Grade bolts for a head bolt...

[Dan Truax]

Brand new head for my 51 8N has been painted and drying with old spark plugs in it but I am missing one head bolt, what grade bolt should I use/buy?

Thanks, Dan.

 

[rustred]

look at the old ones and see what they are, I would use grade 8.

 

[Dan Truax]

I did, they are all flat after I buzz off the 3 layers of paint (red, blue then red), no markings...

 

[TheOldHokie]

(quoted from post at 06:35:26 04/11/19) I did, they are all flat after I buzz off the 3 layers of paint (red, blue then red), no markings...

The OEM bolts predate the SAE fastener grading system. Modern grade 5 or 8 will work just fine.

TOH

 

[4play]

Don't quote me on the head torque specs, but using studs/nuts would be around 55 foot pounds, the bolts around 70 foot pounds. If I was using bolts, it would be grade 8, 70 foot pounds is over torquing a grade 5 bolt.

 

[Farmer Dan]

(quoted from post at 17:55:41 04/10/19) Brand new head for my 51 8N has been painted and drying with old spark plugs in it but I am missing one head bolt, what grade bolt should I use/buy?

Thanks, Dan.

They don't cost that much, replace them all with brand new grade 8 and be happy.

 

[Farmer Dan]

old used bolts and new clean bolts will not torque the same. Replace them all to they torque equally.