The 73GTV6

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It started out in 1973 as a US Spec GTV, meaning a 2.0 4-cyl engine with Spica injection and a lovely burgundy exterior.  I would guess the interior was tan or pigskin - I never saw it.  It lived in New York for about 10 years where the winters did a job on the body. Some geek put in a homemade sunroof using screen door hardware.
 

73GTV6 v 2.5 with owner.

In the early 80's it arrived in Georgia.  The paint was chemically stripped and the interior, glass and trim pieces all disappeared.  It was left outside for a couple of years, wrapped in plastic, to hold in the moisture.  It was the sorriest GTV I had ever seen. But it did have a nice set of BWA mags, and the suspension was all there.

I wanted only the wheels, but had to buy the whole car.  I sold the wheels for the same amount, so I ended up with a free GTV.  Out of pity, I had most of the rust sanded off and new rocker panels installed.  We had the roof replaced and several coats of high body fiber reinforced primer applied.  It started looking much better, but we still did not have a plan for the car, so it sat (inside) for a couple of years. Meanwhile, I had received a couple of V6 engines and transmissions for Alfa 6 sedans from Holland.  I did not have any plans for them, either.  One of the V6s had thrown a rod thru the side of the block.  As I disassembled it, I realized the Alfa 6 engine had a different oil pan and heads but was otherwise identical to the 2.5 Milano V6.  The Alfa 6 oil pan had the same batwing shape as a 4-cyl Alfa oilpan.  I had been thinking about putting a Milano V6 in a spider, but the deep, rectangular V6 oil pan would require cutting a 16" piece out of the front crossmember.  This is the front subframe that all the sheetmetal attaches to, as well as the front suspension.  And it also carries the engine.  But now I had a V6 oil pan shaped just like a 4-cyl oil pan.  Using the pan, the empty block and a pair of bare heads, we put together a dummy engine - a mock up.  Barely a hundred pounds, easy to drop into different cars.  It fit an 85 spider perfectly, as well as the 73 GTV.  The spider was not mine, (nor are they well suited to engine swaps) but we finally had a plan for the GTV and the Alfa 6 engine.  Using the mock up engine and the Alfa 6 trans, we fabricated mounting pads for the stock V6 motor mounts and made up a sturdier, lower transmount.  An adapter was made up to connect the 8-hole flex joint to the front drive shaft.  The propeller shaft and the rear axle were not modified.  The radiator was fitted with a thicker core and a front mounted electric fan from a A/C equipped Bosch spider.

At this point, we dropped the other Alfa 6 engine into the body and bolted the Alfa 6 trans onto it.  We had done a leakdown test on the engine and it was indeed a junkyard engine.  We decided not to look into the transmission for fear of what we would find. Neither the Milano nor the Alfa 6 exhaust manifolds would fit, so we went for custom headers.  To give ourselves a bit more room, we decided to replace the steering box, linkage and idler box with a rack and pinion set up from a GTV6.  This was not overly complicated, and resulted in much more room for the headers.  These were bent up out of tailpipe stock using a bender that crimps the pipe as it bends it.  Not pretty but cheap.  The headers joined into a 2 1/2 inch pipe with a Super Turbo muffler and a cherry bomb for a resonator.  The exhaust was loud, but it was cheap and it worked. 
 

Rack and pinioin steering is gone. Ready for the 3.1.

That was more than could be said for the rack and pinion setup.  True, the steering effort was very light, but the bumpsteer was scary and resisted most attempts to correct it.  The car had to be driven carefully, because a bump in the road would cause the front tires to go in different directions until it leveled out again.  A bump in a turn was to be avoided at all cost.

During the next couple of years, the body work was completed and topped off with a reasonable paint job.  Glass, interior pieces, lights, chrome trim etc. were gathered, detailed and installed.  Eventually, the car was about 90% complete, most of the electricals worked.  It looked pretty good and it went pretty good as long as it was going straight.  The handling sucked.  Due to lack of time and motivation, it mostly sat around. 

I acquired a set of 3.1 pistons and liners on one of our trips to the fatherland.  These pistons and liners turn a 2.5 V6 into a 3.1 V6.  I did not have any particular plan for the piston and liners set - just had to have them.  By June of 99, the car had not seen much action, and the 3.1 stuff still sat on the shelf.
 

Left: 2.5 liner, 88mm; Right: 3.1 liner, 98mm

At the Kansas City AROC National Convention it was announced that the 2001 Convention would be held in Nashville, TN; close enough to Atlanta that we would drive an Alfa.  But which Alfa - we usually have at least a dozen standing around.  Milanos, Giulia supers, Spiders, GTV6s and a GTV with a 2.5 V6 in it that was not quite finished.  And then there's the Mopar wagon with a 440 and the 6.9 Benz - sorry, they're not Alfas.  The GTV was the easy winner.  Just fix some problems and drive a really unique car to the National Convention.  A car that only Alfa people would notice and appreciate.  So we signed her up when it came time to register for the Alfa Odyssey.  We hadn't fixed the bumpsteer yet, so we only signed up for the Dyno days.

Slowly a reality dawned on me.  We were taking this thing to a National Convention, not just a local club outing with a couple of pals.  Five or six hundred really knowledgeable Alfa people were going to give this thing some long, hard looks and it better be RIGHT!  With that in mind we hemmed and hawed until mid March of this year.  True, we had been fairly busy most of the time, and since I did not want to undertake this project in my spare time, it had been put off.  So while we were in Florida for a long weekend in March I decided to go for it, full time.  We would not take on any customer work  until the GTV6 was done.  I called my assistant and told him to get started with the disassembly - pull the trans and drive shaft.  When we got back home a few days later I pulled the 2.5 V6, disassembled it and sent the block out to be bored for the 3.1 liners.  Finally, I had a plan for the 3.1 stuff.

Several years ago I had put a set of much modified 2.5 carburetor heads on a 3.0 block and installed this engine in a 1981 GTV6.  The Bosch L-jet was removed and put in a box.  At the time, 108 octane gas was available locally so the engine ran quite well.  The compression  ratio was around 13.6 to one.  Eventually the 108 gas disappeared and we had to use Moroso Octane Builder, at $38 per gallon, but the engine did not run the same, so we prepared a pair of fuel injection 3.0 heads, installed them in the 81 GTV6, along with the L-Jetronic, ANSA headers, and power steering and sold the car to a guy in Texas, and we put the 2.5 carb heads in a bag on a shelf.
 

2.5 carb head (Right). Note the porting and the ends of the valve guides.

Now we had a use for those heads.  They only had a couple of thousand miles on them, and showed no wear upon teardown. 

While the block was being bored for the 3.1 liners, the 3.1 pistons, rods, crankshaft, flywheel and front pulley had been balanced.  I collected all the pieces, double checked the fit and clearances, cleaned everything and assembled the new 3.1.  It was a thing of beauty.  The leak-down test showed five % on all cylinders - not bad for an engine that had not yet been started.

We sat it on a stand, covered it up and went to the body. Out came the rack and pinion.  We rebuilt a GTV steering box and reassembled the linkages, idler box, etc.  Ball joints, tie rods, brakes etc, etc - everything was rebuilt or replaced.  Several years ago we had installed a complete rear axle from a 1992 Spider with automatic trans because of its 3.70 ratio.  Before that we had run both a 4.10 rear end, and a 4.55.  Both were too low.  We installed red Konis in the rear, with new OEM springs and red trailing arm bushings, and yellow Konis in the front.
 

3.1 piston and liner installed in a 2.5 block. Note the engine number - AR01913 indicates a Euro 2.5. AR01911 indicates a U.S. 2.5.

We removed the dash and console so we could replace both and clean out old bondo dust.  We replaced the heater core, fan, control and hoses.  We replaced the fuse box, column switch and detailed every electrical connector.  Every day we were one day closer to the Alfa Odyssey.  About two weeks before D-Day, we installed the 3.1 engine and original Alfa 6 trans, which had turned out to be fine.  A new, one piece driveshaft had been made up locally and fit perfectly.  We loaded the 73GTV6 onto the wrecker and had it delivered to Grand Mufflers.  In about three days they built up a set of headers from mandrel-bent tubing and a set of Alfa Ricambi flanges.  After deburring and grinding down the welds, the headers were sent to Jet-Hot for the high luster inside and out coating.  Due to careful design the headers installed in no time and bolted up to a Y pipe which went into a 2 1/2" resonator. The sound is tolerable at low load, but as the revs go up, there's nothing subtle about it.  At this point it became the 73GTV6 v 3.1.
 

The original shifter hole has been closed up. The new shifter hole has been placed 6" further back, but the shift knob is in the same location as the original.

We did some local driving to fine tune the carbs and attend to other details.  The ignition was left stock.  The Alfa 6 distributor uses a spring-loaded rotor, which acts as a rev-igniter, so I replaced it with a Bosch rotor.  The nut behind the wheel is now the rev limiter.  The cap, wires and coil are all stock.  The Champion plugs were opened up to.040.

Finally, it was time to clean it up and put some wheels and tires on it.  A perfect set of Montreal wheels (6 1/2 X 14) and Sumitomo 215/0 X 14 tires did the job.  We were ready for Nashville.

The 300+ miles to Nashville and the Alfa Odyssey were run at varying speeds, to help break in the engine.

The first event we attended was the Thursday Dyno Day, sponsored by Italian Motor Works.  The Bonneville racer sounded awesome on the Dyno, but was silenced mid-song due to a faulty super charger.  Those boys were not happy, and it left the Dyno idle.  I was scheduled for the following day, but volunteered to run the 73GTV6 right then and there.  Before I knew it, we were strapped in and onto the Dyno.  I had not know that this was an above-ground Dyno.  During the strapping down process, bunches of peoples inspected the under side very carefully.  Go ahead, I thought.  This sucker's right.  The Dyno runs showed around 170 hp at the rear wheels with 195 ft lbs of torque.  We were using stock 3.0 cams at the time.  Since then, we've made improvements to the drive shaft and the ignition advance curve and did some more fine tuning to the carbs and the fresh-air inlet. It's over 200 hp now.
 

The 73GTV6 v 3.1 on the dyno at the 2001 Alfa Odyssey in Nashville.

As with most engine swaps, many issues raised their ugly head.  Things like weight distribution, handling, braking, driveline configuration, noise, vibration, driveability, engine cooling, etc.  all had to be dealt with.  My goal was to solve these issues at least as well as the Alfa engineers did when it was a 4 cylinder car.  My big advantage was that I  could spend more time and money than they could.  And in all respects, the car is as good as or better than original, with two exceptions:

1) The total weight of the car is 40 lbs (that's 18 kg) more than the original.
2) Net rear wheel horsepower is double the original.
3) My version costs around $25,000.
 

The 73GTV6 v 3.1 - finito!

The other side. Note the fresh air intake.

The 73GTV6 Specifications