7m head bolt pattern?

Insidious Surmiser

Insidious Surmiser

Formerly 89jdm7m
May 12, 2006
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so, I got this car from a friend of mine, he had the engine rebuilt forever ago, but never really drove the car that much (think a few hundred miles) anyhow, I took the valve covers off to check the torque on the head bolts, don't want a BHG... especially considering how strong this one is running w/ stock exhaust, intake, and boost levels, as soon as I uncork it I know it'll easy make enough power to obliterate the HG under OE torque specs


PROBLEM: what bolt pattern do the 7m head bolts have? I read somewhere that I needed a 10mm allen socket... so that's what I have... definitely doesn't fit though...
 
D

Dan_Gyoba

Turbo Swapper
Aug 9, 2007
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www.gyoba.com
ARP bolts are 14mm 12 point. So are the nuts for the studs. The factory head bolts are a 10mm allen key head. I am not aware of any other bolt heads being used on the 7M

Factory head bolts should be torques to 72 ft-lbs. (Original factory sped is 56 ft-lbs. Updated spec courtesy Reg Reimer.)

ARP bolts should be torqued to 85 ft-lbs as per instructions from memory.

ARP studs should be torqued to 90 ft-lbs as per instructions, again from memory.

Torquing pattern as per TSRM, torque down from inside to outside, release from outside to inside. (Not that this answers OP question but since it was mentioned...)
 
Insidious Surmiser

Insidious Surmiser

Formerly 89jdm7m
May 12, 2006
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ARP's are supposed to be standard (at least old ones are), not metric. my head bolts require 1/2" 12pt socket (thanks, IJ) the bolts are pretty old (engine was built ~8 yrs ago) I'm'll go take a look though, just to make sure

looks like my car has a metal head gasket as well :cool:
 
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radiod

radiod

Supramania Contributor
Dec 13, 2007
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My ARP studs were definitely 14mm 12-point......had to go buy a socket specifically for them because all I had was 6 point sockets. Using a deep 3/8" drive socket that has thinner walls should let you clear the cams when rotated to TDC marks.

Stockers should be the 10mm allen as mentioned.
 
Insidious Surmiser

Insidious Surmiser

Formerly 89jdm7m
May 12, 2006
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sorry, I was out working on it for several hours then I bolted off to my real job... but for the record guys, I was right in believing what I did... they ARE 1/2" (again thanks, IJ) he posted the info in a thread in 2011... but from what I can tell, for your ARP head bolts to be 1/2" they'd have to be 5 yrs old (if not older)

It's still not quite back together... I'm just going over a lot of things on the car, since it's new to me (the make, model, or engine are by no means new to me, but this particular car is) I believe my PS system has PS fluid in it :( gotta get that out ASAP... I would for once like to have a car w/ working PS... my spark plugs were gapped WAAY off and were the wrong type of plugs too... fixed that
 
grimreaper

grimreaper

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Jul 2, 2008
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what is the truth behind that myth?

How is fluid selected for a power steering system at an OEM level? Tolerances of the rack?

Why do some specify trans fluid and others a specific power steering fluid, like honda? google brings up a bunch of bob is the oil guy crap. Didnt realize so many people were engineers now a days..
 
Insidious Surmiser

Insidious Surmiser

Formerly 89jdm7m
May 12, 2006
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jetjock;1919009 said:
Crack me up. I wish that myth would die.
Click to expand...
than why don't you kill it? you say one thing, but your actions say something else entirely

It's my understanding that our PS system calls for ATF (which is red IIRC) mine has clear fluid in it... I know both are hydraulic fluids, but is viscosity the same?
 
supraguy@aol

supraguy@aol

Well-Known Member
Dec 30, 2005
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3p141592654;1919062 said:
ARP bolts are 1/2" 12pt, at least mine were. ARP stud with nuts are 9/16" 12pt, which is so close to 14mm (14.3mm) that they both fit.
Click to expand...

Aha, never knew that the studs were specifically 9/16. Is the average 9/16 socket slightly narrower or slightly wider than 14mm? I'm wondering for the purposes of ease of socket fitment past the cams.
 
jdmfreak

jdmfreak

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Oct 8, 2010
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supraguy@aol;1919144 said:
Aha, never knew that the studs were specifically 9/16. Is the average 9/16 socket slightly narrower or slightly wider than 14mm? I'm wondering for the purposes of ease of socket fitment past the cams.
Click to expand...

You answered your own question.... The post you quoted said 9/16 is 14.3mm
 
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