Head Gasket Failure & Replacement Saga

[alexiskai]

Originally Posted by Bob Bidonde

It would be a significant aide to our hobby if someone would take a scrap cylinder block, insert some studs, torque them to failure, measure the force when failure occurs and describe what failed.

I've seen Brent say in the past that over-torquing either results in sheared threads, if the threads are already corroded or marginal, or more likely it will distort the block, pulling that entire area of the block upward toward the head.

[johnneilson]

Bob,

I do some testing on the blocks before I do anything else, pressure test for cracks and then do a head stud thread test.
For the test, I use an ARP stud about 3" long and a wrist pin that the ID is close to the stud dia. Place the stud full depth into the block without forcing it, sometimes the threads need a cleaning. Place the WP over the stud and add washer and nut. Then I take the torque up to 75#. If the threads hold, all is good, usually if it is going to fail the stud just pulls out.
Once a block passes that test, it goes out for blanchard grind TOP and Bottom.

When the decks are being done, it usually shows the un supported sections pulled up away from the edges and the bores, and random movement around the valves.

It is interesting though and this is just an observation, that contributing factors into gasket failures come from the gasket compressibility, and the rigidity of the head.
I have noticed when someone runs two head gaskets the deck is deformed more than a single. In addition, we can run a solid copper gasket or no gasket and copper wires without failure. These in supercharged motors and NA high CR 13:1+
All of this using 55ft# torque. no more.

Best, John

[Ed in Maine]

I hate replacing head gaskets. It seems that I always get to do the job twice. The above comments are excellent and I will make note of them. There has been one comment about coolant seepage between the block and the graphite gasket that could prevent a good seal to be made if the coolant leaves a residue on the block surface. In the future I will use just water. Further, it may make sense to install the graphite gasket and torque the head to 55 ft-lbs and then let it sit for a week. Retorque as necessary to maintain 55 ft.-lbs but leave the engine dry for a period of time. If what you guys are saying, a waiting period before filling the coolant, should help the "bonding" process between the block and the gasket and the head. Ed

[Flathead]

I ran the engine briefly with NO water or coolant.

[Synchro909]

Originally Posted by alexiskai

the 509g seals well dry, if the mating surface is clean and flat. Aer did theirs that way for years.

aer???

[alexiskai]

Sponsored Links (Register now to hide all advertisements)

Originally Posted by Synchro909

aer???

Antique Engine Rebuilding (formerly of Illinois, now of Indiana).

[Y-Blockhead]

I have always followed Secrets of Speed Society recommendations and never have a issue.

[Bruce of MN]

One more vote for no antifreeze here. I followed the advice and the gasket is doing well with a 6:1 head,

https://www.fordbarn.com/forum/showt...te#post1145107

[cw253748]

I forgot where I read it but when I retorque my head gasket I always loosen the nut 1/8 of a turn and then torque to 55 lbs. That way you get a truer torque because it may take more than 55 lbs. of torque to over come the friction of the nut to head

[GPierce]

From the FORD GARAGE.COM

https://www.fordgarage.com/pages/bru...structions.htm


When re-torquing, it is usually not normal practice to back off nuts or bolts. However, on a Ford flathead, some of the cylinder head nuts can develop an increase or higher static friction as compared to the static friction of some of the other cylinder head nuts or a resistance to movement after they have been previously tightened or torqued. Or in other words, once tightened they sometimes tend to stick and the amount of torque required to get the nut to move is a little greater than the torque value that was intended to be applied.

When the torque is applied by the torque wrench in the standard way, the force must be great enough to break the nut free and move tighter. In the process, some of the torque is wasted overcoming the higher friction and the wrench may not apply the correct torque amount as set or viewed on the wrench. The result is the applied torque can be incorrect. And, if the increase in static friction is high enough, the nut may not break free at all at the torque amount set on the wrench.

In other words, the installer can be fooled into thinking that the nut is at the value set on the wrench whereas if the nut was not sticking it would turn tighter, as it should when the gasket has not completed its compression process. This possible sticking of the nuts can happen to a degree even with lubed threads after a little time goes by and a few hot/cold cycles. Talk about possible uneven clamp from nut to nut, leaky gaskets and premature gasket failure!! …. Anybody ought to be able to understand it.

If it could be guaranteed that the nuts would never stick, then backing them off would be unnecessary. However, to avoid the problem and to assure accurate re-torques and and even clamp from nut to nut, the nuts should be backed off, or cracked back slightly before being re-torqued and then retightened or re-torqued immediately.

Backing each nut off 1/8 turn does not loosen them in the true meaning of the word, loose. The procedure merely moves the nut only 45 degrees of rotation and just enough to overcome the stick that may or may not have occurred between the nut and stud threads and including the stud boss and nut face.

Since the torque readings are dependent upon the coefficients of friction present under the nut face and in the threads, there must be a smooth, uninterrupted rotation to have accuracy when the re-torque is applied. And last but not least, nuts have been observed that appeared to be tight at the final torque amount, when re-torqued and NOT backed off, only to turn as much as 2/3 to nearly a full turn farther when backed off and re-torqued at the same torque amount!

Apart from gasket surfaces being too far out of flat, insufficient final torque amounts, worn or low strength studs and nuts, etc.; many a leaking or seeping gasket and many a premature gasket failure on Model A’s are caused by the uneven clamp that is possible from nut to nut due to improper re-torques.

Larry Brumfield
July 2016

[katy]

Originally Posted by cw253748

I forgot where I read it but when I retorque my head gasket I always loosen the nut 1/8 of a turn and then torque to 55 lbs. That way you get a truer torque because it may take more than 55 lbs. of torque to over come the friction of the nut to head

True

[Cape Codder]

Mike Peters- Thanks for your post to this question. I do have a question about your statement below in part:
"but several club members have, and they tell me that the Snyder's head straight out of the box can be as much as .012" out of flat at the head gasket mating surface, and had to be taken to a machine shop to be resurfaced".

Do you know if any of the several members ever contacted Snyder's about the problem? I ask this because I feel that a head should be delivered FLAT or Snyder's should be responsible for the cost of the resurfacing!

Several years ago I had my motor rebuilt and at that time I decided to purchase a NEW Head from Snyder's. Upon receiving it I found that the head was 1/8" - 3/16" too short for the block, so I called Snyder's to inform them of the problem. I was told the best they could do was send me another head! Upon receiving the second head I found the same problem!

In the end I returned BOTH heads to Snyder's and was given a full refund including postage that I had paid to get them. I have always wondered if the problem had ever been resolved?

I understand the problems vendors are having BUT if no one tells them of problems they will just keep on buying the same product without any corrective action!

Lastly, I must say I still order parts from Snyder's because even with the disappointment in the above product they are a Great company!

Originally Posted by Mike Peters

Bob: Have you ever had your 6 to 1 Snyders head checked for flat? I personally have never had a Snyders head, but several club members have, and they tell me that the Snyders head straight out of the box can be as much as .012" out of flat at the head gasket mating surface, and had to be taken to a machine shop to be resurfaced. Installing the new head straight out of the box without checking has resulted in the same problems that you describe. Anyway, that's the word from the Rockford A's.

[alexiskai]

Originally Posted by Cape Codder

Several years ago I had my motor rebuilt and at that time I decided to purchase a NEW Head from Snyder's. Upon receiving it I found that the head was 1/8" - 3/16" too short for the block, so I called Snyder's to inform them of the problem. I was told the best they could do was send me another head! Upon receiving the second head I found the same problem!

In the end I returned BOTH heads to Snyder's and was given a full refund including postage that I had paid to get them. I have always wondered if the problem had ever been resolved?

This is a "known bug" with the Snyder's 5.5:1 and 6:1 heads. What I've been told is that the heads were designed by making a mold from a stock head and then altering the combustion chamber. When you make a mold from a cast iron object and then use that mold to duplicate the object, the copy will be very slightly smaller than the original because the iron shrinks as it cools. So all the Snyder's heads are very slightly shorter on the outside than the stock heads and the block. This is not a problem the new Burtz heads have, since they were designed by laser-scanning an original head into a computer.

[Fhane]

Makes me wonder who is doing the machine work on the Snyder heads. Most installers would not check the dimensions on a head The would assume the head is good. If I remember correctly, all of the new heads we installed in the last 8 years or so had to be resurfaced to make true. Some of the newer customer heads we replaced were out of whack.

[Steves46]

Since I recently blew a head gasket using a Snyder’s Head I am taking it have the flatness checked. I will say I was running it for 2 years before it blew so maybe mine will be good. Will share the results.

[Y-Blockhead]

Originally Posted by Y-Blockhead

I have always followed Secrets of Speed Society recommendations and never have a issue.

Altho I have never had a problem not using a sealant, it has been pointed out to me by Vince Falter (Ford Garage http://www.fordgarage.com) that BEST recommends using a sealant with their GraphTite gaskets so I will be following their recommendation from now on. Best to go with manufacturer.
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[alexiskai]

Originally Posted by Y-Blockhead

BEST recommends using a sealant with their GraphTite gaskets so I will be following their recommendation from now on.

I suspect the difference in recommendations is due to the fact that the rebuilders on this forum have control over the mating surfaces. They can ensure that the head and block are flat, with the proper finish, so no sealant is needed. Best’s recommendations need to account for the hobbyist with warped surfaces who just blew a head gasket and wants to get back on the road.

[BrianH]

Interesting info about backing off the head nuts before retorquing.

My Snyder head 6.1 had to have right at .006 taken off to get flat. I also had my block surfaced flat so hopefully I won't have a head gasket issue any time soon.

[Steves46]

Originally Posted by Steves46

Since I recently blew a head gasket using a Snyder’s Head I am taking it have the flatness checked. I will say I was running it for 2 years before it blew so maybe mine will be good. Will share the results.

The flatness was good so it's all clean an ready installation. However I had to order a replacement stud and darn it all it only makes one turn by hand and nothing more. Sure hate to try and force it in so one of my local Model A buddies has a bunch in his stash and will try one of those.