Clearance and block warpage questions.

[Stainbox12]

I just sent, my block to the machine shop, and they told me, that the block has 0.03 of warpage, and 0.05 wear on the cylinder walls. Im going to reuse the block as it is, but i would like to know, if 0.03 of warpage across the surface is reasonable, or it may cause overheating? Whats the max cleareance allowed of warpage for the block surface? Thanks.

 

[talon187]

i would deck the block or else you may have headgasket issues

 

[SlowSpyder]

you mean .003 and .005 right? if thats the case then decking the block and boring/honing to the next piston size will work.

 

[delta448]

Are you stating values in inches or millimeters? I'll assume inches unless you correct me.

The block needs decked. You should expect right around 0.001 inches of clearance under a straightedge laid across the top of the block from corner to corner if you're building any high performance inline 4.

The cylinders should be bored as well, but 0.050" is a huge amount of wear, you might be better off with another block.

 

[Freerevving]

what they said

 

[Stainbox12]

Yes, i made a typo, its actually .003 warpage across the surface. Im not honing the cylinders even if its, .005 off, since im going to spray this engine till it dies, so i don´t really care even if i loose some compression. And thanks, for the one, who said that, .003 across the surface is way too much and .001 is the normal value. Btw, yes values are in inches. So just to confirm, you would say that .003 would cause overheat? because thats the main reason i sent the block to the machine shop, since the head was decked and it still overheated. Thanks all.

 

[Freerevving]

Especially if you're spraying, you're going to have more problems with the .005" scuff than the warpage. Stock pistons are supposed to have no more than .0015 clearance, a little more won't hurt it, but .005 is going to have problems with spray

If the warpage is even (convex/concave block) you can get away with it by torquing down the head a little tighter... If there are sudden .003 low spots you are sure to have problems.

Sounds like you found two problems that should be nailed down before you continue. Remember that re-assembly can cause small problems to become big.

 

[Stainbox12]

So actually .0015 is less than .005 on the cylinders? The block is going to be decked, because when i reassambled the first time, after my overheating problem, and decked the head, the engine still overheated so i tore down the engine, to take the block to the machine shop. So i hope really, that the deck on the block would clear the overheating problem.

 

[Freerevving]

So actually .0015 is less than .005 on the cylinders?

yes .005 is 5 thousandths...
and .0015 is 1.5 thousandths

I'd say that scuff is about 2 thousandths too deep... but you might get away with it... I just wouldn't take the chance with nitrous... don't say I didn't warn you