What is the best way to clean the intake and exhaust manifolds inside and out? I have some that have been sitting for 15 - 20 years - all kinds of criters have claimed them as their home.

 

I recently purchased a good size blasting cabinet, and have been using 80 grit glass bead for cleaning inside and out. Give the parts a rough cleaning with solvent prior to blasting to get the caked on oil and grease off. On the intake manifolds it takes a while. Aluminum oxide may work better as an abrasive for cast iron, but havent tried it yet. I cleaned one set of heads so far, and by putting the nozzle tip right into the water jacket openings it cleans the inside water passages pretty well, a lot better than just having them dipped at the machine shop.

 

I have used Red Devil lye to clean the carbon out of the exhaust cross-over passages. I would use the same thing for the insides of the exhaust manifolds. Bead blast the exterior of the manifolds. Avoid beading the mounting surface of the carb and intake manifold ports. The exhaust manifold might want to be milled flat.

 

The glass bead doesnt have any effect on cast iron mounting surfaces. It can have detrimental effects on aluminum parts.

 

I have found that a steel brush worked very well on the exterior - these guys look like brand new now.... except the inside of course.

PC, how did you use the lye? 46y - I wish I was still in your neck of the woods. I'd like to the see finished product.

Thanks guys!!

 

Brian, there is another thing I tried on a very rusty 2V intake just to see what happened. I more or less immersed it in straight sulfuric acid from the hardware store. The stuff is really dangerous, but it worked fairly well on loosening rust. Would have worked better had it sat longer. Basically there was little to no effect on the patches of paint still present. Rinsed it very well and wire brushed the remaining rust fairly easily. This is more for idle chat than a recommended method, but one that a machinist said he had tried once. He cautioned to do it outside, because if done inside it left an orange corrosion on tools and other metal parts.

And I would like to see the finished product too! Ordered one of John Mummert's new aluminum intakes today, so when it gets here, on to the top and in with the new engine.

 

just took mine down to the parts house and had them hot tanked.

 

The small area around Grants Pass has 4 machine shops that I know of. Only one of them has the traditional type acid dipping hot tank, and it may be illegal. An owner told me the city and/or county didnt allow them, so most have been forced to go with a type of solvent washing machine. The washers dont seem to do as well as hot tanks. Quite a bit of debris remains in the water jackets and even paint isnt removed sometimes. So after the washing machine, heads, manifolds, etc. are bead blasted, which runs costs up.

 

I would think if Oregon is tuff on hot tanks, California would be a major problem... but I will see what I can find.