2gm20 rebuild

[PaulMcK]

i'm rebuilding a 2gm20 after giving up on a 1gm10 that needs a new head. manual is telling me to torque the three head studs into the block(57.ft/lb)
i torqued them the slightest bit just to test. wound them out again to find them harder to take out than to screw in, like it was crushing threads on the block.
apart from the manual i can't find anywhere online that tell you to torque them in.
is my manual wrong or should i trust it?
also it says to lightly lub nuts when torquing head on but doesnt say wether to lub studs
i,ve limited experience so any help appreciated
thanks

 

[earlybird]

I'd put lubricant on all threads. Workshop manual torque figures are normally quoted for that condition.
Stud threads are often tighter on the block end so that it's the nut that unscrews, but shouldn't be too hard to screw in. I assume that you are using the original studs.

 

[jwfrary]

First question to ask is when or has your torque wrench been calibrated. Sometimes they jam!

Some oil on the studs, but careful not to fill the tapped hole in the block, as you can cause a hydraulic action and crack the block.

The threads need to be clean, I usually get a long bolt of the same thread and use an angle grinder to create what is essentially a very blunt fluted tap. You can use this to free the corrosion in the existing threads then blow out with compressed air.

Insert your studs, torque down with double nuts then torque the head down in the sequence in the manual. Don't forget to put the gasket on the right way up! It's not a bad idea to pre lube the bores a little if you have been fully disassembled.

Hope that helps. Good luck