51 Buick cylinder head bolts

Hi, hope someone can help I live in the U.K. and I am having difficulty in locating cylinder head bolts for my 51 Buick Super.Does anyone out there know where I could buy some, I need them pretty quick as I need to get this engine back together before the end of March, have Weddings coming up fast.

Many thanks,

Nick

I would think that standard grade 5 bolts in the correct dimension would work.

with a torque spec of 65-70 ft lb.

here in the US they can be ordered online from Granger, Mcmaster Carr , etc.

Thanks for that I will check them out .

Hi, hope someone can help I live in the U.K. and I am having difficulty in locating cylinder head bolts for my 51 Buick Super.Does anyone out there know where I could buy some, I need them pretty quick as I need to get this engine back together before the end of March, have Weddings coming up fast.

Many thanks,

Nick

What is wrong with the old ones? Unlike newer cars, your Buick came with very strong bolts that last the life of the car.

If you need replacements you should get proper head bolts from ARP, Buick or some other supplier that has the right kind. Ordinary hardware bolts are not the same.

I really can't imagine that in 1951 there were better bolts than standard grade " hardware" type bolts.

and they lasted untill now.

I really can't imagine that in 1951 there were better bolts than standard grade " hardware" type bolts.

and they lasted untill now.

By 1951 Bolts, as used in cylinder heads, were of a known and selected alloy, forged to spec, and heat treated to a desired strength and toughness to perform a given task. Todays hardware grade bolts are of unknown alloy, of unknown origin, sized to "one size fits all" specs, and manufactured to meet minimum standards..........Ya'll be careful now....................Bob

You read this somewhere

source?

Just used these standard hardware grade 8 bolts(beside pop can)to hold this 550 hp hydraulic pump together , torqued to 450 lb ft.

Bought online from Mcmaster carr

I think they will do!!!

ya all keep it real !!!!

What is your definition of standard hardware grade bolts?

(OK, I see you edited post to specify grade 8. Those are high strength bolts.)

While some stores carry Grade 8 bolts most run of the mill hardware store "standard" bolts are grade 2 or 5. But, the point is OEM cylinder head bolts are designed and produced to specific specs to do a specific job. Often with subtle but important design elements. Will a grade 8 bolt work. Maybe. Or maybe not. Maybe a hunk of all thread and a nut would work. Maybe for awhile. Maybe forever. If I was stuck in the middle of nowhere and needed a quick fix to get home I would not hesitate to use any of the above.

But when rebuilding an engine I don't think it's wise to speculate or improvise if the real deal is available..................Bob

Cylinder head bolts are designed and made specifically for the purpose. Ordinary hardware bolts are not the same, even grade 8. They may work, then again they might not. I would use the old ones or buy new head bolts from ARP or a vintage parts specialist.

What is wrong with the old ones? Unlike newer cars, your Buick came with very strong bolts that last the life of the car.

If you need replacements you should get proper head bolts from ARP, Buick or some other supplier that has the right kind. Ordinary hardware bolts are not the same.

It looks like somone replaced three original bolts with something different at one time in the cars past and we are a bit concerened about cranking them up again since stripping down.I will try ARP. Thanks. Nick .

I have worked on everything from automobiles , new and old , wind tunnels for NASA and US navy ships.

I have a little more experience than most shade tree mechanics as to what will and won't work , and these bolts will hold the head on any automotive engine built in 1951 period.

Have you ever noticed that head bolts are reduced in diameter for part of their length? Do you know what material they are made of and why? Do you know how the threads are formed and why? Did you ever notice any of the details by which head bolts differ from regular bolts? They are different from regular hardware and they are made the way they are for a reason.

On modern cars yes , we replaced every head bolt with the correct part No. when I was a tech at the chevy/ buick / cadilac dealership back in the 80s and 90s.

on old cars it is just not an issue, low compression , heavy iron that dosen't flex as much when you torque it etc.

I have worked on everything from automobiles , new and old , wind tunnels for NASA and US navy ships.

I have a little more experience than most shade tree mechanics as to what will and won't work , and these bolts will hold the head on any automotive engine built in 1951 period.

And yet one still must wonder why GM felt it necessary to design and manufacture a specific use bolt rather than use a less expensive off the shelf bolt..............Bob

Bhigdog and Rusty are correct. Use the old ones or ARP's.

Never the chinese replacement grade 5 or 8 bolts made these days for something important!

I bet NickST has enough information to make his decision, so why not cease the arguments!

when I did the head on my 54 Chrysler I ordered new head bolts from the machine shop that milled the head. I assumed they got me the right stuff. that was 7 years ago, the car has been sold and the new owner drives it a lot more than I did. I still have the box they came in and the old bolts. I will look at the box next time I go out to the garage. previous to that job I always used the old bolts and never had issues. I would not use hardware store bolts, but they may be just as good. skyler

I bet NickST has enough information to make his decision, so why not cease the arguments!

Hardly an argument. Just some folks sharing opinions and information. A discussion that just might help someone else make an informed decision. Unlike your reply...................Bob

Some pretty interesting discussions re head bolt design. It seems head bolts are thinner in the mid section to allow for a certain amount of controlled stretch. This provides for a constant clamping force against the head gasket. A bolt with a full shank diameter would not stretch sufficiently at factory torque to provide constant clamping force without stripping the threads. For those interested do google search of Cylinder head bolt. It's pretty interesting...........Bob

Bolt Stretch and Loading

Though head bolts seem to be pretty rigid fasteners, they are actually designed to stretch. Stretching a bolt is like stretching a rubber band. It allows the fastener to exert force against a surface to hold the parts together. This is especially important with gasketed surfaces because the gaskets have a certain amount of give that must be overcome by the fasteners to maintain a tight seal.

When you tighten a head bolt, the force exerted by the wrench is accomplishing two things. First, it is overcoming the friction between the threads on the fastener and the hole threads in the block and the friction of the underside of the bolt head as it turns against the cylinder head. This accounts for about 90 percent of the force exerted on the wrench! Second, tightening the fastener stretches it to create clamping force. This accounts for the remaining 10 percent of the force exerted on the wrench

GM started using the cheap head bolts when they went to aluminum heads. Aluminum expands more than iron and the bolts have to stretch or they will crush the soft aluminum and when the engine cools down the bolts will be loose.

These cheap stretchy head bolts are only good for one use. After they have been torqued once and used they are too over stressed to use again, half of them will break when you torque them.

The old head bolts were completely different. They were the strongest bolts on the car and could be reused several times.

They may have been designed to stretch a certain amount but the other reason for making them thin in the middle was so they would not seize in the head.

When reusing original head bolts, resist the temptation to clean the threads with a wire wheel or to "chase" the bolt holes. I've always used carb cleaner and compressed air on both.

GM started using the cheap head bolts when they went to aluminum heads. Aluminum expands more than iron and the bolts have to stretch or they will crush the soft aluminum and when the engine cools down the bolts will be loose.

These cheap stretchy head bolts are only good for one use. After they have been torqued once and used they are too over stressed to use again, half of them will break when you torque them.

The old head bolts were completely different. They were the strongest bolts on the car and could be reused several times.

They may have been designed to stretch a certain amount but the other reason for making them thin in the middle was so they would not seize in the head.

I would disagree on the "cheap" headbolt comment. With the new design engines with aluminum heads, blocks and all of the different types of material in the engine there was a need to change the design of the head bolts so you did not have head gasket failure.

New head bolts are "torque to yield" design which is why the bold has a smaller diameter between the threads and the bolt head. The installation procedure is usually to tighten the bolt to a low torque value say 35lbs and then in two steps turn them an additional 90degrees rotation twice. (there may be differing procedures so this is a general statement) This process puts a constant tension on the head to block or "prevailing torque" value so the head to block stays sealed properly.

This torque to yield which means the bolt stretches some by design when installed is why they are a one time use part. It has good engineering basis for this design. I have not measured a used bolt vs/ a new bolt, but I would guess that in the area of the thinner part the used bolt is a smaller diameter in at least some area of the thinner part. This is where the bolt yielded meaning necked down to provide the optimum clamp force.

I am quite sure that the new style head bolts cost a lot more than any standard grade 8 bolt.

I didn't mean cheap in the sense of not costing much money especially if you buy them from the GM dealer. I meant cheap in the sense of inferior quality.

I didn't mean cheap in the sense of not costing much money especially if you buy them from the GM dealer. I meant cheap in the sense of inferior quality.

The new bolts are not of inferior quality. They are designed for a specific purpose as I noted earlier.