Bellhousing Pattern Gen III...
Bellhousing Pattern
Gen III engines bolt up to any automatic transmission that works with the older 350s and 454s. The only difference is that Gen III engines aren't cast to accept one of the passenger-side bellhousing bolts that most auto transmission dipsticks bolt to (arrow). The other five bolt holes have proven to be enough to support the TH700R4 in our Blazer, so don't be dumb and drill and tap the block for the sixth hole because you will cut into the No. 8 cylinder.
Engine Mount (Option A) For...
Engine Mount (Option A)
For some reason Chevy moved the engine mount locations about 4 inches rearward on the new Gen III blocks. To bolt our 6.0L in where a small-block used to live, Advance Adapters sells these steel plates (PN 713088-P) that pick up the four holes in the Gen III block and mimic the traditional three-bolt mounting pattern Chevy V-8s have used for the last 50 years.
Engine Mount (Option B) To...
Engine Mount (Option B)
To make more room for the exhaust manifolds (above) we ditched the original GM frame brackets and built new mounts to swap the Turnkey Engine Supply 6.0L into our Blazer using Camaro rubber isolators (GM PN 22179268). For mock-up purposes we bolted this damaged LS1 block to our TH700R4 and NP241 transfer case to figure out where the mounts would need to go. Using a floor jack under the oil pan, we squared up and leveled the mock-up engine in the Blazer's chassis. Oil-pan-to-front-driveshaft clearance shouldn't be an issue with most swaps, but now is the time to check.
Once we were sure of the engine's...
Once we were sure of the engine's position, we bolted the Camaro isolators to the block and made these cardboard templates (right, top) to span the gap between the framerails. Keep in mind that the more compact you make the engine mounts, the more room you will have for exhaust manifolds or headers.
From our cardboard templates...
From our cardboard templates we built these crude but effective mounts (right, bottom) from 1/4-inch steel plate and square tube. We used three existing holes in the Blazer's frame and drilled three more to secure the new brackets. When building your own mounts be sure to tie them into the original engine-mount crossmember (arrow) or the frame will twist in this area.
Frame Trimming The Gen III...
Frame Trimming
The Gen III engines fit very well in older GM trucks, but there are still a few areas that you will have to trim. Here we've cut the engine-mount crossmember for block clearance and marked where we still need to remove metal to fit the power-steering pump.
The crank pulley (right) on...
The crank pulley (right) on our 6.0L could contact the engine-mount crossmember when the frame flexed. To keep that from happening we used this 3/4-inch steel block to mark where we need to cut to give the engine a little room to move on its mounts.
Preparing the New Home The...
Preparing the New Home
The modified engine crossmember was boxed with pieces of 1/8-inch steel plate to make up for the sections we cut out of it. Then we had Steve Cole of TTS roll the MIG-welder out and weld the engine mounts and frame reinforcements. After some soap and a few coats of black spray paint our engine's new home was ready.
Flexplate/Flywheel Selection...
Flexplate/Flywheel Selection
To run our TCI-built TH700R4 with the 6.0L, we used this flat GM flexplate (PN 12551367) on the left designed for the 4L80E transmission. If we had an LS1 engine we could have used the beveled flexplate (PN 12563136) on the right and skipped the next step. Manual transmission users will want to order a GM flywheel (PN 12561680) and crank pilot bushing (PN 12557583) to run a 12-inch clutch.
Flexplate Modification
We felt like hacks doing it, but we modified our new 300mm-bolt circle flexplate to work with our TH700R4's 298mm-bolt circle torque converter by elongating three of the six holes in the flexplate. It may be possible to have someone punch the correct holes in the hardened steel, but we used a rat-tail file and carefully lengthened the holes without making them any wider. After 7,000 miles there's still no sign of cracking.
Fuel Pump
Gen III fuel-injected engines require 53 to 63 psi of fuel pressure to operate. Turnkey Engine Supply has had good results with an externally mounted Bosch fuel pump in sand rails, but for what we had planned for this engine we wanted to run an in-tank fuel pump. We wanted to bolt in a fuel tank from an '87-'91 TBI fuel-injected Blazer and swap the low-pressure pump for a high-pressure unit (GM PN 25163473). We couldn't find one cheap enough so we modified our original diesel fuel tank with a new fuel pump and strainer for a 5.7L LT1 V-8-powered '96 Chevy Caprice. Orme Brothers brazed a -8 fitting onto the end of the 3/8-inch feed line that goes to the engine and a -6 fitting onto the return line that brings the unused fuel back to the tank. The original fuel-sending unit wiring was used to power the fuel pump, and a separate sending unit was added to the tank when we had it professionally cleaned at a local radiator shop.
Exhaust Options
At this point our 6.0L bolted in to our Blazer and mated up to our TH700R4, but we still needed to plumb and wire it. Cole let us rummage through his collection of Gen III exhaust manifolds to find a set that would fit in our Blazer's chassis. The set of '98 Camaro/Firebird manifolds (top) worked best for us (PN 12567706 RH, 12559507 LH). Other possibilities include '99-'03 Camaro/Firebird (second from top), '99-'03 C/K Silverado (second from bottom), and '97-'03 Corvette (bottom). These manifolds have 2 1/2-inch outlets that Cole was able to build a complete exhaust off of.
Almost There!
Next month we'll finish up the wiring, fuel, and cooling system installation. And we'll finally get to tell you about that monster Magnuson Radix supercharger sitting on top of our 6.0L. Stay tuned!