Model A cyl. head

[broommaker]

Went to visit a fellow yesterday, which had 3 cyl. heads for sale. I took my scraper with me and cleaned the heads for an inspection. All three had the same crack, located at the #1 stud to the water passage. Is this pretty common?

Jim

 

[Dave in MN]

Yes it is. They can typically be repaired by "sleeving" the hole. I use a cast iron valve guide ...first drilling and reaming the hole on my Bridgeport mill for an interference fit of about .001". I then coat the hole with Loctite and press the guide in place. The guide is then rough cut to protrude slightly at the top and bottom. The top is then milled flush...the bottom is flushed when the head is re-surfaced. The guide is then drilled to match the size of the other holes. If you need it, I could get you the guide number and the ream size. They don't leak.
Good Day!

 

[grantsauder]

Dave in MN
I have two heads with the same cracks at No.1 hole in each. I have to do at least one head for my 30 Tudor. I would appreciate the guide number and the reame size.
My son has a machine shop and will do the work for me. Thanks. Grant.

 

[Dave in MN]

Dave in MN
I have two heads with the same cracks at No.1 hole in each. I have to do at least one head for my 30 Tudor. I would appreciate the guide number and the reame size.
My son has a machine shop and will do the work for me. Thanks. Grant.

I'll get the numbers for you late today and post this evening or tomorrow. The guides, being cast iron, expand and contract at the same rate as the head so the fix is long lasting. Easy fix once you are set up. I try to repair a couple heads at the same time to take advantage of the set-up. Ask your son to drill and ream from the same set-up on the Bridgeport for accurate alignment. Think about doing the second head while you are at it.
Good Day!

 

[Mike V. Florida]

Please post the info here and not via a PM. This is good info for all of us to have, Thanks in advance

 

[broommaker]

Dave, in MN.
Sure do think you for the info. on the cyl. head crack at #1 stud. I would like the info. on the valve guide and drill size. What valve guide do you use?
Guess I should go back and get the heads, they were cheap....$25 ea.

Thanks again, Jim Norris

 

[broommaker]

I forgot to admit the reason I'm looking for a cyl. head. On our 28 Phaeton I removed the head and the head is cracked like the three I looked at yesterday. Sure glad to hear of the fix, from Dave in MN.

Thanks again, Jim

 

[Mike V. Florida]

I forgot to admit the reason I'm looking for a cyl. head. On our 28 Phaeton I removed the head and the head is cracked like the three I looked at yesterday. Sure glad to hear of the fix, from Dave in MN.

Thanks again, Jim

Might not be worth it to do one head but several I would think would be good to do.

 

[Dave in MN]

Model A cyl. head crack repair

Please post the info here and not via a PM. This is good info for all of us to have, Thanks in advance

The repair shown below solves the problem with coolant leaking around a head stud and nut from a cracked head. Repaired...they don't leak!

The repair involves installing a cast iron sleeve in the stud hole that has a crack that runs into the water jacket. The sleeve is made from a cast iron valve guide.

Here is the cast iron guide and tooling info to complete the cracked head repair.....

The cast iron guide I use is available from Engine Parts Warehouse and possibly other sources.
The guide is: SBI #1408591
Outside diameter: .5635"
Length: 4" (I would have chosen a shorter guide...but couldn't find one...)

The ream is sized to be .001" smaller than the outside diameter of the guide. I use one from Rock River Tool #246518
Size is 9/16" or .5625"

The drill bit used to prep the hole for the reamer is a 9/16" undersize that mic's at .560".

You can use any cast iron guide that has an outside diameter close to the size above. I chose this particular guide because it left a reasonable amount of the original cast iron in the head available to surround the guide and the required .5625 (9/16") reamer is readily available. Don't go to much larger or you may machine or break into the water jacket area. When choosing the components you will use, the important thing to keep in mind is that you should have about .001" interference fit. Note that the ream referenced above is .001" smaller than the guide. The guide I chose has a chamfered end to make it easier to install and to allow the Loctite to build between the guide and the head as it is pressed in place...a sharp edge would just wipe the Loctite from the surfaces. I use a Bridgeport but you could use a good drill press...clamp the head on parallel bars top side up, locate the center of the hole being repaired, drill the hole and then ream the hole from the same "set-up". Remove the head to prepare for pressing the guide in place. I lightly but completely coat the surface of the drilled hole and the guide with Blue Loctite Gel and press it in place leaving a bit of the guide protruding from each side of the head. After installing the guide, rough cut the excess on both sides with a cut off blade installed in an angle grinder. Carefully grind the gasket side flush knowing that the final surface will be cleaned up when the head is surfaced. (I always lightly surface the head after making these repairs but it would not be necessary if the head was straight and you don't mess it up when flushing the guide.) The top side is then milled flush with the original surface. At this point the installed guide is drilled the same size as the original stud holes. The size of drill escapes me at the moment... just match the size to the original holes. I have included a photo of the items needed for the repair, two photos of the installed guide and a micrometer showing the size of the undersize drill bit.
I often repair two locations in a head as the adjoining hole to the distributor often has a similar crack. The installed guide photos below show the repair prior to the head being surfaced.
Check back as I will revise this post with some set-up photos the next time I repair a head. I have one I will repair this coming weekend. Let me know if you have any questions.
Good Day!
www.durableperformance.net

 

[Steve Plucker]

Re: Model A cyl. head crack repair

The repair shown below solves the problem with coolant leaking around a head stud and nut from a cracked head. They don't leak!

Here is the info on the cracked head repair.....

The cast iron guide I use is available from Engine Parts Warehouse and possibly other sources.
The guide is: SBI #1408591
Outside diameter: .5635"
Length: 4" (I could have chosen a shorter guide...but couldn't find one...)

The ream is sized to be .001" smaller than the outside diameter of the guide. I use one from Rock River Tool #246518
Size is 9/16" or .5625"

The drill bit used to prep the hole for the ream is a 9/16" undersize that mic's at .560".

You can use any cast iron guide that has an outside diameter close to the size above. I chose this particular guide because it left a reasonable amount of the original cast iron in the head available to surround the guide. I did not want to break into the water jacket when drilling the initial hole. When choosing the components you will use, the important thing to keep in mind is that you should have about .001" interference fit. Note that the ream referenced above is .001" smaller than the guide. The guide I chose has a chamfered end to make it easier to install and to allow the Loctite to build between the guide and the head as it is pressed in place...a sharp edge would just wipe the Loctite from the surfaces. I use a Bridgeport but you could use a good drill press...clamp the head on parallel bars top side up, locate the center of the hole being repaired, drill the hole and then ream the hole from the same "set-up". Remove the head to prepare for pressing the guide in place. I lightly but completely coat the surface of the drilled hole and the guide with Blue Loctite Gel and press it in place leaving a bit of the guide protruding from each side of the head. After installing the guide, rough cut the excess on both sides with a cut off blade installed in an angle grinder. Carefully grind the gasket side flush knowing that the final surface will be cleaned up when the head is surfaced. (I always lightly surface the head after making these repairs.) The top side is then milled flush with the original surface. At this point the installed guide is drilled the same size as the original stud holes. The size of drill escapes me at the moment... just match them up. I have included a photo of the items needed for the repair, two photos of the installed guide and a micrometer showing the size of the undersize drill bit.
I often repair two locations in a head as the adjoining hole to the distributor often has a similar crack. The installed guide photos below show the repair prior to the head being surfaced.
Check back as I will revise this post with some set-up photos the next time I repair a head. I have one I will repair this coming weekend. Let me know if you have any questions.
Good Day!
www.durableperformance.nethttp://www.durableperformance.nethttp://www.durableperformance.net

Dave,

GREAT INFORMATION!...Would you consider sending the repair process for an article to either MARC (Model A News) or MAFCA (The Restorer) for publication in their magizine?

Thanks.

Pluck

 

[broommaker]

Re: Model A cyl. head crack repair

Dave, very good information, thanks so much for passing this on.

"THE OLE BROOMMAKER" Jim Norris