I was torquing head bolts wrong for years until a buddy pointed out my mistake

I was putting a 2.4L back together in my home garage and my friend, who used to work at a Toyota dealer, asked why I was going in a circle. I'd always done a criss-cross pattern but started at the center, which he said can warp the block on some engines. How do you guys handle the sequence on inline fours, especially older ones with cast iron?

3 comments

3 Comments

coleman.avery2mo ago

Wait, doesn't starting at the center actually help avoid warping, @perry.joel?

lilychen22d ago

Oh yeah, that pancake thing got me good. I read somewhere that starting in the middle actually lets the metal stretch out evenly as you go, so less chance of it getting all wavy. But then @perry.joel is right about the manual having a specific pattern for those older engines. I tried the center-first trick on a small block Chevy and it did warp a little on me, so now I just follow whatever the book says. Guessing it depends on the block material and how thick the head is.

perry.joel2mo ago

Wait, you mean the "start in the middle and work your way out" method isn't just for eating a stack of pancakes? I did the same thing on an old Civic head, felt like a real genius until I found the factory manual diagram stuffed in the glovebox. For my old Datsun L20B, the book shows a real specific spiral pattern from the center, but you don't actually torque the center bolts first.