I've been reading the posts about washers under head bolts and realize I may have made a mistake in restoring the engine compartment on my 50 Mercury. It has the original flat head engine. I replaced several of the head bolts with original style bolts and put washers under them. These were SAE washers purchased at a local hardware store.

According to the posts here, these may be too soft. I repainted the engine so I'm reluctant to pull the bolts and replace them with hardened washers. Should I run the engine, re-torque the bolts and wait to see if a problem develops? Or do I need to replace them now? If so, how do I know the washer is hardened?

P.S. I'm postimg here because this site gets more responses than anywhere else I've posted. Thanks Guys!

Do You own a car built by Durant? 1925 Star

Hello Vince,
The bolts that you can buy at the hardware store are usually just grade 5 or less.
Head bolts are a minimum of grade 8 sometimes 10 or 10.8.
The washers are the same grade. Basically some of the torque will be transfered into the soft steel and not onto the head. Or the bolts stretch as you tighten them. All it means is that the head gasket might leak. If they are all torqued the same you head should be ok not to get distorted.
Franz

I guess I'd leave them for now. You don't explain whether you're using aluminum or cast iron heads. And it also depends on what torque you are going to. More torque isn't always better, because soft gaskets have a certain range before you crush them too much. You also should have surfaces under the nut or washer that are flat, smooth and square to the stud. If it's cockeyed, you get a false reading of tension in the stud.

The farm tractor engines use hard washers, as well as the Chevy 350's etc.

Normally, an engineer would preliminarily check the hardness with a portable or pocket-type hardness checker. Usually a Rockwell hardness test, which impresses a small point into the metal under a standard force. The size of the imprint is related to hardness. 60 Rockwell C-scale is about as hard as a case-hardened gear tooth. A mild steel might be on the order of 22-24 Rockwell C. Aluminum is so soft, you need another scale. These testers cost somewhere approaching $2000.00, but a certified lab machine would be much higher.

If you can make an imprint with a center punch, they are soft washers. If they are hard, the punch might dull. (but don't hit so hard.) You could take one of the washers of the type you used and get one of the hardened ones from an auto supply store, and check them side-by-side on your work bench. Hardened washers are somewhere between 35c and 75c each.

Do You own a car built by Durant? y

I agree with both Franz and Cdmn in all the above.

You can remove individual "Soft" washers [or even Bad studs] "one at a Time". Then Retorque each correctly with a Hard washer, before moving(randomly)on to the next stud with no trouble.

This is especially true on our LOW compression engines of this period. These Heads were meant to be taken on and off frequently to "Decoke" or remove the carbon build up in the cylinders, even reusing the same head-gasket (Not recommended now}. Use a new Head gasket if you remove the head totally.

Hope this helps you,
Lance C.

Do You own a car built by Durant? 25 Locomobile JR-8 Brougham, 25 Loco JR-8 Sedan, 26 Loco JR-8 Roadster project, 30 Durant 610 Deluxe Sedan