I gotta hole in the head.

[Mr. Belvedere]

I removed the cylinder head on a spare flattie I am working on and found a small blind hole in the head over combustion chamber #6. It is about 1/8th inch in diameter and roughly 3/4 of an inch or so deep. It appears to be there by design but for what purpose? Any Ideas???

[aero3113]

Does it have a hex cap on the top side? If it does it is so you can remove the cap and insert a rod to determine if you are at top dead center.

[TodFitch]

I removed the cylinder head on a spare flattie I am working on and found a small blind hole in the head over combustion chamber #6. It is about 1/8th inch in diameter and roughly 3/4 of an inch or so deep. It appears to be there by design but for what purpose? Any Ideas???

It should have a pipe plug in it when it is not being used to measure the piston position for checking the cam/valve timing. Not sure why you say it is a blind hole unless the plug has been filed flat to the head and is not visible through the accumulation of dirt.

[Don Coatney]

Plug is normal for reasons already discussed.

[Mr. Belvedere]

No it is not a blind hole I thought it was but went out and checked and sure enough it has a plug. Mystery solved. Thanks, knew I could get an answer quick here.

[james curl]

The shop that milled my head fixed the casting flaw in the #6 combustion chamber for me. I informed him what the casting flaw was used for and he said he would not charge me for the fix. He was supposed to know all about old MoPars, guess he forgot some things.

[Normspeed]

The head on my motor had the same fix by a previous owner. welded up the hole real nice.

[49plymouthdotcom]

Page 97 of the 46-50 shop manual shows the special tool involved. It says it's called the "timing hole".

After reading this I went to the shop where my engine is being rebuilt. My head was sitting on the milling machine. I said, "Hey! Don't mess with my timing hole!" They knew what I was talking about.