200 HP Chev V6 in a 1979 Fiat X19

 

This project started in 1989 with the idea of putting the largest engine possible into the back of an X19.  Not having that much money to work with, it required finding junk yard parts that were a few years old.  Started out by cutting out the firewall leaving about 2” below the window and cut out the main cross member that supports the forward A-arms.  Everything was removed clear up to the sheet metal behind the seats.  Then cut out the rear trunk floor and rear cross member, leaving about 2” of the rear cross member just in case these points were needed later.  Being a hot-rodder I settled on “Detroit Iron”.  Picked up a 350 Chev V8 and a 1967 Olds Toronado transaxle.  Bolted those together via an adapter and lowered into the X19 and it actually fit.  Decided the engine needed to face to the rear to get more weight forward.  Now that the engine faced backwards, the final drive needed to be turned upside down so the car would go in the correct direction.  The 1967 Olds Totonado trans to final drive had a real short splined shaft so any adapter would leave too little spline.  So the 1967 was tossed and a 1980 Buick Riveria transaxle was obtained.  The 1980 is lighter and has a splined shaft between the trans and final drive that measured near 1-1/2”.  This meant that an adapter could be made and there will still be enough shaft left to carry the horse power.

 

The V8 and 1980 transaxle was fitted in the X19 and looked pretty good except that the front pulley was even with the rear grill.  This would be OK except I felt I needed mufflers.  Next was to buy a 1980 90 degree 229(~3.8L) cubic inches Chev V6.  It came out of a Monte Carlo.   The V6 fit much better, there was enough room for a muffler, plus the front of the engine lined up with the existing X19 rear cross member which meant that a new cross member could go straight across and be welded into the existing X19 rear cross member structure area that was already designed to take the load.  So now the engine and trans combination was decided.  Next came motor mounts etc.

 

Chassis and Motor Mounts

Removed the X19 coolant lines that run under the car to the radiator.  Left the two vertical sides primarily because it was difficult to remove right up to the floor pan.  Fabricated a new sub-frame out of two 2”x 2”x 0.080 wall square tubing.  The tubing is placed where the coolant lines were and run the full length from the front suspension pickups to just behind the rear interior panel.  Welded out riggers on the tubes at each end and attached as follows:  Fronts attach to the X19 suspension pick-ups, Rears attach to the side frame rails.  Did not weld up the square tube ends because the new coolant lines(1-3/4” exhaust pipe) will go inside these tubes.  The two 2”x2” tubes seem to stiffen things pretty good because the car feels pretty rigid.

 

For the rear engine motor mount, used the same type 2x2 square tubing to fabricate a cross member that takes off where the stock cross member was, utilizing the existing Fiat stubs.  The rear cross member is where the engine motor mount will go plus it will also be where the rear suspension pick-up and tie rods will attach.  Did some engineering calculations and estimate the sideways center of gravity of the engine/transaxle assembly.  As a final check, placed the engine/transaxle assembly on a sheet of plywood with a wooden dowel under the plywood going fore and aft.  Balanced the engine/transaxle assembly to verify the center of gravity.  This determines where it will go in the chassis.  Turned out that the transaxle is fairly heavy and the engine will end up being offset toward the driver side.  Placed the engine/transaxle in the chassis and designed/built the motor mounts.  Two forward mounts attach to the transaxle and to the new sub frame near where the sub-frame is welded to the Fiat frame.  The addition of the motor mounts between the sub frame and Fiat side rails provided the opportunity to gusset and strengthen that area.   The rear(single) motor mount goes between the front of the engine and the center of the rear cross member.

 

With the engine facing toward the rear, all of the transaxle weight and 4 of the 6 cylinder weight was ahead of the rear wheels.  The only thing behind the rear wheels is 2 of the six cylinders, an aluminum water pump, the alternator and then the muffler.  So this design should not be too tail heavy, especially with the 16 gallon fuel cell in the front.

 

Note: Spent many hours under the car with a hair dryer and putty knife removing the old dried on Fiat under coating.  Found many places where there was rust underneath the under coating.  Then went over with a wire brush and then re-sealed everything.

Mating the Engine to the Transaxle

An adapter was purchased to bolt the Chev to the Buick transaxle.  Many companies make a Chev-to-BOP(Buick-Olds-Pontiac) adapter; however, it is designed to bolt the Chev to BOP bolt pattern for a front engine rear wheel drive car.  I phoned the adapter manufacturer and asked about bolting to the transaxle and was told that the adapter was not designed to be used with the transaxle.  I figured that it would bolt up so I could make it work.    

 

The adapter placed the engine approx 0.30” away from the transaxle so I made a collar that fit in the crank that held and centered the torque converter.  This also required three spacers to move the torque converter 0.30” away from the engine flex plate.  A dust cover was made to cover the lower part of the torque converter.  Another cover was made to go over the starter motor hole in the transaxle.

 

Made an adapter that rotated the final drive 180 degrees.  This placed the ring gear outside away from the engine.  The transaxle utilizes a short and long stub axle.  Both are held in by a snap ring and can be moved from side to side.  With the final drive rotated 180 degrees the stub axle that went under the engine was just long enough to miss the block, so all that was required was to make a bracket to hold the end of the stub axle to the block at the correct(centering) location.

 

Placing Engine/Trans in the Chassis

The Fiat X19 is not a tall car and the Chev/Trans combo is pretty tall.  GM designed the combo so the transaxle sits some what below the engine.  The goal was to fit the tires inside the stock Fiat wheel wells.  Stock Olds steel wheels with 186-60/R14 were used(no fancy wheels on this car, it had to look stock).  The final drive was gutted and the engine/trans was lowered into the chassis.  A wooden dowel was run through the transaxle’s axle holes, the wheels were set at ride height and the engine/trans was moved around so the center of the final drive axles were about ½” above the center of the wheels.  This placed the transaxle’s pan to close to the ground so the entire assembly was rotated so the back of the engine was higher than the front.  Final results gave 4” ground clearance at the transaxle oil pan.  Even getting the transaxle as low as possible the air cleaner is near 2” above the stock 79’ Fiat engine cover. 

Transaxle

The transaxle used was a 1980 Buick Riviera.  This transaxle also comes in the Olds Tornado and Cadillac Seville and Eldorado.  It is a 3 speed automatic with a final drive of 2.41.  A 4 speed version was produced in the 82’-85’ years with a 3.01 final drive ratio.  The 82’-85’ versions added the 4^th gear behind the chain which increased the length of the transaxle by approx 2”.  The 80’ version was used because of the limited room.  I am using the 3.01 final drive which gives better off-the-line acceleration, but does wind a bit on the freeway, ie: 2000 = 42 MPH and 3000 = 64 MPH(5500RPM = 117MPH).  Am planning on changing to the 2.41 to give me about 2400RPM at 65MPH. 

 

The final drive mates to the transmission via a splined shaft.  Shaft engagement is about 1-1/2” so it is possible to move the final drive ¼” away from the transmission housing and still maintain enough spline to transmit the torque.  An adapter was made to rotate the final drive 180 degrees so the transmission. 

 

The transaxle has  been rebuilt to handle the horse power of a blown small block Chev.  It includes the kit plus using the chain from the turbocharged Riviera.  Since the transaxle is facing the wrong way, the oil pickup is at the wrong end of the pan.  The trans rebuilder suggested running the oil higher and there should be no problems.  So far it has worked out fine and am able to accelerate with good shifts.  That is another rework on my list: relocate the oil pickup to the other end of the pan.

 

 

Engine

The engine is a 1980 Chev 90 degree V6 out of a Monte Carlo.  Major work had to be done to the crank because the Chev is internally balanced therefore has counter weights are right in the way where the axle has to go.  The machine shop ground some of the counter weights and then I ground some more.  Finally got the crank so it would clear the tube in the pan by 0.050”.  The machine shop had to use “Heavy Metal” to rebalance.  I had all the machine work done in Huntsville by Huntsville Engine since they do a lot of ‘NASCAR’ engines.  The block was trued, line bored and all that stuff.  The bore is 0.030” over with flat top pistons.  It calculates out to 9.5:1 compression.  Decided to go with the Chev aluminum heads.  They come with 2.02” and 1.65” valves and high intake ports.  An Edlebrock  intake was used, but required the machine shop to weld about ¼” to the top of all the runners near the head.  I then was able to grind the intake manifold ports close to those of the heads.  I ported and polished the heads and intake.  A GM ‘Marine’ cam was selected since this is a street machine.  Bought header flanges from ‘Headers by Ed’ and a pile of U-bends from JC Whitney and proceeded to build the headers.  A stock muffler with two 2-1/4” inlets and one 2-1/4” outlet is used.  With the short length it sounds pretty good.  Utilized a Holly 390 CFM 4-Barrol which is scheduled to be replaced with a throttlebody some day.  Huntsville Engine estimated  the horse power around 220 with the 390 CFM carb. 

 

Rear Suspension

The rear suspension was the most challenging aspect of the project.  Final spindle selection was from a 1990 Olds 98.  It is a McPherson strut design.  It turns out that GM didn’t change axle splines between 1980 and 1990 so the earlier axle will mate with the later spline.  I suspect the GM full sized cars of today still use the same spline.  Now, the Riviera axle will slide into the 90’ spindle.  All that was required is to machine a small callar that slides over the CV housing and is sized to fit the grease seal on the 90’ spindle. 

 

Next was to work the shock problem.  Wanted to use a shock that was easy to come by so settled on the VW Rabbit.  The VW Rabbit shock will slide inside the Olds shock tubing after a little sanding on the Rabbit shock housing.  Then cutting the shock towers from a VW Sirocco and welding them to the Fiat solved the upper end problem.  I then used Taccico adjustable inserts.  Used the stock Fiat rear springs cut down.  Mating the Fiat upper spring perch to the VW perch took care of the top and reworking the Fiat lower spring perch to go over the VW spring perch took care of the lower end.

 

Rear A-arms are highly modified Fiat rears.  Bought a replacement ball joint for the Olds from a parts house and bolted it to the modified A-arm.  Welded the fore and aft pick up points near the newly installed sub-frame and the other below the new rear cross member.  To help with the bump steer, the center of the tie rod end needed to be as low as possible.  The Olds tie rod end has it’s taper so the rod comes in from the top.  Went to the wrecker to find a tie rod with a large taper.  Ended up with a tie rod from a 70’s Dodge van.  Took the spindles to a machine shop and had new tapers machined from the bottom.  Bump steer test consisted of clamping a 36” piece of wood to the spindle going out the back of the car.  With the chassis on jack stands, jack the spindle all the way up and then down to get full travel.  Support a vertical piece of wood on the floor and place it next to the end of the piece clamped to the spindle.  When you jack the spindle through full travel it should follow the vertical piece if wood(no bump steer).  With full travel of over 8” I was able to find an inner tie rod location that resulted in less than 1/8” deviation from the vertical.

 

Cooling and Oil

Cooling is a major problem if your engine generates any amount of power.  A special radiator was fabricated.  Only the upper and lower Fiat mounting brackets were used.  The radiator is thicker and required cutting into the front spoiler to make room.  1-3/4” exhaust pipe was used to fabricate the coolant lines from the radiator, through the 2” square tubing, back to the engine bay.  With the radiator out it is possible to slide the fabricated coolant lines in the square tubes.  Each coolant line was wrapped with a Kevlar type tape for abrasion and cooling insulation.  An oil cooler was added near the passenger side air intake.  It is sealed off so all air that comes through the air intake must go through the oil cooler.  A remote oil adapter was used to run all oil through the remote filter and cooler.

 

With the Chev motor facing backwards, it was decided to change the pan so the oil pick-up was near the front of the engine(rearward in the car).  A lower section from another Chev oil pan was welded to the front of the V6 pan.  Baffles were welded.  An oil pick-up from a Chev II was used since it locates the oil pump pickup forward on the V8 version.  Machine shop welded the pick-up tube to the pump and I built a bracket to hold the pump off one of the main caps.  The new front part of the pan is about an inch lower that the stock V6 so it holds 7-8 quarts of oil.  The pan has a tube running through it for the axle to go through.

 

A transmission oil cooler was placed near the driver side air intake.  It was also sealed so all air coming through the vent will go through the oil cooler.

 

Axles

The transaxle uses one idler axle that runs under the engine.  A bracket was fabricated to hold the axle in alignment with the transaxle.  The bracket was bolted to the stock Chev motor mount.  This placed the CV joint close to the block so an after-market small gear type starter motor was required.  A 153 teeth flex plate was used.  As it turned out, the axle on the driver side fit the installation without any changes.  Only the passenger side need shortening.  The axle has enough diameter so new splines were cold machined.  The result is very short axle.  It is short enough that the two rubber CV joint boots are touching.

 

Fuel Cell   

Since the gas tank was removed, it was required to mount the gas tank in the front.  A 16 gallon fuel cell was chosen.  The fuel cell was about ¼” wider than the space available, so the forward panel for the cooling fan chamber was jacked forward.  A 3/8” fuel line and ¼” vent line was run back to the engine bay.  The stock Fiat fuel level sending unit was installed in the tank after some of the foam was cut away to allow for float movement.  The long Fiat float arm was shortened and the readings are accurate enough for this type of conversion, when it says empty you still have some fuel left.  An electric fuel pump and filter are mounted in the same bay as the fuel cell.  The fuel cell is low enough that the Targa top still fits in the front.  However there is no room for a spare tire, so an emergency inflator/sealer in carried all the time.

 

Brakes, Shocks and Springs

The front uses stock Fiat discs with cut down springs and KYB shocks.  The rear is a different story.  Springs are cut down Fiats and Tacicco shocks.  The rear utilized the stock 1990 Olds 98 vented disk and caliper.  The major problem was the area of the caliper piston is twice that of the Fiat.  The solution was to leave the clutch master cylinder in place, cut off part of the clutch petal, heat and bend both petals, attach them together so one petal actuates the clutch and brake master cylinders at the same time.  Then the rear portion of the brake master cylinder was plumed in parallel with the clutch master cylinder, to a proportional valve then to the rear brakes.  Now the petal goes down the correct amount and the car stops OK.  Utilizing the existing Olds caliper leaves the car with no emergency brake.  That problem will be worked in the future.

 

Electrical and Lighting

Head Lights: Decided against the pop-up head lights so went to a wrecking yard and bought a dual light setup from a Mustang.  The holder is plastic so all that was required was to saw it in two and fiberglass it in place.  Then metal covers(brows) were fabricated.  Removed all the forward wiring that dealt with the motors.

 

Tachometer: Took the tach apart and found out that it utilized a Texas Instrument counter chip.  Contacted Texas Instruments and they provided the spec sheet for the chip. The spec sheet happened to have a suggested tachometer circuit, which matched the circuit Fiat used.  The circuit showed a potentiometer used to calibrate the tach.  Connected the input to a function generator set to for pulses for a 6 cylinder engine at 3000 rpm and adjusted the pot.  Checked other rpm’s and they looked OK.  So now I had a stock Fiat tachometer that could be used with the 6 cylinder.  It presently runs on a MSD 6AL tach output and works real good.

 

Water Temperature Sensor:  Tapped a plug for the stock Fiat water temperature sensor, and screwed it into the intake manifold.  Stock sensor and gauge works.

 

Fuel Gauge: Mounted the stock Fiat fuel gauge in the fuel cell with a modified float arm.

 

Oil Pressure Light:  Used some GM sender connected to the Fiat idiot light

 

Removed the radio and heater controls and added the following gages: Vacuum/Boost,  Engine oil pressure, Engine oil temperature, Transmission oil temperature.

 

 

 

Firewall

The sheet metal behind the seats was left unchanged and a new firewall was fabricated.  The new firewall attached where the old was cut off just below the window and curved back and then down so it was about 1” away from the internal sheet metal.  This left a small space between the two where the MSD box is mounted.  The MSD box can now be accessed via the original spare tire door.  Cut some ventilation slots in the spare tire door so the MSD box will keep cool.  The same are will be utilized for the Megasquirt controller when the throttlebody is unstalled.

 

I hope this was fun reading.  I really had a fun time building the car.

 

Wayne Wright, waynewlw@msn.com