On the recent Arizona speedster run, I blew a cylinder head gasket. We have had the engine for over twenty years and this is the third gasket failure.... So I have been looking at the parts more closely before just replacing the the gasket.
This is the failed gasket.
The block is a standard T block and I have been using a standard Model T gasket. They seem to match....
So I started by looking at a standard head and sure enough it matches the T block.
However I noticed that the standard T gasket does not match the aluminum Z head. The gasket failed where there a hole in the head and not in the block or standard gasket.
Notice the head has two large holes while the block has one large hole and one small round hole.
Next I looked at a Lizard head, it is different again...
I would think in a perfect world, the head should match the block. Then I would expect the gasket to match the block and head.
Should I modify the holes in the head to match the block?
Should I modify the block to match the head and then have a special gasket made?
Do nothing and plan on replacing the gasket every couple of years?
Any other, hopefully better suggestions?
Damn that last picture was the wrong one.
It should be this...
Have you checked the block and head to ensure both are level? I might consider modifying the port in the block after consulting a good machinest to determine the need for such modification.
Sell the Lizard head to someone who collects curiosities, they're not known as a successful head. The Z head has been very successful but is often fitting less than good with the gasket - it's just that it rarely gives problems as you've experienced.. Maybe your Z is worse than most?
I would have bought a Prus head instead - they fit the gasket and are machined in the combustion chambers above the pistons to be uniform - Z heads sometimes have too little clearance there. The Prus head has about the same compression as the Z, but gives about 2 hp more. (28 hp compared to 26)
Now the pictures loaded in my slow phone, Your alu head seems to be something else than a Z head - no squish area above the pistons. My recommendation stands.
Your gasket failure seems to be the result of problems with re-pro head castings... now if the re-pro guys can get the water passages in correct placement and physical size........ what's the difficulty ??
My "Z" head has never been a problem with gasket failures, must be the better gasket from the guys in Spokane, Washington.
Sorry that you had the problem. I've seen them blow between 1&2 or 3&4 before, but never between 2&3. First thing I would suspect has been spoken to in an earlier post. That would be the surface of the block and the head being perfectly flat. Second would be the gasket fit to the head. Does the squish area of the gasket at the edge of the cylilnder fit to the head? Only other thing I can think of would be whether the bolts bottom out in the holes before the head is completly tight. If all these are OK, maybe a little more torque on the bolts, but then you run the risk of pulling out threads or breaking off bolts.
Good luck, Tony
The last two times this occurred I had the head surfaced. As far as I can tell with a straight edge the block is flat.
The problem seems to be the lack of support on the head around the second hole.
I torque the head sequentially to 55#ft, which is the usual recommended value.
1. Please confirm that the engine that blew a head gasket 3 times in 20 years is the block you show in the photo.
2. Please confirm if it blew the head gasket with the same head or if it had the same head the first 2 times or second 2 times or a different head each time.
3. My initial thought is the head, block or both are not level. [That assumes you torqued the head bolts properly, ensured none of them bottom out before they torque to the correct figure, and that you checked them again after running the engine. (I do that again over the years but I've been told it isn't necessary).]
4. Looking at the photos I believe you can see where the block & head allowed the coolant to seep past the opening in the block and head. I.e. if the block and head were both level/straight you should have only seen an area similar in size and shape to the oval area in the head. But I believe you can see where the coolant appears to have gone past that on both sides. See below:
5. While not nearly as accurate as a machine shop -- if you take a good straight edge like a carpenter's square and lay it across the block, and also check the head, you should not be able to run a feeler gauge under it. If the square is not straight (that happens sometimes) you may notice that the same spot on the ruler is always where the feeler gauge will go under the straight edge. In that case -- use a different area or a better straight edge.
6. My Dad used that method for checking a manifold that had been resurfaced but that he thought was not done properly. The machine shop said they a very expensive straight edge/straight table surface and they had checked it and it was level. Dad asked if they would show him that straight edge on the manifold. When they did he already knew where to slip the .010 feeler gauge and it easily slid under their straight edge. They machined it again for free and it was much better that time. No, my Dad's square and feeler gauge would not be nearly as good as the machine shops equipment. But if it was bad enough for the .010 to go under -- it was bad enough for the Sears square and feeler gauge to notice it also.
7. If you do not have a long enough straight edge you could also try the following: If you have access to an ink pad and roller or something similar -- you could roll the ink onto block. Insert a couple of studs in the block to keep the head from moving around a lot as you lower the head onto the block. Then take it back off. Is the ink evenly transferred from the block to the head? I suspect you will find that it doesn't transfer in the area the head gasket blew out. You might be able to use Prussian Blue in a similar manner.
8. Good luck and we look forward to learning what you discover and how it will be corrected.
Hap l9l5 cut off
1. It is the same block since we built the car in 1994.
2. It is the same head since 1994, bought new.
3. It has always been torqued to 55 pounds. They do not bottom out, checked without gasket and washers.
4. The block is level. The head is no longer level. It has been milled twice and each time it was level before installation.
5. I used a straight edge and feeler gauges, currently the head is greater than 0.01"
I wonder if the aluminium has gone "soft" and is allowing the head to warp either side of the long gap, which should not be there....
Incidentally I used copper gaskets and copper sealant on each use.
That's not a Z head. At least not the one I'm familiar with.
That alum head you have shouldn't have that large center coolant hole, part of the gasket sealing issue.
Your head on the left. 'Z' head,(L) Ricardo,(C) and Ford iron(R) in photo to compare.
If a head is only .001" off it is perfect.
I have never had luck with a solid brass head gasket.
If I get one with no sealant I spray it twice with the copper stuff and torque to 45 lbs., re-torque after 20 minutes of running and again a couple of times after every hundred miles.
A gasket with beads of sealant already on it should go on just the way it comes out of the wrapper.
Aaron, the dip is about 0.010" not 0.001" as you seemed to think.
I guess it is not a Z head. Mine is the same as the 3001HCL in the Langs catalog and it has the same huge unsupported slot. The Z head is listed as 3001HCH in the same catalog has the single hole as shown in Dan's photos.
Any idea what to do(besides to throw it away) ?
Heliarc a piece of aluminum into it and resurface it.
Tom has the best idea to save the head.
Send it my way and I'll do it for ya
Just for the record, please confirm that all 3 times the head gasket blew it was the same area between #2 and #3 cylinders.
I suspect that is the case. And if so, Tom's recommendation would be great.
Hap l9l5 cut off
i had a model b engine that would not keep a head gasket for long either. both surfaces planed, used spray copper, etc. finally charley yapp (secrets of speed editor) told me to plug the small weep holes by tapping threads and then plug with allen head screws. never had a problem again
Hi Hal, all three failures have been at he same place between cylinders 2 and 3 by the large unsupported hole.
Gene, I am shaping a lump of aluminium to fill the slot and I may take you up on your offer.
It's a Reeder head, I've run 2 without any trouble.... Not saying it isn't a head problem, just mentioning I recognize it.
It looks a bit corroded around other passages, while having that spot worked on you may want to have it looked over elsewhere also.
What you have is a Reeder Head, made by Ralph Reeder. I run one of those with no trouble. I would just have yours redecked and torque it down to 50 ft-lbs, run it a bit, then retorque. Should be o.k.
Jerry, This is the third time in twenty years I have had this identical problem, the last two times I have had the head resurfaced and then torqued to 55 pounds. I think the aluminium is "soft" due to the lack of support around the hole. I am going to get it welded up....
OK so I am in the process of welding up the slot, but raises a question about the hole in the true Z head, see the picture from Dan Treace above. It shows a round hole on the water inlet side of the head, yet I don't remember seeing a gasket with such a hole, or even a block.
Why does the Z have the extra round hole?
If you look again you will see the same hole in the T head. I just went and looked at a T head gasket and it also has the hole. I just looked at the top of a block on line and thee is not hole. Good question about why the hole is the in the original setup.
Mark, if you look at a Model A or a Model B the same situation exists. I never could figure out why those holes were there. I have removed A heads and the gasket was bulged up in that area and the block is almost always pitted there.
That hole is probably there for removing the sand after casting.
Mark, my second picture shows one of my Ford heads and there is no large hole and in my fifth picture of a head gasket, again there is no large hole. I guess Ken's idea is the most likely. I wonder if we could drill the block to match the hole when using the Z head, of course that would need a custom gasket....
Don't drill the block. Weld the head.
This problem is possibly due to differences in expansion between the iron, the copper, and the aluminum. It is very possible that the aluminum raises above the block at that point when the engine is hot. If you weld the aluminum and just leave a small hole to match the hole in the block, you would have much more gasket surface contact at that point. From your pictures the gasket blows from the combustion chamber into the water jacket which would indicate the gasket is not being compressed enough at that point. The head is much easier to discard and replace than the block, so do your experiments on the head rather than the block.
I just rechecked the head gasket I had looked at, duhh, it's a Model A. I looked at 3 other gaskets, that are Model T. All three have markings to show that the hole is there in the block or head. The only loose head I can look at is a low head, no hole, same as the head you show (3ed photo). The high head (your head and the group of three side by side)does have the hole.
With a hole in that location in the bock, the water would take a shortcut and not get to the back of the water jacket as well.
The hole in the high heads may very well have been used as part of the casting as stated to help get the sand out.
After what Mark posted I began to think about things.
That hole is right above the water intake into the engine. The cooled water enters and goes right through that hole and up into the radiator. Therefore, the water in the two ends of the block is hotter than the water at the center. I think that the cause of the gasket problem is uneven temperatures causing uneven expansion when the engine is running. Therefore what Mark says and what I have concluded would reinforce my previous post that filling the hole in the head and drilling to the same size as the standard head, should fix your problem. Of course, it might take a few years to prove it, since it has only blown 3 times in the last 20 years!
Iwould like to show a headgasket I blew on the Montana 500. I ran in 11 500s and had no problems until the 12th. I cracked the head which in turn blew the head gasket. I ran in the 12 races with a head milled two hundred thousands and the block milled forty thousands. On the last race I was having a great time passing some of the other drivers but the T started running poorly and I finally pulled over and loaded it on the trailer.
You're going to love this. After what Tom and Jerry posted!!!!
Jerry posted that the head is a Reader head. I have had similar problems with the Reader head on my speedster, as have a couple of New Zealand friends.
Tom posted the solution. We welded blanking pieces into the head to make the water passages co-incide with the block and re-machined the head. Problem solved so far.
Hope this helps.
Allan from down under.
That's good news, Tony has made a support filler piece to fit in the hole and I'll weld it up for him after I pick it up on Mother's Day. Hope this solves his problem except we won't know for another few years.
I made a plug and Gene Carrothers was kind enough to weld it in position. Over the weekend I set up the mill and it is now level.
Now I have to check the bolts do not bottom out with the milled head.
Tony, that looks pretty good. Glad it worked out.
How much did you have to take off?
I used a fly cutter on the mill and I can take about 0.002" with each cut. I did 6 cuts, so I estimate about 0.012". I checked with a measurement before and after from the top of the head which confirmed the measurement.