You won't believe how much these cost. Take a guess...

[FElony]

$216.80 each for the samples, $25.12 each for a quantity of 300.

I think that is simply ridiculous.  I have to supply 10 of each of these with each pair of cylinder heads.  That will increase the cost of the heads by $250!  Unacceptable.  I will be finding a different alternative, even if it means making them myself.

This totals 11,872 bucks for the 20 + 300. This comes out to 3.96 per cheezburgr. I said $4 each. Could I possibly be more bitchin'? Don't you guys get it by now? Get that Cobra ready to roll, Jay. No whining about "plans" or anything. I'll be there on Thursday. Be happy I don't ding you for shipping costs.

[FElony]

No wonder I flunked math.  I forgot to take the Cheezeburger Constant into account.  Life must be endlessly fascinating in FElony world  .   You probably played Calvinball when you were a kid)).

Calvin was created in 1985, according to the Net. I was old, toothless, and senile by then. I've never heard of Calvinball until now, but it does sound like a game I could excel at. And for heaven's sake, learn how to spell cheezburgr.

[frnkeore]

I'm a retired aircraft machine shop owner. Your application doesn't require AQ specs so, I would suggest the following:

I assuming that they will have to HTed? You don't need 1 5/8 blanks, 1.5 is plenty. You will get 92 pieces to a 12 ft bar @ 1.50"

1. Use 3/4 Hex, 1144 steel, It's easy to machine and as strong and hard as 1045. You don't need 4140.

2. Change counter bore to 7/8" or turn the lower part to 13/16

3. Call the local job shops, in your area and get multiple quotes.

4. Call the heat treater's in your area and get a quote for that.

[jayb]

Frank, thanks for the suggestions.  Heat treat is easy, there's a big heat treat place near my house that charges $33 for up to 20 pounds of small pieces.  But I was going to go with ETD-150, which is a modified 4140 and is 130Kpsi as is, so no heat treat is required.  I will look into your suggestions, though...

[preaction]

Depth of thread only needs to be 1.5 times the diameter after that no more strength is gained.

[frnkeore]

A quick question: How are you going to oil the rocker shafts?

[jayb]

Through the pushrods.

[babybolt]

The price reflects California taxes and overhead including fancy new CNC machines - rather than a big old fashioned screw machine spitting out a part every minute at pennies a piece.

[WConley]

+1.  My guess assumed that ARP didn't want your business.  A run of only 320 small parts ties up a lot of design and setup time.  It's also opportunity cost for an expensive screw machine that could be spitting out many thousands of production parts a day.

I'm surprised the per-piece quote for the 300 was that low!

[Falcon67]

Dang, that's nearly 4 cases of toilet paper these days.

As above - having come from a background of manufacturing where we bought in smaller quantities and those lot sizes cost us dearly.  Not only in mechanical parts but PCB runs, PCB assembly processes, etc.  We did many things in-house because of the lot sizes.  You could look around for a smaller job shop that might be interested in work because orders may be thin right  now due to current conditions in the world. 

+1.  My guess assumed that ARP didn't want your business.  A run of only 320 small parts ties up a lot of design and setup time.  It's also opportunity cost for an expensive screw machine that could be spitting out many thousands of production parts a day.

I'm surprised the per-piece quote for the 300 was that low!

[Hemi Joel]

Jay, can you bore the holes in the plates from 3/8 out to half inch? that way you could just use a longer stud, and a regular nut to hold the plate and the head down simultaneously. Or else you could use just a regular 1/2" coupler nut to hold the head down, and then a short stud or bolt through the plate and into the upper half of the coupler nut.

[jayb]

I think getting longer than stock studs would be even more expensive than trying to get the nuts.  Also, room is real tight there, Joel, those are good suggestions but unfortunately not practical in this case.

[70tp]

Does the nut have to be smaller on top?   Maybe use a larger hex stock and leave the od alone or maybe turn the bottom or top part smaller if it gets in the way?   It’s easier to turn hex to round than to mill round to hex, at least for me. 

[jayb]

Does the nut have to be smaller on top? 

Yes, to allow clearance between the socket and the counterbore that the nut goes into.

[Hemi Joel]

Would you have to heat treat the nuts you make after machining?