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914World.com _ 914World Garage _ 96mm Big Bore

Posted by: 74914LE Jul 26 2004, 08:56 AM

Advice Needed:

The engine that the 96mm Big Bore Kit (1.8ltr) is installed in is a 1.7ltr that has
the heads fly cut to accept the larger size. (This is an NPR kit from about 12 years ago)
Before the new set up had 25 miles on it, #3 exhaust valve came loose in the seat. Killed the motor before things got out of hand, and fixed this problem. From the looks of the tops of the pistons, the setup was running too rich. Now that I am ready to put things back together, I know that I should have the glaze taken off the cylinders, (The original honing is still visible on them) and clean the carbon off the pistons. My question is should I, or do I have to replace the rings? They look almost brand new, and there is nothing to clean from inside the grooves on the pistons. I picked up a set to install, but I do not want to waste perfectly good rings, if these will seal if given the opportunity.
Your thoughts are appreciated.

74914LE

Posted by: akellym Jul 26 2004, 11:54 AM

Why take the chance. I sure wouldn't want to take all a part again.

Posted by: Jake Raby Jul 26 2004, 12:21 PM

Replace the rings if the end gap when installed in the cylinder half way down the bore (ensre it totally square in the bore using a piston as a guide) are worn to the point where a .023 feeler gauge can be slid through them...

I would replace them anyway if it were my engine.... ENSURE if you replace them that you DO NOT use Grant rings!

Posted by: Targa Jul 26 2004, 02:17 PM

Jake,

What type of rings would you use instead of Grant? Deeves? Total Seals?

Posted by: Brett W Jul 26 2004, 02:43 PM

Hastings are good rings, Total Seals are not worth the money. Been down that road. Deves are good although I hear they are a little hard. Grant's suck ass.

Posted by: Jake Raby Jul 26 2004, 02:43 PM

Hastings are all we use.. Total seals and a TIV don't get along!

Posted by: Targa Jul 26 2004, 04:53 PM

What would your opinions be on using the hastings rings with a total seal 2nd ring only?

Posted by: Brett W Jul 26 2004, 05:53 PM

No don't bother. Engines need some blowby to make the rinds work properly.

Posted by: 74914LE Jul 26 2004, 06:07 PM

As it turns out, they are Grant's. Looks like I will be
doing some guage work to verify if the set currently
on the pistons will work. Thanks for the heads up
on the Grant's. Next time I will be very specifc with
what I ask for from the parts house.
Thanks!

Posted by: Jake Raby Jul 26 2004, 06:17 PM

DO NOT USE TOTAL SEALS!!
trust me, I lost about 6,000 bucks figuring out that they don't work!

Posted by: Targa Jul 26 2004, 07:40 PM

Thanks Jake and Brett for the advise and learning things the hard way for myself and everyone else too so we don't have to!

Posted by: 74914LE Jul 26 2004, 08:03 PM

Jake,
Any idea what the rings are that came stock with
this NPR set up? It was purchased in 1992. The
oil ring has a pull apart spring in the middle that sits
behind the center part of the ring. These Grant's that
I just purchased have a three piece oil ring arrangement. The center part looks corrogated.

Posted by: Jake Raby Jul 26 2004, 08:41 PM

NPR stands for "Nippon piston ring" and thats what the older NPR sets used for rings. They are good but they do have some blowby issues with higher cylinder pressures.

Hastings makes a replacement ring, we use them..