308 Cylinder Head Torque Sequence
I did a search for this topic, but did not find any. I am ready to replace the head gasket and cylinder head (cast iron) on my '54 Hornet.
I have the original factory torque sequence, and also one from Clifford Research that was supposedly improved over the factory. Anyone have any suggestions or opinions on this?
Thanks, Scott
I have the original factory torque sequence, and also one from Clifford Research that was supposedly improved over the factory. Anyone have any suggestions or opinions on this?
Thanks, Scott
0
Comments
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The approved factory update method has you do the center row first, working alternately from the middle bolt to the front and rear, then the right side row in the same manner, then the left side row.0
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Here is a chart--
Also a tip sent to me from Rudy Bennett--Use a MOPAR Hemi crank pulley bolt and washer for the Hudson pulley and it will never come loose (ARP-245-2501 KIT) IT IS GRADE 8. The hudson bolt is soft and it will stretch.
I was looking for this note from Ivan Zaremba and just found it, also some good info on the head torque question--Jack Clifford gave me good advice about torqueing a Hudson head. Use Copper Coat (or aluminum paint) on both sides of the gasket lightly, sealer like Permatex on the bolt threads and motor oil under the head of the bolt. Initially, use the standard shop manual sequence and a lower torque figure like 40 ft/lbs, but after the first 9 fasteners are done, go back to the beginning and go over them in sequence again and then go on to do the next 6. Then go back to the first one again and do the 15 again and continue through the last 6. Then repeat the whole 21 starting at the beginning. Now you are ready to move the torque value up to 50 ft/lbs and go through that “wave” technique to insure that the head pulls down evenly. Increase the torque and repeat until you reach the final value. Walt Mordenti would tell you that letting the torqued head sit overnight and repeating the final pull in the morning is the thing to do!
Another note from Ivan---
After starting the engine and bringing it up to normal temp with the thermostat opening and water circulating fully, shut it off and wait at least four hours for it to cool off and do the first re-torque.
The re-torque does not involve the “Clifford Waves”. Just back the fasteners off 1/8 to 1/4 turn pull them to torque. I mark a line crossways on the heads of the fasteners with a felt pen after the first heat cycle and re-torque. This gives a visual indication of the change as the head gasket “comes down”. Basically, when you re-torque and all the fasteners stay with the marks in the same position, you are finished. The Best gaskets do not require as much re-torqueing as the NOS Felpro and the original type gaskets.
I do it after the first heat cycle, after 25 miles, after 100 miles, and again after 500. The Best gaskets do not seem to change after 100 miles and three re-torques.
Sounds complicated, but results are worth it!
Cheers,
IvanI have worked with aluminum cylinder heads for fifty years without “wearing out the spark plug threads”.
Anti-seize—sure! Torque them in another iron head—Bah Humbug! Just torque them to the recommended figure. The need for re-torqueing the head multiple times at intervals until it does “come down” any further is also key. I don’t think I consider it done until after 500 miles of running and 3,4, or 5 torque sessions.
The corrosion and erosion issues with aluminum heads are real. They can be dealt with by using distilled water with coolant and, additionally, not letting the engines sit dormant. The curious chemistry of the corrosion inhibitors in coolants/antifreeze is such that at the location where electrolytic corrosion occurs between dissimilar metals, those inhibitors are consumed locally. The coolant must be circulated by running the engine to leave coolant with inhibitors in the problem areas. That is why vehicles that are driven daily or regularly do not have this problem and “hobby” cars that are run occasionally do. You may have noticed where a radiator hose is clamped over an aluminum part (and there is therefore no circulation) you always find the white aluminum corrosion evident. So change the coolant annually and run the engine to open the thermostat weekly. Some restorers actually paint these areas under the hose with an epoxy that shields the aluminum. Such is my work world—that where $50K engine overhauls are common. Check out my company website: http://www.philreillycompany.com/index.htm0
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