Hey,

This may sound dumb but...

I was looking the another day to get a new set of AC Delco Rpaid Fire Plugs for my 87 Iroc (5.7L). The problem is that the cross reference book gave two numbers for the plugs...one for aluminum heads and the other for cast iron heads. How do I know what kind I have??



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1987 Camaro Iroc Z
T-Tops
Maui Medium Blue
5.7 L TPI
TH-700R-4 Tranny
Dynomax Super Turbo
Removed Cat

Check out my ride in the Readers Rides

https://www.thirdgen.org/rides/index...ew&rideid=6920

Better to look at it than to look for it "

 

You have cast iron. To check it just put a magnet on the head.

 

Ok...I will have to do that the next time I get check my car out (its stored and the place is not readily accessible)..

So as another question... which heads are better? Aluminum or Cast Iron?

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1987 Camaro Iroc Z
T-Tops
Maui Medium Blue
5.7 L TPI
TH-700R-4 Tranny
Dynomax Super Turbo
Removed Cat

Check out my ride in the Readers Rides

https://www.thirdgen.org/rides/index...ew&rideid=6920

Better to look at it than to look for it "

 

For long life in a street engine, cast iron. Aluminum heads disipate heat better and can run at higher compression ratios. They are lighter than cast iron. The downside of aluminum heads on a street car is that the aluminum corrodes from poor coolent mixtures and with the constant cooling and heating of the engine they will eventually warp. Aluminum heads are available on a few engines from the factory but are mainly produced for the performance enthuesiest. I doubt you would find aluminum heads on a street car that has 200,000 miles on it.

 

I'm sure that there are plenty of 200k mile aluminum headed cars out there; probably even plenty of LT1s. LOTS of 4 cylinder engines run aluminum heads and are just fine.

 

Duh...Mercedes have been using them for decades..

 

Yeah, I had a buddy with both a 450SL and 380SEL. Both needed a valve job after in little over 100,000 miles (or it would blow blue, and was down on power). I can say one thing, rebuilding a set of Mercedes V8 heads is a very expensive proposition.

It has been my experience on the various vehicles and engines that I've owned that had aluminum heads, tended to need rebuilds much sooner than iron heads. The good aluminum heads were always "rebuildable". But I can see how a poorer designed aluminum head might not be due to warpage.

What I've always hated about aluminum heads is "cross-threading", especially the spark plugs. I've had few of those too in my life time.