Piston Rings replacement

dan476 · 05-11-2007, 04:43 PM

Hey guys, i am going to do a rebuild on a '87 924S engine, to Replace my tired out '83 944 engine.
I am thinking about picking up complete rebuild kit either from Lindsay or Zims.
I have not seen the insides of the engine and have not even picked it up yet, but while i am doing a rebuild should I replace piston rings? I've heard different opinions on that one, some say go ahead, some say I shouldn't as I might lose some compression.
Can anyone give me an educated advice?

thanks,

onZedge · 05-11-2007, 05:00 PM

If you have the engine out and your rebuilding it, it doesn't make sense NOT to change the rings since the donor engine probably has some miles on it. Make sure the piston grooves are clean, end gaps are within the correct tolerance (adjust as necessary) and they are "clocked" correctly when installed.

badjones · badjones's Garage

Dan, most of the debate is around the honing of the cylinders not the replacement of the rings. By all means replace the rings as they are a wearing item but DO NOT hone the bore as per a traditional cast iron bore. Clean the bore with detergent and a pressure washer if necassary but do not go near it with a normal stone type hone.

924RACR · 05-12-2007, 04:25 AM

As an alternative supplier - I've been very happy with EBS Racing (www.ebsracing.com) for stuff like that, especially their re-ring kits, and they know their P-cars, especially front-Porches, and excellent customer service.

Agreed with all of the above - do the rings, don't touch the bores, and be sure to at bare minimum replace the valve stem seals and re-lap the valves for best sealing. We just recently refreshed the engine on a race 924S here, and it was losing nearly 20% on a leakdown test on nearly all 4 due to valves not sealing... this after something like 160kmi IIRC.

dan476 · 05-12-2007, 07:23 AM

cool sounds good, thanks.
I think i am going to go with Zims as he provides the whole rebuild kit, top and bottom for 667

Thanks again

hpaulb · 05-14-2007, 06:23 AM

Should have replaced mine when I did the engine. Take the head in to any machine shop to have it checked. Valve stem seals are easy if you want to do them yourself.