Would putting aluminum heads on a cast iron block cause a problem down the road. I was told that alum. heads expand and thats not good if its on a cast iron block.

 

There are tens of thousands of cars out there on the road right now with aluminum heads and iron blocks.

 

Most cars for the past few years have come with factory aluminum heads. Dozens of hotrodders have been running aluminum heads for years without ill effect. I run them on my car. Love em....19lbs each vs. 49lbs each for my stock 305TPI heads. That's saving 60lbs total

 

Only problem i have heard about was that the different metals will use the antifreeze as an electrolite and basically make your cooling system a large battery. I believe some cars measured around 2v or something. Just check or change the af every year or so and you shouldnt hav corrosion problems.

IIRC dexcool will solve this problem but im not 100% sure.

 

That's why you use deionized water in your cooling system, and you change it at appropriate intervals to prevent it from becoming acidic.

 

The only time i see cast iron heads now are on pretty old cars [my T\A for example] .
Most cars these days are alloy head, iron block.
The real benfit of cast iron is in the event of a head gasket failure, its extremely rare to ever skim the head, the minus point with iron is its weight [if that bothers you at all].
Every alloy head that comes to me for head gasket failure has to be skimmed at an engineering shop, and usually pressure tested for leaks etc. Even huge Jaguar XJ heads warp, so you can imagine Fiat, and all the other little toy cars twisting like hell.
I'm old fashioned, i grew up when iron heads were the norm, and only Ferraris and exotica had anything alloy on them.
Btw the headskim and test adds about $130 to every bill, and theres only a certain number of times it can be skimmed before detonation becomes a problem.
A bad design on Rover 4 cylinder engines led to catastrophic overheating and head\engine failures, they are all alloy btw.
Toyota as an example would never give skim measurements they reckon you should buy a new head.

 

Aluminum heads can deteriorate if the coolant is a bit bad .. I've got two aluminum heads in the garage, both for an inline four cylinder Fiat engine, and my stock one .. well ... if I would use it I would have to have the coolant passages welded up

Keep the coolant system nice and clean.. ... no problem

Iron will rust and turn orange chip break up .. aluminum can corrode too

 

aluminum heads will give you a problem down the road...back in the day you never replaced a head gasket...with an iron block and aluminum heads, a head gasket replacement will eventually need to be replaced...it wont be for many miles though. I believe its called "scrubbing", how aluminum heads shift on iron blocks because the metal expands at different rates. I dont know if aluminum heads are more prone to warpage, does anyone?

they are much lighter though, and pretty much any aftermarket performance heads will give you a hp increase

 

Aluminum heats up faster.. however it disipates heat faster as well

Regarding the headgasket etc ... in one of the Navy manuals there's a chaper describing how aluminum can corrode ... it does not like being connected to certain other materials.. and add salt water to it.. and bye bye goes aluminum


That's the material .. chemical.. etc


Now in reality ... engine wise .... iron heads will rust on the surface .. ya need paint ... something


Just go with aluminum ... as long as the engine is run right.. coolant system flushed and run correctly .. heck.. the advantages win over the disadvantages


Oh yeah supposedly iron heads would originally be better for low compression engines.. keeping the heat inside longer ... aluminum heads were originally for higher compression