Installing New Head Gasket

E

Ed in Maine

Well-known member
I am in the process of installing Helicoils and a new head gasket. I know the head studs should be snug in the block but when you are setting their correct height how do you get them tight if the hole is too deep in the block? Should a small shim be placed below the stud so that they are at the correct height and can be tightened in the block?

When torqueing the head nuts to 55 ft-lbs. should the nuts be torqued when the engine is hot, warmed or cold for the second, third and fourth trials? Over the years after replacing head gaskets, I have run the car for 5 minutes with the new head gasket, stopped the engine and retorqued. Then run the car for 10-15 minutes and repeat the procedure. I do this until the torque settings remain at 55 ft-lbs. What other procedures are you using that have proved successful?

Thank you for your suggestions. Ed
 
They don't have to bottom out. In fact some builders suggest that they are actually backed off a half turn. It is the nut that you are tightening to specs.
Remember that one stud, the one that holds the distributor clamp to the head is a bit longer than the other short ones. I missed this once and put the longer short one in the wrong hole. Wasn't using the cable clamp anyway, but it was one of those oops that I noticed every time I opened the hood... Chap
 
The first sequence of torquing is done with the installation. Most recommended is something like 35, 45, 55 pounds. If using a high compression head, final torque should be 65 pounds. However, the two studs for the water neck should stop at 55 pounds.... Then, After running the motor and driving it for 50-200 miles, allow it to cool down... perhaps overnight. Then while cold, re-torque to the 55-65 pounds.
 
Ed in Maine said:
I am in the process of installing Helicoils and a new head gasket. I know the head studs should be snug in the block but when you are setting their correct height how do you get them tight if the hole is too deep in the block? Should a small shim be placed below the stud so that they are at the correct height and can be tightened in the block?

When torqueing the head nuts to 55 ft-lbs. should the nuts be torqued when the engine is hot, warmed or cold for the second, third and fourth trials? Over the years after replacing head gaskets, I have run the car for 5 minutes with the new head gasket, stopped the engine and retorqued. Then run the car for 10-15 minutes and repeat the procedure. I do this until the torque settings remain at 55 ft-lbs. What other procedures are you using that have proved successful?

Thank you for your suggestions. Ed
Click to expand...

Ed, any good quality thread sealant used on the stud and threaded inserts will hold them firmly. Lowes or any parts store will carry something that will work.

If you will use a dial caliper to measure the thickness of the cylinder head stud hole (-from the area where the nut seats all the way thru to the gasket surface), and then add that measurement to the thickness of an uncompressed head gasket, -followed by adding both those numbers to the thickness of the head stud nut, this will give you a pretty close measurement to know how much of the stud to leave sticking out of the deck surface. Once the head is torqued and the gasket is compressed, you will likely see about a thread protruding thru the nut as prescribed in the JS & RG book.
 
Hi Ed, Here's a quick easy way that I do it (assuming you have checked for piston to head clearance already).
Be sure the threads are cleaned with a proper thread chaser, not a tap. A tap will remove metal from Henry's nice thread fit.

Use anti-seize on the coarse threads that go into the block. The don't need sealant as the holes are blind, but you want them to come out when needed.
As chap52 said, bottom them out, then back off a tad (for now).
Slide the head on without the gasket and set a nut beside a stud and turn the stud until it is two threads higher than the nut.
When they are all done, remove the head, now install the gasket and head.
Squirt a drip of 30 weight oil on each stud and install the nuts. You may need to stop the stud from turning with a small slotted driver.
This method should have the round portion of the stud just poking above the nut.


Hope this helps!
 
AroundTheBlockEngines said:
Be sure the threads are cleaned with a proper thread chaser, not a tap. A tap will remove metal from Henry's nice thread fit.
Click to expand...

Thank you for mentioning this! I was taught this in High School machine Shop. I see so many people chase threads with a tap... And a set of thread chasers are so inexpensive.

And welcome to the Barn.
 
I use a touch of anti-seize and set them finger tight in the holes. Use Brent's method of measurement if you insist on absolute correct height. Through the years the deck has certainly been shaved and the head sits whatever thousands lower, hence the studs will poke out a but higher above the head. (Measure the block height to be precise. Then you get into gasket thickness per Brent......)
 
AroundTheBlockEngines said:
Hi Ed,

Use anti-seize on the coarse threads that go into the block. The don't need sealant as the holes are blind,
Click to expand...

Last month, I was tidying up a motor that has done who knows how many miles. It has been sleeved and is out to +0.080" again. While cleaning out the water jacket, I found 2 chunks of cast iron - both from someone screwing the head studs in too far and breaking out the bottom of the hole. Butchers!
I simply used some thread sealer, put it together and I'm sure it will be right now till the sleeves have to be replaced when I'd be happy to do the same thing again.
 
"Be sure the threads are cleaned with a proper thread chaser, not a tap. A tap will remove metal from Henry's nice thread fit."

A properly threaded hole should NOT have any rust or corrosion in it at assembly time. If a threaded hole is rusty and corroded, a "chaser" will not clean it out down to bare metal which is needed to achieve proper torque value on the fastener.
If you tap the holes in a machine that will hold the tap straight and rigid, ARP studs will fit perfectly. Studs should NOT be bottomed in the threads. They should screw in finger tight and backed off 1/2 turn. Depending on whether you want water seeping or not, you can use high temp. RTV on the threads and let it dry overnight. The RTV does NOT dry rigid so the studs will self align when torqued.
This method along with another mod will hold 100 ft. lb. of torque if you needed it.
 
As others have mentioned the nuts in this case should be lubricated with a good heavy motor oil and if you don't have a diagram showing the torque pattern, years ago one instructor told us that torquing a head gasket is like spreading out a piece of paper! He told us that if you don't have a pattern in a shop manual, a circular pattern spreading outward will work. Start in the very middle and move from bolt to bolt in a clockwise circular pattern. Don't start on the ends but instead start in the middle and work your way out! A much lower torque at first and higher in steps until the final torque. When to retorque? Cast iron heads you bring the engine up to normal operating temperature and then retorque hot. Aluminum heads you bring the engine up to normal operating temperature and allow the engine to cool to room temperature and then you retorque. Aluminum expands at three times the rate as cast iron and retorquing while fully expanded is not good.
As Pete mentioned the threads MUST be clean! If they are rusted and dirty this will cause drag and give a false reading fooling you into thinking they are tighter than they really are. They should turn freely or glide as you turn them and clean, lubricate and turn with fingers until they feel right and if not repeat until they do! Don't forget to lubricate under the head of the bolt as well. When the torque increases there will be drag between the bottom of the bolt head and the surface of the head, washer if used and the bolt!

There is never time to do it right but there is always time to do it over!

PS
Make sure the surface of the head and block are also spotless and clean of rust, dirt, any gasket material as well. A razor blade scraper works good as well as a fine sandpaper using your finger tips until a shiny surface is obtained. Roloc pads are great but don't stay in one spot but keep moving so you don't damage the surface.
 
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