Chevy 350 in a Jaguar XJ6 - Hybrid Heaven


Early in 1994, I purchased a Jaguar XJ6 from a local seller. The car was complete, but there was water in the oil. It was the general opinion that the problem was a bad head gasket and/or head. It did not matter much to me - I purchased the car for next to nothing and fixing the head gasket would be a snap.

I started to remove the head, and I discovered why Jaguar mechanics are such special people. I personally am comfortable working on any of the major USA car brands, since I have had my share of cars which needed fixing. The Jaguar 4.2 motor, however, was a learning experience. The thing that made me ponder the reason why the car was sold so inexpensively was when the cylinder head refused to budge loose because of corrosion in the head studs (it turns out that the studs penetrate the water jacket). I had to use a chain hoist hooked to the head, and winching the ENTIRE car up by the head and waiting for a day, the head to eventually slid off.

I had heard from numerous sources that many people have removed the original Jaguar motors and transmissions, and put in Chevy or Ford powerplants. Why would anyone turn a Jag into a hybrid monstrosity? The reasons stated were "Parts are much more inexpensive for Chevy motors than Jaguars", "Better gas mileage", "I can drive anywhere in the USA and if I have car problems, I can have the thing fixed right there without waiting for parts to come in", "I am more familiar with Chevy engines than Jaguars", etc. I discovered that in the case of a Chevy swap, it is almost a "bolt-in" affair - one can perform a swap without any cutting or welding on the Jag body whatsoever. For instance, one can use a driveshaft from a '70's Nova and it is the correct length to go between a Turbo 350 and the Jag differential, and Jaguar uses the same U-joint as Chevy, so it bolts right up. The power steering lines also bolt right up. One can put in a Camaro radiator in place of the Jag unit, without any cutting.

So, after the research, I decided to put in a Chevy 350 and Turbo 700R4 overdrive automatic. The funny thing is when I posted what I was planning on doing, Ryan Border inquired on what I was going to do with the original 4.2 Jaguar motor. He purchased the motor, and I boxed it up (I live in Virginia) and proceeded to ship it to California. It now lives in Ryan's 1959 MK1. There is even a picture of the original motor before installation in Ryan's car. The following are the actual postings to the "Jag-Lovers" mailgroup. Even though not everyone agreed on the philosophy of the swap, everyone helped out with numerous technical questions. This may help portray the difficulty of the swap (which was much simpler than I first imagined), and yield some important technical details for others. I have put on over 20,000 miles on the converted car (June 1995), with absolutely NO problems associated with the swap.

The following are actual postings from the Jag-Lovers mailgroup from January
to May, 1994.  Authors comments (after the fact) to questions posed are
denoted by square brackets [ ].

I have been looking at the different options on the V8 conversion. The two options which look attractive are the so-called "kits" which contain some or all of the parts needed to perform the chevy 350 swap, or instruction on how one does this "homebrew", fabricating and acquiring the parts him/herself.

The two kit manufacturers that I looked at were John's cars and Suncoast Conversions. Johns Cars seems to be known by everyone - he (they) had 8 different ads in the latest hemmings mag! With the cost of the kit, I can see why! For my car (83 XJ6), the basic kit cost $995.00, which includes the motor/tranny mounts, power steering/radiator/AC hoses, wire loom, nuts and bolts, everything needed except driveshaft and radiator. For $1350.00, they sell a kit which include the radiator and new driveshaft - they state absolutely everything needed to perform the swap - you only need the motor, tranny, and the chevrolet "center-dump" or rams-horn exhaust manifold, and I almost forgot the trip to the muffler center for the exhaust (like catalytic convertor(s), header pipe,etc). They state that the swap takes about 16 hours to complete. The catalog indicates that they hold their kits in highest regard, and that car resale value is the greatest is you use their kits. They also will not sell most parts separately (like the motor mounts - they indicate that people may misrepresent their hacked car as a complete and genuine John's car conversion and not as the true counterfeit that it is - like the Chevy motor swap is not conterfiet enough in a Jag). The parts that they will sell, like the radiator, they tack on an additional $50.00 to each part if you don't use their kit, I reckon a punishment. I guess that they figure that they have done very many successful conversions, and one should pay for that knowledge.

SunCoast conversion was somewhat less expensive ($375.00), but it also included less - I think (because I never got their catalog in the mail (yet)) the only thing included are the motor/tranny mounts. They seem willing to sell parts separately, and they offer a TPI conversion manual for those wanting to do a Camaro/Firebird/Corvette Tuned-port Injection engine (Johns cars seem to offer info only on carbureted V8s). You can buy their installation manual for $75.00 - supposedly their REAL installation manual sent with the kit. Johns cars will only sell an non-illustrated version of their manual - I guess that this is further protection from the evil crooks lurking about (they must have been "burned" in the past from other conversionists, or something else....). SunCoast offers exhaust headerpipes and electric speedometer conversion parts. [SunCoast number : 1-800-940-JAGS - They were the most helpful of all of the conversion houses]

It is interesting to note that when each of the above were asked about the other, and why I should buy from them and not their competition, they were both very polite towards their competition, but they got in their subtle "digs" into each other. John's cars indicated to me that SunCoast and other conversion kits were like using "bailing wire", and that their conversions were "backyard mechanic-like". SunCoast said that Johns cars were "extremely overpriced for what you get", and that "Johns was OK if you want every nut and bolt and wire tie and dont mind paying dearly for them" This whole conversion market appears very competitive. But each side conceded that the other persons conversion "may work", but also indicated that there may be potential gotchas.

Then I received in the mail a complete do-it-yourself plan and manual from "Jaguars That Run" in California - $39.95.[510-462-3619] The author is Mike Knell, who is well-known for performing engine swaps - lots of his results have been publish in many magazines. His book has the complete list of what parts I will need to get to perform the swap. He also has drawings and scales of his motor and transmission mounts. The motor mounts are made from 1/4 inch steel bent twice with several holes drilled in it - simplicity itself, and no welding! He uses stock Chevy motor mounts from a truck, with an aluminum spacer between the block and stock motor mount. The tranny mount is 3/8 steel strip about 20 inches long and 4 inches wide, bent a few times with a few holes. I can make the mounts for the price of a few strips of steel and a few hours of cutting, drilling, and bending. I have the steel and aluminum lying about, so total dollar cost (for me) is nothing. if one was to buy the materials, he would pay probably $35.00 for everything, not including the drilling and bending.

He is not as kind, though, towards the "kits". Throughout the book, he indicates that they are not as complete as they tend to lead on, and that the time estimates are way off - it indicates that the swap will take about 60 hours, even if you use the kit. The book says that preparing the Chevy engine takes the longest time - getting the wiring, sensors, shift linkage, etc installed. He (Knell) also states that some kits tend to place the motor high in the car which produces hood clearance problems which requires ripping most of the hood bracing off (I dont like the sounds of that). The book-fabbed motor mounts set the engine lower in the engine bay, eliminating the hood problem, but introducing a interference between the oil pan and steering rack. The book's solution is a brutal banging of the oil pan with a sledge hammer in order to clear the rack. I would (because I am an gentle sort) re-weld the pan it eliminate the interference.[I ended up bashing the pan with a lead pipe, and ruining the first pan's gasket area because I did not bolt it to a old engine block first in order to preserve the sealing surface shape. The second pan I bashed so much, the oil baffle came loose, which I had to tack weld back in place. But it worked fine, with plenty of steering rack room]

As you have probably guessed, I am going to perform the conversion without a kit. I am comfortable with metal fabrication, welding, etc. I may be making the wrong decision, but my philosophy about kits appears to match Knells. I have a good junkyard source and I am very cheap at heart! The book gives part numbers and/or vehicle types and years for each part, for example the book says to use a fan shroud from a 77 Ford Granada. I am also very aware of appearance, and will put in the extra effort to make a nice-looking conversion - the pictures in the book look "pretty good", but a few minor changes would probably improve their craftsmanship a bit. [The conversion DID turn out nice in appearance - I have had numerous positive compliments]

I am going to use a 350 carbureted and a turbo-350 transmission. I would like to go all the way and install a tuned-port engine, but these are hard to find and are expensive ($1500.00 with a 700R4 overdrive tranny and the ECU and wiring harness).[I used a 700R4 instead] I also want to get this done this century, so I will first put in the carbureted version, and then wait for a wrecked Camaro/Firebird to come into the junkyard and swap motors again. This effectively makes this a two-stage installation - the first stage works out the mechanical mountings, radiator, etc, and the second stage will concentrate more on the wiring of the TPI and the intake ducting. I can also drive the car between stages, which is the ultimate goal. [Now starting to work on the TPI stage]

More on the V8 conversion saga........

As I stated earlier, I finally removed the engine, which turned out to be in pretty good shape, overall. Do not ask me why I am still doing this - I probably could have fixed the old motor for less money, and a whole lot less aggravation. I am doing this probably now more for the challenge than for any other reason!

Anyway, I went to my favorite salvage yard and purchased a replacement engine and transmission. The engine came out of a 1983 Impala sedan, a police model. The numbers on the block indicate a 4-bolt main unit. The motor has in excess of 180,000 miles on it, and it blows some smoke while running. It will need a rebuild, probably oversized pistons. Now I am faced with all of the glorious items of any rebuild - New gaskets, cam, lifters, chain, etc, and all of the machining - boring, torque-plate honing (an absolute must - I have seen first hand what the application of the torque plate does), etc. Is it too late to change my mind and put back in the old motor? No, I am stubborn.

After some research I have decided to use a T700R4 overdrive transmission, mainly for gas mileage. I have a 2.88 ring-pinion set in the car. Here how the gearing compares with a Turbo-350 and 400:

                Trans Gear                 Final drive gearing (x 2.88)
   XMISSION    1st   2nd   3rd   4th       1st   2nd   3rd   4th
   TH-350      2.52  1.52  1.00  ---       7.25  4.37  2.88  ---
   TH-400      2.48  1.48  1.00  ---       7.14  4.26  2.88  ---
   TH-700R4    3.06  1.62  1.00  .70       8.81  4.65  2.88  2.01

As can be seen, the overdrive transmission has taller 1st and 2nd gears than the 3-speed units, which should improve acceleration and torque in these gears. Also, the overdrive should help gas mileage during interstate cruising. This, however, could introduce a new problem. Factoring in my tire radius, at 65 MPH, the engine will be turing about 1700 RPM. This is fine and dandy, but the torque curve of the engine is way low at this region. This can lead to acceleration problems at crusing speeds. The problem is further enhanced by the fact that I plan on using a carburetor, and not fuel injection (initially). My Lincoln town-car experiences this problem, and I usually turn off the overdrive so that I can get rid of the "sluggishness" the car has on the interstate. I need to do everything in my power to improve the low-end torque of the chevy 350 engine. Some thing that may help are the following: (1. variable-duration hydraulic lifters. (2. longer connecting rod length, (3. a camshaft with a lot of lift, but somewhat short duration, or 1.6 ratio rockers (instead of 1.5), (4. advancing the cam centerline a few degrees. I think that I will go with the variable-duration (Rhoads) lifters, moderate-big lift and short duration cam (maybe a roller cam unit, the price is reasonable), and advancing the cam. [Used regular lifters]

By the way, I still have a few leftover jag parts (automatic xmission, driveshaft, radiator, fuel pump, etc.) CHEAP - so let me know your wishlist!

Some more info on the TH700-R4 tranny I plan on using for the V8 conversion.....

Like I stated earlier, the 700R4 uses a lockup converter. This lockup mechanism is electrically-controlled by an external wire, usually coming from some sort of an ECU unit. I plan on using a plain-old carburetor, and all of the air pollution stuff will operate mechanically. So i will not have an ECU to operate the lockup feature.

After much digging, I found some lockup alternatives. First, a description of the wiring. The connector on the transmission is a four wire unit, with the following uses:

        Pin A = +12 volt feed - purple wire
        Pin B = connected to a normally-closed switch, which internally
                grounds when the xmission is in 1,2, or 3, and opens
                (floats) when in overdrive (fourth) - Blue or Dk green
        Pin C = not used
        Pin D = TCC solenoid, when grounded the converter locks up - 
                tan w/ black tracer.

Most of the time, you want the converter to lock up only in overdrive. One popular way is to replace the normally-closed switch (going to pin B) with a normally-open unit (GM # 8642473), and connect pins B and D together. This way the switch closes only in overdrive, which grounds the TCC wire and energizes the solenoid in the tranny.

Most ECU's unlock the converter when the brakes are activated, by removing the +12 source. In the above scheme, a relay can be energized when the brake lights are on, removing the +12 volts from the xmission.

Instead of using a new internal switch, one can simply wire a relay that is energized in gears 1,2, and 3, and deenergized in overdrive, closing a set of contacts grounding the TCC lead. However, the fail position of the relay is TCC grounded, not a good default state.

I know that B&M sells a lockup box, which I have been told hooks into the speedometer cable and locks up based on speed. Anyone have anymore info on this???

SInce I am a dreamer, I was contemplating building a active circuit to do the above, with a little more. It would be nice if the lockup occurred only if (1. you are in overdrive, and 2) you are not accelerating or deaccelerating. (1. above is easy, as described. 2) is somewhat harder. I want to stay locked during gentle acceleration or deacceleration. Moderate rates-of-change would like disengagement of the lockup. Wide-open throttle forces you into 3rd gear, unlocking the tranny by 1). There needs to be some sort of deadband so that the unit is not constantly locking and unlocking. The tach wire from the distributor would be a good place to determine engine RPM, also the 83 and newer XJ6 cars have electric speedometer senders, which put out 2 pulses per speedo gear revolution. Since the convertor is locked, either one would work - however, the tach input represents what the engine is doing, hopefully a function of the driver's foot. Or maybe I could use a throttle-position sensor, but my carb does'nt have one, so I can't. All you Electrical Engineers out there - here's your million-dollar chance - design the circuit to do the above. Maybe a op-amp integrator would suffice.

Enough dreaming - I will probably replace the switch in the transmission and be done with it.[ The switch swap has worked beautifully, no problems]

Had a chance to pull the steering rack out in order to get at the bushings. The bushings pressed right out with little fight (resistance was futile against a 50 ton press!)

The bushing were in very sorry shape. The rubber was cracked and broken up, but it still held the metal insert from coming out. I needed to remove all of the rubber in order to use the steel insert for the new bushings (described later), so I burned out the rubber. I set them on fire with a welding torch. Usually in the past when I have done such a thing (on Chrysler and Ford bushings) the rubber burned for a least an half-hour. These burned for about 10 minutes. When I was done, no trace of rubber was left on the metal, and a pile of rubber ash remained on the ground.

Many people that I have talked to, mostly racers, feel that the quality of rubber used for things like bushings and motor mounts has greatly diminished. Rubber seems not to last as long, crack earlier, and generally not as durable. I have been told that bushing that used to last 10 years now last 3. Many new cars from Detroit (and others?) seem to be plagued with short-lived rubber suspension parts. Does anyone know what is going on here. I have a motor mount for a Barracuda which I bought new in 1987 from the dealer. It has remained sealed in a plastic bag until last month, when I gave it to a friend. It had cracked in several places. Whats going on????

Anyway, I decided to fabricate new bushings. I was first going to use urethane, but I have decided to use Delrin instead. It is somewhat harder (I do not know the specific Durometer number), but this is the material used in aftermarket performance bushings. I want to stiffen up the steering rack, and this should do it. It took me about 1 hour to turn down the Delrin stock, and I am now ready to install them. The Delrin cost me $8.00 new at the local plastic store, and I will end up with first-rate bushings which should last quite a while. The added shock that may cause accelerated wear on the steering rack, but I will sacrifice that for increased feel of the road.[Bushings have lasted 20,000 miles, and they still work]

More on the trip computer. I have been told that the computer derives the fuel flow from a black box mounted next to the ECU in the trunk. It's input is from the ECU , monitoring one fuel injector for fuel flow. The black box output goes to the trip computer. Does anyone know what the output from this box looks like?? Is it a pulse, and if it is, what is its relation to the input FI pulse width? I have a flow sensor made by super-flow (the dyno people) which puts out pulses. I may be able to convert this to the proper input for the trip computer. [It never happened]

I do not have to have the trip computer working, but it seems like one area that is overlooked ALL the V8 conversions I have seen (yes, even by John's cars!). The speed sensor hookup is trivial (also, for that matter, the speedometer sensor is also easy, but I have to track down a 90-degree speedometer drive gear bend from a XJS in order to fit the sender in the transmission tunnel).

An update on the Chevy 350 conversion in my 83 XJ6:

I am now in the process of assembling the Chevy 350 motor. It is experiencing a complete teardown and rebuild. The block I am using is a four-bolt main unit (1976). The crank is a forged unit which has been turned down ten thousandths and polished (also magnafluxed). I purchased a master rebuild kit from summit racing which included new forged TRW pistons, gaskets, HV oil pump, true roller timing chain, cost $230.00. I also bought a new cam from Ultradyne, they use a asymmetric lobe design which chevy motors appear to like (or so is said!). Hopefully the motor will be together next week.[More like next month]

The transmission, a TH700-R4, is ready. I had to replace the pressure switch in the unit so that the torque convertor locks up in fourth gear only. I purchased new speedometer driven and drive gears (driven 39 tooth, drive 17 tooth, for use with my 2.88 rearend). I turned down the speedometer gear housing slightly on a lathe, and cut new threads on the housing (.040 separation) so that the speedometer transducer from the jaguar would screw on. The square slot opening on the speedo gear had to be opened up slightly so that the transducer drive would slide in. Incidently, here is the speedometer gear chart for other conversions:

Rearend Gear           TURBO 350                 TURBO 400/700R4
Ratio             Drive Gear  Driven Gear     Drive Gear  Driven Gear
3.54          |    9         |    24       |    15       |    40     |
              |    8         |    21       |    17       |    45     |
              |    7         |    19       |             |           |
3.31          |    10        |    24       |    15       |    38     |
              |    9         |    22       |    17       |    42     |
              |    8         |    20       |             |           |
3.08          |    10        |    23       |    15       |    34     |
              |    9         |    21       |    17       |    39     |
              |    8         |    18       |             |           |
2.88          |    10        |    22       |    15       |    32     |
              |    9         |    19       |    17       |    37     |
              |    8         |    17       |             |           |

I found a drive shaft from a 1971 Chevy Nova which should bolt right in without any cutting or mods (yes, even the U-joint will connect to the jag rear end flange).[I had to cut off 2 inches, because of the 700R4]

I also calibrated the tachometer - all this required was adding a 330 ohm, 1/4 watt resistor in series with the red wire going to the movement on the tachometer.[Tachometer agrees with commercial unit]

AND I also made up a new wiring harness. This was much easier than I thought originally. Here is the wiring harness connections by jaguar color codes:

	Alternator light - Brown-Black
	Ignition (HEI)   - White
        Tach term on HEI - White-Grey-Blue
        Oil Warning      - Black-Brown

        Oil Gauge        - White-Brown
        Water Temp       - Green-Blue 

The FI wiring (jag) will just hang there, sadly unconnected (but I removed the Fuel pump relay, because I removed the electric fuel pump).

More updates to come.....

The V8 swap continues......

I FINALLY got the Chevy 350 motor rebuilt! The rebuilding part was easy It was the chasing down of new parts that took the time. I also took the oil pan and bashed it with a pipe around where part which will be near the crossmember, just to find that the pan was the wrong one - I am using a 4-bolt main block which has the oil dipstick on the drivers side, but the pan I was using had the dipstick on the other side. So I had to get another pan and bash it also (I should have checked beforehand, but what can I say - I am an idiot!). I also located a pair of center-dump "rams-horn" cast iron exhaust manifolds, a must-have item for this swap. I purchased 90 degree exhaust header pipes from Suncoast conversions, which should make the exhaust hookup much easier. I plan on placing a Y pipe in front of the catalytic converter and attaching to the head pipes. This arrangement passes the strict California emission test shops, and here in Virginia, the local inspector rarely checks if you even have ANY exhaust - all you need is a working horn and $22.00 to pass. I will put an AIR fitting somewhere near the Y-pipe to hook up the smog pump, just like Ford does.

The 700R4 transmission is also ready (the lockup switch was changed via. a mod mentioned in a previous message) and bolted to the engine. The speedo transducer is attached to the speedo gear, with the right gear installed (I thought that Jag pats were expensive - the driven gear was $21.00 from the dealer, and yes it is plastic and probably cost 10 cents to make). I got a tranny shifter lever off of a XJS TH400, bolt on. I fabricated a bracket that will hold the shifter cable to the transmission. One problem is that the 700R4 does not have a Neutral safety switch on it. I have been told that one can use the switch off of a late-model XJS, which is attached near the shifter handle. Is this true? How does it mount up, and will it to a XJ6?[Yes, I am still running around with no neutral safety switch, but it is high on the list of things to fix]

The engine is totally dressed, with the wiring harness, starter, power steering, water, A/C, AIR, carb, etc...... The engine mount stands are bolted to the Jag frame (same mounting place as stock). The motor mounts are attached to the engine.

So all I have to do is "lower 'er in". I am sure the nightmare is just beginning, maybe this weekend.

Update on the V8 conversion.....

These last few weeks I have had very little time to do anything fun, but I finally got the swap to the point that I started up the engine and broke it in. Some of the hassles I had getting to this point:

1) The radiator I used came out of a Camaro - a 4-core unit. The lower crossmember on the left, where it curves up, prevented the radiator to sit down all the way. So I did a terrible thing - I cut some of the curve out and welded in a square corner (the first and hopefully only cutting I have done to the car, so far). The radiator fit inside perfectly. By the way, the core dimensions were 26 3/8 inches. If I had used a 25 inch core and/or the small water tanks, no cutting would have been needed. Oh well...[Next time, I would modify the radiator, instead of the crossmember]

2) Mounting the fan shroud for the engine-driven fan, which came off of a 79 Ford Granada V8 car, was a little tricky underneath. I fashioned little brackets to hold the bottom away from the surface of the radiator. I do not like the looks of the job that I did, so this weekend I will try to do it again, better.[new bracket performing fine]

3) I have hunted many places trying to find a driveshaft that is the right length, with no luck. The driveshaft that came closest was off of a 72 Nova, which is 53.5 inches from center to center of U-joints. I need something around 51 inches. So the shaft is at the machine shop being shortened. I shoved in a spare yoke in the tranny when I started up the engine, to keep the fluid inside. If I had used a turbo-400 tranny, instead of a 700R4, the shaft would of fit just fine. Oh well...

4) To test the engine, I quickly wired up the spark plug wires, and just draped them over the valve covers. Since I am using the Rams-horn exhaust manifolds (it is necessary for the swap), which curve upwards instead of under, like most manifolds, the wires burned to a crispy critter! As I was told many times, you must route the wires between the side of the engine block and the manifold, and not over the top. Liberal use of wire spacers which attach to the oil pan bolts are also needed. I needed new wires anyway.

The engine did start up with no problems. Even though the car still has not moved under its own power, just gently revving it up makes the whole engine lurch in its motor mounts, indicating the possible need for a torque strap (yes the motor mounts used are fail-safe, but extra precaution never hurts). So initial results are encouraging - I may have the needed low-end torque to drive the car in overdrive, but this still remains to be seen.

I still need to hook up the driveshaft, get a replacement oil sender unit (the old one is faulty), hook up a radiator overfill tank, get rid of the electric fuel pump (its still there in series with the new mechanical pump, acting as a unwanted restriction), put the bonnet back on and try to keep the hood shut (which brings up a question- I have been told to cut off a few coils on each spring located on the hood latch, in order to keep the bonnet from popping open - is this a good idea?), hook up the A/C compressor[not done yet], calibrate the tachometer, etc.......

It may roll soon....

Well, the Jag is alive again.......

I finally got to take the Jag out on its first voyage with its new Chevy powerplant. And all I can say is that the effort was WELL worth it. I am absolutely pleased with the results!

I have only driven the car about 50 miles, so the engine is still very "un-broken-in", and it is hard for me to keep from punching the gas but in a few instances I gave into the temptation. The overdrive gear is TOTALLY usable, the engine has more than enough torque to operate in that severe gearing (0.70 overdrive, 2.88 diff ratio).

The car seem to keep all of its original ride characteristics, and I did not notice any funny maneuvering problems, but I still have'nt driven it very much. I am noticing a very slight "whine" coming from the differential. I have'nt checked the fluid in the unit, it is probably low, because I noticed that the differential has a bad leak from the pinion seal. How hard is it to replace - do I have to take out the unit to do this, or can i do it on the car?

I do think that I may have used a little too much cam. I did reach my goal of low-end torque (quite), but I have had to open the carburetor throttle plate idle adjustment somewhat to get the engine to idle, and I am in the transition slot region of the Quadrajet carb, which makes the adjustability if the idle-mixture screws very lame. I will fix this by drilling two 1/16 inch holes in the primary throttle plates (one in each), which will allow more air in, and allowing me to bring back the plates, out of the transition slot. If I still do not have enough adjustability, I will open up the idle feed restriction. [I opened it up a little too much, so idle is a little "smokey"]

The motor is also experiencing a slight surging at about 45 MPH. I am using port advance, which may be the problem - I am going to switch to spark advance to the distributor. Total advance happens at about 3000 RPM and is 36 degrees, and so far I have'nt noticed any detonation, but the engine needs more break-in.

I have to hook up the starter safety switch and reverse lights before I can get it inspected (yes, I have been driving it around illegally - I am a criminal). I also have to hook up a AIR tube in the exhaust line for the air pump.

So you really can put a Chevy lump in a Jag........

Update on the V8 conversion.....

Well, I am finally in at the long-awaited "tuning" mode of the project. I have put about 150 miles on the car so far, with no major problems, other than a buzzer that would not shut up (it is now history). The only concerning problem is a slight whine from the differential. I have not checked the fluid level yet (yes... where is the fill plug located?), and I noticed that the pinion seal is anti-sealing. If it gives me enough problems, I'll shove in a Dana 60 replacement (joke!).[Yes, it still whines]

As I stated earlier, the carburetor was somewhat lean in all RPM ranges, so I ripped it apart. The carb is a Rochester Quadrajet - I did not use a Holley because of hood clearance problems, even though I have quite a stock of various Holleys laying around. The jet (primary) I found was a 73, a good value for my engine setup. The metering rods were 55, which are a little large (this was an emissions carb (was)) which I replaced with 45's to allow more fuel at idle (the rods insert into the jets at idle and are removed at high venturi air velocities). I also drilled open the idle-feed restriction by two thousandths (tricky, because it is recessed down a well about 1.5 inches). When I first started the car, I had to open the throttle plates quite a bit in order for the car to idle at a reasonable speed. The butterfly plates were in the transition slot, so the idle circuit had little effect on the idle. In order to move the plates back (more closed), I drilled 1/8 inch holes through the throttle plates which allowed more air to pass, and allowed the plates to return back to a more normal position (I also switched to manifold vacuum advance, which increased the RPMS at idle, allowing the plates to close down even further). I restrained myself from modifying the power valve spring, but it still may get chopped yet...

Speaking of timing, I limited the mechanical advance curve so that at about 750 RPM, the mechanical advance is about 20 degrees, and reaches a peak advance of 38 degrees at 3000 RPM, with no more advance above that. This limit was achieved by welding up part of the advance slot on the HEI distributor. Remember my goal is to get as much low-end torque as possible, because of my rear-end gearing (2.88) and the use of the 700R4 transmission with the 0.7 overdrive gear. The cam in the engine is somewhat excessive in the duration, which is making me do all of the drilling and welding of everything. But it yields gobs of low-end torque, and the gearing setup is VERY usable in normal driving.

But the engine STILL NEEDS MORE fuel at idle, so the idle feed restriction will be tampered with again! Mid-range and WOT seem OK, but I might increase the jetting a little. If I drill up the carb too much, I'll just get another one - Quadrajets are plentiful at the boneyard, and cost around $25.00.

Once I get the carburetor setup just right, I am going to throw it away and either get a multiport fuel injection with an Electromotive or Arizona Speed n' Machine ECU, or use the Holley pro-jection TBI setup.

I am still being somewhat gentle with the motor, but I did achieve 0 to 60 MPH in roughly 6.8 seconds. As soon as it is more thoroughly-tuned, the car is going to the dragstrip, in order to accurately judge 60-foot times - it is then easy to judge the results of changes in tuning. Tire hook-up is extremely bad, if I have to I will use a pair of slicks at the track.

No info on gas mileage yet, and I'm sure all the drilling is doing wonders for it. Alot of my driving is interstate, and the overdrive should help there, as well as the lockup converter.

One change I would do next time - I would use a torque converter from a Camaro or Corvette when using the 700R4 tranny. The unit I have, from an Impala, has a lower stahl speed and produces some "creeping" at idle. My idle speed is around 750 RPM, and I hope to lower it to around 650-700 after more carb work which will help this problem.

An update on the V8 conversion status....

I have put about 3,000 miles on the engine, with absolutely no problems with the motor. The timing advance curve still needs some more tinkering, but it is pretty close, as well as the carburetor. No oil leaks. And the temperature has never gotten above 90 degrees C, even on 95-plus(F) days in traffic. The Camaro radiator setup has worked excellently.

Most of my displeasure (very slight) is toward the 700-R4 transmission. The unit was, after installation, "soft shifting" from 2nd to 3rd. Mucking with the throttle TV cable eliminated the slipping 2-3 shift, and moved it to the 1-2 shift. After some external investigation, it turns out that this is NORMAL for these transmissions to slip somewhat between shifts. As is well known with racers of automatics, slipping usually leads to increased tranny wear - it is best to have a unit which shifts "hard" (the clutch paks and bands are the things which are slipping because the control pressure is applied in a "ramping" fashion).

So to firm-up the shifts, I have ordered two items. One, from Darryl Youngs in California, is a new TV valve unit, which increases line pressure, and a new 2-4 servo unit, from Fairbanks Racing Automatics, which has an increased surface area in the servo which applies the band "tighter" when activated. Yes, i am trading smooth shifting with a more harsh action, but I value tranny life and performance more.

And the differential is still howling, but 140 weight gear lube has slightly masked the whine until I feel like or am forced to fix the unit. And it still leaks.

The differential is the thing which is keeping me from acting like a complete and total idiot speed demon on the road. The Jag alone tends to make a driver cocky, and with the extra power, life becomes more ticket-prone.

Bruce Bowling
Bruce Bowling Done