Hemi Motor Mount Location for Mopar Performance block

[AJ Rettenmaier]

I have a now assembled 426 Hemi from a Mopar Performance Block. The holes for the Hemi Motor Mounts are not drilled and tapped. Can anyone help locating the stud holes and depth?

 

[tonysrt]

You might be able to use the elephant ear mounting plate that goes behind the water pump housing, because drilling and tapping the block would have to be done with some kind of template and of course somebody capable and knowledgeable of doing such a project. I have a hemi in a 71 Cuda and mounts have to be placed pretty accurate cause there isn't a lot of room to make a mistake. Good luck with this problem.

 

[MoparCarGuy]

You can likely locate the holes using conversion motor mounts and mark the holes in reference to the block's machined casting features. The conversion motor mounts allow you to mount your Hemi on a non-Hemi K-frame. Small-Block A-engine and Big-Block B/RB-engine K-frames are the same for E-bodies.
You can use the conversion mount brackets to locate the holes on the machined pad of the block. The drill bit size is 23/64" (nearest fractional bit) for factory 7/16"-14 NC (Coarse thread) bolts but you may want to work up to the correct 23/64" hole in 3 stages starting with a 1/4" drill bit and then a 5/16" drill bit. Measure the bolts in the conversion mount kit for length (below the bolt head to the end of the bolt) and drill the hole depth to that length using a drill bit stop collar to prevent drilling too deep. Use lots of oil for drilling and tapping and take your time as this is high-nickel iron and murder on drill bits. You may need a several 23/64" bits to make drilling go faster.
Next, tap the holes using a new bottoming tap (7/16"-14). The motor mount bracket thickness prevents the bolts from bottoming out.

Here is a link for the mounts and some good photos: BCE-Body Hemi Installation
The below diagram shows some measurements for these holes and should not be that difficult if you have the brackets in hand to mark them using a center punch.

Hope this help out. Let us know what you end up doing.