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Discussion Starter · #1 ·
I want to test my sr20det head for warpage and would prefer not to spent hundreds of dollars on a proper straight edge.

Can anyone else tell me another way to test the head and block for warpage.

Thanks ......
 

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Resurface the head and block.

Think about it..your spending a pile of cash on a build. Most machine shops dont charge much for surfacing a head. The block may cost alittle more, but you will have cofidence in your parts then...
 

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Hmmm a level laser would work... Be pretty hard but would work.
 

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Im a for a staight and level head.

I have been around engines all my life, and honestly I really don't know of any way to check head runout. You are talking thousandths of inches, something that is not easily visable to the naked eye. If you do come up with an idea that works I would love to know.
 

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The way shown in the Haynes and other manuals, including factory, is to lay a known good straight edge across the long end and various other angles (corner to corner, corner to center, etc) and try to slip a particular width of feeler guage under it. It takes a while to check a head this way, but you should get some pretty definitive results. Most head warpage will be pretty noticeable using this method.
 

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♣Zen31ZR♣ said:
The way shown in the Haynes and other manuals, including factory, is to lay a known good straight edge across the long end and various other angles (corner to corner, corner to center, etc) and try to slip a particular width of feeler guage under it. It takes a while to check a head this way, but you should get some pretty definitive results. Most head warpage will be pretty noticeable using this method.
Shine a bright light behind the straight edge and sight along the surface of the head for light shining through to spot areas for measurement.

Lew
 

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the problem here is the guy doesn't have a straightedge.

I suggest taking the head and blobk to a machine shop and pay them a few bucks to check it out for you. much cheaper than a good Starrett straightedge that you'd only use once.
 

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Matt93SE said:
the problem here is the guy doesn't have a straightedge.

I suggest taking the head and blobk to a machine shop and pay them a few bucks to check it out for you. much cheaper than a good Starrett straightedge that you'd only use once.
I use straight edges a lot. ;) And at todays prices I doubt having a machine shop check anything is "only a few bucks". Generally they charge by the hour, and any part of an hour is a full hour. I'd say minumum $50 to do this, more like $75-$80. I could buy 10 straight edges for that......
 

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♣Zen31ZR♣ said:
I use straight edges a lot. ;) And at todays prices I doubt having a machine shop check anything is "only a few bucks". Generally they charge by the hour, and any part of an hour is a full hour. I'd say minumum $50 to do this, more like $75-$80. I could buy 10 straight edges for that......

mind telling me where to find a Starrett straightedge for $8? :)
 

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Well in automotive applications I don't think I would invest in Starrett anything. I don't think it warrants the extra digits in cost. I suggested that one above, though there are shorter cheaper ones on amazon, only because to measure the head I think you need to be able to do the diagonals too if I remember the FSM correctly.
 

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♣Zen31ZR♣ said:
Yeah, pretty sure a $7 Stanley would do the same trick.
I don't know about that... Usually companies like that make stuff for wood working and don't really need precise flat surfaces. I mean generally moving metal parts usually require something that can be accurate in the thousandths. I think a good 50-100 buck flat edge is good enough.

By the way I'm going to edit some of the comments in this thread to keep it on subject.
 

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James said:
I don't know about that... Usually companies like that make stuff for wood working and don't really need precise flat surfaces. I mean generally moving metal parts usually require something that can be accurate in the thousandths. I think a good 50-100 buck flat edge is good enough.

By the way I'm going to edit some of the comments in this thread to keep it on subject.
A 24" Starrett like the one mentioned above is about $57, pends on where you buy it..... And that is a woodworking straightedge.
 

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Discussion Starter · #17 ·
STRAIGHT EDGE ??

I went to the hardware and bought a "straigh edge" L shaped metel.

I got home and found that it is far too in-acurate.

I am trying to measure increments to 0.03 which is impossible with anything other than a professional "straight edge". When they say "straight edge" they dont just mean something that has a "straight edge".

They sell proper usable "straight edge" for $300 (au). It is a machined precise straight edge that can measure increments to 0.001, etc., which is what is needed. When the difference between 0.09 and 0.1 means usable or junk it is important, as I have found after research and trial and error, to use the professional piece.

Some machine shops professionally machine a piece of metel on their precise machine instead of buying a "straight edge".

I found that a piece of picture frame glass was more accurate than the "straight edge" someone listed above (the L shaped one).

I bought the exact same L shape one from the hardware for $37 and it is useless.

I am going to order a proper straight edge from Brisbane for around $300 after I try to pay a machine shop to make me one on their machine.

If anyone can point me in the right direction to get one please let me know.

The machine shop quoted me about $30 to put a proper straight edge on the block and measure it with a fila quage, which is reasonable as it will only take them a few minutes.

I also found that by putting the cams back in and feeling if they spin without rubbing can give a very rough estimate.

Thankyou all for the input.

Also, when putting the cams back in how do I know what position they go if I didn't mark them when I took them out....doh.

At the moment (sr20det...1992 model red top) I have the no.1. cam 'nodes' facing opposite with the marks at : intake 10 oclock and exhaust 12 oclock.

I do not want to be even 1 link out so please someone let me know how to be sure.
 

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when rebuilding the engine, you definitely need to pick up a service manual and follow the cam timing instructions there.
the gears on the cams are keyed. just turn the engine about 30 degrees from TDC so you're sure all the pistons will clear the valves, then you can turn the cams as needed to get them in place.
 

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If you want to check if your head is warp. this is the way you can check...
first you lay you head on apair of V block with combustion chambers facing up.
then you get a straight steel rod and a feeler guage. measure the head in aletter X with a limit of .004 anymore than that. your gonna have to get it staighten out by getting it bakedin the oven then surface the head. that way you save and have a more equal combustion area. well I hope this helps or other than that try spinning the cam and see if you feel any binding thats a quick way to check for head warpage.... But correct me anyone if Im wrong
 
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