Wanted R21 (j7r) head bolts needed urgently

[Andy Mayo]

Hi guys, I need to rebuild the R21 turbo engine in our HoverAid hovercraft and the head bolts we ordered turned out to be the wrong ones. Does anyone have a set we can buy and get hold of in the next 48 hours? We have a fundraising event on Saturday... Help!
Cheers
Andy Mayo

 

[andybond]

@DaveL485 ?

 

[Andyquadra]

Why not use the old ones, they aren't stretch bolts

 

[Andy Mayo]

Why not use the old ones, they aren't stretch bolts

That is a crucial piece of information that I had been looking for and couldn't find - thanks, that will solve the problem. Probably should have just asked that shouldn't I!!!! With it being an Ali head and block I wasn;t sure, and the 1.7 engine uses a torque-angle protocol so i though there was a chance the 2.0 would be stretch bolts

 

[DaveL485]

Yep as Andy said they are NOT stretch bolts and you can reuse them several times.

Makes sure you three-stage torque them starting with the middle-inlet side, to 36lbft, then the middle exhaust side, then spiral outwards, each to 36lb ft. Repeat at 57lb/ft then the third time around to 70lb/ft. Run the engine up to fan temp (about 90°c) then let it cool for at least three hours, then starting with the middle-inlet side bolt release it right off to finger tight then immediately retorque it to 70lbft. Repeat with the other 9 bolts in the same spiral pattern.

Make sure you brush a small smear of engine oil or lube on the bolt threads before refitting. Not loads, just a little.