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Kev writes: "There is a company that makes faux ones that snap over your existing head bolts."

That is EXACTLY what i was going to recommend, especialy had acorns not been "legit". I use the snap on type with good success. Need to use some RTV sealer or cement to secure them.

Lets see, the head studs on the Packard 8 are 7/16-20.

That's a pretty hefty size and should hold up pretty well. I would check the stud height using an ordinary hex nut. I would also dress the threads with a thread chaser - not a die. After that I would chuck a grade 8 bolt up in a vise and do a yield test using a good torque wrench. If the fasteners are junk then they should strip out.

I'm not doubting that crummy merchandise is being sold, but if there is a problem I would throw grade 8 nuts on the motor and run it. Acorns can be put on later.

Also, torque wrenches need to be periodically tested. I have seen torque wrenches fail a calibration test because they are certified worn out junk.

Torque Wrench check how to???
I have used the micrometer Torque wrench before and wondered over it's correctness. I may be a bit old school but I like the old bending rod with a needle style. I know even this styles measurement can change can change with age and use. I just have more confidence in the older style.

Any way how do I check to see if it is correct.

If you're asking how do you check a torque wrench, it's not hard to at least be sure you're in the ballpark. As an example, 50 lb-ft of torque is a 50 lb. pull at a length of 1 foot. So locate a fish scale of appropriate range, check it by hanging a known weight on it. and then use it and a 1 foot length of extension or other fixture, pull to 50# and see what the scale on the wrench says.

PS - I too prefer the old scale and pointer torque wrenches, too many folks (myself occasionally included) forget to crank the spring back to zero for storage on the dial-up type.

Obtain a SECOND torque wrench. Use a socket, usualy a 1/2" drive 1/2" 8 point or 7/16 12 point socket will work. Place the socket on one torque wrench and insert the other end of the SECOND torque wrench into the 8 point or 12 point recess of the socket.

Twist them against each other and check the readings on BOTH torque wrenches.

I hesitate to add the following but will anyway:

The 'clicker' , preset or so called micomenter torque wrenches are primarily for mass production or high volumn work such as in dealerships where mechanics are working on commision and quite frankly don't realy give a shit. Get it torques up FAST to get onto the next job. It's someone elses car.

For custom engine work the old bending bar type are best EVEN if off by 5 pounds. It allows for rather ez torquing 10 to 15 pounds ata time thru out the sequence of bolt pattern.

The clicker type wrenches also have rather large head on them so they are not applicable to tight spaces.

The clicker type are strictly for production "close enuf for rock'n roll" type work or for the shop that just needs a lot of that Snap-On chrome for bragging rights or to impress a girl scout troop on a field trip thru the shop.

Back in the late 60s and 70s when I was in the Navy working on the LTV A7 aircraft we used the micrometer type torque wrenches exclusively. The bending bar type were not used at all. I often wondered how accurate and more so how repeatable the micrometer type were. They were sent to calibration on a regular bassis.

Just for clarification, the "bending bar" style ones are called Beam torque wrenches.