Block work

[John M.]

Duke and all. I visited an automotive machine shop today and talked with this very interesting old guy about the work that may need to be done. It's a 67 327-300.
He sounded very knowledgeable and understood that I didn't want the engine stampings disturbed. But, he tumbles the block in the machine with the steel shot. He had a block in there and it looked great except the texture of the pad was completely changed. This must have happened to others, how to prevent this?
Cleaning, but skip the steel shot??
Thanks
John McRae 30025

[H S.]

Re: Block work

John,
I made a protective piece out of 1 1/4 x 1 1/4 angle iron x 3 1/2" long. Drilled one 13/32 hole in one leg which picked up the upper water pump bolt just below the pad for mounting. I have had two blocks blasted with it and worked well. You will have to remove the radius on the inside of the angle to get a good tight fit.

H P Shuttleworth 25130

[John M.]

Re: Block work

Thank you very much HP
John

[Chuck S.]

Re: Block work

Does he still have a "hot tank"?...That's what most machine shops use. Tumbling an engine block with steel shot does not sound like a good idea.

[Clem Z.]

hot tanks are a "NO NO" because of disposing

of the caustic that was used in them causes a enviromental problems.thank your federal govt. for making everything more difficult

[Steven C.]

Re: Block work

I've heard of tumbling blocks/heads, it relieves any residual stresses in the castings before machine work; sorta like the the reason many people prefer "seasoned" blocks for rebuilding instead of new engines.

I really like HP's suggestion of the protective plate.

Steve

[Duke W.]

Re: Block work

I think some shops now have water based ultrasonic cleaning tanks that are even more effective than the old caustic "hot tanks". I don't like the idea of "tumbling" the block, and I question how such a process can clean out the internal cooling and oil passages, which is just important, if not more, so than cleaning the exterior and crankcase.

Tumbling is popular for small parts, like water pump castings, but it completely changes the surface patina of the part.

Check around to see if you can find a shop with an ultrasonic tank.

Duke

[Rob A.]

Re: Block work

John,

With regard to shops using the term "hot tanking"...when I had my block "hot tanked" it turned out that they still use the term, but don't use the caustic solution(California). You have to ask them exactly what solution they plan to use. When I got my block back, the paint was still on it and I had to remove it myself...not what I had planned. If you plan on re-using the cam bearings actually hot tanking with caustic solution will dissolve them.

[Chuck S.]

Dang...Didn't Know That...

My last "hot tank" experience was almost 15 years ago...It cleaned EVERYTHING off to virgin cast iron.

[Chuck S.]

Are Platers Also Affected?...

I've been away from the plating businees awhile too...A HOT CAUSTIC bath is either the first or second tank for most plating processes.

[Terry F.]

Re: Block work

I would not tumble the block. You can find places that use ovens, etc but don't tumble it. It has gone through plenty of heat cycles. I would assume a lot of stress has been gotten rid of. It is hard to justify it especially since it will totally change the deck surface, even if you protect the VIN. I really don't think there is enough benefit. MHO Terry

[Bill W.]

Re: Block work

the service dept at the chev dealer I work at uses a water hot tank. I had my block dipped at redi strip. looked brand new inside & out.Bill

[Jack H.]

The old pro here...

has a klin and he slowly elevates the temp up (close to the melting point of cast iron) and allows used classic castings to heat soak overnight. Then, he lets the kiln naturally cool for a day.

The process BURNS contaminants + strain relieves residual stress. Plus, due to the difference in thermal expansion co-efficient between iron and rust, surface scale in the water jacket passageways spalls itself free. It's blown out as dust with compressed air shots after the block/heads have cooled to room temp.

[Mike McKown]

Re: Block work

I've had several blocks/heads done at Redi-Strip. It's a franchised outfit. They used a caustic solution at that time. Later, the business dropped the franchise and they now use and acid solution. It got this block clean but the machined surfaces had slight etching. Not enough to hurt functionality but cosmetically, it had changed.

That oven idea sounds great.

[Chuck S.]

Re: Block work

So, Mike, you're saying the tank ate your broach marks??