My attempt at releiving

Zeke...PA

Zeke...PA

Well-known member
I wanted to remove deep rust pits left in a stuck 8BA block. Heres what I came up with, a 1/4" end mill in my router with a guide and a mask to hold it in the surface area to be removed. I laid out the mask using a head gasket and some trail and error. Worked well I used a 180 small disc to polish out the marks left by the end mill. I need to polish the ports of the deep pits left. I'm hoping the cylinder walls will clean up at .125 . All but one piston had to be broken out and the valves cut out. Zeke:rolleyes:
 

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Those pits look deeper then .125. Plus there's no way you can get the cylinder perfectly round and the piston and rings will never be correct. Why don't you have it bored?
 
I intend to have it bored, I wanted to releive it and polish the ports first. The pits I wanted to remove were on top of the block. I also drilled the lifter bores and ground them down for easier adjusting. Zeke
 
Looks good for a street engine.
Remember, with the very poor gas we have now, you don't need compression. Breathing is more important. A deep relief will really help.
The engine will run better, and make more power if you can run it at optimum spark advance than if you have too much compression and have to retard the spark to keep it from pinging.
 
The guide is part of the router kit, surrounds the end mill and follows the cut out opening,the mask is 1/4" masonite. I have EAB heads so the compression ratio should remain virtually the same. Zeke
 
I can't say I agree with Pete. Yes I've relieved my share of b;ocks and some applications will benefit by this. However even with this bad gas compression still builds torque. The last dozen or so engines I've built have 8.5CR This a measured compression. Long cams will bleed this down. Now the larber the displacement of the engine the easier it is to get a Hi CR , but small engines have to work for it,. A 258 with 8:1 CR can be had with an EAB head, non relieved block, tight Combustion chamber. This will give good drivability &economy. Ya don't need power at 4 grand. to get groceries. Nice looking relief.
 
Guess I don't see what is so bad about today's gas. I would build with as much compression as I can for a street engine. Mine is a little over 8 to 1 and it runs just fine on 87 octane fuel. I built that engine 18 years ago and didn't really tighten up the combustion chamber as much as I would now. Could always bump up to 93 octane. Remember this is equivalent to about 97 octane by the old way of measuring.
 
Yes a normal wood router with a guide on base plate and a 1/4" end mill from McMaster Carr, works great. Main reason for the relief was deep pitting in the area between valves and cylinder, not to mention the deep pitting in the cylinder walls. Now working on the pitted intake runners which is slow work because it's free hand with burrs , stones and abrasive rolls . Zeke
 
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