McCully Racing Motors

Welcome to McCully Racing Motors!

McCully Racing Motors

Allentown/Barto, PA

To Order email or call the following:




Phone: 267.254.6687



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Because two heads are ALWAYS better than one.

In the Works:

* “MS3 Plug and Play Harness” A plug and play harness that can be used to add a MS3 with MS3X board to any 5.0, 331 or 347 Mustang or Miata-still working on this-stay tuned!

*”Tech Pages” here at MRM to guide you through some difficult areas of the conversion process

* “Customers’ Rides” section featuring some of the machines MRM parts have helped get on the road


850 TFI Kits Sold!

We It took five years to sell 500 kits and a little over a year more to hit 850! We are glad to have been able to help the owners of that many older Fords keep their TFI Equipped vehicles on the road and track!

Two new TFI kits Available!

We’ve been working on two more versions of our popular TFI kit over the last few years and are now ready to include them in our line of TFI relocation products.  The first is an all-in-one Jumper and TFI extension kit we are calling the:

 “MkIII” TFI Relocation Kit.

This kit combines the old TFI wire extender we offered in the past and our standard jumper harness to make a complete OEM-looking plug-and-play kit. More information can be found here:

Check it out here

Our second new offering addresses the concerns of those who have asked for a way of covering the distributor connections of our jumper harness as well as those who want a more OEM look to the distributor end of the TFI relocation. Rather than make up a little panel to cover the connections why not just use a plug like Ford did in 1994? Introducing the:

SN95 Distributor Conversion Kit

This kit allows you to retrofit a distributor from a 1994-1995 Mustang into your earlier Fox body 5.0 without any cutting or splicing.

More info here:

Check Check it out here out here

New “Square” 1.9 Liter Bottom end

Success with our 2.0 liter bored and sleeved bottom ends has led us to develop a second option for those seeking greater displacement. The 1.9 utilizes a 85mm bore which does not require a sleeve, greatly reducing cost while still increasing displacement.  As an added bonus the resulting geometry creates a completely square engine (85mm bore x 85mm stroke).

More info here

We’re Going VTEC

At this point we’ve built four Ford V8 Miatas, rebuilt or finished another six, and made harnesses for about seventy customer’s Ford V8 builds. We’re looking for something new. Recently a kit became available to mount a first or second generation Honda J series V6 in a Miata. The kit keeps the majority of the Miata driveline and uses a unique adapter/engine mount unit and a custom front subframe to make it all work.  We’re going to begin a build using this kit in the late summer/fall of this year. As usual, we can’t just do it the way the kit designer intended. We’re going to be passing up the Gen 2 J32a2 and J35a4 the kit was designed for and jump up to a J32a3 from a 2004-6 Acura TL. This engine offers several advantages over the earlier engines including 270hp/249tq, integrated exhaust manifolds, cam/crank sensors that work with Megasquirt III, and very light/lower/better flowing intake manifolds. We’re also going to try to keep the 1999 donor car’s OBD2 functionality intact by running the MS3 ecu in parallel with the stock ecu. If all goes as planned we’ll have a formula that can be used on any 1990—2005 Miata to gain power similar to that of an early Ford 5.0 swap for about 1/3 the conversion cost. As we have with the Ford 5.0 conversions, we should be able to offer to our customers anything that we use beyond the basic kit so that they can emulate our work (harnesses, throttle body adapters, MS3 tune files, etc.).