Low Head

Discuss all things Model T related.
Forum rules
If you need help logging in, or have question about how something works, use the Support forum located here Support Forum
Complete set of Forum Rules Forum Rules

Topic author
Vrayfoster
Posts: 55
Joined: Tue Apr 30, 2019 1:05 am
First Name: Victor
Last Name: Foster
Location: Santa Maria, CA
Board Member Since: 2002

Low Head

Post by Vrayfoster » Fri Oct 23, 2020 5:52 pm

I have a '15 car with a low head, Unfortunately it is cracked. Now I have 3 spare heads. One, a high head, one a low head with a spark plug hole that needs repairing. Now, here is the confusing part. The last head is good, magnafluxed with no cracks but needs surfacing. It is clearly dated 7-27, yet it is a low head and It has the Ford logo cast into it. I've looked at it multiple times comparing it to a high head and to the cracked head with a 15 cast date in it. It is in fact a low head. My question is, how can it be a low head with the 27 cast date in it? Did Ford make low head replacement parts way out to '27, or do I have an aftermarket head with a fake Ford logo cast on it? Anyone know what the heck I might actually have?


Allan
Posts: 1690
Joined: Sun Jan 06, 2019 7:21 pm
First Name: Allan
Last Name: Bennett
Location: Gawler, Australia

Re: Low Head

Post by Allan » Fri Oct 23, 2020 5:55 pm

The cast date you have may well be July 27 of any year.

Allan from down under.


Topic author
Vrayfoster
Posts: 55
Joined: Tue Apr 30, 2019 1:05 am
First Name: Victor
Last Name: Foster
Location: Santa Maria, CA
Board Member Since: 2002

Re: Low Head

Post by Vrayfoster » Fri Oct 23, 2020 6:16 pm

Now that's an interesting thought.


Wayne Sheldon
Posts: 1761
Joined: Sun Jan 06, 2019 3:13 pm
First Name: Wayne
Last Name: Sheldon
Location: Grass Valley Califunny, USA
Board Member Since: 2005

Re: Low Head

Post by Wayne Sheldon » Fri Oct 23, 2020 7:13 pm

Absolutely definitely positively confirmed by some of the top researchers in model T minutia that most model T heads made in the USA did NOT have the year as part of the casting date, if they had a casting date on them at all. Some Canadian heads had the year included in their casting dates, and a very few USA heads have been found with the year. Most of those had other oddities indicating that they were likely provided by one of the alternate suppliers.
So a 7-27 head would be a July 27 of some year appropriate for all the rest of the details. Likely anywhere from '13 to may be '16.


Les Schubert
Posts: 628
Joined: Thu Jan 10, 2019 5:47 pm
First Name: Les
Last Name: Schubert
Location: Calgary

Re: Low Head

Post by Les Schubert » Fri Oct 23, 2020 7:26 pm

Helicoil makes a repair kit for the spark plug thread (1/2” npt). I have done them over the years and they work great.


Topic author
Vrayfoster
Posts: 55
Joined: Tue Apr 30, 2019 1:05 am
First Name: Victor
Last Name: Foster
Location: Santa Maria, CA
Board Member Since: 2002

Re: Low Head

Post by Vrayfoster » Sat Oct 24, 2020 3:00 pm

Thanks for the responses. I erroneously assumed the cast date was month year and that confused the heck out of me. The helicoil idea is one I have thought of but the kit is several hundred bucks. However, I will keep that in mind now knowing I have a usable head that only needs surfacing. Lang's Model T Parts (Don Lang) gave me contact information for a guy in Mass. that repairs heads using stitching. He has a picture of the crack and will let me know if he thinks it can be fixed. Also said he could repair the spark plug hole using a bushing. So, if the cracked head can be repaired and the spark plug hole repaired I will have two spare low heads of which I only need to keep one.


Wayne Sheldon
Posts: 1761
Joined: Sun Jan 06, 2019 3:13 pm
First Name: Wayne
Last Name: Sheldon
Location: Grass Valley Califunny, USA
Board Member Since: 2005

Re: Low Head

Post by Wayne Sheldon » Sun Oct 25, 2020 3:46 am

There are exceptions of course. However, most spark plug holes I have seen that were damaged, whether by water/rust, or forcing in a wrong or damaged spark plug? Were reparable by simply running a correct tapered pipe thread tap in. Never go any farther than absolutely necessary to make the hole work with a good spark plug. If a plug threads in too far, it could lead to problems. It is amazing how little it sometimes takes to correct a bad area of thread. Of course, if the treaded area is completely gone due to rust? And I have seen one that was that bad. It may even be beyond a threaded bushing repair?


Kerry
Posts: 510
Joined: Mon Jan 07, 2019 2:42 pm
First Name: Frank
Last Name: van Ekeren
Location: Rosedale Vic Australia

Re: Low Head

Post by Kerry » Sun Oct 25, 2020 4:23 am

What I do is an easy fix, tap to 3/4" pipe, fit a brass plumber 1/2"-3/4" adaptor, knock 3 spots on the inside then mill off the nut of the top.
000_0671.JPG
000_0672.JPG


Topic author
Vrayfoster
Posts: 55
Joined: Tue Apr 30, 2019 1:05 am
First Name: Victor
Last Name: Foster
Location: Santa Maria, CA
Board Member Since: 2002

Re: Low Head

Post by Vrayfoster » Sun Oct 25, 2020 9:45 pm

That's a perfect fix for my head. One set of threads are gone. Another, the spark plug goes all the way in by fingers, so 2 are in need of repairing. I had thought of doing something similar, but wasn't convinced it would work. Obviously it's a good repair. Thank you for taking the time to post your results.

User avatar

Mark Gregush
Posts: 2582
Joined: Sat Jan 05, 2019 1:57 pm
First Name: Mark
Last Name: Gregush
Location: Portland Or
Board Member Since: 1999

Re: Low Head

Post by Mark Gregush » Sun Oct 25, 2020 10:13 pm

Frank, Brilliant!! :D
I know the voices aren't real but damn they have some good ideas! :shock:

1921 Huckster
1925 Cut down pickup

User avatar

Susanne
Posts: 551
Joined: Sat Apr 13, 2019 6:06 pm
First Name: Susanne
Last Name: Rohner
Location: Northeastern California
MTFCA Number: 464
MTFCA Life Member: YES
Board Member Since: 1999
Contact:

Re: Low Head

Post by Susanne » Mon Oct 26, 2020 12:33 pm

Some do, some don't. The original from my car has 12 7 15 on it, which matches both the serial on the motor (9978XX) and the casting date on the block. I have one on it now that has one with a 1913 date, I also have one that is just a month and date... I'm sure somewhere they made the change from one to another, probably mentioned in some ascension somewhere...

I remember reading in numerous sources that people would swap a later low head for an earlier one because it gave higher compression, but I wonder what the difference was... and how you can tell if you can't go by a casting date...


Topic author
Vrayfoster
Posts: 55
Joined: Tue Apr 30, 2019 1:05 am
First Name: Victor
Last Name: Foster
Location: Santa Maria, CA
Board Member Since: 2002

Re: Low Head

Post by Vrayfoster » Mon Oct 26, 2020 1:01 pm

An update on head repairs: I priced a 3/4" NPT tap at $20, so tapping and installing bushings using Franks repair method will be inexpensive. Once again, thank you Frank for your response. I also checked on having the cracked head stitch repaired by a gentleman in MASS. The crack is a stress crack per him and he said it would be about $80 plus shipping. I have one low head ready to go to the machine shop for surfacing. And I will have 2 good spares available.

To figure out head volume, plug the spark plug hole and fill the chamber with water from a graduated cylinder. That will give the volume of the head. That only needs to be done on one chamber as the rest will be close. Determine the volume of the next head and you will know which one is the higher compression.

Post Reply Previous topicNext topic