Aluminum or Iron Heads?

[quote="SnoPro"]This is my first post after trolling the forums for a few weeks. I am thinking about building up the 327 in a '66 Bel Air station wagon that has been siting in a barn for 20 plus years. I am debating on weather to use some iron vortec heads or aluminum heads of some sort. From what I understand aluminum disipates heat better so you can run higher compression and are also lighter witch might also help mpg. Or would the heat holding abilitys of iron heads but low comp. ratios do more to help mpg.[/quote]

Welcome! Thanks for joining in.

Theres more to it than just the material. It's a common question and in theory the iron heads should make more power and economy due to retaining heat in the chamber better. That is assuming ports, flow, volumes, chamber shape and all else is equal. Every test I've seen actually puts the aluminum heads slightly ahead...like 5-10 hp or less. BUT these heads, to the best of my knowledge, while close in flow, ports etc were not otherwise the exact same head. Of course if one was to increase the compression to take advantage of the aluminum power would have increased further.

I like the aluminum due to weight and MPGMike is set up to put grooves and lynz in them. We are generally building engines around whatever OEM heads were used. You are in a rather unique position with a small block chevy as factory and aftermarket iron and aluminum heads are available. Personally I'd run whatever gives the most bang for the buck. If you are going to spend $1000 for a set of alloy heads you'll never see enough improvement in mileage to pay for them. If running aluminum heads I'd also use thermal coatings to keep the heat in the chambers which should get it more on pare with the iron heads in that regard. Lastly, using grooves, and lynz, along with improved cooling , possibly a cam change and running vapor vs atomized fuel you should be able to run much higher compression with the iron heads and not have problems with detonation.

Probably not giving you the answer you're looking for but I just generally use whats available. One consideration you might consider is that that 327 really isn't a mileage engine. NOT to say it won't respond well to mileage/performance improvements but if you want a high mpg small block chevy you could probably sell off that 327 to a collector and build a 305 or something else cheaper. You'd then have hard valve seats...another consideration when running older engines/heads. If you're rebuild a 350 you might still look at running 305 heads to cheaply get the compression up with mild ports and valve sized suited to mileage and torque.

A fellow in MN was selling a product called the Power Plate back in the '80s that went between the carb & intake. I added one to my '70 Duster & went from (in already modified form) 29 mpg to 44 mpg and the power went through the roof! This was the early inspiration for my Powre Lynz.

The aluminum heads, so long as they have good combustion chamber design, will offer more versitility to you for immediate and future mods. It's a lot easier to carve into an aluminum head.

My personal opinion about which is better, the one with the best flow characteristics and combustion chamber design will win reguardless of what it's made of.

Mike

[quote="daves66nova"][quote="SnoPro"] The 327 should be a solid short block with 4 bolt mains and a steel crank [/quote]no such thing as a 4 bolt main 327![/quote]

Hey, good call. Not being a die hard chevy guy I didn't know that. Welcome aboard.

[quote="SnoPro"]Really? I'm sorry I just assumed they were I thought I read that some where. I am not really a Chevy guy more of a Mopar man and I have not tore the engine down yet. I does have a forged steel crank doesn't it?[/quote]

I did a quick search and one place says

327 Cubic Inch (1962-1967) Forged Steel 327 Cubic Inch (1968) Cast Iron