Valve vs piston question D24, L 6, 230 engine

[OnlyMopar]

Almost  ashamed to ask this but .... On my 47 D 24, 230, L 6 motor, what am I seeing when I look down into the spark plug hole is it the top of the piston or the top of a valve? I ask this because, what I am seeing and measuring the travel of , only moves up and down about 1/2 inch. This is true with all cylinders. This car has set idle for almost 20 years. The engine is tight when rotating by hand but turns freely with the starter, no grinding,no knocking, compression low at 70 - 72 all cylinders, cranking oil pressure with multiple revolutions steady at 35 pounds. So back to the question, am I seeing the valves move up and down?  I have only worked on engines with the spark hole directly above the piston not off set. So I provide you all with a chance to  offer some peace of mind,other than the low compression, or get a good belly 😂 from my question,thanks.

[DonaldSmith]

The spark plug is over the valves.  Somebody will post pictures, I'm sure. 

[OnlyMopar]

Thanks, will sleep a little better tonight,LOL. I really thought that was the case but not sure. Will move forward with my efforts to see if I can get it yo fire up.

[Loren]

If you look over the top of #6 cylinder you will see a hex pipe plug. Chrysler used pretty much the same bore in the Dodge/Plymouth family of engines and the Chrysler/DeSoto family of engines so to determine what size engine you are looking at they bored a hole in the cylinder head so you could stick a wire down the hole ( to the top of the piston ) so measure the stroke. You can also use the hole to find Top Dead Center.

Most of the time the hole is full of carbon so you have to work to chip it out.

[clarkede]

1 hour ago, Loren said:

If you look over the top of #6 cylinder you will see a hex pipe plug. Chrysler used pretty much the same bore in the Dodge/Plymouth family of engines and the Chrysler/DeSoto family of engines so to determine what size engine you are looking at they bored a hole in the cylinder head so you could stick a wire down the hole ( to the top of the piston ) so measure the stroke. You can also use the hole to find Top Dead Center.

Most of the time the hole is full of carbon so you have to work to chip it out.

I'm really interested in knowing what size engine I have.  I originally had a 218, but that engine blew a rod and I had a hole the size of a grapefruit in the side of the block.  I replaced the engine with a 1952 Dodge Coronet engine (which I think is a 230).

 

So, I should be able to simply remove this plug and start my measurements (presuming it isn't all carbon-ed up)? Do you by chance know the stroke difference in the 218 and the 230? If not, I will look it up. 

 

I will also be looking for TDC soon because I've removed everything off of the engine and I'm in the process of re-assembling it.  Is there another simple trick to determining if the TDC is at the top of the compression or exhaust stroke?  I'm guessing you can simply feel the compression through the spark plug hole on #6, but there might be another way.

 

[DonaldSmith]

You can roughly find TDC for No.1 cylinder by placing the thumb over the spark plug hole while cranking the engine.  Plugs out, of course, ignition off.  

[OnlyMopar]

11 hours ago, Loren said:

If you look over the top of #6 cylinder you will see a hex pipe plug. Chrysler used pretty much the same bore in the Dodge/Plymouth family of engines and the Chrysler/DeSoto family of engines so to determine what size engine you are looking at they bored a hole in the cylinder head so you could stick a wire down the hole ( to the top of the piston ) so measure the stroke. You can also use the hole to find Top Dead Center.

Most of the time the hole is full of carbon so you have to work to chip it out.

Thanks, good info

[OnlyMopar]

13 hours ago, OnlyMopar said:

Thanks, will sleep a little better tonight,LOL. I really thought that was the case but not sure. Will move forward with my efforts to see if I can get it yo fire up.

Thanks

[OnlyMopar]

2 hours ago, DonaldSmith said:

You can roughly find TDC for No.1 cylinder by placing the thumb over the spark plug hole while cranking the engine.  Plugs out, of course, ignition off.  

Yeah, have used that method most of my life, also use compressed air thru # 1 cylinder to verify TDC from BDC by listening/ feeling air back thru the carb.

[Sniper]

They used to make a whistle that would screw into the plug hole to allow you to listen while hand cranking the engine over.

 

Well, well, seems Mr Gasket still makes one.

 

https://www.holley.com/products/tools/engine_building_tools/parts/8016MRG

[Los_Control]

10 minutes ago, Sniper said:

Well, well, seems Mr Gasket still makes one.

That's the shizzle there!!!! .... I want one    

[Los_Control]

I have laid awake many sleepless nights wondering why the engineers thought to put the timing plug over #6 instead of #1? 🤔

 

#1 and #6 are both at TDC at the same time, one is on exhaust and other is on compression.

I just use a small piece of toilette paper, just big enough to cover the spark plug hole ... when it starts to flutter or move while turning the engine over by hand ... you know 6 is coming up on TDC. Then remove the timing plug and insert a long wire and watch travel of wire to find TDC. ..... Now 6 is TDC on compression stroke.

One full engine revolution and then 1 will be TDC on compression ........Why not just put the plug on #1 cylinder instead of #6?

No where ever, does the manual say ... put #6 on TDC.

 

Just a tip, when I removed the timing plug on my engine ... the hole was plugged with carbon. I just took a nail and pushed it through .... bad idea.

When I started the engine, there was a hard piece of carbon bouncing around in the cylinder.

I suggest taking a drill and drill it out ... turn it into powder to get sucked out of exhaust.

[Ivan_B]

2 hours ago, Los_Control said:

That's the shizzle there!!!! .... I want one

I can totally see more than one use for such a device 😆

 

46 minutes ago, Los_Control said:

I suggest taking a drill and drill it out ... turn it into powder to get sucked out of exhaust.

Or, open up the exhaust valve and connect a vacuum cleaner to the spark-plug hole to pick it up while you push/drill. Or, just forget about the whole deal and set TDC using the crank pulley mark 🙃

[Harley PHD]

I heard somewhere you can adjust your idle mixture by removing that plug and adjust for a blue flame while it is idling.  I did it once a long time ago, it worked OK.

[Ivan_B]

Yes, and there a special tool available for that... I would probably not try doing that with a leaky cylinder.

[Los_Control]

19 minutes ago, Ivan_B said:

Or, open up the exhaust valve and connect a vacuum cleaner to the spark-plug hole to pick it up while you push/drill. Or, just forget about the whole deal and set TDC using the crank pulley mark 🙃

Well if a guy was intelligent enough to do that .... they probably would not put themselves in that position in the first place 

Worse part was, the wife just happened to be standing there when I started it up.

 

First you hear a tink tink tink  .... then it starts to run rough while it is stuck under the exhaust valve .... then it finally gets sucked through and runs fine again.

Whole thing last about 45 seconds.

 

vacuum works great for adjusting idle.

[OnlyMopar]

11 minutes ago, Ivan_B said:

Yes, and there a special tool available for that... I would probably not try doing that with a leaky cylinder.

Really

[Sniper]

34 minutes ago, OnlyMopar said:

Really

 It's called color tune and can be used for more than just idle mixture settings.

 

https://www.gunsonshop.com/contents/en-us/p209_G4074-G4171-G4172-Gunson-Colortune-See-Through-Spark-Plug-Kit.html

[Ivan_B]

1 hour ago, Los_Control said:

Worse part was, the wife just happened to be standing there when I started it up.

Hey, we've all done stupid things... I once, literally started the oil filter on fire, ain't proud of that either 😂

 

27 minutes ago, Sniper said:

It's called color tune and can be used for more than just idle mixture settings.

That's right. You can buy them on eBay, etc. Very useful on carbureted engines.

Edited Monday at 08:06 PM by Ivan_B

[soth122003]

2 hours ago, Los_Control said:

Why not just put the plug on #1 cylinder instead of #6?

Thermostat housing and water jackets in the head take up much of the area of the no. one piston area. It might cause a weak point to induce cracks in the head.

 

Joe Lee

[desoto1939]

4 hours ago, Los_Control said:

I have laid awake many sleepless nights wondering why the engineers thought to put the timing plug over #6 instead of #1? 🤔

 

#1 and #6 are both at TDC at the same time, one is on exhaust and other is on compression.

I just use a small piece of toilette paper, just big enough to cover the spark plug hole ... when it starts to flutter or move while turning the engine over by hand ... you know 6 is coming up on TDC. Then remove the timing plug and insert a long wire and watch travel of wire to find TDC. ..... Now 6 is TDC on compression stroke.

One full engine revolution and then 1 will be TDC on compression ........Why not just put the plug on #1 cylinder instead of #6?

No where ever, does the manual say ... put #6 on TDC.

 

Just a tip, when I removed the timing plug on my engine ... the hole was plugged with carbon. I just took a nail and pushed it through .... bad idea.

When I started the engine, there was a hard piece of carbon bouncing around in the cylinder.

I suggest taking a drill and drill it out ... turn it into powder to get sucked out of exhaust.

I think the Chrysler engineers might have been aware that by having the timing lamp used on number 6 was a pre-osha safety issue.  By having on #6 there would be less chance of being near the fan blade when the engine was running and getting you hand or arm cut off by the blade. Plus you are also closer to the distributor and can make the adjustment for advance or retard the timing and also have a direct eye o the timing light.

 

I use a 12volt sears timing light that has the plastic clamp that goes over the spark plug wire and I always time off on number 6. Less chance of any wires getting caught up in the fan blade when aiming the light at the timing mark on the vibration dampener on my 39 Desoto.  safety is always my first priority. I am still 6 v pos ground and get plenty of light to flash when the timing mark comes around.

 

his is just my 2 cents worth of input.

 

Rich hartung

desoto1939@aol.com

[keithb7]

You cant have the threaded timing inspection hole above cylinder 1 because the thermostat is in the way.  They picked the next best place, cylinder #6. As piston 1 and 6 are clocked in the exact same positions on the crank.  They just happen run at 360 degrees apart on valve timing. The piston block and crank can’t tell the difference between TDC of compression stroke or intake stroke.  Just the valve-train really knows whats going on. 
 

Maybe this video will help the originator of this thread see what he/she is looking at down in the spark plug hole. 
 

https://youtu.be/RQNszFmHJHQ?si=ZF7iZxWWUDiXBuma

 

 

[OnlyMopar]

19 hours ago, keithb7 said:

You cant have the threaded timing inspection hole above cylinder 1 because the thermostat is in the way.  They picked the next best place, cylinder #6. As piston 1 and 6 are clocked in the exact same positions on the crank.  They just happen run at 360 degrees apart on valve timing. The piston block and crank can’t tell the difference between TDC of compression stroke or intake stroke.  Just the valve-train really knows whats going on. 
 

Maybe this video will help the originator of this thread see what he/she is looking at down in the spark plug hole. 
 

https://youtu.be/RQNszFmHJHQ?si=ZF7iZxWWUDiXBuma

 

 

Thanks for info and link to.