I pulled the heads off my truck, which is a 6.2L diesel that has been modified a little and about to get modded a whole lot more.
I noticed there was a good bit of scale build up in side the heads when I was enlarging the coolant passage at the rear of each head to match the head gasket.
What is a good cheap easy way to remove the scale build up?
Over all the heads are in great shape for being 26 years old with 240,000 miles, they are nice and flat with less than .0015'' of warp, the factory hardened valve seats are still good and the valve guides aren't worn so I don't want to take them to the machine shop.
I was considering buying some Hydrochloric acid from the hard ware store and diluteing it to less than 18% if needed (I think hard ware store acid is 12%) and blocking the openings in the heads turning them up side down and filling the water jacket with the acid. And yes I do have the head to toe saftey gear for some thing like this.
Does any one have a better way?

 

sounds like a good idea i was going to suggest"lime-a
-way",but that is probably just acid too

 

Yes, "Lime away" is what originally gave me the idea.
The thing that makes "Lime away" work so good is HCl.

 

HCL is good stuff.
it will get rid of scale, but as you probably already know, it will get rid of your skin just as easy.
ive gotten burns from 10% HCL mixes, and the straight stuff is just plain scary.
one other thing, when you mix it, add the appropriate water to an empty container, THEN add the acid.
the reason is that the acid is thicker than water and if you add water to acid it can splash HCL all over the place

 

Acid into Water, very important.
A into W.
Remember A&W like root beer.
I saw this got a good number of views, just some thing to remember.
If this were mythbusters they would say don't try this at home.