Correct head bolt torque for 1592?

[hayesbd]

I have the 1592 motor and I just blew a head gasket that had only around 20,000 miles on it. It's burned through 3-4, as is somewhat typical and could have been due simply to running too hot (never really overheated into the red zone, though). However, since I have the factory shop manual, I followed it when installing the head the last time and it states the head bolt torque is only 54 ft-lbs for this engine (132 series) instead of the more typical 61.5 ft-lbs for the rest of them (125 series).

Should I use the higher torque for this next installation? For what it's worth, this engine uses the in-head thermostat.

Thanks,
Brian

[frischling]

Retorqued after 1000 mls ?
Its important....

[hayesbd]

No, I typically re-torque after 500 miles. Any idea why the 132 series has different torque values than the 125 series?

[nelsonj]

I replaced my head some time ago and have very good luck so far. It's an 1800 so I torqued to 61-65 lbs. However I used a "bender" torque wrench to make sure the bolts were truly holding. And then I think I rechecked after about 500 miles. Anyway, I don't trust "breaker" torque wrenches for this job. FWIW, this is what I did:

I did things in four steps, following the pattern (in the manual) each time.
Step 1: I just put in all the bolts with almost no torque just with a normal socket
Step 2: I used a 'Breaker" torque wrench and put on 50 lbs on each bolt
Step 3: I used a "bender" torque wrench and put about 61 lbs on each bolt. I made sure they could hold the 61 lbs for 5 seconds without moving. At least with my wrench, it was hard to be accurate. I had between 61 and 65 lbs per bolt.
Step 4: I rechecked all the bolts in order with the "bender" wrench to make sure they were holding at least 61 lbs for 5 seconds. I think 2 bolts needed additional torquing.

Peace.
Out.

[samakijoe]

Can you give us more info on the "bender" torque wrench?

[nelsonj]

A "bender" torque wrench looks like this:


Rather than "breaking" once you reach torque, the "bender" actually bends and moves an attached gauge needle that shows how much torque you're applying. You don't set it for a value, you apply torque and reach the results as you go.

I like the "bender" because you can hold a torque on the bolt for any amount of time, and you know how close you are to reaching torque as you turn the bolt. With a "breaker" you only know you've reach torque once it breaks. As a result, you can't hold that torque on the bolt, rather you only apply the correct torque for a split second.

I found it important to hold the torque for some time because the head bolts would typically move after having proper torque applied for say a full second. I made sure each bolt could hold torque for 5 seconds before I was satisfied.

Hope that helps.

Amazon has one here:
https://www.amazon.com/Tooluxe-03703L-T ... que+wrench

[djape1977]

that's way undertorqued. you need to be in 100-110nm range, according to online calculator, that's 73-81 lb-ft
and it's same for all fiat twin cam engines

[hayesbd]

I did a little bit of figuring and for a Class 10.9 M10 X 1.25 screw into cast iron, you can expect the head bolts to be from 96-117% of proof load at 60 ft-lbs. If you put something slippery (like anti-seize) on the threads, I would not be surprised to see head bolts commonly getting yielded at this level.

[So Cal Mark]

if the gasket burned through between 2 cylinders and not into a water jacket, you may have a head that's not flat or detonation rather than a heating issue

[hayesbd]

Mark,

As i mentioned, it was running a bit hot and I think my problem was the integral thermostat/housing (old in-head style with a non-replaceable thermostat element). From the indications of the temperature gauge, it would typically heat up, overshoot the steady value and then after a few miles, would quickly snap back to the normal running temperature. After looking at the thermostat housing seat, I concluded that it was sticking in the soft aluminum. I have now modified the thermostat housing to work with a conventional (and easily replaceable) in-head thermostat.

Another problem I found was that that of valve recession on cylinders 2 and 3. I had very little exhaust valve clearance which would also explain some of the hot running conditions. Fortunately, the seats are not burned as it still holds fine with a compression check. From what little research I found regarding hardened valve seats, it seems that Fiat may have switched to them during this 1973 model year, so perhaps that may explain the seat wear. Recommendations, anyone, on a fuel additive? Or should I just look for another head and send it out for a complete re-build with new hardened seats?

I checked the head flatness and it was out only about a half thousandth, so I don't think that was a problem.

Thanks,
Brian

[hayesbd]

Hi all!

It's been a rather busy time for me for the last few months (medically) and unfortunately, I have not been able to get much work done on this issue. I have been unable to start the car after replacing the head gasket and after re-running the compression check today, I got the following:
Cylinder 1 - 145 psi with a quick rise to this value
Cylinder 2 - 110 psi with a slow rise
Cylinder 3 - 120 psi with a slow rise
Cylinder 4 - 145 psi with a quick rise

Both the valve and ignition timing have been checked and were spot on (I even used a dial indicator to find TDC). The valve clearances are also in spec, but trying to start it produced backfiring through the carburetor. I pulled the head again and found no apparent issue with the block or cracks in the head, but will disassemble the valves to check the seats. I expect to find them in bad shape. Does anyone know for sure if the 1973 1592 motors had hardened (Stellite) valve seats? Is it a big deal to get a (good) machine shop to put new hardened seats in? Should I send this head out to a specialist (like you, Mark)?

Thanks for any advice!

Brian

[hayesbd]

After a great local machinist performed a nice 3-angle valve job, I finally have everything back up and running. The car is truly a joy to drive and makes some lovely noises even if I am not speeding . Unfortunately, as of yesterday, I am out of the driving business for two months due to seizures - epilepsy is not much fun and I don't recommend it. I will be able to drive again right when salt goes on the roads here. Oh well, things could be a lot worse! Now is probably a good time to start attacking rust and ordering new tires...

Cheers,
Brian

[phaetn]

Glad to hear the car got sorted out, sorry to hear about your seizures.

In my province, it's a year of being seizure-free before you are allowed back on the road if your license was pulled. (Depends on the MD if they do the paperwork or not). I had to drive a colleague to work and back a lot a few years ago b/c of seizures.

Onto Fiats: I, too, took my 1800 head to a machinst and got a 3 angle valve seating. So far so good! I hope to autocross the car next year but we'll see.

Cheers and stay in good health,
phaetn