New head bolts query??

mgbv8 · Post by **mgbv8** » Wed Sep 17, 2008 7:20 pm

I've built another 3500 engine. I'm not fitting ARP to this one as its a gentle road car only. The new head bolts look like the old style stretch bolts, but are more matt black. I'm only fitting 10 bolts and have been told to fit them 15ft/lbs, then 90 degree's, and another 90 degree's.
I did the 15ft/lbs, and then did the first 90 degree's. But getting to the first 90 degree's felt pretty tight. I've run the torque wrench over them after an hours settle time after the first 90 degree's. And they click the wrench at 68 ft/lbs. At 72 ft/lbs they will just try to move. I would only normally fit at 70 ft/lbs so I'm poop scared of trying the next 90 degree's as I reckon something will go wrong.
Or am I just being a wimp as they will stretch on the next 90 degree's??

I've tried to contact the engine builder (who I trust completely) but he's away for a while.

Not that it should make any difference, but I have had the heads skimmed and the block decked and am using comp gaskets.

Any suggestions chappies??

I'm all for leaving them at 70ft/lbs and perhaps nipping them down after its been up to full temp and gone cold again just to see if they will take anymore.

Perry

ChrisJC · Post by **ChrisJC** » Wed Sep 17, 2008 7:45 pm

'Old style stretch bolts' ? The old style bolts (the ones with washers) are not stretch bolts, and should be torqued up, whereas the new stretch bolts (without washers) should be angle tightened.

Chris.

mgbv8 · Post by **mgbv8** » Wed Sep 17, 2008 7:50 pm

Chris
The new bolts dont have loose washers. The washer section is sort of moulded into the bottom of the bolt head as one piece.

RoverP6B · Post by **RoverP6B** » Wed Sep 17, 2008 8:27 pm

Hello Perry,

If your new head bolts have the washer section moulded as part of the head, then they are "stretch" bolts, and as Chris indicated must be angle tightened.

Ron.

mgbv8 · Post by **mgbv8** » Wed Sep 17, 2008 8:39 pm

Time to bite the bullet eh chaps??

I'll go back to the garage and try the second 90 degree's then...

ChrisJC · Post by **ChrisJC** » Wed Sep 17, 2008 9:01 pm

I never like those stretch bolts. They seem to turn without getting any tighter, at about 90lbft in my experience.

Chris.

ian.stewart · Post by **ian.stewart** » Wed Sep 17, 2008 9:02 pm

Perry, why have you changed the bolts, I have a pile of the things under my toolbox.

andyv8van · Post by **andyv8van** » Fri Sep 26, 2008 7:02 pm

Hi Perry,

just got a set of ARP head bolts for my engine,What torque setting do you do them up too?

Andy

mgbv8 · Post by **mgbv8** » Mon Sep 29, 2008 10:55 pm

I've fitted ARP studs to my 4.6 Andy. From memory they only go to 68-70 ft/lbs with ARP lube.

I've done the second 90 degree's on the 3.5 I'm building and all seems fine.

andyv8van · Post by **andyv8van** » Mon Sep 29, 2008 10:58 pm

Hi Perry,

thanks for the info.

i remember doing my bolts on this engine and it seemed hard work getting the 90 degree turns on the bolts,when i had the engine layed out on the bench.

Andy