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



Latest News!!!!!!!




Who is MRM?



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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

*”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

* “Hardware Pack” for Monster Miata kits: All the bolts, nuts and washers you need in one rather heavy box (not everyone has an Ace hardware near by…)

500 TFI Kits Sold!

We can hardly believe it ourselves but we have finally sold 500 of our popular TFI relocation kits! We now have customers using our kits as far north as northern Canada and as far south as the outback of Australia! Thank you everyone who has trusted our kit to keep their TFI cool!

About Jumper Harness Length: Although the standard length of our pre-made, no need to learn to solder, jumper harness is at least 36” (we cut our wires at 48” before we start building them), we are, and always have been,  more than willing to build it to whatever length you need.

You are not limited to a 36” Harness!

We choose 36” as the standard length because it places the relocated TFI within the engine bay. We have seen very bad things happen when TFIs are relocated in places where they can encounter moisture. We DO NOT recommend relocating it in front of the radiator! Unrelocated TFIs fail because they are using the distributor as a heat sink which is actually transferring heat the other way: into the TFI from the engine. Simply removing it from the engine is all that is needed to alleviate the problem. Locating it in front of the radiator, installing a fan, etc. is not necessary! Our TFI on our blue car survives 7-hour endurance track events on 90+ degree days in the engine bay only mounted to one of our heat fan.


For more info...


Visit our TFI page for more info


AC Conversion Kits now UNIVERSAL!

We’ve taken our popular AC hose conversion kit and made it universal to all 1990—2005 Miatas using Fox body Ford Mustang accessories. We did this by adding 24” to the high pressure line so that it can wrap around the radiator core without the need for a 1990-93 aluminum hard line.

Check it out here

We Now Modify 1994-95 “SN95” Mustang Harnesses

With the help of a few pioneering customers we’ve developed the ability to utilize an  SN95 harness as the starting point for your V8 Miata conversion. The pricing is the same as our standard Fox body conversion prices.

More info here

Our ‘94 Laguna: FOR SALE!

Its been a fun five years with our 1994 Laguna 331 Miata but now its time to let it go. We’re planning on cleaning up a few details on it and then offering it for sale in the spring. If interested let us know!

Sorry, no more Drive Shafts...sort of

While we’ve enjoyed offering aluminum drive shafts to our customers the increase in offerings from other sources as well a change in agreement with our supplier has led us to make the decision to no longer stock drive shafts. If you still need one we may be able to get it for you but only in orders of two. Since most people do not need two drive shafts this means in order for us to get one for you you’ll need a “drive shaft buddy”. If you are still interested let us know near the start of your build time and we’ll let you know when someone else is ready to pull the trigger. If that does not happen we are more than happy to lead you to some other drive shaft sources.