48 KB-5; GRD 233 Head Bolts

I cleaned up one of the head bolts from my 213 engine and if you look at the head stamp, it is clearly a grade 8 marking. If it were my engine, I would buy some new 7/16"-14 X 3.0" grade 8 bolts and go with that. It is not my engine, so do as you prefer, of course. Below is the head stamp.

Thanks Jim, I down loaded that to save it. I have a Motors manual from the 41 to 51 for trucks and tractors, but additional info is always appreciated.
Bill

email sent

After much deliberation, going through the available stock for head bolts at my most likely sources and coming up with only a partial set, and considering putting good used back in, I decided to go with the following. (many thanks to Oldihc members for giving me the opportunity to obtain used stock head bolts from your personal part bins- truly appreciated.) My solution is only a little over $50, is likely overkill, but I will never have to deal with the head bolts again. They are socket head cap screws so won’t look stock, but given that new head bolts aren’t available, decided to go for quality. I did consider replacing with studs, but I understand there might be a difference in the way they are torqued vs bolts. Plus converting to studs cost a bit more. These bolts are often used in high temperature injection molds that go to higher temps and pressures that this old engine will ever see, so are overkill. I personally like the black oxide finish rather than a silver or yellow bright finish.

McMaster-Carr- http://www.mcmaster.com

Product No: 91274A416;
Coated Alloy Steel Socket Head Cap Screw, 7/16"-14 Thread, 3" Length,
“Ultra Corrosion Resistant Coated Alloy Steel”.
Description: states they will withstand 1,000 hours of salt spray per ASTM B117. They have a class 3 thread fit (the tightest tolerance grade) so should hold. Normal bolts have a class 2 fit, that why they "slop around" a bit. They claim: "they are the ”standard among high-strength fasteners, these screws are stronger than Grade 8 steel screws. They have a minimum tensile strength of 170,000 psi (pretty dang good) and a minimum Rockwell hardness of C37 (not too hard, not too soft -- just right!)”.

Product No: 98029A032;
Black-Oxide Steel Thick Flat Washer, 7/16" Screw Size, 1" OD, .11"-.14" Thick,
Description: Black-oxide case-hardened steel washers are made from C1008, C1010, or 12L14 steel and have a minimum surface hardness of Rockwell C40. If a lot harder than C40, they will crack. The low carbon steel (C1008, or C1010) will be tougher and resist corrosion more than the higher carbon steel washers. The 12L14 is a low carbon sulfur carburized steel with some lead in it for machinability, so if they are this steel, should be fine as well.

I would always use new head bolts. cheap insurance in the long run.

Those socket head cap screws will work just fine. On a GRD, the head bolt holes are not blind, they thread right through into the water jacket. You'll need to apply some sealant to the bolts to keep coolant from weeping up past the threads.

Yes put sealer on the threads. My personal choice is Permatex Aviation sealer #2, it is a non-hardening sealer, have used it for over 30 years, works good.
Bill

Never did post the results. Head bolts worked out fine. I think the cap screws I used shouldn't cause an issue (my "guess") with being too strong to stretch, as would be with a modern much higher compression engine. I'm no expert though. Engine runs smooth as silk. Couldn't drive it though due to overheating. A re-core of the radiator fixed that. It just purrs, and motors down the road.

Jim , retorque the head bolts after they have been run.
Bill