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Discussion Starter #1
I have been putting my 69 ss396 back together after a new paint job,three months into putting all the glass,wires ,chrome,new interior,headliner,vynal top,new motor and tranny I started the motor to break in the cam when after 8 minutes is died and made lots of ugly noises. I pulled the pass side head and found one of the intake valves broken on top of the beat to death piston. after close inspection all the intake valves are hitting the pistons,so it's back at the machine shop.
I need a beer!!!
 

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VINTAGE MOTORHEAD
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Sorry to hear this. Do you think the pistons need larger pockets or was the cam out of time? What kind of deck cleaerance did you have ?Hopefully, you didn't injure the crank or rod bearings. I hope it works out okay for you.
 

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...and a bottle of Jack...for a chaser:let_it_all_out::beer:
Fixed yer comment:smileyb:


To the OP
Hope the shop will take care of you.
I bought a GMPP 454HO and it was outta warrantee before I even started it up.
Had to have it rebuilt at 2600 miles as some monkey at GM installed the rings upside down,
And the motor used oil faster than I could put it in.
 

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I really feel bad...lot's of work has to be re done.
Please share the problem,maybe you'll save others from a minor mistake.:secret:
 

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If the pistons aren't too beat up. the tops can maybe be cleaned up. Piston-to-valve clearance is usually recommended to be .125 " minimum, and can be checked with some play dough, stuck on the top of a piston with the head temporarily held on with a couple bolts. Yours is way too close to do it that way. Wrong pistons for the valve lift, is what it sounds like...reliefs aren't deep enough.
 

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ouch.man you need to always double check a big block.i always use a solid lifter to clearance check any big block.did it drop the valve or break it ? did you degree the cam.
 

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Discussion Starter #9
ouch.man you need to always double check a big block.i always use a solid lifter to clearance check any big block.did it drop the valve or break it ? did you degree the cam.
The motor was rebuilt by a machine shop,so i'm not sure what they did about checking clearance's but I think it broke off. good news is he is covering the repairs other than the r& r labor
 

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i would worry about his work. i have never seen a shop built big block die that way,the builder i use always uses all new top shelf head parts,stainless valves,heat treated keepers and behive springs,billet retainers.as much spring pressure as big blocks have you cant cheap out on valve train parts or miss anything on the set up
 
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