LS3 Engine Install

Delivery Day!

I ordered a “turnkey” engine and transmission package from Roadcraft Repower with the following specification (LS3 500BHP):

  • Chevy 6.2L 376/500+ turn-key engine.
  • Chevy LS3 alloy crate engine converted to an HO version with aftermarket items.
  • GM LS3/L92 alloy cylinder heads with aftermarket beehive springs.
  • Aftermarket roller-cam, GM roller lifters.
  • OEM valve and timing covers.
  • GM LS3 intake manifold.
  • GM OEM pulleys to suit water pump and power steering.
  • GM water pump, high output alternator and power steering pump.
  • GM LS3 Corvette oil pan.
  • GM oil pump and pick-up.
  • GM roller timing set.
  • Mini hi-torque starter.
  • Tremec TKO600 transmission with Quick-time bell housing.
  • Ram SFI steel flywheel with 12” HD single disc clutch assembly.
  • Output yoke and necessary fasteners.
  • Omex 710 ECU system complete with harness

The first thing to bear in mind is to consider the size of the delivery vehicle that may be used! My engine was delivered on the back of an enormous lorry that couldn’t make the turning circle to get into the drive. Also worth noting that the engine and transmission is delivered on a pallet, so make sure you’re able to manoeuvre this into your garage. I borrowed a mates pallet truck which seemed to do the trick.

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Engine and transmission delivered on a pallet.

The package included the following components:

  • Alternator
  • Starter motor
  • TKO-600 transmission
  • Engine wiring loom
  • Omex710 controller
  • Omex idle throttle motor
  • Omex fuel pressure regulator

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Engine and transmission package. The two boxes on the left contain the LS3 hose kit provided separately by AK (not included in the Roadcraft package)

2014-12-20 14.23.332014-12-20 13.10.35The first step is to mate the transmission to bell housing. This is a pretty simple process where you careful slot it in and gently twist to align the splines. You won’t be able to push it all the way home so carefully nip the two together by tightening the bolts to bring the transmission onto the bell housing. You Tube Guide Here. Its a good idea to fit the billet slave cylinder bracket at the same time as it fits onto the passenger side of the bell housing using the two bolts that also connect the transmission to the bell housing.

Next up, install billet slave cylinder following the instructions provided by Roadcraft. Depress the rod into the cylinder, then back it back out 5mm (to allow for future clutch wear). Take up the slack in the clutch fork and then adjust the rounded end piece so that it sits nicely within the clutch fork depression.

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UPDATE: It really helps if you can install the mechanical speedo plug at this point (before fitting the transmission and body like I ended up doing.. ahem.) Unless of course you are using the mech speedo port, but in that case you might want to install the mech drive now. The plug looks like this and you can get them from Real Steel or eBay:


Make Chassis ready by removing header tank, putting wheels back on (remove front callipers) and raise the rear end of the chassis to make it easier to feed the transmission into the tunnel.

Borrow or hire an engine hoist, you won’t lift it on your own! When locating the lifting straps, be very careful that they tend snag or foul any delicate components and that they are secure so they cannot slip out from under the engine when your adjusting the angle or giving it a “bit of a nudge” to align it.


Just in case you’re wondering what all those connectors and ports are on the TKO, this should give you an idea:

TKO Connections

Engine Install

  1. Fit power steering hose connector (AK supplied) to the power steering pump and check that it is securely fastened and pointing at 90 degress out from the engine. It is very difficult to get too in the future!
  2. Fit bobbins to chassis engine mounts
  3. Fit engine mounting plates to engine using M10 30mm stainless bolts and flat washers. My mounts didn’t quite line up with the engine tapped holes so I milled out the holes in the engine mount ever so slightly until I could install the mounts on the engine.
  4. Hoist the engine making sure the transmission is lower than the block. I used a ratchet strap to allow me to raise the transmission as the block was dropped. I also jacked up the rear end of the car to help make it easier to thread the gear box into the tunnel. (Thanks to Tommy for this idea, you can also read about his install here (very useful blog for those AK builders out there, thanks for sharing Tommy!)).
  5. Gently lower the engine mounts onto the bobbins. Mine needed a little gentle persuasion to line up with the engine mounts (tap on the side of the bobbins with a hammer).
  6. Support the underside of the transmission with a trolley jack or axle stand, secure the engine to the bobbins and remove the hoist.
  7. Install the anti-vibration mounts to the bottom of the transmission
  8. Bolt the transmission mount onto the anti-vibration mount and then rack up into place.
  9. G-clamp the bracket in place. Mark and modifications required (i needed to grind off a section and redress two holes to make sure they were in the centre of the chassis). Drill and tap the chassis with M10 tap (4no holes in total) before bolting the transmission mount to the chassis with M10 stainless bolts and flat washers. Use thread lock in the chassis taps.

Engine Plumbing

Heres a few parts labelled up on the LS3 block (not massively useful though i’m afraid):



  1. Read this excellent guide to cooling systems
  2. Connect header tank to radiator with a 130mm length of 45mm hose  (OD)
  3. Fit alternator – do not tighten bottom bolt and leave top bolt loose
  4. Fit fan belt to this pattern. BeltPut belt over all pulleys and tensioners with the exception of the alternator. Pivot the alternator down on the bottom bolt and thread the belt onto the alternator pulley. Now pivot the alternator back up to its proper position and secure the top bolt. As you pivot you should see the spring loaded tensioner pivot to provide the necessary slack.
  5. Use shorter 90degree bend to connect header tank to water pump
  6. Connector the air intake stainless pipe to the intake manifold using the largest diameter rubber hose connector.
  7. Connect front port of the header tank to the top right port on the radiator with the 18mm OD hose.
  8. Connect the stainless steel water pipe to the bottom right hand port (looking from the back) of the radiator to the temperature sensor on the engine. You will need to take of the sensor and rotate it 180degrees so it points towards the passenger side to avoid the steering rack. Use a 100mm length of the 45mm hose to connect the stainless pipe to the radiator.
  9. Secure the stainless steel water pipe to the chassis using either zip ties or a p-clip. If using zip ties, put a piece of rubber between the chassis and pipe to avoid nuisance vibrations and rattling.
  10. There are three small pipe connections on the air intake stainless pipe, connect the two opposite each other to the rocker breather connections on the engine and the third to the idle motor. Use 10mm ID hose for these connections.
  11. Fit the Omex air temperature sensor into the hole in the underside of the air intake pipe, you will need to get an M10x1.25mm pitch brass nut for this as its not supplied with the sensor (not annoying at all…)
  12. Connect the power steering rack via the black rubberised hose to the power steering pump connection (that you fitted before installing the engine, if you didn’t, time to take the belt and alternator off, you can then just about reach the 4no nuts that hold the steering pump in place, remove these and you can wriggle the pump out and connect the adapter). Connect the braided hose to the power steering rack, then feed through to the power steering reservoir, shorten hose to suit (electricians tape then a dremel does the trick) then connect with a clamp onto the reservoir.


Comments 4

    1. Post
  1. Hello,

    I found your website on the internet. as I’m looking for help on settings for Omex 710 connected to LS3.

    Would it be possible to contact you by email?

    Kind regards,

    Rocco Jansen
    The Netherlands

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