In part one we delved into the whys and wherefores of sleeving our little Chrysler Hemi six. The standard 265ci block copped a hit in the front and holed cylinder number one, so we decided to rescue the 40-year-old core rather than tossing it away.This is particularly relevant for those people wishing to keep the original block with their car or who want to maintain the value of their factory-original muscle cars.
So when we left our engine last time, it had been sleeved, bored, honed and decked, but there’s a whole lot more to do before we can assemble and dyno our donk.
Machining an engine is a bit of a dark art, and to most people the machine shop is just a mysterious place full of complicated, expensive gear and crusty old blokes with permanently stained hands mumbling about 0.010-inch clearances.
In many cases the average punter drops off a wounded motor to their engine builder who then offloads the bits to a machinist. Or maybe you’re lucky and your engine builder is a machinist as well. Either way, you’re usually just dropping the engine off and then picking it up again a few weeks later, with no idea about the magic that happens in between.
So let’s take a look at some of what goes on when the machinist has his way with your engine. In our case we’ve got Johnny Pilla and his team at Powerhouse Engines going through our Hemi six. They’re machining and building killer engines all the time, and responsible for some of the toughest burnout engines in Australia. They’ll make sure everything is perfect before it’s assembled and dropped on the dyno.
Once it’s all done the engine will be heading into my VG wagon, which is in sore need of some horsepower. In the meantime, let’s go to town on our revived Hemi.
This is where we left off last time with our block fresh from the Sunnen SV-10 honing machine. Our first job this time is setting the block up for line honing
Before line honing the block the boys had to make sure the caps were perfectly flat. To do this Chook put the caps in the Sunnen cap grinder and shaved 4-thou off, then measured them for accuracy
Green equals good
Hemi sixes have pretty decent bottom ends but these ARP main studs and rod bolts will make sure it all stays together. Hemi sixes use the same main studs as Holden V8s – you just need two boxes of them (PN: 205-4501)
Using ARP’s own assembly goop yields more consistent torque reading compared to engine oil or other lubricants
The studs were wound in with an Allen key and then backed off half a turn before our main studs were torqued down to 80lb/ft in three stages
First job for our conrods was pressing out the old rod bolts in preparation for a new set of ARP wave-loc bolts (PN: 144-6401)
Then Chook cleaned up the mating faces on the rod grinder in preparation for resizing
Before and after views of some freshly ground rods
From here we move over to the 40-ton hydraulic press to fit the new rod bolts
To protect the rods they’re clamped in an aluminium vice where they’re assembled and the rod bolts torqued to the right specs before resizing. Conrods should always be resized after fitting new bolts
The assembled rods are resized on the Sunnen rod hone
Then each end is checked with a dial bore gauge. Typically it’s just the big ends that are resized
Moving on to balancing, we put the very long Hemi crank on CWT Industries Multi-Bal 5000.
The crank wasn’t too bad to start, but removing metal in just the right spots gets the balance just right
The balance is now correct to mere tenths of a gram
The Sunnen line hone is a bit more physical than most of the machines, requiring Johnny to push and pull the line hone through the torqued main caps.
Johnny checks the realigned main caps with a dial bore gauge. Now the main bearing tunnel is perfectly aligned and correct
Balancing the rods starts with weighing all the rods individually, and finding the lightest
Then they remove metal from the big ends with a linishing belt to match them all up
After the big ends are done the whole process is repeated for the small ends, but in this case the rods are weighed as a whole and ground to match
Then all the pistons and pins are weighed to find the lightest; the difference from lightest to heaviest was as much as six grams, which was way too much
Then material is removed carefully to match them all up
Now we’re getting pretty close to getting the engine together. Next time we’ll sort out the cylinder head, throw it together, and throw it on the dyno to crunch some numbers
In part three, we unlock the secrets of Chrysler’s Hemi six cylinder head