Suggest a straightedge

[Jawn]

I am doing a head gasket job on my truck and I'd like to verify the head/block aren't warped too badly before putting it back together. Snap-On has one for $120+, Summit and Jegs have 'em closer to $50, and somebody suggested a woodworking place to me - they have one for $25. Would one of these be my best bet, or is there something else that may suffice in a pinch?

It's not something I'd use real often, but I'd hate to get this thing back together and have the head gasket turn loose again right away.

 

[devoncoolman]

Central tools best one in my opinion. It needs to be machined flat. Typical wood working straight edges are not as prescise.

 

[TheGrooveking]

I'm a Starrett man myself.

TheGrooveking

 

[ADSR]

Some warps are hard to find even with a good one. I'd get the heads machined no matter what.

 

[Fixnair]

Any kind of a straight edge would work as long as it's long enough. You should be able to buy a long one at an office supply store. To check it for straight coat one edge with a black magic marker. Then get a sheet of 180 grit Emory paper and a flat piece of glass. Lay the sandpaper on the glass and rub the coated edge of the straight edge lengthwise across the Emory paper, without bending it, a couple of times. Give it a couple of strokes then check to see that all the magic marker has been removed.
Then lay the straight edge across your head, shine a flashlight at the straightedge and look between the edge and the head for light. If there is light shining then get your feeler gauges and test for how much warp there is.

 

[dtt454]

i saw a guy once use a fluroescent light tube. im not saying it was right but it seemed to work

 

[ihredo4]

I bought a piece of precision ground stock from Starrett in significant length.

 

[A_Pmech]

I bought a piece of precision ground stock from Starrett in significant length.

Precision ground flat stock is square and parallel, but not straight. In fact, I don't recall that Starrett even specifies a straightness tolerance.

 

[amitchell]

I use a planer knife.

 

[Jawn]

Just a follow up... I ended up ordering the $50 one from Jegs. Turns up the head is barely within spec... I'm going to put it back together as-is. It's just a beater anyway. Worst case I'm doing this job again sometime.

 

[A_Pmech]

If it was within the specification, chances are good that it will be fine. Cylinder head fastener layouts are designed take into account "un-warping" the head a certain amount to fit the block, which is the stiffer of the two components.

 

[Jawn]

Yeah, further making me feel better about it - the spec allows the same amount of warpage in the block as well, but the block is dead flat as far as I can tell.

 

[Dave455]

The British made Maun is my choice! They are only about £20 (for an 18 inch) if anyone else need one!

 

[retDAC]

Thanks for the followup. Wish everybody did that.