328 engine rebuilt

can anyone tell me what "de-glazing" (of the cynlinder liners) means in the context of an engine rebuilt?

 

Running a cylinder hone in the bore to put a crosshatch in there. This helps the rings seat.

The idea here is to NOT remove alot of metal, just "scuff it up"

 

thx but pardon the ignorance, is a cylinder hone some kind of a specilaised tool? my mechanic told me that he would just do it by running very fine sand paper around the liners. sound right?

 

This would be a typical cylinder hone

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=11786&group_ID=1589&store=snapon-store&dir=catalog

or this one

http://buy1.snapon.com/catalog/item.asp?P65=&tool=all&item_ID=11804&group_ID=1592&store=snapon-store&dir=catalog

Using sand paper on you hand is a low tech and slower way to do it. A proper hone does a better job

 

The liners of a 328 are Nikasil coated and should be de-glazed with a lubricated ball hone by a qualified technician, IE (someone who knows what they are doing).

Ask your mechanic if he has ever heard of Nikasil.
If not, well good luck!

 

The deglaze is required to help seat the rings, but also the "scratches" left by the honing hold oil to lubricate the rings and the pistons. Without the scratches the rings would wipe the oil off.

Mark

 

Wasn't there a conversion option available, a while back, to change that?

I remember seeing a 288GTO mill getting a conversion either from or to nikasil.

 

thx for the input. would a manual approach using sandpaper achieve more or less the same result though? despite the nikasil coating? the mechanic seems to think so and does not think it's such a big deal. i've known the guy for a long time and do trust him so if his judgment was misguided it would be an honest mistake. he is an experienced Porche mechanic and has rebuilt many p-car engines before but never a F-car engine. any guidance from you experts would be gratefully received

 

Really?

In your first thread about this engine the experts came to the conclusion that your engine seemed fine, and that the bottom end with a minimal 40k miles on it did not require a rebuild.
It was also suggested that a simple leak down test would reveal any problems with the engine, and that all you really needed were likely valve guide seals.
It was also suggested that you get a second opinion on the condition of your engine from a mechanic that has experience working on a Ferrari, since your mechanic had no experience with Ferraris, just Porsche.
Now it appears that your mechanic has talked you into a complete rebuild of your 328 engine and you are questioning his work.

Go figure.

 

I think you need to find a good F-mechanic
The Nic coating is VERY thin and the base metal under it is really soft. if you scratch thru it you are screwed.

 

why not call TRutlands and just do a swap out for a rebuilt motor

 

i know i know Dave it may sound dubious but it's not what it seems. he didn't really "push" me into doing it and had agreed that it probably didn't "need' it yet. it's actually me that had really wanted to take the opportunity to do a complete job and restore the car to its best possible condition since we're doing the "top-end" and having an engine-out service for the first time in the last 7 years anyway. i did ask him to measure the gap bewteen ring and liner as well as chk the rings. findings: gaps are beyond factory specified acceptable wear and some of the rings are cracked. he was also honest about not having rebuild an f-car engine before but i figure cars are cars and there have not realy been quantum leaps in the technology and design of the internal combustion engine itself in the last 100years, and also another factor is that here in Hong Kong where i live there aren't the same level of appreciation for older cars and people (especially f-car owners) seldom rebuild their engines (i did ask around) so i figure better go with someone i'm comfortable with (he's done all my cars in the last 5 years or so) and i supervise/help out with specific knowledge about this car from experts like you.

So back to my question on de-glazing procedure in my penultimate thead. any insights?

 

you can't do it with sandpaper and your hand, you will push harder in one place and less hard in one other and mess up the bore.

You can't do it with sandpaper, you can't control your hand to the required precision and will end up with a football shaped cylinder (well not really but it will no longer be round)

You can't do it with sandpaper, you will push harder near the top then you will at the bottom and mess up your cylinders.

You can't do it...well by now you should have the idea. A ball hone will do the job and they are not that expensive if you insist on doing it by hand get a ball hone on the end of a drill. The CORRECT way is by a experienced machinist with a ball hone on a honing machine that keeps everything perfect but I have used a ball hone by hand with good results.

(boy, is it me or are there lost of possible jokes in the above, lets keep it on subject please).

Your mechanic may be the best Porsche mechanic around but trying to hone cylinders by hand, he would not see any of my cars. The cylinders and pistons require rather tight perfect tolerances for the motor to last more than a few blocks without burning oil or worse seize up. What else is he going to do by hand ? measure piston skirt to cylinder clearances ? main to crank tolerances ?

 

At a Porsche swap meet I talked to a vender who "replates" Nikasil and he said you can hone it. I think he talked about some kind of a two stone process one being a course one to put the cross hatch and the other a finer grit to smooth-out the "ridges" of the cross hatch "scratches". It is my understanding that one of the problems with Nikasil is that any "minor burrs" left from the honing will not be "scrapped-off" by the rings and the rings will then wear-out extremely quickly. He gave me a brochure, but I can't find it :-(
However, I did a Google search with Nikasil honing and there was some info including http://www.babcox.com/editorial/ar/eb110242.htm and http://www.usnicom.com/What_Is_NiCom/what_is_nicom.html

If the Nikasil is .0025-.003 thick it will be very difficult to hone thru it with a drill mounted hone.

Mark

 

Nikasil is very hard, and it would be difficult to wear through it if it has not been damaged by defective pistons or rings.

I doubt that he will taper the bore if doing it by hand.

Worst case scenario, it takes some time for the rings to seat, and the motor smokes a little.

 

The absolute minimum you should do when replacing the piston rings is to give the cylinder a light hone with a flexable stone honing tool available at most auto parts retailers.

All mechanics with any engine building experience will know how this is done.
It really is quite simple and i would certainly have my doughts about trusting my Ferrari in the hands of someone that suggests otherwise.

I don't know what grade of paper your mechanic is planning on using, but if no damage is done during the process the best you could hope for is a temporary fix. If the depth of the honing process is not correct the rings will not bed into the cylider correctly and will wear prematurely due to lack of lubrication. (The honing holds oil in the cylinder to help lubricate)

This is just my honest humble opinion.
All the best