After removing the head on my 1930 coupe for a head gasket replacement I found the head was cracked thru the water jacket ports in line with the distributor hole. I went to a local model a parts supplier to buy a used head and 3 of the 4 he had were also cracked in the same place, this seems to be the weak spot in the head but I am wondering if the torque sequence in the Less Andrews book might also be the problem, It calls for starting in the center of the head and working out towards the ends. I'm thinking this might cause the ends to try to lift up causing the center to crack, When I retorque after running the engine I plan to torque the center bolt last not first. Any Thoughts? Thanks, Keith T.
Cracked head
- Thread starter akroflyer
- Start date
Tom Wesenberg
Well-known member
That's why it is so important to torque in at least 4 steps. I start by lightly snugging them, then go to 10 to 15 pounds torque, then 25, 35, 45 and then 55.
edmondclinton
BANNED
Those heads you looked at were overheated at one time or another OR milled several times and are thinner plus a possible overheat at one time or another.
Torquing from the center out is the correct way to do it. It's sort of like smoothing out a table cloth.
sethkestenbaum
Well-known member
Akroflyer,
I have a similar crack (which can be seen on my current blog post). I've heard lots of advice from "just replace it with a new one -- a more powerful one" to "ignore it" to "metal stitch it". I've opted for the latter with the hopes that my days of overheating have been eliminated. This all might explain why people kept telling me I needed "to get my head fixed".
I have a similar crack (which can be seen on my current blog post). I've heard lots of advice from "just replace it with a new one -- a more powerful one" to "ignore it" to "metal stitch it". I've opted for the latter with the hopes that my days of overheating have been eliminated. This all might explain why people kept telling me I needed "to get my head fixed".
hardtimes
Well-known member
Hey Keith,
Lots of speculation is made from your crack description. IMO, your right that torqueing down a used head will cause cracks....if the surfaces are NOT flat when tightened ! New and/or used head, make sure that the mating surfaces are FLAT, then torque with several graduated increased until you achieve the maximum that you want. Same attention to torque detail after repeated heating cycling after running.
Also, your plan to weld/stitch will work, then flatten surface.
BTW, after cleaning everything good to eat off of, also check flatness of top of block. Good luck
Lots of speculation is made from your crack description. IMO, your right that torqueing down a used head will cause cracks....if the surfaces are NOT flat when tightened ! New and/or used head, make sure that the mating surfaces are FLAT, then torque with several graduated increased until you achieve the maximum that you want. Same attention to torque detail after repeated heating cycling after running.
Also, your plan to weld/stitch will work, then flatten surface.
BTW, after cleaning everything good to eat off of, also check flatness of top of block. Good luck
edmondclinton
BANNED
Heads that have been overheated are frequently cracked there. That's the traditional place. It is also where the majority warp or become low when overheated.
Some people run them cracked there and get by with it but the area is weaker and is more prone to warpage than a head with no cracks.
edmondclinton
BANNED
Hey Keith,
Lots of speculation is made from your crack description. IMO, your right that torqueing down a used head will cause cracks....if the surfaces are NOT flat when tightened ! New and/or used head, make sure that the mating surfaces are FLAT, then torque with several graduated increased until you achieve the maximum that you want. Same attention to torque detail after repeated heating cycling after running.
Also, your plan to weld/stitch will work, then flatten surface.
BTW, after cleaning everything good to eat off of, also check flatness of top of block. Good luck
I have never seen one crack just because it was not flat. The gasket is thick and it gives. They leak or blow gaskets when they are not flat enough.
Kurt in NJ
Well-known member
My head has the crack that goes through the center water holes---and to the stud hole next to the dist, no problems from it --even with having it for over 40 years, same headgasket too--even though the head has been off 2 times ---yes, I reused the headgasket ---havn't touched it for over 25 years
Tom Wesenberg
Well-known member
If this is the stock head with cracks, now would be a good time to buy the high compression head.
J and M Machine
Senior Member
Typical problem for Model A engines is the head and block cracks.
These can be readily repaired and less expensive than purchasing a new head if you want to keep it stock.
Most all engines start bolt torque from the center and work their way out to the edges. Main thing to remember is to torque in steps and not all at once. You will also have to to do multiple retorques as that is the weakness of the copper head gasket. It has no resilience to keep a torque like modern style head gaskets of today, torque once and forget it.
As shown in the pictures common cracks we see in stock heads.
I would recommend you have the head cleaned and checked thoroughly as it may have other cracks as well.
www.jandm-machine.com
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Mike V. Florida
Well-known member
Ditto