I'm preparing to have my EA82T cylinders bored to .5mm OS. None of the machine shops in Eugene, OR or all of Oregon have a deck plate for this motor. Some will make them for some considerable $$$.

All of these shops say that it is unnecessary of this block since the heads only get torqued to 45-50ftlbs. They also say that since the block is well seasoned (180k) it won't move under torque

 

I have read posts from the airplane guys that say it is absolutely manditory to use deck plates when boring cylinders

 

My thoughts are that if the heads are dead flat and the coresponding surface of the block is also dead flat, there should be no problem.

 

What do you all think?

It's not flatness of the head and deck that the boring plate addresses, but a roundness of cylinder issue. When the heads are bolted on, it stresses the block. If the cylinders are bored perfectly round without a boring plate, then the head is bolted on, the cylinders are no longer perfectly round. The boring plate simulates the head being bolted on, and results in a perfectly round bore with the head installed. This reduces friction, decreases blowby, reduces break-in time, and adds horsepower.

 

On the other hand, very, very few production engines are bored and honed using a boring plate. It takes too long.

If you can't find someone who has a plate, then just consider the lifespan of a stock soob.

 

Personally, I wouldn't worry too much about it, unless you were trying to win the WRC. Airplane guys live's depend on the thing running flawlessly, so you are comparing apples to oranges there.

My ER27 was bored 2mm and the final result was: 479cc combustion chamber volume and a displacement of 2915cc (after stroking) The deck height is .04ish as I recall and everything was nice and true, no plate available so no plate used.

well, I was going to say "everyone always tells me YES!"

 

but then again, those are people with V8s and american engines. (which are way different in working order than our engines)

 

If subarubrat has his ER27 in his Brat rebuilt without using a deck, then I would say it's a moderately safe idea.

So you've decided on .5mm - let me know when you are ready to get those rings (re)ordered. If you have the time, we can order them ground UPS and save a couple of bucks on freight.

Hey partsman

 

you don't work on Wednesdays?

 

I'll call tomorrow.

 

Must order .5mm oversize rings from

beck-arnely

 

garner