need more book smarts ;)

I have more questions than answers and it's too long to ask correctly in writing, so where can I get books on machining and/or theory on machining blocks and heads etc.

Ah Fooey, I'll ask anyways:
So honing the block .oo1" equals about .oo3" IN RING END GAP OPENING
and just one "?"
YOU ARE LINE HONING THE BLOCK, and you need .ooo5" more clearance - how much more honing is needed, IF NO BEARINGS (odd sized bearings +/-.001") are available.
And how does line hone or bore hone work exactly? (If you cut the block any doesn't that change the bearing bore size and make it too big)

THANKS IN ADVANCE
STEVE M.

 

Steve, yes ,in theory if you go by the math .001 in bore should open the ring gap .003
basic math is diameter X 3.14 = circumference
But I hope you are honing your block to set the proper piston skirt to cylinder wall clearance ,not your ring end gap

As far as line honing goes I'm not shure if understand the first half of your question but you don't need oversize O.D. bearings and the second part of your question, the answer is
No because the linebore/ honing process is done after you grind the parting line surface of the main cap ,which closes the bore diameter of the main and then you re-bore and hone back to the correct bearing bore size.

 

blown375

thanks very much

I understand what ya'll are saying about it, our machinist says his hone takes some out of the block and the cap, but i didnt understand how this could be as it would make the bore too big if any was taken out of the block. The problem I am having is that the bores (ID) of all the mains is the same size and the crank journals (OD) are all the same size.

But when you put a bearing in #3 main is .0015" and the rest are all .002" (the clearances)

I go well lets change the bearing from a different saddle to a different saddle and what do you know. #3 is still .0015" and the rest are all still .002".

So i am flabbergasted as to how this could be
then we took the block back to the machinist
and now I am here scratching my head.

Any more thoughts

Steve M.

 

If all the bores measure the same and correct, then the next thing I would check is that the notch in the main saddle and cap on #3... Is it large enough that it isn't wedging in the bearing tab when you torque down the main cap.

I know this is going to sound weird but, it is an accepted practice to get a bearing with an extra +.001 clearance and use it or just one half of it with one of the existing bearing halves that you now have to get the clearance you want.

I take it this isn't a blown alcohol car with .002 main bearing clearance.

 

very good point on the bearing "tang" as we call it. I will check it to make sure there is enough room. We are running a blown alky motor, it is a small block chevy 406. The machinist said that is the clearance he wants for us. The thrust bearing has been opened to .0027", he did not want to go more because he is not a fan of floating the crank in oil.

I will let you know about the notches for the "tangs"

Thanks

Steve M

 

Sounds like to me you need to find you a new machinist with blown alky experience. With those clearance numbers you can be looking for blue crank journals or changing bearings every run to try and stay ahead of it. We didn't run clearances that tight back in the 50's.

 

I would think it'd be better to have it floating in oil than sinking to the bottom when you throw it overboard.

 

You can do what you want but....
When I ran a blown alcohol smallblock I played with bearings and clearance and I had the best luck when I ran a Bryant crank with clevite v rod bearings with .0045 clearance on the rods and clevite H bearings with .005 clearance on the mains with ,50w bradpenn oil and and 130lbs oil pressure ,the bearings came out of it looking like they were never in a running engine.
You need to allow room for that smallblock crank to flex without grabing a bearing.

Let me guess, did this engine builder recomended steel rods too??????