopefully flow more when I'm ready to cam my stock motor. He said complete valve job is $250 for the pair, and to port and polish starts at $225. Do you guys think this is a fair starting point? Trying to see if I should just rebuild what i have or to start saving for a lloyd elliot heads and cam kit.
1 - 20 of 27 Posts
'someone' and 'starting point' while maybe fine, I'd dig more into it vs a known performers like lloyd.
just save for a H/C package from Lloyd. Not worth the $ spending on the iron heads

with that said if you were NOT later changing to AL heads, then what your guy does "may" help from a performance standpoint on the iron heads.
No everyone is in love with aluminum heads.
  • Like
Reactions: 2
The iron heads are actually very good. But the aluminum ones have more ultimate potential. I made 320 rear wheel hp with ported iron heads and an 845 cam, which translates to just about 400 hp at the crank. I could have probably picked up another 20 hp with a better cam.
  • Like
  • Helpful
Reactions: 2
Will Lloyd will port customer supplied heads? I was under the impression that is what his pricing was for.
  • Like
Reactions: 1
Lloyd will port heads you ship to him, if you don’t have any he can get you some for I believe $350.
  • Like
Reactions: 1
IDK if Lloyd ports iron heads. My $.02 is the OP's intent is to later buy LE AL H/C package, don't spend any $ porting the stock iron heads now.

With that said I would think unshrouding the valves some on iron heads would improve flow thus add some HP...just not as much as ported AL heads. Ironically, IIRC, stock iron heads flow better than stock AL (LT1) heads.
  • Like
Reactions: 2
You guys are awesome i will be saving money for the lloyd elliot heads and cam next
But the aluminum ones have more ultimate potential.
How so? Have any details? Not saying you’re wrong, just curious what makes the difference.
Higher thermal conductivity so you can run more timing and compression ratio without detonation
  • Like
Reactions: 1
Aluminum heads have higher compression, are lightweight and have better ports when compared to iron heads.
Engine I bought to build for my car is from a 94 Z28 so I'm using the Aluminum heads that are on it. Lloyd does good work so they will go to him at some point.
  • Like
Reactions: 1
Aluminum heads have higher compression, are lightweight and have better ports when compared to iron heads.
Better? Are we talking stock AL heads? Better than these iron versions at 196cc intake runners? With larger valves that cannot fit into the hardened seat of an aluminum head? Raised port roofs steeper than the LT4?





Higher compression? These irons result in a static of 11.09 with 53cc chambers on a stock bore/stroke. As related above, it was good enough to net 342HP/407.6 ft/lb at the wheels. If the goal is higher, aftermarket is probably the better choice.
The iron heads are actually very good. But the aluminum ones have more ultimate potential. I made 320 rear wheel hp with ported iron heads and an 845 cam, which translates to just about 400 hp at the crank. I could have probably picked up another 20 hp with a better cam.
Good estimation. I'm not sure if a Comp 07-305-08 is "better," but with forged rockers and some tuning, the result is just about exactly 20HP above that number (342HP/407.6 ft/lb).
  • Like
Reactions: 1
Aluminum heads have higher compression, are lightweight and have better ports when compared to iron heads.
Higher compression is a moot point when talking about worked on heads imo

Better ports in what way? Even after getting worked on?

The weight is the best part though for sure.
  • Like
Reactions: 1
Better? Are we talking stock AL heads? Better than these iron versions at 196cc intake runners? With larger valves that cannot fit into the hardened seat of an aluminum head? Raised port roofs steeper than the LT4?





Higher compression? These irons result in a static of 11.09 with 53cc chambers on a stock bore/stroke. As related above, it was good enough to net 342HP/407.6 ft/lb at the wheels. If the goal is higher, aftermarket is probably the better choice.
I think you're confusing the LT1 350 heads, that have 64cc chambers, with the baby 265 ci LT1 heads. The 350 LT1 with iron heads came with 10.0 compression. The aluminum heads on the vette came with 10.5 compression, as I recall. Even when I bumped the compression to 10.4 with my iron heads by decking, they had issues with detonation.

Yes, the iron heads flow better out of the box. But, the thermal properties of aluminum more than made up for that by allowing higher compression and more timing. If the factory could have made more power with the iron heads, you know they would have wound up on the vette, heavier or no.

And because of the casting properties of iron vs. aluminum, the aluminum heads have to be cast with thicker walls on the intake and exhaust ports - meaning the aluminum heads can ultimately be ported to flow more.

Having said that, there's a link to a hotrod article on the cam thread where they used iron vortec heads (identical to the iron LT1 heads) to make 447 hp at the crank on a 350 smallblock with a tiny 224/224 cam.
See less See more
i would do a 3 angle valve job and cam and call it good. I don’t know maybe a couple other minor upgrades. porting them can’t hurt even if you only gain only a few hp for 2-300 bucks.Aluminum sounds all well and good but the truth is it is inferior when it comes to reliability. Think about issues like plugs blowing out/welding themselves to the threads. dont Forget your block is still cast iron which expands at a different rate then aluminum so maybe you will end up with head gasket issues Or something else.
iron block/AL head V8's are not a problem for reliability. (head gasket issues).

The stock iron heads by themselves make decent HP but have limits the AL heads do not relative to press in vs screw in RR studs, lower lift limit on cam vs AL and narrow PR slot. Back in the day though a B body with a Crane 227 cam, 1:6/1:5 RR split (lift on EXH side with 1:6 is too much for stock iron head) with an aftermarket PCM tune, 3:73's and a 2400-2600 TC was the bomb back in the 90's
  • Like
Reactions: 2
1 - 20 of 27 Posts
Top