Torque Plate Offset Bore

[donforeman]

Thank you for all the replies. I learn a lot here. The plate is going back to CCA when the post office opens up tomorrow. A big thank you to Mike for fixing something that he was not involved in producing.

[CCA Racing Products]

Just adding a thought here.
I always wanted the plate to be at least a little bit larger than the block bore to avoid issues when honing.
In this case there is a 73mm bore and 73mm plate where the plate is aluminum and the block cast iron.
That is not going to be a happy honing process.

...

Oh, and if it wasn't mentioned before the head locating dowels must be installed and used.

All my plates (and those sold by my predecessor) are 0.005" over the labeled bore size so you should be able to go to the labeled size without hitting (if the bores are in the right places!). I may change that, though, as I have run into a few instances of tolerance stack between the block and the plate causing issues with dowel fitment. I generally go 0.004" oversize on dowels for torque plates, and 0.0015-0.002" oversize for o-ring tool register plates. If the machinist has not corrected bore locations in the block during the boring process, obviously not having another 0.010-0.015" of slop in the dowels can be an issue. Some designs are constrained in the two planes using one precision fit dowel and one slotted dowel. I include this in my designs because obviously the factory understood their GD&T better than I do, so it is best to just copy what they specified for the OEM gaskets in most cases. All that said, I have found my customers to take a wide variety of approaches to this, which is why I custom cut every plate rather than having shelf stock.

As to the second point, what amazes me is that the vast majority of shops don't seem to use the dowels at all. I found out that the Buick design the old owner had been selling for fifteen years had the dowel locations reversed and no one had ever found out until this year when I had a customer call to point it out. Even he said the only reason he ever reinstalls the dowels for honing is when the finished bore size is very close to the plate bore size to make setup easier. There are also some designs (The Ford 7.3L Godzilla and the CAT 3116 come to mind) where the plate would be much larger than necessary for proper honing use just to include the dowels in the pattern, so the dowels are not included. I can't stock the larger material this would require, and these days getting it is hit or miss (especially because I only use US-sourced aluminum for my products).

I hope I don't sound like I'm trying to turn this into an advertisement, either. It seems like there isn't a ton of great info on torque plates and rather than just punching holes in aluminum I'd like to become a better technical resource as well. I'm glad I found this post - I just logged on on a whim to look up something Mike Jones had posted a while back and saw it. Divine Providence, I suppose.

[BlitzA64]

Hey CCA, pretty cool for you to stand behind this deal! Great customer service and advertising for your company......

[Dave Koehler]

I can't stock the larger material this would require, and these days getting it is hit or miss (especially because I only use US-sourced aluminum for my products).

Boy, isn't that the truth. I just placed a recurring stock order for some 6061 bar. I am sitting here stunned at the price increase over even last year.
I have to do some serious math to see if this is currently feasible to even make as it pushes the customer cost out the door.

[CCA Racing Products]

Yeah my 6061-T6511 from Kaiser or Service Center is up about 54% over the last 6-8 months. To be clear, I don't buy mill quantities, but these are the mills that my local vendors uses. Word is Service Center had to start buying some offshore ingot for alloying as domestic supplies are too hit or miss. The quality hasn't changed so I'm still alright with that. It got to the point in June that I had to increase prices to reflect the change in material cost, and I had to put a moratorium on new rental inventory.

That said, check out Howard Precision Metals; If they have a location near you I don't think you'll find a better (and cheaper) vendor of quality aluminum extrusion.

[CCA Racing Products]

Don, this is headed back your way today. Thanks for your patience as I've been swamped lately. To make up for the offset I had to enlarge the bores to 74mm. You should not run into issues using the gasket you sent along with it as there will be less than 0.020" of the fire ring uncovered.



Please let me know if there is anything else you need moving forward, and best of luck with the build!

[donforeman]

Thank you Mike!