Cylinder Head Retorque

[Joao46]

Hi. I have a 1931 Chrysler Imperial that the previous owner had recently replaced a head gasket , which for that engine (6.2 liter inline flathead) I would assume is a copper gasket.

 

After running it for a bit I noticed a slight leak of coolant from a spot in the rear of the engine. I retorqued the head and it was clear it needed it as most of the nuts turned a little. 
 

Leak went away, then I drove the car about 30 miles and ran the engine a few times in the garage as I tuned it.

 

Then as I revved the engine, checking the timing , I saw a small puff of smoke coming from one rear head nut. 
 

I again retorqued the head, noticed a little bit of movement on most nuts (much less than before) and the puff of smoke went away.

 

I’m assuming these little leaks I noticed were signs I needed to retorque the head, since it was recently replaced. 
 

Im just sharing this to get some of the experts here opinions. Do you agree these issues were just signs I needed to retorque the head? 
 
Or is there something more serious going on?

[Mark Gregush]

Did they use any copper coat sealant that you can see looking at the seam? I retorque heads several times after going through several hot/cold cycles. 

[Grimy]

Reproduction sandwich-style head gaskets with plastic rather than asbestos centers require at least five re-torques, in my experience, before all the potential "squish" is taken up.  When available, I'm happy to pay the extra money for NOS asbestos-center gaskets which generally only require one or perhaps two re-torques.

[c49er]

It will soon stop showing tiny signs of leaking on your 385ci. aluminum head Imperial engine after your re-torque's.

[EmTee]

I'd continue to check the cold torque as needed until it no longer requires tightening.

[DFeeney]

If you have the head off in the future be sure to check for flatness.   As many heat cycles as these old engines have don't be surprised if it out of spec.

[Gunsmoke]

curious what ft/lbs you are torqueing the head bolts. On my '31 Chrysler CD8 (240CI) I was advised to be cautious of over-torqueing after I did the valves and installed a new gasket (old style, copper asbestos). Gradually re-torqued in a set of stages, 50, 60, 70 lbs etc using sequence pattern recommended. I think my studs were 7/16". No leaks after a couple of warmups, but engine has not been run for more than a few minutes. I plan to re-torque after next run, but was advised to be careful about going above 75 ft/lbs, not sure what recommendation is for your engine. 

[keiser31]

1 hour ago, Gunsmoke said:

curious what ft/lbs you are torqueing the head bolts. On my '31 Chrysler CD8 (240CI) I was advised to be cautious of over-torqueing after I did the valves and installed a new gasket (old style, copper asbestos). Gradually re-torqued in a set of stages, 50, 60, 70 lbs etc using sequence pattern recommended. I think my studs were 7/16". No leaks after a couple of warmups, but engine has not been run for more than a few minutes. I plan to re-torque after next run, but was advised to be careful about going above 75 ft/lbs, not sure what recommendation is for your engine. 

I go by this most times....

[Joao46]

My head is iron and I was advised by a mechanic familiar with the car to tighten to 55 ft lb

[Grimy]

I agree with 55.  As the owner of three Pierce-Arrow 8s, I'm aghast at the 83 specified in Keiser's chart for those engines.  I torque my iron heads to 55-58 max.

[Joao46]

Speaking of torque, what about the wheels? My car has 7 lug bolts. Would 100 ft lb be too much?

[JFranklin]

My average wheel torque usually is 70 Ft#.

[John Watkinson]

Could Kaiser31 enlarge the torque settings for cylinder heads - Chrysler to Studebaker

Thanks

[keiser31]

31 minutes ago, John Watkinson said:

Could Kaiser31 enlarge the torque settings for cylinder heads - Chrysler to Studebaker

Thanks

I am having a problem with enlarging capabilities these days.

[JFranklin]

34 minutes ago, John Watkinson said:

Could Kaiser31 enlarge the torque settings for cylinder heads - Chrysler to Studebaker

Thanks

Have you tried enlarging it on your computer? I am able to read it on mine.

[John Watkinson]

Yes , I’ve enlarged the document but lost definition - I don’t want to guess the numbers . 

On 12/26/2023 at 4:14 PM, keiser31 said:

I go by this most times....

 

[keiser31]

5 hours ago, John Watkinson said:

Could Kaiser31 enlarge the torque settings for cylinder heads - Chrysler to Studebaker

Thanks

I can send it to you in a private message and maybe you can work with it.

[philipj]

I have been told that GM cast iron heads (In this case a 1936 Olds F36) can be retorqued hot, is that correct? By hot I mean 180F after running the car and shutting it off, or is that a no-no? There is also one method of loosening the bolt being retorqued (Is this the proper way?) at least one quarter turn before re-torquing, which I did not do... On the plus side, I was staying at a conservative 45 Lbs instead of the 60 Lbs recommended to avoid problems...

 

Lastly, can the original copper asbestos gaskets be reused?

 

 

 

 

Edited July 8 by philipj (see edit history)

[JFranklin]

Don't know about hot or cold but you need to torque to the proper specification listed. A copper asbestos gasket can be re-used if it is not damaged. 

[c49er]

385's I believe use 7/16" studs and 7/16" x 20 nuts...55" lbs  torque.

Do not over torque the head as the deck could be pulled up...possibly cracking the drivers side of the block.

Just saying...

[EmTee]

16 hours ago, philipj said:

There is also one method of loosening the bolt being retorqued (Is this the proper way?) at least one quarter turn before re-torquing, which I did not do...

That makes sense, as if the nut or bolt heat is 'stuck' to the head (e.g., due to corrosion) the torque reading would be artificially high.  Loosening the fastener 1/4 turn would break it free and allow correct torque to be read.

[philipj]

Thank you for the replies... A bit surprised but it is nice to know that I can re-use the copper/asbestos gasket again which was new and undamaged...Good news! I can also increase the torque to 50-55 Lbs. A little under what is recommended, but since the stuff is not new, I do not want to run into trouble again. I will stay a little under which should be all right...

 

As it is, I have to helicoil 2 more holes and I have a question about that...

 

1- Is it necessary to use permanent Loctite on the helicoils?

2- Can I leave the tangs in place if the length of the bolt will not interfere with them?

3- Is Permatex thread sealant # 80632 the best to avoid any leaks as opposed to #2 aviation sealant?

 

But back to the helicoil job, I said I did not want to run into trouble again, since I am pulling the head for the second time! I did two helicoils 1/2-20 before and had trouble breaking the tang off, which may have stretched the coils on the bottom and created a problem whereby I was very difficult to fully tighten the bolts... It is not the first time doing this job, but I have really never run into this problem before...
 

I have since removed all three helicoils and I will try a different brand, or leave the tangs in place... I also have to do two more, so I would like to get this right this time... I really do not want to pull the head a third time!

Original bolts on this head were 7/16-14, but someone redid all the bolts to 1/2-20... Luckily there is plenty of meat on these f-36 blocks, but you still have to bore the head to accommodate the bigger bolts... I don't really know why someone would choose to go this route instead of the right size helicoil, seems unnecessary having 24 bolts on that head...

 

The bolts holes with red paint indicate the problem areas before and after...

 

 

 

 

 

Edited July 10 by philipj (see edit history)

[68LTD]

2 thoughts:  use Evans coolant that can run with -0- lb cap.  Get a digital torque wrench, I will never use a clicker again.  Pricey but worth it. 

[Stude Light]

On 7/12/2024 at 4:51 PM, 68LTD said:

use Evans coolant

Careful with that. Evans has a really poor heat transfer coefficient- like 0.68 compared to 50/50 glycol water of about 0.8 and pure water of 1.00. Evans is also more viscous than water or glycol/water mix which reduces total flow rate. What does this mean?

 

In a cooling system with a lot of reserve capacity, Evans coolant may run just slightly hotter although the temperature of the internals (like cylinder walls) will run hotter. In a cooling system designed to just get the job done…due to all the weight, space and cost factors involved in automobile design AND in a system that is compromised from 93 years of use, Evans will run significantly hotter. While it may not “boil over” your engine will be running hotter than what it was designed to. I run pure water and No-Rosion in my early cars to get the absolute best cooling system performance but they have no freeze protection. In my cars requiring some freeze protection I usually run 25% glycol which gets me down to 15 deg F and very little loss in heat transfer coefficient. If it is a car that is going to be outside during a Michigan winter then 50% glycol and I give up 20% of my heat transfer coefficient.

 

While Evans gives you good corrosion protection and boil over protection I will never use it as a coolant in a car due to its poor heat transfer properties and significantly higher engine operating temperatures (I’m talking internals, not just what the coolant itself runs at).

[philipj]

Very interesting information about Evans coolant, thank you... I run regular antifreeze @ 50/50 here in Florida, but I see that it is not necessary... I am doing it more for lubrication and to keep corrosion to a minimum but it seems that I should cut it down to 25% for better heat transfer...

 

But I had hoped that someone would address the questions related to the topic which was cylinder head retorque/head assembly... I have the repairs done and everything assembled for the second time... I used permanent Loctite on the Heli coils set for a couple of days and re installed the head using Permatex thread sealant #80632 for the head bolts. I don't dare to go any higher 50 Lbs. of torque after 5 Heli coil repairs. I did have some "sweating" on some bolts before a retorque to 50 Lbs. but I did not get the car up to running temp again to see if I still have the same issue...I will drive the car tomorrow for a bit and check everything again...

Edited Tuesday at 08:33 PM by philipj (see edit history)

[Stude Light]

2 hours ago, philipj said:

Very interesting information about Evans coolant, thank you... I run regular antifreeze @ 50/50 here in Florida, but I see that it is not necessary... I am doing it more for lubrication and to keep corrosion to a minimum but it seems that I should cut it down to 25% for better heat transfer...

 

But I had hoped that someone would address the questions related to the topic which was cylinder head retorque/head assembly... I have the repairs done and everything assembled for the second time... I used permanent Loctite on the Heli coils set for a couple of days and re installed the head using Permatex thread sealant #80632 for the head bolts. I don't dare to go any higher 50 Lbs. of torque after 5 Heli coil repairs. I did have some "sweating" on some bolts before a retorque to 50 Lbs. but I did not get the car up to running temp again to see if I still have the same issue...I will drive the car tomorrow for a bit and check everything again...

I think the first 4 replies answered the question....you should do several retorques after a few thermal cycles. Do them cold. Regarding sealant...I prefer using Permatex #2 on head bolts that terminate into water jackets. I find it is more reliable than the thread sealant, especially after retorquing but you are probably fine.

 

[EmTee]

Just keep checking the cold torque before the next drive until they stop needing any further adjustment.  Beware any bolt that isn't requiring ever smaller twists with each cycle.

[philipj]

On 7/23/2024 at 7:54 PM, EmTee said:

Beware any bolt that isn't requiring ever smaller twists with each cycle.

Thank you for the advice, but what do you exactly mean here? I have retorqued the head to 50Lbs. and it seems fine, even though I did it when the engine was slightly warm to the touch... I know I should have waited but that can only mean that my values are off, yet I don't know how much or how bad it can be...

[EmTee]

I suggested always doing the torque checks coldfor uniformity.  If the engine is warm, the metal expands and not uniformly, as there are 'hot spots' here and there (e.g., in the vicinity of the exhaust ports).  If torqued hot, those bolts will wind-up somewhat tighter than others when the engine cools since those bolts expanded more with heat.  I don't know how big an effect that is (and it probably varies by engine) but if done cold, everything is at the same temperature.

 

What I have observed is when re-torquing the bolts is the first re-torque most all bolts will take some additional twist to restore the set torque (e.g., 50 ft-lbs) as the gasket settles in.  The second re-torque usually has most taking a smaller turn of the wrench, or none at all.  By the third cycle (i.e., day #3) maybe 1 or 2 bolts require a 5 ~ 10° turn.  From that point on, the torque remains at the set value.

 

If a bolt doesn't behave that way (i.e., it continues to require a 1/4 to 1/2 turn or more) then I would worry that either (1) the threads in the block are failing, or the bolt is being stretched past its yield point and is in the 'plastic' range where it has lost its elasticity and will stretch until it fails.

[philipj]

Hello EmTee,

Thank you very much for the explanation, makes perfect sense... Getting impatient can get you in trouble, but I hope that I did not over extend myself too much by not waiting until the engine was stone cold... I looked at the temp gauge at it was @100 or less, but your point about hot spots means that some bolts may be 55 Lbs. as opposed to 50 Lbs. in areas... Now how much that will affect a cast iron 2" tall flat head I don't know, but I would think I am catching a break since I am under the 60 Lbs. recommended torque... Again, to your very good point, some bolts will have more stress than others, but there are no leaks this time so I am inclined to leave it alone...

[EmTee]

Just check them all again when cold.  If the wrench 'clicks' at 50 ft-lbs without turning the bolt you're good.  I wouldn't worry about any that are actually 55 or 60; just get them all to 'click' at 50. 

[Frank DuVal]

Use a beam type. Never goes out of calibration, except for checking that the pointer points to zero when holding it in your hand. Bend to adjust. Done. $0.

 

Electronic digital or click types should be calibrated maybe yearly.  $80+ And, always set a clicker to the lowest rating when storing or it needs calibrating right away.

 

These bolts do not care if it is 54 or 56 ft-lbs of pull on them, really. You think anyone in the late thirties owned a torque wrench? 

 

As we used to say, Flame Suit on!🤣