Torque to Yield....what an unnerving procedure

[CarMichael Angelo]

Working like mad to get the car back running, today, I put the new heads on the newly painted (red) shortblock. The Chilton manual I have details a 6 step procedure for installing the damn head bolts:

1. Torque to 28-31 lb/ft
2. Tighten an additional 90 degrees
3. Back off bolt one turn
4. Torque to 28-31 lb/ft
5. Tighten an additional 90 degrees ( I'm wondering what the torque value is about now)
6. Tighten an additional 90 degress ( I know I'm gritting my teeth as I'm expecting the bolt to break off in the damn block)

I followed this procedure, but the additional 90 degrees required a big-assed 1/2" breaker to get the bolt the final 1/4 turn. And the drivers side head was a "push" rather than a pull, (bout wore me out) Seems like I'm torquing 460 head bolts. Chalk me up as mildly concerned

 

[ID89GT]

Did you use new bolts? Or reuse the old ones? I thought torque to yield was a one time use

 

[CarMichael Angelo]

Did you use new bolts? Or reuse the old ones? I thought torque to yield was a one time use

Yeah, I used new bolts.

 

[wythors]

When I did the heads on my white car, the "push side" just about kicked my butt. I have since bought a mondo 1/2" ratchet for the next time.

 

[1991notchbackLX]

This is the procedure most of the gorillas I work with use. Seems to work for them.

1. Cross thread
2. Torque until bolt breaks
3. Back off 1/2 turn
4. Blame someone else

 

[Mr. Rustypwnz]

I go like this on a modular:

tighten all up with a rachet
go 40ft from inside out
then do 75ft from inside out
then recheck.

never fails. That and the fact you have to be mentally retared to blow a hg on a n/a 4.6.

 

[Mr. Rustypwnz]

That whole procedure makes no sense. Those bolts are as strong as any other head bolt.

 

[LarsD]

I never understood the whole 1/4 turn, 90 degrees bs. Just give me a damn torque value!

 

[srtthis]

I never understood the whole 1/4 turn, 90 degrees bs. Just give me a damn torque value!

i actually questioned an engine builder about this.. and he said its more accurate this way since the bolt is stretching.

 

[Jason 302]

I would just buy some ARP's and use the torque values. Has always worked for me!

 

[03ghoststang]

i actually questioned an engine builder about this.. and he said its more accurate this way since the bolt is stretching.

this is true they are stretch type bolts ^^^^^..... to the O.P that torque sequence is what they call for and it varies from engine to engine....

 

[LarsD]

i actually questioned an engine builder about this.. and he said its more accurate this way since the bolt is stretching.

True, measuring bolt stretch is the way to go.

 

[jrichker]

From what I have been told there are no touque too yield bolts on a 5.0 Fox Mustang. The old head bolts are supposed to be reuseable, but the cost of new bolts is small compared to the amount of labor needed to replace a broken or stripped bolt.

Remember that Never Seeze is your friend: spent $20 or so at NAPA and get the BIG container.

Be aware that the ARP bolts have a radiused shank under the bolt head. The ARP washers have a matching radius machined into them. Be sure that the machined radius of the washer is fitted next to the machined radius on the ARP bolt heads. Forget this little fact and you will never get the head bolts to torque down properly.

Coat the underside of all bolt heads with anti seize and the threads of the long bolts. The short bolts thread directly into the water jacket and need a different treatment. Use Teflon Pipe dope on the threads of the short head bolts. It will prevent any coolant seepage from around the threads. You can get the Teflon pipe dope from the hardware stores, Home Depot or Lowes.

 

[CarMichael Angelo]

From what I have been told there are no touque too yield bolts on a 5.0 Fox Mustang. The old head bolts are supposed to be reuseable, but the cost of new bolts is small compared to the amount of labor needed to replace a broken or stripped bolt.

Remember that Never Seeze is your friend: spent $20 or so at NAPA and get the BIG container.

Be aware that the ARP bolts have a radiused shank under the bolt head. The ARP washers have a matching radius machined into them. Be sure that the machined radius of the washer is fitted next to the machined radius on the ARP bolt heads. Forget this little fact and you will never get the head bolts to torque down properly.

Coat the underside of all bolt heads with anti seize and the threads of the long bolts. The short bolts thread directly into the water jacket and need a different treatment. Use Teflon Pipe dope on the threads of the short head bolts. It will prevent any coolant seepage from around the threads. You can get the Teflon pipe dope from the hardware stores, Home Depot or Lowes.

Don't have a 5.0. I have one of those "other" Mustang engines.

 

[wythors]

From what I have been told there are no touque too yield bolts on a 5.0 Fox Mustang. .

Strange, the FRPP bolt kit I used to do the cylinder heads on my LX were torque to yield and my factory service manual give the procedure for torquing them down on the car.

 

[ghostang93]

Torque to yield bolts have been used in the aerospace industry for years. IIRC the T-Y bolts that hold an H60 propeller housing together were something like 3/4" shank. Yes, it was a two-man job, one to look at the gauge and the other to use the 5' torque wrench... Those were fun. Even with the smaller ones on aircraft, I've never heard anyone break one, by accident, unless it was cross-threaded.

 

[VibrantRedGT]

I've always used the 3-Step process with torque values, working on the center bolts first and working my way out. I hate that 1/2", turn 90 degree, do jumping jacks, clap your hands crap they suggest.

 

[4G-KDMP]

Strange, the FRPP bolt kit I used to do the cylinder heads on my LX were torque to yield and my factory service manual give the procedure for torquing them down on the car.

Your saying that your shop manual says torque them down in 2 steps correct?

Not This Method
1. Torque to 28-31 lb/ft
2. Tighten an additional 90 degrees
3. Back off bolt one turn
4. Torque to 28-31 lb/ft
5. Tighten an additional 90 degrees ( I'm wondering what the torque value is about now)
6. Tighten an additional 90 degress ( I know I'm gritting my teeth as I'm expecting the bolt to break off in the damn block)

 

[StreetsideStig]

Ugh. That would unnerve me, too. I ruined an engine once by overtorquing.

 

[CarMichael Angelo]

Your saying that your shop manual says torque them down in 2 steps correct?

Not This Method
1. Torque to 28-31 lb/ft
2. Tighten an additional 90 degrees
3. Back off bolt one turn
4. Torque to 28-31 lb/ft
5. Tighten an additional 90 degrees ( I'm wondering what the torque value is about now)
6. Tighten an additional 90 degress ( I know I'm gritting my teeth as I'm expecting the bolt to break off in the damn block)

Don't quite know how this happened, but.....see below