Machine Shop Selection & Work List

Located in Nanaimo, BC - Canada
Once it was decided to rebuild Turbo Camaro's Inline 6 a machine shop needed to be selected. Several calls were made and prices were quoted but eventually Thompson Machine Ltd. in Nanaimo, British Columbia was selected. The staff were friendly, knowledgeable and seemed willing to take as long as needed to explain and discuss the build. It also worked out well as their total cost quote was the cheapest. On a side note, one of the shops actually said "why would you want to rebuild a straight 6?!" in a heavy tone. It was quite clear their customer service was shit and they didn't want the job. Perhaps this seems picky, but if you're going to spend $1200US somewhere, you should make sure the workmanship is solid and the people deserve your business.

The list of services completed by Thompson Machine were as follows:

  • Clean & Qualify the block - no cracks found.
  • Ultra-sound check of cylinders for wall thickness - thinnest casting was cylinder 6 at 0.134" which is well within spec for these blocks.
  • Remove old pistons from connecting rods.
  • Upgrade to ARP connecting rod bolts.
  • Polish Crankshaft.
  • Drill/tap Crankshaft nose for retainer bolt and balancer tool.
  • Supply new Crankshaft bearings.
  • Supply and install new Camshaft bearings.
  • Heat press on new Compcams steel Camshaft gear.
  • Deck the block head surface.
  • Bore and hone cylinders for 0.070" over bore pistons.
  • Balance rotating assembly.

Ultrasound results (click to enlarge)
Some of these services were requested due to the new pistons, bolt changes and intended power increase. A few of them could be done at home, but the time and effort required is much higher than if the shop does it with the proper tool, in less time, for a minimal fee.

Initially, the connecting rod bolts were going to stay stock, but with the investment in the internals those bolts seemed like the weakest link. The stock cast Crankshaft is known to handle up to 600HP, the new forged pistons should also handle well over 600HP and the forged connecting rods are fairly robust even though they're stock. With the lighter pistons the rods should be fine to 500-600HP too. But those bolts... you just never know. With ARP bolts installed the rotating assembly is bulletproof, at least for a pro street car.

The stock Camshaft gear is a fiber material and is a weak spot in the rotating assembly. Fiber gears work fine in a low power stock inline 6, but shouldn't be used in performance applications. A CompCams steel timing gear set was purchased to replace the existing gears. The shop will heat-press on the new Cam & Crankshaft gear but this is a process you could do at home by putting them in a freezer overnight and then heating the gear in the oven for a few minutes. The microscopically slimmer Camshaft snout will easily accept the microscopically enlarged gear. As it was mentioned, this process is easy but it just makes sense to have the shop do it properly in just a few minutes.

Compcams inline 6 steel timing gear set
Balacing the rotating assembly is not a mandatory rebuild service. If the engine was being rebuilt with original or NOS parts, the weight and size of each part would be almost exactly the same (within a few grams) and the Crankshafts counterweights would do just fine keeping the parts balanced. Since Turbo Camaro has custom forged pistons, a more aggressive Camshaft, steel timing gear and ARP rod bolts, the weight is significantly different and not having it balanced could result in heavy vibration when running. This vibration can cause excessive wear and premature part failure. It would be the type of vibration you could feel throughout the whole car. Even though this service is worth $100-200, it is well worth it in the end.

The best advice you can get is to not rush when choosing your machine shop. You can research rebuild services and engine builds all you want but in the end, a good machine shop will give you all the information you need to get your project done the way you want it. If they shop doesn't seem helpful or knowledgeable about your specific goals, you might want to look elsewhere. Just keep in mind, a friendly and genuinely interested shop can be hard to come by. Lastly, if you've never worked in a closed office/shop before, the guys there love fresh coffee and donuts. It's these sort of gestures that get people invested in your project.

Turbo | Camaro