JohnInKansas
JohnInKansas SuperDork
12/30/20 4:28 p.m.

Challenge rookie question.

In the process of a head rebuild. "New" head is an unknown, but right now is an very low budget hit.

Teammate has been talking to one of his car buddies who wants us to have the new head checked for flatness and pressure. Says he (the shop he works for) can do it for as little as $100. He's telling my teammate if the head is a little bit warped/cracked, we'll blow a head gasket and maybe hydrolock a cylinder and wreck the engine. 

We have no reason to suspect the head any more than any used head, and we're planning on thoroughly compression testing before attempting to start the engine, and rechecking with a warm engine after we get it started again. If this does somehow trash the engine, we have a spare shortblock already included in the budget.

If we have the head checked and its bad, its just money out of pocket because the head won't go on the car. If we have it checked and its good, now its a head that we have $100+ tied up in.

I'm inclined to send it without paying for testing, teammate is convinced it will be our doom if we do.

What say the engine/budget experts?

jfryjfry (FS)
jfryjfry (FS) Dork
12/30/20 4:30 p.m.

Get a straightedge and start checking!  Lay it across in different orientations and use feeler gauges to measure gaps. 
 

Dusterbd13-michael (Forum Supporter)
Dusterbd13-michael (Forum Supporter) MegaDork
12/30/20 4:36 p.m.
jfryjfry (FS) said:

Get a straightedge and start checking!  Lay it across in different orientations and use feeler gauges to measure gaps. 
 

This is the correct way to scientifically send it for the challenge. 

JohnInKansas
JohnInKansas SuperDork
12/30/20 4:43 p.m.

Okay, how precision does the straight edge need to be? Don't have a machinist's rule on hand, but I have a carpenter's square...

I fear that saying that out loud may be tempting fate too much.

Dusterbd13-michael (Forum Supporter)
Dusterbd13-michael (Forum Supporter) MegaDork
12/30/20 4:44 p.m.
JohnInKansas said:

Okay, how precision does the straight edge need to be? Don't have a machinist's rule on hand, but I have a carpenter's square...

I fear that saying that out loud may be tempting fate too much.

Carpenter square is tempting the gods, man. 

JohnInKansas
JohnInKansas SuperDork
12/30/20 5:03 p.m.

In reply to Dusterbd13-michael (Forum Supporter) :

It felt dirty saying it.

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
12/30/20 5:23 p.m.

In reply to JohnInKansas :

Specify that he's testing to see if it's _bad_. That way, if it's _good_, it fails the test and you don't have to pay!

AngryCorvair (Forum Supporter)
AngryCorvair (Forum Supporter) MegaDork
12/30/20 5:24 p.m.

Also, carpenter square and feeler gauge is Challenge-precision measuring equipment.

NOT A TA
NOT A TA SuperDork
12/30/20 5:47 p.m.

Anyone on the team have old drafting equipment like triangles etc.  If so test with various straight edges, don't rely on just one particular edge.

Anyone have a laser pointer, laser level, or similar? Using one from the side in the dark is pretty accurate.

I will add that buying a machinists straight edge isn't a budget hit because it's a tool.

Find something good and flat. I used a high dollar piece of plywood. Glue sandpaper to it and block sand in a crosshatch pattern. Watch to see how flat it sands.

Mr_Asa
Mr_Asa SuperDork
12/30/20 6:26 p.m.

You could even use one edge of a bathroom mirror.  Those get ground along a belt-fed grinder that gives nice straight lines.

A quality beam level is also very straight. 

What kind of engine?

Some engines have multiple styles of gaskets available and often a "little bit bad" doesn't matter. SBC, B16A, Ford 2.3 all have a LOT of options. Don't be afraid of being cheap if it's something that will work efficiently.

JohnInKansas
JohnInKansas SuperDork
12/30/20 8:51 p.m.

In reply to QuasiMofo (John Brown) Forum Supporter :

VW 2.8L VR6.

03Panther
03Panther SuperDork
12/30/20 9:11 p.m.

If you are still in AL, I have a good metal level, or a precision square that has a great edge surface. to be able to use. A carpenters square will do for a feeler gauge... as long as you don't try to use it as a 90 deg. measuring tool!!!

JohnInKansas
JohnInKansas SuperDork
12/31/20 10:06 a.m.

In reply to 03Panther :

Car is in Kansas. I'm headed back to Alabama this weekend, was hoping to have the old girl make noise (or at least have the engine buttoned up) before I leave again.

noddaz
noddaz UltraDork
12/31/20 1:22 p.m.

STRAIGHT EDGE   $38.99

And then you will have it for next time.

CrustyRedXpress (Forum Supporter)
CrustyRedXpress (Forum Supporter) Reader
12/31/20 4:23 p.m.

I think it depends on the engine and what you're doing with it. We started with a poorly running 1991 Honda with 200k+ miles and the original gasket. Since we knew we were going turbo, we paid 90$ to have it tanked and surfaced.

This year I'm doing the same thing for the block for 125$. Yeah, having 10% of your budget in machine work sucks, but so does overheating under boost. 

Are these things known for blowing HGs?

Stampie (FS)
Stampie (FS) GRM+ Memberand MegaDork
12/31/20 4:40 p.m.

Y'all want to run some real shady E36 M3 then run with us cheap berkers in half budget.

RacetruckRon
RacetruckRon GRM+ Memberand Dork
12/31/20 5:24 p.m.

Copper spray and send it.

lrrs
lrrs HalfDork
12/31/20 5:35 p.m.

Do every measurement twice, reversing the square. 

If the measurment changes, your straight edges ain't so straight 

Our Preferred Partners
2dl3MGpW6PeOJj1Crm9zb60vG8L3GCEkU50IqmqKd9QQceymLsXhnDuzPkQusqLi