Small washers under iron head bolts

[Edward M.]

Has anybody ever used small flat washers under the head bolts on iron heads? I am thinking about small diameter, thin flat washersthat fit under the head bolts and are virtually undetectible.

I am concerned about the possibility of damaging the outer head bolt bosses on a pair of 56 2 x 4 heads as the bolts are torqued.

Thoughts?

[Kenny C.]

Re: Small washers under iron head bolts

I would recommend that you do NOT put washers where the factory did not intend them to be. Putting a washer under a head bolt can cause an inaccurate torque reading and wind up allowing the head bolt to loosen up with the expansion and contraction that occurs when the engine heats and cools. I would suggest that you use new head bolts when assembling the motor, head bolts stretch and loose there tensile strength after just one torquing and over time. Although you may not be able to find exact original bolts you can get structurally superior ones and frankly in certain critical locations I would want better rather than correct.
Best Regards
Kenny

[Gene M.]

Re: Small washers under iron head bolts

Ed,
If GM just used the bolts and no washers that is good enough for me. They have built millions of engines.

I also feel reuse of the original bolts on an engine that is having it's first or second rebuild is just fine. The bolts were good for the last 40 years plus and will out live us. Need to replace them (unless rust has gotten to them) is a bunch of hog wash.

You should stay within GM's torque spec.

[Edward J.]

Re: Small washers under iron head bolts

Ed, just to add to Gene's comment on the head bolts, small block head bolts also had a small shoulder on them so they would not chew up the head castings.

also being a GM dealer Mech. we did reuse head bolts. today LS series engines are torque to yield and when you remove the heads you throw the head bolts away and use new ones.

[Ken A.]

Re: Small washers under iron head bolts

The use of hardened head bolt washers has been in use for over 40 years. They prevent galling and produce a more accurate torque reading. Most important, in your case, they prevent cracking of the head on the short bolts. In fact, the "General" has a part # for head bolt washers - 3899696, but I don't know whether it's still good.

[Edward J.]

Re: Small washers under iron head bolts

Ken A.,

Ken could that part no. have been for alum. head engines. cast iron head engines never left the factory with washers that I re-call. The head design on the smaller lower bolts had recesses I believe that maynot allow for a washer and the upper bolts cornors bolts were very tight quarters (oil drain back area).

Im not trying to create confussion on this post stating only my experience.

[William C.]

Re: Small washers under iron head bolts

Engine shops have access to the hardened washers, very usefull if a set of (usually rare) heads have seen much service. They have been used for many years, with as noted the benefit of more consistant torque readings that a scarred head surface, and should result in only a very minor judging deduct if detected.

[Edward M.]

Re: Small washers under iron head bolts

The use of hardened head bolt washers has been in use for over 40 years. They prevent galling and produce a more accurate torque reading. Most important, in your case, they prevent cracking of the head on the short bolts. In fact, the "General" has a part # for head bolt washers - 3899696, but I don't know whether it's still good.

Part number vshows up on GM Parts Direct, package of 10 for $1.00 The description that accompanies the listing is:

Washer 0.45"I.D.x0.86"O.D. Sold individually(Big-block)

[Edward M.]

Re: Small washers under iron head bolts

Just to make sure we are all clear on the use of this washer, I am thinking about a small flat washer under the cylinder head bolts (particularly the ouside edge head bolts).

The purpose is to prevent the head bolt from applying any "twisting friction" to the cast iron head directly. The washer would (hopefully) allow the head bolt to "silde" as it is being torqued.

I have seen a number of early V-8 cylinder heads with cracked or broken outside edge cylinder head bolt bosses.

Just looking for ways to avoid damaging a set of valuable / expensive cylinder heads.

On a related note, what is wrong with re-using a set of original 56 cylinder head bolts that were only torqued once (I assume because the engine had never been apart until I disassembled it)?

[Edward J.]

Re: Small washers under iron head bolts

Ed,

Im not aware of the problems related to the 56 cylinder heads cracking at the cornors,unless this was a design flaw in the early cylinders heads , if so this maybe a exception to the rule for the washers, cylinder head torque on small block chevys was not that much, just seems that maybe a over torque of the heads may cause a problem.

Maybe Mr. Clupper has a comment.

[Joe L.]

Re: Small washers under iron head bolts

Just to make sure we are all clear on the use of this washer, I am thinking about a small flat washer under the cylinder head bolts (particularly the ouside edge head bolts).

The purpose is to prevent the head bolt from applying any "twisting friction" to the cast iron head directly. The washer would (hopefully) allow the head bolt to "silde" as it is being torqued.

I have seen a number of early V-8 cylinder heads with cracked or broken outside edge cylinder head bolt bosses.

Just looking for ways to avoid damaging a set of valuable / expensive cylinder heads.

On a related note, what is wrong with re-using a set of original 56 cylinder head bolts that were only torqued once (I assume because the engine had never been apart until I disassembled it)?

Ed-----

There is nothing wrong with using a set of "first-run" 1956 head bolts as long as there is no damage to the threads (e.g. corrosion-related). "First-run" means they were previously installed at the factory and no one has messed with them since. It's even ok to use head bolts that have been previously re-used. The only problem here is that you don't know if some previous "klutz" ever over-torqued them. With "first-run" bolts, you know they were never over-torqued.

As far as the washers go, I would NEVER assemble a small block without using them. Personally, I think this was a flaw in the GM design. They much later corrected it by going to FLANGED HEAD bolts. If you buy a head bolt today from GM for any small block application back to 1955 it will be a flanged head bolt. These eliminate the need for washers. Of course, the bolt head configuration is markedly different than original bolts and this may pose a problem for restorations.

If washers are used under the head bolts, they MUST be of the hardened and ground type. It would SEEM like as long as they were as hard as the substrate cast iron (which is not very hard), it should be OK, but it's NOT.

I would use washers GM #14011040 (0.778" OD) or GM #10051155 (0.750" OD). The latter is designed for aluminum heads but will work fine with cast iron heads. Using either of these is better than using the big block washers since these are smaller in OD and, thus, less noticeable.

There is one downside to using the washers. That is the fact that these washers are about 3/32" thick and, consequently, head bolt thread engagement is reduced by that much. It's not a real problem, though. Use them!

[Edward M.]

Re: Small washers under iron head bolts

Thanks Joe, I appreciate the info.

I am still trying to recall what someone told me about some small, thin, stainless steel washers that were almost undetectible when installed under the cylinder head bolts. The sole purpose of these washers was to keep the rotating friction off of the head bolt bosses.

I can't recall who told me this, or where the info is now.

NCRS disease sucks.

[Edward J.]

Re: Small washers under iron head bolts

Ed, I would think that a stainless washer maynot hold the torque, with the constant heating and cooling of the bolt, may cause movement, like said in aprev. post the washers would be hardened and may even have a slight cup to hold the torque.

Most of the head bolts you cannot even see, I don.t remember if the exhaust manifolds go under or over the spark plugs . either way may be hard to detect.

[Timothy B.]

Re: Small washers under iron head bolts

Edward McComas,

Could you be thinking about the washers under the aluminum intake manifold bolts. I don't know where to get them but they have been mentioned here before.

[Dan D.]

Re: Small washers under iron head bolts

I broke a head bolt boss a long time ago on a 870 head. It was, of course, one of the lower short bolts. The problem was I borrowed a torque wrench from a friend and it was grossly out of calibration. Expensive lesson. The only time I have seen a boss break is when it was over torqued, so make sure your torque wrench is accurate. I question the accuracy of the cheap off-shore wrenches sold at discount and big box stores.
With respect to using a thick washer and decreasing the amount of thread engagement, you only need 3 complete threads to capture full strength. More than 3 doesn't do anything as the bolts stretch. The first 3 threads provide all the engagement strength. -Dan-