Pictures inside the precup chamber

[cpdenton]

For years I understood how our indirect injection worked, but there is nothing like seeing it for yourself. I know there are a lot of guys on here that have never even taken the head off one of these engines.

I had a set of heads(no good cracked junk btw) that I am going to strip down all the parts and hang on to them. I decided to take some pictures during disassembly and post them up.

Combustion side of the head. Valves and pre-cup opening visible.

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Now the pre-cup is out. The glow plug is clearly visible sticking out into th combustion area and the injector nozzle can be seen all the way down in the bottom.

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Backside of the cup.

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And now, the combustion area its the glow plug and injector removed. You can see light through the injector hole.

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By the way. This engine has all the classic symptoms of over fueling. There are cracks between the valve in the heads, the throats of the pre-cups are cracked, and the Pistons have cracks on the tops of them. This is what happens when you max out you IP and roal coal like a fool. Anybody think it's cool now?

 

[cpdenton]

Here is some pretty good information on this.

It consists of a spherical chamber located in the cylinder head and separated from the engine cylinder by a tangential throat. About 50%[citation needed] of the air enters the swirl chamber during the compression stroke of the engine, producing a swirl. After combustion, the products return through the same throat to the main cylinder at much higher velocity. So more heat loss to walls of the passage takes place. This type of chamber finds application in engines in which fuel control and engine stability are more important than fuel economy. These are Ricardo chambers.[3][4]


Copy and paste this from Wikipedia.

https://en.m.wikipedia.org/wiki/Indirect_injection

 

[typ4]

If the cracks in the precups are less than 3/8 long save them.

 

[cpdenton]

If the cracks in the precups are less than 3/8 long save them.

They will be saved then. Most have small cracks right around the opening to the throat. Are they still usable, or fixable?

 

[cpdenton]

Got all of them out. After cleaning though, looks,like they are all cracked pretty good.

Still curious about the 3/8 inch thing. I guess, as long as they weren't cracked through to the outside edge, or past the fire ring, they would still be usable?

 

[typ4]

3/8 is the max spec. if one cracked across the fire ring, the gasket would leave.

 

[jhenegh]

How do you pop pre cups out?

 

[G. Mann]

How do you get pre cups out?

Just wanted to get on this thread.. and thanks for the great pics.

 

[Wvdirtroad]

Attempt to start the truck with ether and the glow plugs connected.

 

[icanfixall]

Ford has a special tool to remove precups but.. We all know not many is any have the tool so.. a long brass drift punch thru the injector hole and hammer it out. Just do the cup a favor and round off the punch so it does not harm the cup. The brass is softer but why risk damaging an expensive part. As for cracks. Look at it this way. The longer the crack the thicker the cracked material so they usually will not run bigger. If you look closely at the first pic you can see how much gasket material cover the top of the cup and how it covers the combustion cylinder circle.

 

[cpdenton]

The correct tool would have been much easier. I was able to slip a flathead screwdriver down the throat, and with some gentle persuasion,(no prying on the metal at the opening) mine lifted out little at a time. Made sure the pressure was deep in the metal of the throat.

 

[G. Mann]

So.. looks like a brass pin punch slightly smaller than the injector threads is the desired method.. slightly rounded so no marks... and gentle persuasion with a hammer from the injector side to "push" the cup out?

Is there any indexing to be observed on re-assembly? Any tips for putting them back in?

Thanks to all.. I've got a head gasket job waiting in the driveway... so.. Soon I'll be right there.

 

[cpdenton]

They will install only one way. If you look at the second picture, you can see a notch that indexes them the right way. There is a tab on the cup that has to line up or it will not seat in the head at all.

 

[G. Mann]

Thanks, I missed that detail..

Got it now...

 

[icanfixall]

Cups have a depth reading that MUST be observed or a head gasket will leak. The factory setting is the cup can be up or below the head deck by 2 1/2 thousands. Aerokroil is you friend when removing a cup.