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Old 10-11-2010, 11:46 AM
oldbogie oldbogie is online now
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Quote:
Originally Posted by kbuhagiar
Hello Folks,

On the small block chevy engine, which of the seventeen head bolts enter the water jacket (and thus need to be sealed)?

Thanks in advance.
They all do but check each and every one. The reason for checking is that you will be applying a thread sealer and if anyone hole happens not to be open any sealer ahead of the bolt that becomes trapped between the bolt end and the bottom of a closed hole will form a hydraulic lock as the bolt is turned in and this lock will have sufficient force to crack the casting at the bottom of any blind hole.

I have come to simply using Teflon plumberís pipe thread sealant. It is effective, doesnít form solid particles that can become dislodged and circulate with the coolant, possibly plugging small passage as it does. The Teflon sealant also has properties most similar to lubricating oil which is most often the thread lubricant used when torque setting that make the prescribed bolt stretch are established and published, however, when using none OEM fasteners carefully check with the manufacturer such as ARP for example as often their torque specs are made with their proprietary lubricant or sealer. So just take time to study up before crossing types and brands of fasteners and sealants/lubricants.

As has been sighted, the threads both male and female need to be clean and undamaged other wise they will give false torque readings which will be that the prescribed amount of torque will be reached before the needed stretch of the fastener is achieved. Brushing the threads to clean them and running a thread restorer tap or die to both clean and refinish them is a good idea. Thread restorers
Are not the same as thread cutting dies or taps. These tools are made from a softer material than thread cutters and are intended to clean and massage the threads back into shape, not cut new ones. Threads come in different specifications and most fasteners use a rolled thread fasteners rather than cut. So taking a thread cutting tool may greatly alter the dimensional and shape detail of the thread itself to some other than the OEMís design. While such threads will fir together by having the same overall diameter and pitch, the specific differences in the shape and dimension of the thread itself can compromise the contact area.

Donít forget to lubricate where the fasteners head makes contact with the surface being fastened, there is a lot of friction here and if left dry, like poor quality threads, it will lead to a falsely high torque reading before the fastener reaches its intended stretch. If youíre fastening aluminum, there needs to be a hardened washer between the fastenerís head and the surface being fastened, otherwise the fastener digs into the softer aluminum damaging the aluminum part and again developing a false torque before the needed stretch is achieved.

Bogie
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