Oldsmobile and a very special 4-4-2

Most of us simply go to the kettle, hit the switch and water boils…..easy. Not so for Oldsmobile though, these boys decided to do the boiling water trick in a whole different way. Better still they did this matching Cosworth in some special engineering in the ‘60s

455 Olds Pushrod four valve

Mildly tuned, this engine produced 500+ Bhp….the giveaway is the spark plug location which tells us that it is something special. Dr Oldsmobile was scheduling a serious injection….

The Oldsmobile 4-4-2….That Stirring nameplate comes from a vastly more carefree Muscle car era and from a motor company that, sadly, has had to give that name up to the sands of time. Oldsmobile, however, have a proud history in the car business and particularly that of innovators and engine development boffins. John Beltz the company CEO in the 60’s, the father of that 4-4-2, cut his teeth as a first-class engine man involved in some of the first High Compression engine developments in the USA, his Rocket 88 engines powering  50’s and 60’s ‘Olds’ product into folklore .


Oldsmobile’s signature Moniker signified that  high compression Rocket 88 V8 going back as far as ‘49

Often described as the ultimate car guy in the GM world of the 60’s and 70’s, his successful career can be followed in Oldsmobile development throughout his tenure. As the driving force behind the front wheel drive Toronado, Beltz embodied the innovator tradition at Oldsmobile by championing this very off-the-wall concept for a company like GM, right through to production….that, believe me, takes some smarts.

1966 Olds Toronado

The1966 Oldsmobile Toronado America’s first Front wheel drive Sedan since the Chord in the 30’s.

On the other end of the scale, good engine men do the little things right and in one such case this resulted in Olds supplying the cylinder block for the F1 championship winning Repco 3 Litre V8 of 1966/67.Whilst we know this ‘unique in the USA’ aluminium engine was based on the Buick (ultimately Rover) V8, it is not readily known that the Oldsmobile version of the cylinder block was selected to do duty in the Repco race application. Utilised by Buick, Pontiac and Oldsmobile in passenger cars at the time, the Olds engine’s unique six bolt cylinder head pattern a plus factor for Jack Brabham and his Repco team (the rest running a five bolt set-up).

Olds Repco Engine Block

Oldsmobile alloy engine block showing the additional head bolt location. Basis for Repco F1 engine of 1966/67.

Those were four of many notches in the Olds gun butt….but…. Beltz continued on a mission and went on to initiate an Engine development programme in 1967 that must go down as one of the finest, most successful programmes never to see the light of day. In the process a most cruel irony, so let’s take a quick peek at the background to this and touch on the muscle car environment in the US first.

Beltz’s 4-4-2 was Oldsmobile’s knee jerk reaction to the Pontiac GTO in 1964 but at only 326 cubic inches against 389 for the Pontiac, it was much like bringing that knife to the gun fight. The moniker 4-4-2 stood for “Four barrel Carb, Four Speed Manual transmission and Dual exhausts” ….

1964 Olds 4-4-2

1964 Olds 4-4-2

When GM inter-divisional peer pressure forced the launch of a 400 cubic inch version in 1965, the meaning subtly changed and now stood for….. “400 cubic inches, Four barrel Carb and Dual exhaust”…admittedly a subtle variation but Olds got the message across and were now in the fight competing on level terms with Pontiac and the rest.  By 1968, the Olds Team were getting restless and had partnered with Hurst to produce the first 455 cubic inch Muscle cars late that year. Built under wraps due to the GM limit on engine sizes at 400 cubic inches, this package clearly demonstrated Oldmobile’s intent to stay in the game…..

  • Noted in “No Option but to Option” our first post on this site, John De Lorean flouted GM company policy on the 330cubic inch rule in 1964 with the GTO. Beltz did not …and stuck to the rules. Extreme pressure brought on the executive by Chev, Buick and Olds resulted in this rule being relaxed to a 400Cid max for 1965.
1968 Hurst Olds 2

1968 455 Cubic Inch Hurst Olds 4-4-2…..  GM Skulduggery at its best under the 400 Cid Max rule…Built by Hurst….Not really… just the stripes and shifter. That black stripe was to find a new application in 1973 on the Can Am and 3800GT here in SA.

Can Am 1972 9 hour
3800 GT3

…..but there was something else brewing…. and if the rest of the industry knew what was really happening at the Olds home base in Lansing Michigan, there would have been many sleepless nights indeed.

We know that there was much experimental work going on in motor companies in the 60’s and Ford, Chevrolet, Chrysler  and Pontiac were busy with advanced engine programmes in their skunk works. Some of these labours found their way to the real world, more notably Ford with their SOHC 2v Hemi   ‘427 Cammer’  which broke cover only to fail approval by NASCAR.

This was a cheap and cheerful development on the original pushrod Ford 427 which had served Ford well on track…. the Cammer achieved cult status as a result of the NASCAR ruling…. but a good example of the type of work being conducted. Chrysler were completely off the charts with their view on engine development and the incredible turbine engined car of the period is a good example of just how much effort was being expended.….. Quite surprisingly though, our friends at Oldsmobile were working on a package that was clearly the most serious of all and a major threat to established practise.

This should have been the third version of 4-4-2, incredibly, the meaning now being….“Four valves per cylinder, Four camshafts and Dual exhausts”…big ones. Yes indeed, in 1967 a project commissioned by Beltz to build a 455 ‘Cammer’ got off the ground. This project was to build a four valve version of Olds’s  conventional  2 valve 455….but with a twist….there had to be two versions of the engine, a four overhead cam  version and…wait for it…. a pushrod four valver using as much common hardware between the two as possible. That’s not all, the design included cast iron and aluminium versions of both.

Did they do it? And was it successful?

Absolutely and Absolutely…..

This is ultimately what Beltz had in mind…and successfully developed 

10. W 43 Pushrod Four Valve

This was the “Sleeper 4 valve pushrod version….

The “W43” project kicked off with the pushrod version and moved quickly on to the “WO43” four-cammer so as to maximise development  and design efficiencies.  As with all engine developments, many teething issues needed sorting, however, in relation to the magnitude of the task, the relatively trouble free programme is a tribute to some incredibly astute engineering. Can you imagine being given a clean canvass to produce such an engine, with the only basic requirement being to have the project based on the solid-as-a-rock 455 engine block? The mind boggles at the thought.

This is the first similarity we have between this outfit and the Cosworth boffins on the other side of the pond who were themselves doing multivalve applications on the Ford Kent engine block. I had initially wanted to post the story of the ground-breaking Ford/Cosworth 4-valve work before covering the Olds programme but decided on this one first to illustrate just how smart the Olds guys were in putting this particular package together. We will get to that Ford detail but the most significant issue is that with Cosworth’s FVA/DFV work being conducted at the same time in 1967, both teams were dealing with four valve cylinder head design from a new perspective.

The two groups independently arrived at a basic cylinder head configuration, so similar in execution, that one would think there had been a fax line linking the two. A subtle jab in the ribs for the Fordies out there is that Cosworth were doing the work, while Ford provided the $…..GM had these Oldsmobile bright boys in-house.

W 43 Iron Cylinder Head

Oldsmobile 4 valve cylinder head 1968


Cosworth BDA 4 valve cylinder head 1969 

. W 43 and WO43 Comb Chamber

4 valve Pentroof Combustion chamber Oldsmobile 1968 – single squish area inlet side.     

FVA cylinder head

4 Valve Pentroof Combustion chamber Cosworth FVA 1967 – dual squish area – inlet & Exh

This was no ‘toes in the water’ job running as a feasibility study or high level R&D….the task was a serious development on a scale commensurate with moving to full production. Bear in mind that four valve tech was not a known science back then and this was not only a mechanical ‘Everest’ but an understanding of new cylinder filling and combustion processes. For a company steeped in the tradition of pushrods and  wedge style 2v chambers with power outputs of around 45 to 50 bhp per litre…. this was indeed a seminal moment…..and very different to Cosworth who had been in the Go Faster business since 1959 and as a consequence, arguably more experienced.

When one looks at modern pent-roof four valve arrangements we look at the included valve angles as a pointer to the application. This refers to the included angle between the inlet and exhaust valves as viewed from the front of the engine. As a rule of thumb on modern 4v applications, wide angle heads tend to be fitted to road cars with the greater emphasis on fuel economy and narrow angle on race and high performance road cars. Back in 1967 there were few narrow angle heads until Cosworth arrived on the scene. If we take the Alfa Romeo 2 valve Hemi starting back in the 50’s with an included angle of 90 degrees, we see that progressive reductions to 80 and 60 degrees  on more modern Alfa designs was done for exactly the same reason….to improve air flow and as an additional benefit resulting in more compact valve actuation.

Cosworth-Dfv 4

This is an end-on view of the Ford DFV with a 32° included angle between inlet and Exhaust valves. From this we can see the advantages in having the best relative entry angle between the valve and port for the inlet charge.

We could at this point turn this into a debate about things associated to combustion chamber vs port design but that is not the point of this story. The point being made is this was new territory and to have two design operations, on different continents, working on hugely different engines, to arrive at similar solutions to what was needed, is damned cool.

The easiest way to explain the reasons for the variance in included angle has, In turn, to do with the angle at which the inlet charge enters the cylinder. Design engineers will have their .own views but again a simple explanation is that a narrow valve helps with getting the port angles right  for max flow, resulting in higher volumetric efficiency and consequently cylinder filling. The wide valve angles tend to provide better swirl associated with fuel efficiency. Both have good combustion properties and the four valve arrangements give benefits in cylinder filling over a two valve wedge and a two valve Hemi. It is generally accepted today that included angles of around 30° for race engines is a healthy target.

Let’s get to the extent of the work done. It is classic that in the 60’s before we all become clever, both Oldsmobile and Cosworth decided on very flat chambers and narrow included angles. Oldsmobile selected 37°( Inlet 22° Exh 15°) and Cosworth 40° for the FVA.(20° Both) and 32° for the DFV (16° both), all designs being significant departures from that 60° and higher being the more practical norm for 2 valve Hemi applications. This low included angle resulted in an extremely compact, low roof, chamber with the spark plug smack in the centre of activities..  For Olds the decision had, in part, been decided through the use of a unique flow bench used in the port design. Oldsmobile developed their flow bench so as to enable measurement of air flow on a single working cylinder. Interestingly they measured the Exhaust gas volume exiting the exhaust port as the total measure of efficiency. This allowed the team to assess port shapes and valve timing on both pushrod and four cam cylinder heads whilst achieving excellent basics even before the engines fired up for the first time (For 1967 that is SMART). To facilitate testing of different combinations of port shapes and valve geometry, prototypes were made from wood.

The engine block for the two versions of the W engines was common and as already noted, designed for both cast iron as well aluminium manufacture. Cylinder head porting was very similar, with the exception that the pushrod version required channel intrusions into the ports to accommodate the valve actuation. The loss in flow between the two was much less than expected making volumetric efficiency on the pushrod engine a lot closer to the OHC version than expected and hugely better than the original 2V pushrod.

Here again a learning experience for the Cosworth and Oldsmobile boffins. In comparison to equivalent 2v engines, they initially expected 4V flow bench numbers to show improvements in flow throughout the valve lift cycle …not so….The first surprise result was to find that the biggest difference occurred at low and medium valve lifts….with fully open valves almost the same between the new 4V and equivalent 2V. The resultant overall increase in cylinder filling, ultimately being the difference between 4V and 2V engines.

From this we understand why 4V engines have that wonderful torque spread (using suitable long runner inlet tracts)* and achieve impressive power numbers without needing wild valve timing.

* Subsequent developments with Variable Valve Timing have resulted in astonishing cylinder filling capability across the rev range on 4v applications. Even on non turbo engines, many designs flat-lining in healthy areas of the torque curve..

** I was not being offensive when I referred to the Ford Cammer being a cheap and cheerful version of the original, because in the Ford application they had used a reduced cost approach to the development and a single morse chain to drive the two Overhead Cams. The chain was some 7ft long and had massive flex issues…so much so, that cam timing could vary by as much as 6°-8° dynamically between banks. As I understand it though (and it happens this way when any one of us engineers don’t get things quite right)…..the aftermarket has a solution and in this case there was a gear kit available for lovers of the Ford Cammer.

Let’s take look at some of the Olds architecture, the most interesting being the pushrod four valver. The magic is in the layout of the rockers, which because of the narrow valve angle make for a deceptively compact package. The associated pics of the engine complete with rocker covers attest to that. The dual rocker assemblies (individually adjustable) were initially constructed from cast iron, internally bushed and switched to forged  aluminium on needle roller bearings.  From this point the rest was fairly conventional with the inlet manifold breathing through the venerable Rochester Quadrajet.

W 43 Compact Valve Train

Compact 4 Valve rocker arrangement

W 43 Rockers - Cast Iron bushed vs Aluminium Needle bearing

Aluminium Needle bearing Rockers

W 43 Inlet manifold - 500Bhp from a Rochester Quadrajet.

Conventional Big runner Manifold – No Crossover heating channels – keeping things cool

Now to that Brutal OHC WO 43….These boys were not playing around and made this version of the engine superbly strong. Cam lobes were 1 inch wide and bucket cam followers radiused to keep the camshaft contact patch central to the follower. This type of thinking personifies the engineering that went into the design. I enjoy this approach and the resultant reliability of the engines during testing, given the detail being available today is something I would readily write an article about, ….we can learn from this thinking..

Radiused Cam Followers

Radiused Cam Followers minimised side thrust

One inch wide cam journals

Hefty 1” wide Cam Lobe

Camshaft drive on the DOHC engine was cleverly done through an initial morse chain driven from the crankshaft to a central drive gear which in turn powered a series of idler gears to both left and right cylinder heads.  That was smart, because the chain would have damped the rather nasty crankshaft harmonics inherent  In such a big engine and which would otherwise have been transmitted into the valve train on a fully gear driven system.

21. gears-HR-640x414

The timing gear arrangement for the WO 43. Initial drive from the crank to central idler gear by Dual Morse Chain  

One of the few reliability problems found during testing had to do with hair-line cracking of the Camshaft bearing caps. So big and robust was the design, that it was found that the camshafts had inherent imbalance and forces were so large as to result in this potential failure. Fortunately none resulted in in complete fracture but this forced the team to a unique design solution by offsetting the casting between the lobes to balance the camshafts and solve the problem.

The DOHC testing was done with the intent of establishing high power outputs using fairly radical cam timing and 48 IDA Webers.  These carburettors would be borderline in airflow for what amounted to each cylinder being   930cc…that’s nearly a one litre engine in a pot! Despite that the results were seriously impressive.

The obvious next issue is..…what were the power figures? …a lot…..a helluva lot. Certainly hugely more than anything available on the American market and had put Oldsmobile into a completely different league. In the same way we were amazed at the Cosworth FVA and later that same year, the DFV achievements, this was equally spectacular, particularly coming off an American two valve per cylinder base.

The four barrel pushrod “cooking” version produced  in excess of 500 Bhp in a moderate state of tune… a fair bit more than the 375 Bhp figure quoted for the hi power stock 455. In real terms, with both the stock 2V wedge and 4V pushrod in similar states of tune, an increase of 30% would be a comfortable achievement for a production  version of the engine.

The four cam monster became a different beast entirely. Fitted with 4 X 2 BBL 48 IDA Webers, power figures rose in sync with engine rpm….. 300, 400, 500 and 600 @6000. The max power seen was 700 Bhp at just below 7000 Rpm and at that point the Dyno cried enough and boiled the water on the Water Brake!. The surprising thing here was the fact that this engine was running cam profiles unchanged from the original prototypes. The ultimate potential of this version of the engine is not known but estimated max in terms of Bhp per litre is a minimum of 110 in 1960’s values making 800 bhp attainable in a mild race version. If we look at Cosworth achieving  an initial 133 Bhp per litre (FVA/DFV) with very similar architecture and eventually 170 per litre, here we have an engine that could have achieved the Magic 1000Bhp (134 Bhp/litre) normally aspirated with larger carburettors  or throttle bodies and more development….to avoid boiling the Dyno water, further testing at higher rpm was conducted at high part throttle at speeds up to 8400rpm …

All tests using screened standard cast iron crankshafts..

From a production feasibility point of view on the pushrod version, the engine block required minor changes to the stock 455 by lifting the cam bore in the block to achieve the required pushrod to lifter angles. This cleverly achieved by designing bolt-on lifter housings which would not be necessary on the OHC version. The reliability of the engine during development was one of the many outstanding features of the programme and four bolt main bearing caps were introduced only to prevent cap fretting. The four-cammer used the same part…. In cast iron or aluminium of exactly the same design. A dummy camshaft was used to drive ancillaries on the WO 43

W 43 Pushrod geometry

Camshaft raised to align Lifters with pushrods. Bolt on Lifter carriers in this application not used on the OHC WO 43

A really significant outcome was that the 4-cam aluminium engine weighed in 50Lbs lighter than a stock 2v 455….and could fit into the engine bay of a Toronado. Would that not have been something spectacular….a  500 Bhp+ front wheel drive sedan!…or 700 if you’re serious.

The engine development on both versions more than achieved targets set for power, torque and reliability and this was the first four-valve American V8 being readied for a production role ….. But there was one snag ….

Emission regulations in the ‘States were tightening and had to be met by 1973. Engine design teams throughout the industry were working full time to get conventional engine technology to meet the rules. Compression ratios were being lowered, valve timing altered and exhaust gas recirculation pumps installed. The upshot of this was an immediate real power reductions of around 15%  (and more in some cases) in order to meet the requirements.   Sadly this went along with similar increases in fuel consumption.

GM, like all others in the business were now moving into unknown territory and decided to play it safe…consequences for not meeting legislated emissions targets were severe.. Driven by this thinking and by the possibility of PR negatives, this forced some knee jerk reactions not driven engineering fact. One of these was the executive directive to reduce compression ratios to allow the use of 91 octane fuel across the board…… on all of the General’s vehicle line-up. Oldsmobile were given the responsibility for fuel system design and function for the entire GM group. This was to be a massive undertaking,  essentially requiring the company to focus on developing add-ons to allow old tech to meet the legislated targets.  The new-fangled 4 valve approach was considered to be an unnecessary luxury.

Worse…… was the fact that the engineers decided that the pent roof 4 valve arrangement would most probably not give good emission performance…… The project was terminated in 1970 without any engines being tested for emissions . The testing of a similar 4 valve design on the 362 cubic inch Olds engine was also scrapped.

The irony?….History will show that the pent roof combustion chamber is an excellent emissions design….and has become the standard in the industry. Had Oldsmobile continued with testing and then optimising emissions on the 4 valve engine they would have hit the jackpot in performance, emissions and economy way ahead of their rivals….

In fairness, most companies treaded lightly in these times made worse by the fuel crises of late 1973….so there is every justification for Olds (GM) not hanging their hats on the launch of a performance engine in the midst of all this. I do however have a major problem with the fact that these efforts were not brought to fruition once the dust had settled….that pushrod 4 valver particularly, is just plain brilliant….and that’s the one area that the Olds team showed a clean pair of heels to their UK counterparts.   

One could argue that a large portion of emissions success today has to do with engine management and the spectacular effect that modern electronics play in overall engine performance…Fair enough, but to meet the very basic emission requirements back then, electronics were absolutely not necessary….Oldsmobile should have persevered….and my guess is that they could have ended as the choice supplier for GM’s big block package in the generic engine programme …..and maybe, just maybe, the Oldsmobile brand would still be around today


We have not touched on the issue of cost and my summary on the outcome of this work would have me believe that it is this area that forced GM to pull the plug. Marketing types tell us that perception is everything and in this case probably dead right.  How does one sell what is a modern performance based idea into a market preoccupied with a shortage of fuel and the receding Muscle Car hairline…..you don’t. The market in the USA had gone soft and let’s face it, took  many  decades to recover to the point that performance cars made sense again.                                            

Next week we are shifting Gears…. and Continents….. to what I view as one of the most entertaining motor sport series on the planet….. The annual three race Supercar Endurance series in Oz. Folks, we have a month and a half of the best you will see on the planet and with Bathurst the highlight over the weekend of the 7/8th of October get set for the fiercest Ford vs the General combat anywhere…….Nissan is in the picture as well and lets see if the new blue Calsonic livery on the Altimas can get among the top guns. Will post live streaming info as soon as I can. That’s  not  breakfast in America…..but breakfast in Australia on the 17Sept, 7/8thOct and 22Oct….