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Subject: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS

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Tim Daley(MI)    Posted 09-07-2018 at 17:57:42 [URL] [DELETE]        [Reply] [No Email]  
  • CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • FYI: -The N-Series Cylinder Head used a stud and hex nut until mid-8N production and then switched to just a hex head bolt. The head has 18 holes with 15 being the same and 3 being deeper. The switch to the hex head bolts made it so one size was used on all 18 holes. Torque specs differ for the 7/16-20 hex nuts used with the studs and the 7/16-14 x 2-3/8 Hex Head Bolts. JUST8Ns offers just the bolt 'like original' at $5 each. STEINERS offers the 7/16x 3" STUD at $4.50 each. I found better sources for the studs and hex nuts -see LINKs below that are perfect and the price is good at about $31.80 for 20 studs, $39 with shipping. The length is 3", more than the OEM, but you can grind down the ends to match. MPC lists 15 at 2.78"L and 3 listed at 2.9" L. Caution is advised to ensure the thread length isn't too short or too long. You do not want the stud to bottom out on the non-threaded shoulder nor not have enough thread for the nut. The OEM hex nuts have an 11/16" AF dimension too with a 7/16" thickness. I could not find any hex bolts like the original other than the ones Just8Ns sells at $5 per bolt, specially made with 11/16 AF hex head and length at 2-3/8. McMaster-Carr sells a 7/16-20 Hex Nut, Grade 9, exact of original with 11/16" AF and 7/16" thickness. For the costs involved, I'd opt for the studs and hex nuts. Total 20 STUDS = $39.00 + 20 Hex Nuts at $15.76 per 20 pcs, shipping extra. I also found another source for the 7/16 x 3" studs at Mid-States Bolts -p/n 9732.

    OEM style hex nuts: https://www.mcmaster.com/95036a037

    Tim Daley(MI)

    K.LaRue-VA    Posted 09-09-2018 at 22:10:30 [URL] [DELETE]        [Reply] [No Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • It may be a good tip for some that the main reason the torque is less for the cylinder head nuts than for head bolts is that the nuts are fine-threaded. The same clamping force is achieved with much less torque when fasteners are fine-threaded. Over-torquing those fine-threaded cylinder head nuts is very bad. Substituting non-original hardware may result in having coarse threads on both ends of the studs. In that case, the torque for coarse-threaded cylinder head nuts would be the same as for bolts.

    I found a solution for the occasional special 11/16" hex head nut needed to make a full set. I bought several scrap random lengths of 11/16" hex steel bar. Cut off a little fatter than needed, grind until it's the right size/shape, center bore, and tap for whatever thread is needed. Of course with my small lathe it is much easier to drill and tap an inch or two, then machine off as many as needed with that thread. On the lathe, it's not too hard to get the chamfers to look exactly like the original hardware. This works for ungraded hardware. I don't have any way to accurately heat treat, so I won't be making any cylinder head nuts.

    Tim Daley(MI)    Posted 09-10-2018 at 04:12:27 [URL] [DELETE]        [Reply] [No Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • It's always cool to make your own stuff. I made some exact-as-original 351505 flat washers years ago, better than originals actually as I used H13 steel. I had setup and programmed a Mori-Seiki CNC Lathe to turn them complete, with a bar feed cycle and all. I ran off a few hundred and still have a whole bunch. I've made coulter hub bearings, washers, and caps too. My biggest endeavor was to use same CNC process and machine using 1-1/16 hex collet pads to produce the thick Ford 33806 Hex Nuts. I purchased a 1-1/16 hex length of 8620 steel and ran off a supply. I had also acquired a set of 5/8" hex and 11/16" hex collet pads for making other Ford exact hex nuts but never had the chance to. Torque is determined by the fastener material type and thread size. The Ford head torque spec chart I posted designates each the 7/16-20 Hex Nut spec and the 7/16-14 Hex Bolt spec. What I dislike the most about today's hex nuts that are made in Cheena is they don't use the SAE system of marking heads with the lines to designate the Grade. They all now have a mfg logo and/or code so you have to guess what grade they are long after they are in use. Being made in Cheena, how do we even know if their process is correct anyway? They have no Quality Control or even any process control. I recently bought some fasteners, made in Cheena, and no where on the box does it have the Grade 8 listed. When did they change and why did we allow this to happen? Maybe President Trump will fix this too!

    Tim Daley(MI)

    Farmer Dan    Posted 09-08-2018 at 14:38:32 [URL] [DELETE]        [Reply] [Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • I may still have the original studs from my block if you can trust a 78 year old stud. We can look next time your over here.

    Tim Daley(MI)    Posted 09-09-2018 at 15:29:55 [URL] [DELETE]        [Reply] [No Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • OK - we may never use them again but always good to have the OEM part for reference. Once material gets plastically deformed, it reduces characteristics like tensile strength and can also affect torque values. Rust, dirt, oil, all contribute to inaccurate torque readings. Next time I do a block I will invest in the exact hex bolts Just8Ns sells. I've seen some snapped off studs in blocks that take a specialist to retract without boogering up the cast iron head threads. The studs are hardened steel.

    Tim Daley(MI)

    Tim Daley(MI)    Posted 09-08-2018 at 09:34:40 [URL] [DELETE]        [Reply] [No Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • Although this option would be more expensive, if I was doing an engine rebuild, I would replace the studs and hex nuts with an exact-as-original 7/16-14" x 2-3/8" Hex Head Bolt that JUST8Ns makes and sells -see LINK below. The bolt is the exact length of the original with the AF dimension of the head exact as original too -11/16". They are specially made according to Derek, Grade 8, and thus why the $5.10 price tag per unit. Not even McMaster-Carr makes one close. They have Extra Wide/Heavy Head ones but have none listed in the 7/16 thread size. The Hex Head bolts have another advantage too -you can use them in all 18 holes. With the studs, 15 are 2.78" long and 3 are 2.90" long. Also, you don't want to use washers either. OEM's never had them plus they will affect your torque values. Finally, here's the original Ford 4-Cylinder Flat Head torque spec chart for use as a guide. Be sure you know specs are different for the 7/16 hex nuts than the 7/16-14 hex bolts and how to set the value in the correct scale. The chart lists values in Foot-Pounds. Torque wrenches can have scales in one, two, or all of these: Inch-Ounces, Inch-Pounds, Foot-Pounds, Meter-Kilograms, or Newton-Meters. Your wrench should have an instruction sheet with the conversion formulas on it for all. Know the proper use of a torque wrench and the correct method to torque a fastener -in three steps. Take the nominal finish spec, we'll use 54 Ft/Lbs in this example. 54/3=18. Set scale to 18 Ft/Lbs for the first pass and follow torque sequence from chart. For the 2nd pass set the wrench scale to 36 Ft/Lbs and repeat sequence. For the 3rd and final sequence pass, the scale is set to 54 Ft/Lbs. NEVER use a torque wrench to loosen a fastener with -it'll ruin the lead screw and give inaccurate readings. Always loosen the locking ring when making an adjustment. Always turn the thimble back a few revolutions and slowly advance towards the main scale setting number you wish in order to keep the backlash out. Always be sure to lock the ring once setting is reached. If wrench is not to be used in a long while, loosen the locking ring and turn thimble back to the lowest setting and keep well lubed.

    FORD N-SERIES TRACTOR FLATHEAD TORUE SPEC CHART:


    Tim Daley(MI)

    Steve Dabrowski    Posted 09-10-2018 at 14:19:12 [URL] [DELETE]        [Reply] [No Email]  
  • Re: CYLINDER HEAD STUDS, HEX NUTS & HEX BOLTS
  • I've read that the studs on Ford flathead engines have rolled threads so you should not chase the threads in the block using a regular tap as it will screw up the sealing capability of the stud or the bolt. When doing my 8N engine I removed the original head nuts and studs primarily because I installed new sleeves and the engine had had a head gasket leaking problem and I wanted to surface the block to bring the sleeve tops to the same level and ensure a good sealing surface. I also had the head surfaced.

    I reinstalled the original studs after giving them a full wire brush cleaning. I cleaned the block threads using lacquer thinner, a pipe cleaning brush from Home Depot that I cut off to use in the drill followed with a cloth patch on a pistol bore cleaning rod giving very satisfactory results. I reinstalled the original studs using aircraft gasket seal and torqued them into the block using 10 ft-lb torque. I let them set up overnight before installing the head using the original head nuts and torquing in increments to 55 ft-lbs with a Felpro soft gasket. I had a gallon tank that set up allowed me to start and run the engine less the hood and I warmed the engine after the final torque to operating temperature and let it cool fully overnight and re-torqued to 55 lt-lb. After five cycles of doing this the nuts no longer shifted with the torque and I considered it complete and have no further issues.

    I doubt the the bolts, studs or nuts suffer much from the relatively low torque values on these engines and I suspect they are equal to a class 5 fastener in strength. One should consider that these were designed to be worked on,
    literally, in the field by farmers and others and the fasteners reused, so I doubt there is much of a strength issue as head gasket changes as well as bearing changes were pretty routine in those days. I prefer the studs and I have also seen several posters on some of the Ford flathead engine blogs complaining of leaking studs after assembly with replacement studs.

    I recall in my high school days we built 48 Merc blocks with Edelbrock heads, Isky cams, shot peened stock rods and 0.60 overbore with fairly high compression ratios (for the time) and just reused our original head nuts and rod nuts never thinking more about it. Of course we had those nice slip over chrome acorn nut simulators to dress up the heads!

    Just my 2 cents.

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