Heady question

[jimwheeldon]

Upon cleaning my head I discovered there's a small hole in the cylinder head of no#6 piston...Is this supposed to be there? Or is it damaged? I've seen holed pistons before but never a hole in the head-hopefully it's designed that way.

[Norm's Coupe]

Jim, I could be wrong, it's been several years since I've had my head off. (like it better on my shoulders:) ). I don't think that hole in the head is supposed to be there. I don't remember seeing any in my head when I had it off.

[greg g]

It supposed to be there only it should be plugged with a pipe plug. It is the access point directly over the piston. It can be used with a piece of stiff wire to definatively find TDC (#6, and #1 are on TDC at the same time albiet on different strokes) and can also be used again with a piece of stiff wire to measure the length of the piston's stroke. Handy if you don't know if yer dealing with a 218 or 230 and or whatever those measurments are on the long block. So find a suitable NPT threaded plug, and screw it in.

[Young Ed]

There is a plug just towards the middle from the 6th spark plug. If that plug is gone you would have a hole! Is your hole threaded? Kinda hard to see but look in between the last 2 head bolts in the middle row.

[Norm's Coupe]

Ed,

I don't remember that hole going all the way through. Do you?

By the way, what's that wire coming off the head where the heat control valve normally goes. Is that some sort of heat sensor in there? If so, does it control the heaters, or just the temperature gage? OR........is it just the way that wire looks in the picture?

[jimwheeldon]

I should explain better...the pinhole ( actually about 1/32'' diam.) hole is on the inside of the head at the top of the combustion chamber. There is a smalll bolt on top of the head that apears it would be right on top of it. Hopefully I'm describing it better. Thanks for taking the time!-Jim

[Normspeed]

It sounds like the same hole the guys mentioned. See the smaller brass plug near the #6 spark plug in this photo. If that's the location of yours, this hole should be there for checking piston stroke and TDC and should have a threaded plug or bolt in it.[/img]

[jimwheeldon]

Thanks everyone ...I thought maybe I had a real problem! Hopefully my manual will show up soon and I won't be bothering you good folk with so many stupid questions.

[Brendan D25]

Jim, there is no such thing as a stupid question, keep any and all questions coming. That's what makes this forum interesting. Good luck with your project. Brendan.

[Young Ed]

Norm I think thats the trouble light cord. Whatever it is its just an illusion that its connected to the motor. I just have a plug in that spot where the heater valve should be. The heater for my truck is still on the shelf

[Guest rockabillybassman]

I guess if you were building a performance engine, you would want to weld up that hole to keep the combustion chamber cc's equal. A dot of white paint on the crank pulley is all that's needed to find TDC.

[Merle Coggins]

The hole is probably filled with carbon from the underside giving the appearance of a pin hole. It may be a good idea to remove the plug from the top side and clean out the hole. Then reinstall the plug with some pipe thread sealer.

Mine was plugged up too. I didn't even realize it was there until I read about it here a while ago. I then pulled out the plug and ran a drill bit down through the carbon (by hand) until it was open again.

Merle

[Don Coatney]

Here are a couple of pictures of the hole from both sides.

[48mirage]

I had the same question when I got my D30. Here is the tool that fits in that hole. http://www430.pair.com/p15d24/mopar_forum/showthread.php?p=7167#poststop

[james curl]

When I had the machine work done on my engine the shop owner told me after the fact that my head had a flaw in it and they fixed it. I asked him if it was in number 6 cylinder and he said yes, I told him to turn the head over and look at the plug in number six cylinder. I told him what the hole was used for and he said he would not charge me for the fix. The shop was highly recommended because they were Chrysler experts, just not flat head six cylinder experts. Knows all about MOPAR muscle cars.

[Normspeed]

LOL James, nice that they didn't charge you for that fix. I did the same thing, went to a shop that builds lots of old hemis, flathead fords and other vintage motors. Turned out they didn't know a lot about flathead sixes. Turned out ok but should have been better for the $$ it cost.