Services​

WHY JMAC ENGINE SHOP?​

I can rebuild any British car engine but I specialize in the MG Midget/Triumph Spitfire 1500 engine and limit my focus on rebuilding only this engine, the Spitfire 1300, GT6 2000 and the TR6 2500. (Will I rebuild other British engines besides these? Yes, but we would need to talk about it.) I provide a clean, well rebuilt motor that will provide miles of smiles. I have done my homework. The 1500 had some design and manufacturing flaws that in many cases caused the motor to fail long before it should have. When I rebuild a 1500 I correct those flaws and build a motor that will last.

When I set out to rebuild my first 1500 I decided I wasn’t going to try for higher compression, more horsepower, or more torque. My goal was to build a solid engine that would be durable with just enough tweaks to give it plenty of “get up and go”. I’m not a speed shop, adding expensive lightweight connecting rods or roller rockers. I wasn’t building a race engine. I was building an engine that I could depend on for my daily driver. That first rebuild was still running well when I sold that car having put nearly 125,000 miles on it.

Though I can’t guarantee those kinds of results with every engine, I am confident that every engine I rebuild will provide years of great service.

Every engine is given a test run on my test stand for approximately 2 hours to insure it runs properly, builds adequate oil pressure and water temperature. Then I retorque the head and readjust the valves so that when you receive your engine, you too can have confidence your car will take you where you want to go.

SO, YOU NEED AN ENGINE (Two options)

​Option 1: Getting your engine rebuilt
​​If you would like for me to rebuild your motor, it must be shipped (SHIPPING) or delivered to my shop.
  • Rebuilding costs. These can vary greatly with the engine and the extent of the rebuild. Costs can range from $3200 and higher depending mostly on the condition of your engine. I will rebuild it, test it, then ship it back to you.
  • Please contact me for more information and details. Contact me
Option 2: Exchange your engine as a core for one already rebuilt
If you would like to purchase an engine that has already been rebuilt, you can find them under the For Sale tab.
  • At this time, I only stock Triumph Spitfire 1500 and MG Midget 1500 engines at this time.

JMAC​ ENGINE REBUILDING PROCESS

A complete rebuild includes the following:
EVALUATION
As an engine is torn down, each part is checked for excessive wear, damage and failure.
MACHINE SHOP WORK
Each engine I take to the machine shop is:
  • Magnafluxed for cracks in the block, head and crankshaft.
  • Cylinders are bored to the next oversize
  • Crankshaft is turned to the next undersize
  • Main bearing and cam journals are checked for wear and alignment. 
  • Connecting rods are reconditioned by recircling of rod big ends and new small end rod bushings are sized to the new wrist pins.
  • Head receives new valve guides, valve seats are ground, valves are replaced with new as needed and new springs installed.
  • The block and head are hot tank washed.
  • Balancing, from the crank pulley to and including the flywheel; the rotating assembly is balanced. The rod and piston weights are equalized. 
JMAC ENGINE SHOP WORK
  • Updated modifications are made. This includes: 
  1. Resizing the center oil gallery from 1/4" to 5/16" to improve oil supply to #2 and #3 rod bearings.
  2. I decide if the cam journals are worn enough to warrant cam bearings. If they are, I press in new 1300 cam bearings. Whether the cam bearings are installed or not, I replace the cam with a new or reground cam shaft.
  3. Replacing the thrust washers with oversized washers. The thrust washers were a problem for this engine because the ledge created by the main bearing cap was not great enough; the factory spec for end float was too great. I decrease the end float to .003-.005 inches.
  4. Complete brush cleaning of all oil galleries, channels and cylinder walls.
  5. New oversized main and rod bearings are installed.
  6. New oversized flat topped pistons and rings are installed.
  7. Other items replaced with new: front and rear seals, rocker shaft, oil pump, tappets, timing chain and sprockets as needed, ARP head studs and nuts, Payan gaskets (when available), intake/exhaust studs, washers, and nuts.
  8. Set valve timing. Valve timing is determined by setting crankshaft to 110 degrees (or cam manufacturer's recommendation) ATDC with camshaft positioned at the point #1 intake valve is fully open.
  9. The rocker assembly is broken down, cleaned and parts replaced as needed.
  10. All assembly and torque values are as described in the shop manual.
  11. Painting: The oil pan, timing cover, and valve cover are powder coated red. Block is painted black with high temperature paint.
JMAC ENGINE SHOP PERFORMANCE BUILDS
  • When considering performance upgrades my desire has been to keep the same quality as described above but I wanted to offer some performance options.
  • US market 1500s had 53 hp and 7.5:1 compression from the factory. The Euro market had 71 hp and 9.0 compression from the factory. My goal is to produce 80+ hp and 9.5:1 compression. (hp not verified by dyno testing)
  1. ​Install flat top pistons and reduce combustion chamber size  to raise compression to 9.5:1
  2. Install a 270 duration cam for better valve opening and for longer.
  3. Increase the size of the intake valves to 1.438" for better fuel/air intake.
  4. Add double springs for better valve response.
  5. Clean up the ports, removing ridges and rough casting to improve flow through the head.
  6. Add dual timing chain, cam and crankshaft sprockets to ensure durability.
JMAC ENGINE SHOP COMPLETION VIDEOS
View videos here.