Caterpillar1

Hey guys I have an 05 Chevy Silverado 1500 5.3 rebuilding the top end due to the infamous crack issue with these heads. I have a question . Before that here is what I have done . Hydraulic lifters with the full cage rods roller rockers pacesetter shorty headers all top end gaskets etc. I swapped the 706 out for 862 heads I have spark good compression fuel etc.. It is idling very rough like it's choking . Does the PCM need to be tuned due to the higher compression 862? Inside cylinders are firing or hot the out side are warm any help? New double platinum ac plugs too?

1FastBrick

iTrader: (16)

706 and 862 are similar castings. Unless they were milled the compression should be the same.

truckdoug

iTrader: (25)

the one 706 headed motor I got had ZERO cam bearings left…ran like curried cat turds. throw a dial indicator on some rockers and verify valve events? oil pressure? CASE learn?
just spitballin'


good luck mane

Caterpillar1

Compression is around 175 assuming valves are opening closing other wise I'd have a bend rod. CASE??
Do I need to have the PCM ECM tuned? Just weird ...

rpturbo

iTrader: (47)

You should not need to have it tuned for that.

Always2Slow

iTrader: (8)

Double check all connections that you don't have a vacuum leak. Make sure you installed all the ground straps you took off that from the old heads. Sometimes these are missed. Put a scanner on it and let us know what you find or post a log.