Rebuild after shot peen?

standup303 · Jan 16, 2023

I just got some heads and a block that have been shot peened. Do I need to polish the ports of the head out before rebuilding using? Anything I would need to do to the block before building? Only going to use them for 6-12 months until I save and get some aluminum heads.

Demonracer · Jan 17, 2023

Make "SURE" that all of the peening media is flushed out of every tiny nook and cranny. It will do detrimental damage if it turns loose in the engine once assembled.

Garrett Ellison · Jan 17, 2023

That includes chasing all the holes with a tap, too.

toolmanmike · Jan 17, 2023

standup303 said:
I just got some heads and a block that have been shot peened. Do I need to polish the ports of the head out before rebuilding using? Anything I would need to do to the block before building? Only going to use them for 6-12 months until I save and get some aluminum heads.

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The seats should be touched up if they haven't been. I don't know if hand lapping would be good enough.

66fs · Jan 17, 2023

Might want to mill them just enough to get them flat again also.

Oldmanmopar · Jan 17, 2023

Have a skim cut on the surface to get a better finish. Make sure the shop doing them has the correct CBN cutters. Many shops don't. I hope the block surface doesn't look like that.

Shot peening does a number on machined surfaces. Double 0 beads polish as seen in the last photo. Put and aluminum block in a shot peen cabinet and see what happens, Iron block take more abuse but damage is still done.

One thing when a block is shot peened the main bearings and cam bearings should be left in so the surface is not affected unless you plan on line honed the cam and crank tunnels. I had a block done years ago before my son had his own shop . They took the bearings out and destroyed the surface. The block needed to be line honed in both cam and crank tunnels. Also the lifter bores should have rubber plugs put in. This is only for info you can use or ignore. Just what I have found from experience.

The only reason my son has his own shop is we were tired of machine shops destroying our race engines. Now he has more customers that he can handle. He learned what he knows from HTA machine after getting a job there who ended up doing our engines for our cars. HTA machine is one of the best shops in our area but getting out of race engine builds for walk ins without a past.

Its hard to find shops with manual Rottler bed mills. You cannot get them anymore they are all CNC. We bought the last two manual machines we found.