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Holden 6 Cylinder Grey Motor Info & Tuning

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Submitted By dgr01
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|Holden 6 Cylinder Grey Motor |
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|image from original Holden 48/215 sales brochure |
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|Holden gained engine building experience during WW2, when it manufactured both aeroplane, boat and torpedo engines for the war effort. |
|The Grey six (so named because the entire long motor was finished in a "grey" paint) was born with its success to be seen as a measure |
|of GM-H's new car. |
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|Holden wisely choose reliability over innovation, durability over performance. The 6-cylinder design was chosen as a compromise between |
|the British cars, with their sometimes unreliable 4-cylinder engines, and the larger US cars that featured more expensive to |
|manufacture, maintain and run V8 engines. |
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|It was a square engine, featuring a four-bearing crankshaft, gear-driven camshaft and full pressure lubrication system with provision |
|for accessory oil filter. It had a capacity of 132.5 ci (2.15 litres), a compression ratio of 6.8 and developed 60bhp (rated at 21.6hp).|
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|The fuel system used a cam driven mechanical fuel pump feeding a single-barrel, manual choke downdraft Stromberg carburettor. An oil |
|bath air cleaner was an optional accessory. Delco Remy electrics (starter, generator, distributor etc.) were used on early engines until|
|Bosch units were phased in early 1953. |
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|The torquey, low stress unit was extremely flexible, economical and offered at the time lively acceleration. An added benefit was that |
|it was easy to work on. With its success through the '50s and early 1960's the grey engine was carried over into each new model series |
|with only minor modifications - new camshaft, higher compression ratio, incorporation of larger valves and throat surgery in the form of|
|improved carburettors. By the time the FB was released the capacity was up to 138ci (2.26 litres) with a compression ratio of 7.25 and |
|an output of 75bhp (56 kW). If you are trying to identify if the grey engine fitted to your Holden is original, the following engine |
|number sequences may help: |
|48-215 numbers started at 1001 |
|FJ numbers at 121694 |
|FE numbers at L283373 |
|FC numbers at L439507 |
|FB numbers at B1001 |
|EK numbers at B175814 |
|EJ numbers at J1001 |
|The First “Hot” Holden |
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|Not long after the first Holden rolled off the assembly line, there were young rev-heads looking to tune the grey engine in an attempt |
|to extract better performance. At first 100 bhp was considered a respectable goal for an iron headed Holden, by 1960 that figure had |
|jumped to around 135 bhp, and by the end of production it was closer to 150 bhp. We have been told that modifiers who took the |
|alternative route of fitting special cylinder heads to the basic block assembly were rewarded with over 200 bhp. |
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|Among the first Aussie race pioneers to see the Holden’s potential were the likes of Jack Myers, Dick Shaw, Charlie Dean and Tom |
|Geoghegan. With the true potential uncovered, Holden dominated sedan car racing until the advent of the 3.4 Jaguar. This was not the |
|only sphere where Holden was setting the pace. What may have been the very first hot Holden was built up by Sydney tuner Merv Wargott in|
|1949, this iteration being installed in a speedboat – and during the 1950s the “grey” was a popular choice for aquatic propulsion. The |
|engine also made its presence felt in speedway racing. By 1956 almost every enthusiast knew that 100 mph had been shattered with a 105 |
|mph run by Dick Shaw, and a scorching 108 mph by Jack Myers. |
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|This eventually rose to more than 120 mph with the likes of Bob Holden and Leo Geoghegan. At the Bathurst circuit in 1959 Bob Holden's |
|fastest run along straight was almost 122 mph. Both cars were equipped with the Repco Highpower cylinder heads, but Myers and Shaw |
|relied on re-worked versions of the original heads. The Repco head was introduced in 1956 and demonstrated its ability in the very |
|attractive and successful Ausca sports car. Designed by Phil Irving, and manufactured by Repco, this conversion removed restrictions in |
|the engine's breathing. More power was developed even if the standard camshaft was retained. The difference was mainly in the shape of |
|the combustion chambers, the valve arrangement and sizes, and the spark plug location. |
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|The inlet valves were inclined 23 deg but the exhaust valves were upright. This permitted semi-hemispherical combustion chambers to be |
|employed. Two groups of three siamesed inlet ports entered one side of the head, and six individual exhaust ports left the other. |
|Although this conversion head was normally seen almost exclusively on racing engines, from the late 1950s it was made available (in kit |
|form) to the public. Because the grey engine was capable of taking various torque and horsepower combinations, Repco specified any of |
|five stages of tune for normal roadwork. In terms of bhp these ranged from 90 through to 130. Even in its hottest practical road form |
|the engine retained its flexibility. |
|Merv Waggott |
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|In effect, the Repco head simply allowed the engine to develop power that was usually held in check by the mass production head's |
|induction, combustion and exhaust system. For competition purposes, where sheer power was demanded, a Repco-ised engine could be |
|modified to a greater degree. In these examples the average output was about 160 bhp, but in some cases up to 200 bhp was recorded. |
|However, the top spot for the hottest Holden must surely go to Merv Waggott. From 1955 Merv set about the construction (and sale) of a |
|beautifully designed and manufactured “Waggott” double overhead camshaft cylinder heads. This transformed the engine into as potent a |
|piece of machinery as was humanly possible given the technology on offer at the time. One of the best known Waggott engines was built |
|for John French's Centaur – and this unit developed a reliable 208 bhp. |
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|Potent as it was, however, the truth was that little of the original Holden engine remained. Only the cylinder block, crankshaft and |
|connecting rods were manufactured by GM-H. The double overhead camshaft head, special dry-sump lubrication system, pistons, etc, were |
|all produced by Waggott. As you would think, these conversions were not cheap. The Centaur's engine, for example, was allegedly sold in |
|second hand form after finishing service in the Centaur for over A£1000. And that was around half the price of the brand-new version. |
|Unfortunately, however, the reign of the Repco and Waggott engines was relatively short lived. After the inception of Australia's sedan |
|car racing regulations in the early 1960s the old hot Holden’s with their Repco and Waggott heads disappeared from the sedan car scene |
|because they were too radically modified to conform as sedans yet not fast enough to compete successfully in the GT class. |
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|The result was to make competition between modified stock headed Holden’s fiercer than ever before. Des West's engine, after Waggott |
|modifications, produced 150 bhp. A high percentage of the performance was due to a new camshaft and valve train assembly that Merv |
|developed. The cylinders were over-bored to 3 5/16 in to give a capacity of 2500 cc. This, plus meticulous attention to detail, resulted|
|in a basically original engine developing more than twice its original power. While the 3 5/16 in bore was generally considered the |
|practical maximum, even for the hottest engines, there were reportedly a few built with 3.5 in bores, making the capacity 2700cc. |
|Mention must be made of the two seven main bearing engines built by Waggott. These had 3.18 in bores and special seven-bearing |
|crankshafts with a stroke of 3.77 in, which equalled a capacity of 3-litres. |
|David Dunstan’s Rotary Valve Head |
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|Then there was the very promising rotary valve head designed by David Dunstan. Engines fitted with this unusual head were developing |
|about 140 bhp back in 1958, but the project was apparently dropped after the inventor's death. The prototype engines were said to be so |
|smooth in operation that they could maintain 8000 rpm indefinitely, and 10,000 rpm for short periods. So let’s list some of the then |
|popular (albeit orthodox) methods of hotting-up. Starting at the bottom, there are modified sumps. These had increased capacity and they|
|were baffled to prevent oil surge during acceleration, braking and hard cornering. Next, there were supports for the centre main bearing|
|caps or, better still, solid steel caps. If the latter were fitted the block had to be line-bored. Less work was required when |
|installing the bridge-type supports, as they simply bolted over, and strengthened, the existing centre caps. |
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|The crankshaft, flywheel and clutch assembly needed to be dynamically balanced – and this was even more important if the flywheel was |
|lightened and a competition clutch was used. Many tuners also found it worthwhile having the pistons and connecting rods balanced to |
|reduce the chance of failure. As a general rule, grey engine tuners would leave the choice of camshaft grinds until after all the other |
|modifications were finalised. It was essential that the valve-timing and lift characteristics were compatible with the other |
|specifications of a hot engine. A replacement steel, cast iron or nylon timing gear could be fitted to the nose of the camshaft to aim |
|to improve reliability, but it was sometimes achieved at the expense of quiet operation. And as an aid to ensuring positive valve action|
|there were lightweight cam followers and tubular pushrods. |
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|Modifications to the cylinder block depended on the builder's requirements. If the engine was to be used in competition, many were |
|tempted to explore the practical limit and have the cylinders over-bored to 3 5/16 in. However, if reliability was an important factor |
|the over-bore was never more than 3.5 in plus .030 in. Even this demanded that the block was from an FB or later, as they had thicker |
|cylinder walls than earlier models. There were pistons' available to suit virtually any bore size and they were designed to give various|
|specific compression ratios. If ready-made pistons of the desired size and compression were not obtainable there were a number of firms |
|that would manufacture them to the builder's specifications. The cylinder head and its accessories allowed the greatest number of |
|variations. The aforementioned Repco conversion was readily available to private motorists, and arguably provided the best bang for |
|buck. |
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|It was reasonably priced and offered an appreciable boost in power with a minimum of work. Racing sedans from the time were proving that|
|exceptional results could be had from the original cylinder heads if they were modified by a specialist. Many firms undertook this type |
|of work and most offered several different stages, from a mild port and polish to extensively altering the combustion chambers and |
|ports. Larger valves were often fitted, as were alloy valve caps and stronger valve springs. On the induction side there were three |
|popular methods for multiple carburetion. The first utilised the original Stromberg carburettor, while the others required a change to |
|either SU or Weber carbies. The Strombergs and SUs were usually fitted in pairs or threes, while the most common - and least expensive -|
|Weber installations had one or two double-throat downdraft instruments. Another system that gained popularity by the late 1950s was the |
|fitment of one, two or three double-throat Stromberg 97s. |
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|The exhaust department on a grey engine could also have the full treatment. There were non-restrictive mufflers which could be |
|complemented by a large diameter exhaust pipe. Next on the list were the dual exhaust headers - either manufactured in cast iron or |
|fabricated from tube. The hottest engines required extractor exhaust systems to be at their best. The Holden engine could also be made |
|to appear much less mundane. The mass-produced look disappeared when a few alloy and chrome plated parts are fitted – something that |
|remained popular right up until the 1980s. Long standing favourites were alloy finned rocker covers and side cover plates. Chrome plated|
|timing covers, fans, pulleys and air cleaners helped improve the under-bonnet appearance. |
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|The engine was not the only item receiving attention from Holden enthusiasts past. Improved mid-range performance could be obtained with|
|transmission adapters to allow the fitting of four-speed transmissions. As a lesser alternative, more positive gear changing in the |
|normal box could be arranged by fitting a floor-mounted shift. And with all this performance there was need for some stopping. Although |
|the Holden's braking area was small, excellent retardation could be obtained by fitting Repco finned brake drums, a set of competition |
|brake linings and a servo-assister. And of course the HR disc setup would become a popular addition to earlier models. |
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|As far as handling was concerned, there were several beneficial modifications that could be made, including lowering the body and |
|fitting a stronger stabiliser bar to the front suspension. Rear axle tramp, always a problem with early hot Holden’s, could be reduced |
|by fitting torque arms from the axle to the body sub-frame.The grey engine went into its 15th year of service under the bonnet of the EJ|
|model, which ceased production in the middle of 1963, and were the last Holden engines to use solid valve lifters, and an internal oil |
|pump and oil filter. |
|Tuning your Holden Grey Engine: |
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|One of the best things about owning an old Holden is that they are so easy to maintain yourself. To perform a tune, you only need feeler|
|gauges, 3 spanners (5/8 AF, 1/2 AF and 3/16 AF) screw drivers large and small, a spark plug spanner and test light. You will then be |
|ready to start. |
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|Step 1: Run the engine until it reaches normal operating temperature. Switch off the engine and remove the valve rocker cover. |
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|Step 2: Disconnect the leads from the spark plugs, marking or noting the leads for correct assembly. Using the right plug spanner, |
|preferrably rubber lined, remove the spark plugs. |
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|Step 3: Beginning with No. 1 cylinder (nearest radiator), turn the engine until No 1 cylinder is at top-dead-centre (TDC) on the |
|compression stroke. You can find this by removing the distributor cap and checking that the distributor rotor arm is pointing to the |
|distributor cover segment for No. 1 cylinder plug lead. Or alternatively, by checking that the ball bearing located in the flywheel is |
|aligned with the index mark at the - timing hole in the flywheel housing. | Check the rocker arm to valve stem clearance on No. 1 |
|cylinder valves with feeler gauges, using a 0.012" (0.3 mm) feeler for the exhaust valve (first from the radiator) and a 0.008" (0.2 mm)|
|feeler for the inlet valve. Adjust by screwing the adjusting stud and lock nut located at the pushrod end of each rocker arm. Adjust the|
|remaining valve clearances by turning the engine in its normal direction of rotation and by following the firing order sequence |
|1-5-3-6-2-4, checking each at the rotor arm and distributor cap as already described. Starting from the front of the engine the valve |
|sequence is: Exhaust — Inlet I-E/E-I/I-E/E-I/I-E, so ensure that the correct clearance is given to the appropriate valve. Tighten each |
|adjusting screw locknut after adjustment. It is also advisable to recheck the clearance before proceeding to the next valve. |
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|Step 4: Carefully clean the spark plugs with a ground down hacksaw blade to dislodge the carbon deposits. Check the centre electrode for|
|excessive burning and the insulator for cracking. Renew if the plug's condition is very poor. |
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|Step 5: Check the spark plug gap between the electrodes using a 0.028" to 0.030" (0.7 mm to 0.8 mm) feeler gauge. Adjust the gap by |
|bending the earth electrode towards or away from the centre electrode as necessary. DO NOT attempt to bend the centre electrode. |
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|Step 6: With the distributor cap removed, rotate the engine to TDC on No. 1 cylinder and check that the timing marks on the rotor arm |
|and distributor body are aligned as shown by arrows A-A. Disconnect the vacuum pipe arrow B (pipe off), from the distributor advance |
|unit, and the low tension wire Arrow C from the distributor terminal Take out the bolt retaining the distributor to the engine Arrow D |
|and withdraw the distributor. |
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|Step 7: Remove the rotor arm, loosen off and remove the distributor points particularly noting the position of the components and the |
|method of fixing. Examine the contact faces for pitting or burning, and if they are bad fit a new set. If the points are reasonable, |
|dress the contact faces with a fine oil stone, keeping the face of the point flat against the oilstone. Before assembly, clean the |
|points in solvent to remove all traces of oil and dry them thoroughly. New points should be treated similarly to remove the preserving |
|grease. Assemble the points in the reverse order of removal. |
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|Step 8: Turn the distributor shaft until the heel of the moveable point bears on the peak of a cam lobe. Using a 0.014 to 0.016 in. |
|(0.35 to 0.41 mm) feeler gauge check the gap between the points. If necessary release the securing screw and adjust the gap at the |
|adjusting screw until the feeler gauge is a neat sliding fit. Rotate the cam and check the gap at each cam lobe to ensure that any |
|variation does not exceed 0.002 in. (0.05 mm). Smear a minute quantity of high melting point grease on the heel of the moveable point |
|rubbing block. Sketch shows the distributor in detail. |
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|Step 9: If the engine has been turned with the distributor removed turn the engine in clockwise until the steel ball in the flywheel |
|aligns with the index mark at the timing hole in the flywheel housing on the compression stroke for No. 1 cylinder. Enter the |
|distributor into the engine block but do not engage the drive yet, turn the rotor arm until the mark on the arm and the distributor body|
|are in line. Turn the rotor arm clockwise until the heel of the moveable point is approaching the next lobe on the cam (arrowed). With |
|the shaft in this position, and the distributor clamp plate hole above the retaining bolt hole, push in the distributor. The rotor arm |
|should turn in an anti-clockwise direction as the drive is engaged to bring it back to the No. 1 cylinder firing point. Do not force the|
|distributor down if it will not go fully home. |
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|Step 10: If the distributor hasn't gone fully home, maintain a slight downward pressure on the distributor and rotate the engine |
|clockwise. The distributor will fall into position when the drive on the end of the shaft engages with the oil pump drive. Fit the |
|retaining bolt after aligning the zero mark on the clamp plate with the index mark on the engine block, but do not fully tighten until |
|the following timing check has been made. |
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|Step 11: Reconnect the low tension wire to the distributor terminal (Arrow A) together with one lead of a test lamp (Arrow B). Ensure |
|that the test lamp has a bulb of the appropriate voltage for the particular car. Connect the other side of the test lamp to earth. With |
|the engine still at firing point on No 1 cylinder (i.e., the flywheel ball and index mark aligned) rotate the distributor body |
|clockwise, until it is clear of the cam lobe and the points are closed. Now turn the distributor body anti-clockwise until the test lamp|
|lights. At this position tighten the distributor body retaining screw and remove the test lamp. Reconnect the vacuum pipe to the |
|distributor advance unit. |
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|Step 12: Instal the spark plugs and connect the leads according to the marks you made when you removed them. Refit the valve rocker |
|cover, using a new gasket if necessary. Start the engine and bring to normal operating temperature. Adjust the engine idle speed to |
|about 500-550 rpm (as a guide use the generator red warning light which should be flickering at this idle speed). Turn the idling |
|mixture screw (arrowed) clockwise until the engine slows and begins to falter, then turn the mixture screw anti-clockwise until the |
|engine runs smoothly but does not lose speed or hunt. Road test the car and make any small adjustments necessary. |
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