There are a lot of people selling aluminum, "who" do not want you to buy cast iron.
Period.
If you ever blow a hose, have a cooling system air bubble or a thermostat stick, (on a long drive), the threshold and the curve of heat to metal fatige ratio of a cast iron head vs aluminum, is not even close.
You can warp a $1200-$3500 aluminum heads driving as little as 30 seconds after the water hits 260-280 degrees and your gasket blows with hydro lock. Especially if you are on it.
All that white steam coming out of your exhaust is your head getting ruined,
unless you stop and pull over immediately.
When you choose GM ***7.4L*** "Vortec Heads", they have a proprietary vortex cast into the intakes, which swirl the air flow for increased velocity.
30-40 hp is accurate, over Mark IV and V heads. This has been data logged on videos at dyno's by many quality builders.
If you are running a mild to towing camshaft, let's say under .500 lift in and out, the roller allows faster snap at the lifter and better efficiency, than let's say .520-.530, (in and out), using a flat tappet. Probably by a wide margin.
All this dope is saying is, rollerized torque cams, more towards the street able cams, with good vacuum, good performance and low end grunt for truck work loads,
would probably be better off using quality GM Cast iron, over ANY aluminum head, period.
GM Manufactures aluminum heads. They manufacture and sell millions of them every year.
If it was worth it, for the power band, they would have sold them.
*** The problem with the aluminum heads is: GM Marketing Team, requires the heads to last five years or more for the warantee, in order to brainwash the consumer to buy them...***
Something tells me the freak expensive aluminum heads from the video I posted below; are NOT rated for 5 years...?
Bet, after working and filming at Lake X, where the "Gentlemen and Ladies" from Murcury Marine, build and test race boat engines; the guy selling heads in the video for $5K (per head), you most likely get a "walk out the door warantee".
"You break it; You Own It!"
If you have $5000 for the best designed 8.1L VORTE-X head(s), check out the ones that freak out the lemon 8.1L.
Bring your Nitro-Methane or Alcohol...
Please, Check thses video's out, so the rest of my post makes sense:
https://www.raylarengineering.com/cylinder_head.html
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It's the intake that makes the heads work, though...
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If your opinion is based upon the 8.1L heads, then you have a point, however not for the 7.4L L29 heads, used on the Mark V or Mark VI... and especially when used on the Mark IV...
The 7.4L head is NOT the 8.1L Vortec head.
Here's a great thread from 2019, where bucket was already a fan of the 7.4L L29 heads.
https://www.gmsquarebody.com/threads/vortec-454-7-4l-vs-vortec-496-8-1l.26940/
Can tell you from my personal experience, the reason for NOT using the 8.1L format:
The threads on the crankshaft bolt are proprietary pitch. It strips out very easy.
Was asked to service an 8.1L. It had already been abused by whomever replaced the timing chain and whomever used a breaker bar to rotate the engine to start it, after it developed a flat spot on the ring gear; (years before worked on it).
Wanted to pull the engine out, for good reason, because all the oil lines were shot and the ring gear needed to be serviced, (but only AFTER the rear main seal was replaced), and
a new oil pump was installed with upgraded oil pump drive shaft, eliminating the plastic shaft connector crap.
Got over ridden. 220K on the engine... whay would you want to refurbish it, right?
Was humiliated because the other guy knew how to slide the transmission back and replace the ring gear, faster, cheaper better.
When everyone was made aware the crankshaft bolt was shot, from years of abuse, guess who they tried to blame?
The timing set was 120K on it, the oil lines were bleeding, the cir-clips and o-rings were shot every line on the engine.
Instead of reaming the threads and saving the crank, the next mechanic condemned the engine for complete replacement. It went back as a core, completely capable of being overhauled.
During the hundreds of hours of research I poured into the format, I found detailed threads, by quality machine shop owners, stating the 8.1L Vortec heads were not worth rebuilding. The rods were weak, the crank was weak and the heads needed for any power are the ones from above.
You might think my opinion of the 8.1L is not that good, but you are wrong.
The 8.1L, used, with a broken crank bolt, is the exact engine to rebuild with high horsepower parts for any offshore marine engine application.
8.1L can be made to sit with three others, with various rotational mods, using tunnel ram and blowers to drive your offshore boat to scary speeds.
Get this: If your building for offshore, (presuming you own a few helicopters and safety rescue diver's to chase you down when you flip), there are millions of them just waiting for the right wallet to make them great!
Getting the feeling what we have here is a mix up between formats, both using the Vortec name... cross mixed with referencing the 350... Sometimes, it really is rocket science, to figure it out.
Thing is, for many years, the most daring NASA rocket scientists came home in a boat.
*Edited the word "which" to "Who"... and a bunch of spelling errors...
If this saved you thousands of dollars on your big block Chevy Build, please respond with a Like.
