Spark Plug

B

BigE

Junior Member
Striped threads in spark plug hole in head can i fix it with out removing the head?? thanks Ed
 
I had one repaired and it cost me $60. Unless is a special head like a high compression one, it might be cheaper to just replace it, especially if it needs to be surfaced also. To fix mine they drilled it out bigger, tapped it for a piece of pipe, and then treaded the pipe for the spark plug. It came out very nice, can't even tell it has been repaired.
 
First run a tap in the threads and try a new spark plug. If that doesn't do it drill out and get the proper sized helicoil and install it. Helicoil will be just as strong as original.
 
Remove the head. The metal bits from tapping will score the cylinder wall. While the head is off, clean up things and check the valve for leakage.
 
I would try a thread chaser before a tap. Now that I typed that, I had the thought that chasers that are Model A sized are pretty rare, so a tap isn't too bad then.
 
with the exhaust valve open on that cylinder hook up vacuum cleaner on blower and connect to tailpipe and grease tap,this will minimize any debris getting into cylinder.
Unless you can find someone already having a thread repair kit in 7/8 x18 it might be cheaper to buy a head,the aftermarket helicoil kit seems to be a little over 200$,a timesert kit is closer to 500$ with what came up in a search.
If you have 14 mm there are a lot of choices much more reasonably priced .
I have done a lot of more modern cars with the head on and no problem with the chips doing it in assembled engines
 
BigE said:
Striped threads in spark plug hole in head can i fix it with out removing the head?? thanks Ed
Click to expand...

I'd be very apprehensive to do so. How would you get all of the scrap shavings from the combustion chamber?
 
Kurt,
These are very good suggestions, "With the exhaust valve open on that cylinder hook up vacuum cleaner on blower and connect to tailpipe and grease tap, this will minimize any debris getting into cylinder." Thanks for posting them.
 
Bob Bidonde said:
Kurt,
These are very good suggestions, "With the exhaust valve open on that cylinder hook up vacuum cleaner on blower and connect to tailpipe and grease tap, this will minimize any debris getting into cylinder." Thanks for posting them.
Click to expand...

This method will most certainly minimize the debris from entering the combustion chamber. It will NOT eliminate it though.
Just a couple of small shavings can do a ton of damage.
I would never consider doing this repair with the head in place.
 
The mere fact that you felt you had to ask this question tells me that in your heart of hearts, you already know the answer.
NO!
 
Pull the head.

Now you have many options that are safe.

Anything else would be Shade Tree Mechanic work.
 
Off question, I believe I still have a 'stock' head on my A. what advantages does the H.C. Head give me. would it be worth the time to replace what I already have that works.

TKS!
 
Canton,
Replaced the stock head on our '30 coupe this spring with a Burtz 6.5-1 head and picked up an honest 3 miles per gallon. No downside that I can see. Dale
 
Canton_Model_A's said:
Off question, I believe I still have a 'stock' head on my A. what advantages does the H.C. Head give me. would it be worth the time to replace what I already have that works.

TKS!
Click to expand...

You should start a new thread to get more answers.

Everyone I know that has changed to a 5.5 head (or more) was thrilled that they did. They can stay in High gear longer climbing a grade, and overall have more power.
 
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