82 6.2 pre combustion chamber misfit

[thejim662]

Hi All,
Iam rebuilding an 82 6.2 NA engine and have discovered that the pre combustion chambers on numbers 1 and 3 cylinders appear to be installed differently to all the others, i.e. the flat edge of the aperture is nearest the exhaust side of the cylinder.
On the remaining six cylinders the curved edge of the aperture is nearest the exhaust.
Also the chambers on cyl's 1 and 3 have two small indentations on them all the others do not have.
What i need to know is, which is the correct part number for the pre combustion chamber fitted to this engine and does anybody know of a good parts supplier that will ship to the U.K.
Strangely whoever assembled this motor also managed to install number 8 piston with the ricardo cup nearest the intake side of the cylinder, so you now have some idea of the task I have ahead of me!
many thanks
thejim662

[Robyn]

Hmmm
Interesting

The 6.2's in those early ones had small precup ports.

I dont think you can install the cups backwards, IIRC they have a guide key to hold them where they belong.
There is a section here at TDP on all the different cups and such.
The engine will run just fine with any precup but they all need to be the same.
Someone swapped some parts around for sure.

Get the heads set up right with at least a matched set of cups.
better yet find a matched set of heads.
get all the pistons in right and all should be well

[john8662]

Welcome aboard!

The precups can't be installed backwards, but what I think you're saying is that the cup opening is slightly tilted one way or the other (either towards an intake or exhaust port.

This is normal, but can be fixed easily.

You can remove the precups from the heads by using a punch. Look inside the hole before and position your punch so you don't go into the opening of the cup and damage the lip while driving it out.

You'll have your punch tilted.

Remove the cups, mark them before so you know which one went where, sometimes they fit cetrain holes better (as far as protrusion out of the heck deck).

You don't want them stick out, or recessed in the head, they need to be flat, plus or minus .001"

Not sure on the p/n of these things. I only have the p/n for the Turbo precups for 6.5L.

You'll want them matched though.

Might try The Diesel Depot, they have a selection of good used precups out of heads.

J

[Slim shady]

Here is the link to the precup section on fuel economy. This should give you all the info you need to get started. Good luck, and welcome to the forum.

http://www.thedieselpage.com/features/65fueleconomy.htm

[thejim662]

Thanks for the advice, I am sure i will be asking a whole lot more questions soon .
Jim