Posted by: nwracing | August 14, 2012

Pistons & things!

One of the jobs that requires a lot of time and patience is fitting piston rings and having got it wrong once before, am now more aware than ever of how critical it can be to engine performance. So unusually for a man, so I’m told, I spend some time reading up on the specs for the new set that is going in to Andromeda’s Big Block Chevy engine. I have gone for a different set this time with a conventional type top ring but gapless second ring made of better quality material than the last set so it should be able to stand better abuse from the NOS.

I don’t know what it is about men and manuals but my better half always tells me that I never read one before I dive straight in. However, when it comes to engine specs I read and re-read  and then write it down just to be sure, which does annoy her a lot! So I spent some time making sure that the recommendations in the rings box are applied to my engine. Because we use a lot of NOS the ring gaps have to be wider.

In the past I have spent literally hours with a file held in a vice which does work but you have to be incredibly careful in order to get things square. So I decided to invest in a piston rings filer. If you’ve never seen one before take a look at the accompanying picture.

Now to file rings you need some more kit, besides the piston ring filer you need feeler gauges, a fine stone and lots of blue roll and brake cleaner.  Filing rings is easy once you get the hang of it but if you’re going to undertake this for the first time practice on some old rings first so you can work out how much the filer takes off the end of the rings. Gaps that are too big are as bad as gaps that are too small; small gaps can be opened up but you can’t add material if you make it big!

Firstly fit the ring to the cylinder and square the ring about 1inch down the bore. I use an old piston for this. Measure the gap so you have a base point then to the grinder and a few turns, deburr the end of the ring using the fine stone, (very important), clean off using brake cleaner and then back in to the bore for a measure. It is then simply a question of creeping up on the size that you need. The new filer did make the whole process easier and well worth the £65 I spent on it. You can literally spend nearly £1000 on one if you go for the top of the range powered version which if you build engines every day would be a worthwhile investment. I have attached a few pictures so you can see the whole process.

Anyway, the rings are now filed and fitted in to the pistons which have been cleaned ready to go back in to the engine and then full steam ahead to get the engine finished. I do check all the rings and leave them in the engine to make sure they do not get mixed up.

Just a final thought; if you’ve ever wondered why professional engine builders charge so much to build your engines you only have to see the hours it takes; true they are probably way quicker than me but they still have to get the tolerances right. It’s just that here at NWRacing we have to know and I mean medically have to know every little detail of our engine which is why we do it ourselves.

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