Fzj80 Cylinder head torquing (1 Viewer)

[ceylonfj40nut]

I am about to put the cylinder head back on after a headgasket replacement. Bolt holes look clean and thread in without a lot of friction. I plan to use new OEM head bolts oiled per FSM. Reading on mud some say to chase the threads. FSM does not state to do this. I plan to run my bolts down each hole a couple of times before I finally lower them in to torque them to 29 ft lbs and two 90 degree turns (after I blow them out with an air gun). Qs:

1) do you need to chase the threads? If so with what?

2) I have a 1/2" Harbor Freight torque wrench. How many have used it on a cylinder head job on their 80's? Have you had issues? Any recommendations on more affordable but good torque wrenches?

3) what paint do you use to mark the Head bolts before you turn the 90 degree turns?

 

[tominboise]

I chased the threads using a tap specifically for it. I think I bought mine off amazon. First I blew each hole out, chased the threads and blew them again. I believe the thread profile on the chaser to be modified from a "normal" tap so as to not cut the thread any deeper. I used new OEM head bolts.

ARP Individual Thread Cleaning Chasers 912-0011
Amazon.com: ARP 912-0011 11mm x 2.00 Thread Cleaning Tap: Automotive

No experience with a Harbor Freight torque wrench.

I bit the bullet and used an angle gage for the final torque up. I believe that any sort of white paint would work to mark the heads of the bots.

Amazon.com: Lisle 28100 Torque Angle Meter: Automotive

I needed a helper to keep track of the sequence and also to make sure I didn't miss anything. Also, the final torque on the rear bolts is a pain due to the firewall, so the helper assisted in wrenching. (I'm old compared to the helper).

 

[mechanist]

You can chase threads with an old bolt. Use a cutting wheel to make two tapered grooves along opposing sides of the threads on the bolt.

 

[SmokingRocks]

I imagine your HF torque wrench will do the job just fine.

IIRC I ran my APR studs 10ft-lbs over the spec after chasing the threads with the cleaner tap. Then I marked the bolts with a sharpie and drove them the 90 degrees with my breaker bar. I know it's not the "right" way but it worked just fine.

You have to remember the 1fz is not a $30,000 M96 porsche engine, if the head bolts are taken 100 degrees rather than 90 degrees over its not likely to do any harm.

 

[Malleus]

My $0.02:

Toyota uses the "turn of the bolt" method because proper bolt torque is difficult, even in a lab, where the torque values are initially proven. The idea is that beyond a specified torque value, a specified number of turns (or part of a turn) will stretch the bolt threads, providing a dependable preload. This preload is advantageous because it prevents the bolt "unscrewing" itself due to an unloaded, installed condition. This is the accepted standard of practice in structural engineering for critical bolted connections.

There are several important points to consider when using this method.

First, it was developed for bolts and nuts, not screws, which is what "head bolts" are. The difference is important because nuts have significantly fewer threads (and thus thread length) than a tapped hole does. This means that there is more surface area available to "load" the thread in the tapped hole, resulting in a lower required torque and associated preload. This is a good thing in this application, as it means the chance of doing a good job locking the screw in place is high.

Second, once stretched, a bolt should never be reused because it's impossible to determine how close to the plastic region the material was extended. In practice this means reused head bolts are easier to break. I know there will be several hundred comments from people who've never broken a head bolt (posted or just thought about); they've been lucky.

Third, this applies only to tapped holes which have had screws installed in them and then stretched, chasing the threads actually removes material which is required for proper "grip" on the screw. The reason a head bolt, even a new one, will be hard to install at times is that the internal threads (the hole) have been stretched from their initial cut profile, when the external thread (the head bolt) was installed. Based on my manufacturing experience, I would recommend chasing head bolt threads only if they are damaged, for instance if a head bolt had to be extracted because it was broken. Even then, if it was my engine, I'd sleeve the hole.

As always when measuring the installation torque, you should never stop turning the wrench once you start, because the coefficient of static friction (the force it takes to start the fastener) is, in most metals, 140% of the coefficient of dynamic friction (the force it takes to keep the fastener turning). This is with or without lubrication; the ratio between the two is nearly constant. You can prove this to yourself by watching the scale on your wrench as you turn the fastener.

There's no magic to a torque wrench, it works the same way a fish scale does. A spring of a known size is stretched beyond its free length and because of Hook's Law, we know what the force at that new length will be. The digital ones use a load cell, but the principle is the same. The difference in the quality of a given torque wrench is the initial accuracy and the repeatibility of successive measurements.

If you're really concerned about proper torque, there are many labs and scale suppliers around the country who will certify any measuring tool, for a nominal fee. FWIW, gage labs have to have their tools certified on a recurring basis, because the materials used in the tools relax over time and the "zero point" has to be reset. A Google search turned up these results near you:
Google
An easy way to do this yourself is by comparison. Find a torque wrench you know is good (try a machine shop or manufucturing facility) and use it to tighten a screw. Preferably use one the same size and material you intend to use your wrench on, both the fastener and the material it's going into (I would not use your head for this). Check the static and dynamic torque with it, then with yours. Mark yours so you know what the position of the value you need is on your scale. This is what the certification labs do, although their practice is a little more involved.

To your last point, I like using soapstone welding markers for fasteners. It's oil and heat proof, which means I can use it on parts that I haven't meticulously cleaned, but nonpermanent. Something like this:
Soapstone Marker - Welding Supplies - Grainger Industrial Supply

HTH

 

[LandCruisinMy93]

After having built several engines and having snapped a couple new head bolts using HF's torque wrenches set to a middle of the road value instead of the full value, I can say I no longer use it on critical fasteners. As far as chasing the threads goes, use a cleaned up used head bolt. Make sure to blow the holes out well with air and once torqued I use two separate color welding paint pens for marking and also use a torque angle gauge on torque to yield fasteners.

 

[ceylonfj40nut]

Thanks everyone for replying. Any torque wrenches you recommend?

 

[BILT4ME]

Thanks everyone for replying. Any torque wrenches you recommend?

I always buy Snap-On for my critical tools.

I recently purchased a Snap-On Torque wrench in excellent condition from eBay (50-250 LB-FT) for about $140. New, it was over $300. I can take it to my local Snap-On tool dealer to check calibration.

 

[inkpot]

I imagine your HF torque wrench will do the job just fine.

IIRC I ran my APR studs 10ft-lbs over the spec after chasing the threads with the cleaner tap. Then I marked the bolts with a sharpie and drove them the 90 degrees with my breaker bar. I know it's not the "right" way but it worked just fine.

You have to remember the 1fz is not a $30,000 M96 porsche engine, if the head bolts are taken 100 degrees rather than 90 degrees over its not likely to do any harm.

I did not think that ARP studs are torque to yield like OEM bolts?

 

[scottryana]

They are not. They specify the torque, with the "standard" 2JZ studs it is 80-90ft/lbs with upgraded 2JZ studs are 110ft/lbs. Going 10llbs over and then another 90 degrees with an ARP studs is a scary process not one I would want to do.

I did not think that ARP studs are torque to yield like OEM bolts?

 

[ceylonfj40nut]

Malleus.... That was $2 million worth. Nice. Got a bargain on that response. What is your profession?

 

[baldilocks]

Thanks everyone for replying. Any torque wrenches you recommend?

I have a craftsman digital. After I bought it 2 years ago I brought it my work place and used one of our testers (we use torque wrenches a lot) and it was dead on every 10 pound feet up to its 80lbft max.

You only go to 29ftlbs then two 90 degree turns. I'm sure your HF wrench won't be too far off at 29lbft. If you do buy one, it's not necessary to break the bank unless you make a living with it.

 

[SmokingRocks]

They are not. They specify the torque, with the "standard" 2JZ studs it is 80-90ft/lbs with upgraded 2JZ studs are 110ft/lbs. Going 10llbs over and then another 90 degrees with an ARP studs is a scary process not one I would want to do.

I should have clarified, I know my torque wrench measures about 15 under at its mid range which is about the 100ft-lb mark. So I set it 10 over the FSM required spec. I didn't see any spec requirements sent with the ARP studs perhaps I f'ed up but 20,000 miles later its running smooth as silk. It's the first engine I've ever rebuilt and it works well, so if it takes a dump I'll chalk it up to a learning experience.

If you think about it setting the wrench to 30ft-lbs to the bolt plus the FSM directed two 90 degree turns probably landed them right around the 100ft-lb mark maybe a bit more. I'm not worried at all.

So you can take my example as more proof that these engines don't require excruciatingly precise attention to torque when assembling. I'd venture to say that its more important that all of the fasteners have uniform torque even if its high or low slightly.

 

[ceylonfj40nut]

Just got a smoking deal on a Snap On 1/2" on eBay. Just calibrated by Snap On last month.

 

[ceylonfj40nut]

Cost was $145. Cannot even buy even a higher end HF type wrench. Can't wait for it to come in. Put a lot work in so far to do things by the FSM. It is time to put it together with better confidence. Cheap insurance is the way I look at it. Spent $$$ already. I am not planning a redo.

 

[scottryana]

I think you are still confusing the type of bolts that Toyota uses and ARP's. Yes the Toyota bolts use a 29ft/lbs 90*, 90* but ARP does not, the reason they do not is that the ARP material is significantly stronger and much less malleable. The Toyota bolts actually will stretch to provide elastic clamping force. The ARP bolts are strong enough they are not supposed to stretch.

I am glad that you have gotten 20,000 miles out of your rebuild but that does not mean your method is right or that the engine can be thrown together with disregard for proper fastener tightening.

Any engine is only as good as its assembly, tolerances and construction. The reason the first Toyota engines were so valued for their longevity and dependability was cleaner assembly practices, closer tolerances and high quality parts. This gap has since closed or been eliminated with American engines like the LS and LT engines. Some of which are using OEM titanium rods, etc.

But the whole reason the 1FZ is a high quality engine is because it was assembled in a high quality way. A rebuild should follow suit. The bore should be honed and exactly perpendicular to the block, the bearings should all be measured and fitted with the correct oil clearances, the block and head should have the right RA finish for the type of head gasket that you are going to use, the head and main bolts or studs should all be torqued in the proper sequence and the correct method for type, etc. This is what creates a good solid engine that will run to 300,000 miles.

So while again I am glad you have 20,000 miles on your rebuild, that is 1/15th of the service life of an OEM assembled engine so don't say the engine doesn't need precise tolerances to get there since you have a ways to go

I should have clarified, I know my torque wrench measures about 15 under at its mid range which is about the 100ft-lb mark. So I set it 10 over the FSM required spec. I didn't see any spec requirements sent with the ARP studs perhaps I f'ed up but 20,000 miles later its running smooth as silk. It's the first engine I've ever rebuilt and it works well, so if it takes a dump I'll chalk it up to a learning experience.

If you think about it setting the wrench to 30ft-lbs to the bolt plus the FSM directed two 90 degree turns probably landed them right around the 100ft-lb mark maybe a bit more. I'm not worried at all.

So you can take my example as more proof that these engines don't require excruciatingly precise attention to torque when assembling. I'd venture to say that its more important that all of the fasteners have uniform torque even if its high or low slightly.

 

[ceylonfj40nut]

Amen Scottryana. It is why I love these rigs so much. Precision, quality, and beasts all in one package.

 

[scottryana]

And to answer your original questions CeylonFJ40Nut,

1) do you need to chase the threads? If so with what?

Like others have said, blow the holes out, take an old bolt and cut 2 slits down the length of the threads, chase the holes, spray a solent cleaner in the holes and blow them out again, let them dry and check them for final assembly.

2) I have a 1/2" Harbor Freight torque wrench. How many have used it on a cylinder head job on their 80's? Have you had issues? Any recommendations on more affordable but good torque wrenches?

The harbor freight while not ideal should be ok for the 29ft/lbs. If it is off 10% at 29ft/lbs that is only 2.9lbs, and why the torque to yield bolts are so nice in this capacity. If you were using ARP bolts I would suggest borrowing a friends torque wrench.

3) what paint do you use to mark the Head bolts before you turn the 90 degree turns?

I wouldn't paint them with anything before your 90* turn. Your first turn the bolt head will be bare, turn it 90* mark it with a paint pen. Move to the next bolt in sequence... When all the first turns are done your bolts will all have 1 line marked on them. Now start your second turn. Mark each finished bolt with another line. 2 lines = done, 1 line = not finished torquing. And really if you pay attention and follow the sequence you don't need to mark anything.

Amen Scottryana. It is why I love these rigs so much. Precision, quality, and beasts all in one package.

 

[ceylonfj40nut]

Thanks. I like the double mark method. FSM says to get to 29ft-lbs. Then add mark facing radiator (cylinder 1). When two 90s are done mark should point to the cab (cylinder 6).

 

[SmokingRocks]

I completely get the differences between the torque to yield bolts and APR studs even if I didnt at the time. So YES I see the error of my ways @scottryana but thanks for pointing them out again to me. As I said if it fails I'll mark it up to the 'lessons learned' column, others can learn from my experiences. Perhaps you missed the statement in my first post where I clearly said that wasn't the "right" way.

But I disagree with the 'welp you have 20k out of it but it probably won't make it to the OEM life' implied statement. The OEM life was 180k until the HG blew so if I make 180 k on my set up its a win. (BTW I'm already 1/9'th of the way there ) But thats yet to be seen. I stand by my statement that having equal torque across the bolts is more important than anything.

Lets break it down, these engines and cars were designed to have sand poured in the gas tank and s*** stuffed down the oil filler cap. I'm sure there are plenty of 1FZ's out there in africa and elsewhere that were reassembled completely without a torque wrench. They are by nature precision machines as it is an engine, my point is that they are NOT the same as a flat plane ferrari V8. They are more on the line of a tractor motor.

I'll make sure I keep you updated on my shotty rebuild's lifespan.