RexSeven UltraDork
Sept. 1, 2013 6:59 p.m.

One thing I plan on doing with my Alfa 164 while I have the valve covers off for powder coating is retorquing the cylinder heads. Alfa used head studs instead of bolts from the factory. Consider it preventive maintenance as the torque can loosen over time and possibly cause oil to leak into the coolant passages. Retorquing the cylinder heads to spec can prevent this from happening. I don't have any oil in my coolant (or vice-versa) but with over 206,000 miles on the car it seems like a prudent thing to do.

I have a copy of the FSM on CD and the torque specifications are as follows:

18.4 ft.lb. (+240° ±1°)
25nm (+240° ±1°)

What's with the angles, and how do I determine them?

DrBoost PowerDork
Sept. 1, 2013 7:28 p.m.

They are just a more precise way to achieve the correct bolt stretch, though I'm used to seeing something closer to 90 degrees.
I'm almost 100% I have one of these, brand-spanking new. If you're interested I'll take a look when I'm in the garage tomorrow.
$7.50+shipping?

tpwalsh Reader
Sept. 1, 2013 8:06 p.m.

aren't the +x degree bolts usually stretch bolts? But these are stud. Then again 18ft-lbs isnt much, but 240 degrees is. Silly Italians.

RexSeven UltraDork
Sept. 1, 2013 8:10 p.m.

I don't quite get what you are saying. So, for example, I torque the head nuts down to 25nm, then turn it another 240°? Sorry for the n00b question, never done this before.

Also, will I need to loosen the head nuts first, or can I just torque them down? I know each one has to be torqued in a certain order, but I don't need to remove the heads, so I'm not sure why I would need to loosen them first.

logdog Dork
Sept. 1, 2013 8:13 p.m.
RexSeven wrote: I don't quite get what you are saying. So, for example, I torque the head nuts down to 25nm, then turn it another 240°? Sorry for the n00b question, never done this before.

Thats exactly it. Easy with a torque angle gauge. Easier with a fancy torque wrench that has it built in.

RexSeven UltraDork
Sept. 1, 2013 8:19 p.m.

Cool, thanks!

DrBoost, I'll let you know via PM if I need it.

DrBoost PowerDork
Sept. 1, 2013 10:21 p.m.
RexSeven wrote: Cool, thanks! DrBoost, I'll let you know via PM if I need it.

Cool. If your loosening the fasteners, check the book. There's usually a certain order for that as well. If you're just loosening them to re-torque it's not a big deal but I've heard stories about warped heads from not following the order.

motomoron Dork
Sept. 1, 2013 10:35 p.m.

TTY (torque to yield) fasteners are generally single-use. Maybe always single use. - I'd do some research and verify they can be re-torqued or that they even/ever need to be re-torqued. BMW mandates replacement if disturbed for all the ones I've encountered in reciprocating assemblies.

In any case the first number is the installation value. The fastener is installed w/ a conventional torque wrench to this minimal value to assure the assembly is held together and in alignment.

Then, in the sequence defined by the factory manual, the fasteners are twisted the specified amount. The fastener is designed to achieve a certain clamping pressure, and once tightened it functions effectively like a wicked strong spring holding your head/rod caps/main bearing caps on.

Here's the tool - a "torque angle meter" - in use.

driver109x HalfDork
Sept. 2, 2013 1:12 a.m.

I was wondering about that too. I'm planning on replacing the half shaft on my Volvo with a good used one and the Haynes spec'd it at 89 ft.lbs. + 60 deg. on the axle nut.

edit: I also noticed that the nut is not the staked or cotter pin style

Streetwiseguy UltraDork
Sept. 2, 2013 8:30 a.m.

If they give you a torque to yeild number, don't touch them. If its gone 206,000 miles without leaking, anything you do is likely to cause trouble, rather than fixing anything.

Kenny_McCormic SuperDork
Sept. 2, 2013 11:04 a.m.

This is an Italian engine from the 70s we're dealing with, those studs aren't TTY, they just spec an above average accurate way to torque them. All fasteners stretch, that's how they work. Really old Rolls Royce shop books told you to put a dial indicator on the end of the stud and actually stretch the stud as specified.

You'll need to log in to post.

Also on Grassroots Motorsports

Tech Tips: 2006–’15 Mazda MX-5

16 hours ago in Articles

We asked a couple experts for the best way to upgrade the NC MX-5.

Project Turbo Miata: Hitting the Dyno With a Fresh Engine

16 hours ago in Project Cars

After getting a new engine, our turbo Miata project rolled onto the dyno.

Reader's Ride of the Week: Proud Prius

20 hours ago in News

Paul Sexton takes the checker while staying green.

Your Projects: Throwback MR2

20 hours ago in News

Take a Toyota MR2 AW11, add mud flaps and a cool livery, and you're ready for rallycross.

You Need This: Wacky Mazda RX-8

20 hours ago in News

Out with the rotary and in with the luxurious Infiniti drivetrain.

From the GRM Vault: Subaru Bounces Back

3 days ago in Articles

Proof that motorsports involvement can lead to corporate success.

Your Projects: SkinnyG's V8 Pontiac Firefly

3 days ago in News

Talk about a sleeper.

Calling All LS-Powered Track Machines to Holley LS Fest

3 days ago in News

Holley LS Fest will once again feature the Grassroots Motorsports Road Course Challenge.

From the GRM Vault: A Dual-Engine Honda CRX and 10 Other Cool Cars Hit the Dyno

4 days ago in Articles

Back in 1997 we put 11 cool cars on the dyno in search of horsepower and truth.

You Need This: Our Mustang GT CAM-C Project Car

4 days ago in News

Soon for sale: Our Mustang GT autocross project.

Deal of the Month: Christmas in July!

4 days ago in News

Get a year of our magazine for just $10.

Your Projects: Smith College's $2017 Challenge Miata

4 days ago in News

Smith College is entering the Grassroots Motorsports $2017 Challenge

OUR SPONSORS

Grassroots Motorsports Magazine

Subscribe Today

Also get your instant access to the digital edition of Grassroots Motorsports Magazine!

Learn More
vHTyIrpdPPsKdAVLhWnoY3yMGidGO5jH