The Stovebolt Site Forums The Shop Area Engine Shop head/block warpage, not specifically stovebolt question

When someone says get a straight edge and see if a block or head is warped... What is considered a good enough straight edge and how much warpage is acceptable? I am working on a 4 cyl gas tractor engine that blew a head gasket between 2 and 3. We had head planed, machinist said to check block with a straight edge. We can't get a level on it, only thing short enough is an "L" carpenters use. Any input?? I am afraid the only real way to make sure it is right is to pull the block, just hoping.

Look about 1/2 way down this page. http://www.centraltools.com/specialty.html
There's some straightedges, then try putting various feeler gages under the center & see how far down is the 'low spot'.
You'll get different opinions on what is acceptable & part of it depends on over what length it is, what compession, & what head gasket you use but I'd say over 5 thou. is asking for trouble just to start the discussion off here.
Hope this helps - Doug

Yea, .005 would be about all I'd pass on unless I was taking the engine in anyway and then I'd have it decked.

How long is the block? Surely, you can find a machinist scale a lot easier than pulling an engine... I'd give that "L" a shot and see what you get. Unless the level is something fancy made from metal with no dings, I wouldn't waste my time with it.

If the gskt went between cyl,s,,are cyl,s close or are there water holes there? if no water holes and just solid metal,,clean block good then use some blueing and a good file and touch lightly with file blueing will tell you if low where gskt failed,,you can do same if water holes there also...doc

I was 8 thousandths off on my 235. Thinking it was only the head that was warped, I took that off and had a machinist surface that down straight, which improved my compression ratio to about 9.4:1. However, my leakage problems were worse than ever. It turns out my block is warped too.

So yes, a head and block can both be warped. I know if I rebuilt the 235, I could have the block resurfaced to match the head, but I'm not sure if I'd still be at a compression ratio that you can run pump gas on. If I jumped up 1.4 points in compression just getting the head flat, It's gonna be even more once the block is planed flat too.

Plus why do all that work for an engine that would be lucky to exceed 140 miserable horsepower? That's why it's a V8 for me.

Hot Rod - How much did you mill to raise the C.R. 1.4 pts?

L-Kings - A straightedge need not be a hi-dollar tool. Go visit your local sheet metal shop. Look under their shear & pick up a couple scraps maybe 2 or 3 ft. long. Hold the cut edges together & see that there is no gaps. If not, then you have two straight edges in your hands. The heavier gage, the better. You can trim to the length you need.

Doug

I wish I could remember. I know he started to clip the valves when he stopped. I even cc'd the combustion chambers, but I don't remember that either. Sorry, that was a year ago, and I just don't remember.

FLAPS may rent you one or have some flat stock milled to be a straight edge. Be sure to hang it up when done, laying down may cause it to warp or bend slightly,
Scott

Tim posted a real good link in another thread where we were discussing head torque. I won’t quite it, they say it better than I ever could. Take a look at this site and it will answer all your questions on flatness. http://www.valvedirectory.com/valve_04122006.html

Oh, and on the straight edge, they are talking about a precision straight edge, not a carpenter’s square. The machine shop will have that, best to let them check it, I doubt if you want to put out that kind of money just to check the one engine.
http://catalog.starrett.com/catalog/catalog/groups.asp?GroupID=396
http://www.use-enco.com/CGI/INLMK32?PARTPG=INSRAR2

Here is the one that I use; http://rides.webshots.com/photo/2254296400098611668WnQoDO
Denny Graham
Sandwich, IL