In 1975 Chrysler Australia released a mid-sized sedan onto an unsuspecting Australian motoring public.

There was nothing really "new" about the Centura. It was a French based vehicle, and there had been versions already produced in Europe, England, and the U.S.A. with fairly limited success. The basic design called for the fitment of the same four cylinder engine which had powered the Simca and a 4-speed manual transmission.

Chrysler ran with this driveline package, but also decided to treat the general public to a much more potent version. After some redesigning on the front chassis and engine crossmember areas these sedate, roomy, would-be challengers to the Holden (GM) Torana and Ford Cortina were transformed into something a little more performance oriented. The factory at Tonsley Park, South Australia, began fitting the locally based Hemi- headed six cylinder. A smart move. By making the Centura available with a combination of driveline options Chrysler ensured that their 1970's foray into the medium sized family car market would not go completely unnoticed.

A 245(4.0 Litre) or 215(3.5 Litre) cubic inch six with the choice of either three-speed auto, or manual transmission made the Centura more noticeable in the eyes of those seeking more performance. I believe it wasn't until the KC Centura was released in 1977 that a 4-speed manual was available. It is still believed that some escaped the factory with the mighty 265(4.3 Litre) on board, but this cannot be proven beyond doubt, although I have a friend whose 1975 KB has the 265 engine code stamped into the factory build plate.

In 1992 I was motoring around happily in a bronze 1976 KB with 215 Hemi and 3-speed manual when I came into possession of a 1976 KB GL version with 245 and automatic transmission, but that's another story.

The purpose of this page is to go over what was involved in converting that vehicle to a V8 plaything that has brought me many good times and more than a few thrills.

To begin with let me explain that this is not a conversion that was rushed into. Every aspect of the task at hand had been carefully thought out and planned, or so I thought at the time.

I began by reading every article I could get my hands on that dealt with a V8 Centura, not an easy thing to do since they were (at the time) few and far between. The next step was to confer with my local motor vehicle registration authority to find out what they required. I discovered that they would permit any capacity to be fitted without the need to obtain an engineer's report. Unfortunately this was limited to an engine of no more than 5.0 Litres, which basically translated into a Chrysler 273, Ford up to 302, or Chev up to 307. But, being a Mopar it had to be a 273.

I came across a 1965 vintage 273 sitting in an AP6 Valiant at a mate's place and struck a deal. A few dollars changed hands and it was off home for a rebuild. At some point along the way I found I could not afford to carry out the rebuild and resigned myself to the fact that it wasn't going to happen. Then the chance came up to purchase a 1974 VJ Valiant from a fellow member of the local Chrysler club and jumped onto it.

The car came complete with an LA318 and A904 Torqueflite auto and cost the princely sum of $250. Shortly after this my lucky streak really started to get going. My friend Bruce, who happens to own a V8 62 'S' series Valiant, was looking at the same type of conversion for his Mopar. He proposed we fit the 318 into his Valiant, and his freshly thrown together LA273 into my Centura in front of the 904. All he wanted was a 318 to drop into the empty whole between his shock towers. A deal was struck, and it was on with the job.

First off, I must point out that this conversion is so simple that I cannot understand why it has not been performed on another A.C.T registered Centura.

ENGINE BAY

When getting started, one of the first things to do is make sure that the sump plug is moved. It must be relocated to either the underneath, or the side of the sump bowl. This was my only miscalculation and made oil changes impossible. Also, be prepared, when the oil pump seized it cost me three days off the road. At first I had tried to simply jack the engine up( I did not have an engine hoist) but found there was not the clearance needed to remove the sump due to the six cylinder Centura's "D" shaped crossmember, an addition by Chrysler Australia for strengthening. After borrowing a hoist, the engine was lifted clear and the job completed, but take my advice and save yourself the trouble. If you don't take heed of warnings such as that, then you're wasting your time reading this page, and may as well sell your Mopar to make way for one of those toy homeboy cars.

Possibly, by now, you are asking - "What about the engine mounts?"

Well, If you've been saving frantically for this project, good news, you can spend most of it somewhere else. The engine mounts aren't a bother. Turn them to a 90 degree right angle to their six cylinder position. It is a matter of personal choice which mounts you use. I have a smallblock mount on one side and a hemi six mount on the other. The Hemi mount is slightly thicker than the V8 mount and I suppose it's akin to a Slant six setup. The main deal with the engine mounting procedure is to align the holes in the steel bracket so as to bolt the rubber mounts to it. This was trial and error, and took us about an hour or two. No changes were made to the original position of the cradles welded to the chassis rails as the smallblock LA will happily sit straight into where the six had been. There is, unfortunately no space for the battery in the engine bay once this conversion is completed, and even if there was I wouldn't advise it as the heat from the engine would probably kill the battery in no time at all. I didn't even bother to try and moved the battery into the boot.

The standard Hemi six crossflow radiator remains in place, and has served me well. It seems to cope easily with cooling the V8, although an electronic thermo fan is fitted in addition to the factory mechanical item. If your flush with cash you could always speak to a radiator specialist about upgrading, depending upon what part of the seasonal temperature
changes are like where you live. I haven't worried too much about it, even in summer when it gets to the high Thirties (Celsius).

The sump pan itself created no problems at all as it sits in the centre of the D-frame crossmember, although it will sit very close to the back beam. this can be remedied by fitting some sort of spacer under the engine mounts. No problems have presented themselves in this area, and A.C.T DMV passed the conversion and have inspected it twice since, with no objections as to the way it sits near to the steering or chassis. A twin remote oil filter set-up resides under the hood to accommodate the appropriate oil volume and still there is plenty of space.

INDUCTION

Depending on your choice of air filter set-up you may have to go through the bonnet (hood).

Carburettor choice may also affect this. I ran with a Thermoquad for a while, and everything was underneath. But as soon as I changed to a Holley 600 squarebore the middle strengthening bar under the bonnet had to be removed, and the air filter element sat only about one-and-a-half to two inches high. In the end I eventually changed the air filter element and fitted a taller unit anyway. All along I had planned to fit a Hornet scoop in the centre of the bonnet for airflow, so I simply went through.

The inlet manifold may also make a difference. I run a factory 318/360 4-barrel unit, but perhaps one of the big name aftermarket manifolds may sit lower. Either way, you can keep it all hidden if you want to, I'm just a bit of a show off. If you've got it Flaunt it, After all, it's a bit hard to escape the twin exhaust note.

IN THE TUNNEL

The transmission fitment is also fairly straight forward. Just use your head, and keep your eyes open, those suckers are heavy when laid on your back. A Centura transmission tunnel will actually allow for the fitment of a 727 if you're feeling keen or rich enough. When fitting a 340 or 360 I'd recommend one of those baby's. The principle would, however, be the same. You'd just have to make adjustments for the bigger box.

As simple as it may sound I used a Hemi six rubber mount as a spacer under the A904 torqueflite where it bolts to the gearbox mount. The 904 will sit in the same spot as the smaller Borg-Warner 35 that was fitted to the Hemi six, it just sits up a little higher. I picked up a couple of longer gearbox mounting bolts to allow for this (measure it up while your under there) and except for the usual grunting and groaning (not as much fun as making those noises in the back seat with your favourite girl) there were no real problems.

The gearbox crossmember( which should really have been named a frustration bar) can be moved to suit the bigger transmission, with holes already in place. Although these holes are present you may find it handy to have a tap & dye set around. The reason for this is that these bolt holes wont necessarily accommodate the thread of your bolts, no need to change the bolts. The diameter of the bolts is fine, the lack of thread in the extra bolt holes is the thing to allow for. The rod between the shifter and the gearbox linkage in my Centura was hand made, oh yeah real difficult stuff. I cut a low density strip of circular steel to the correct length and bent two right angles into it, one at each end. Don't forget when measuring the distance for this to allow a little extra for the bends. DON'T MAKE IT TOO SHORT!! While making up my first one i also did not give any thought to the fact that when laying upside down under the car, you are looking at the steel rod and linkages upside down/back-to-front also. It sounds strange, but try it and see. Anyway, I wasted a piece of steel rod that way, so bear this in mind.

After fitting the smallblock V8 and torqueflite auto into place it may seem to sit a fair way forward, mine does. You will be able to view more of the bellhousing than usual, that's okay. If you are particularly worried about this then simply make the right measurements and move the whole thing back a couple of inches. I have never suffered from any weight distribution problems, and the car is not nose heavy. It's up to you.

TAILING IT OFF

When fitting a tailshaft to this wonderful new creation, give it some thought and do your measurements. Just as a hint, I fitted a 1974 VJ Valiant sedan item. There was no forethought on this at all. I simply discovered that the Centura shaft was now too short, it seemed that the back end of an A904 is the same as the BW35 that came out, all the extra size is (as most women like it) up front. The Valiant tailshaft was the right length, and fitted without a problem. The yokes are the same between the two shafts( I was missing the yoke from the Valiant shaft and had to fit the Centura one), as are the uni couplings on the differential. The one thing, however, that you may have to go without is the extra little bar that bolts on rear of the gearbox crossmember. This should only occur if you fit dual exhausts ( and why not?) as the chances are the exhaust will interfere with this bar. Mine hasn't been fitted since the conversion and I've never had any problems without it.

FINISHING UP

Be sure to double check that all cables and wires are secured out of harms way. wires to the gearbox, starter and other areas are fairly easy to tie up in a safe place, away from exhausts and the like. Check your oil lines.

Last but by no means least, you will need to replace the speedo cable. The 904 item is a slightly thicker cable, with a much larger end for speedo connection. Once again, no problem. Mine cost me $25. All I did was take my Centura cable and the cable that came with the A904 into the local outlet that sells and fixes gauges, and he refitted a new small end onto the larger cable. Remember the end that slots into the box is also different, so use the A904 cable with a narrow end.

And one final piece of advice - run a transmission cooler.

This page loaded February 11 2000