The Four Cylinder Chevy

[993 Kadett]

The L4 Chevy

Again probably a good idea to have a look at the history of these engines and how they got to SA.
During the 60’s our country was a fully fledged 1st world operation and viewed as such by international business. Development in all things was largely keeping pace with Europe and the USA and certainly our motor industry, though very small by world standards, was hugely sophisticated. Local Motor co’s were required to increase the level of local content, something that was to affect the industry heavily. GM had decided that the engine route was best for them. They had a difficult decision to make in that their European arms were moving to modern OHC engine designs for the latter part of the 60’s and onwards… but had to commit to a local content programme in SA. This was something that would only make sense by localizing engines that would cater for the large range of models and body styles. The localization of the Opel range was considered too expensive and would not cater for the biggies (holden chevs of the day)….. A compromise was put together which ultimately made good sense and that was to go for the Chev L series which would take care of the 2.0 – 4.0 litre range with the Viva Ohv fixing the problem for the littlies.
This left a fair gap in the 1600 engine size range but in retrospect I think it was a good economic decision overall. Market forces, however, were to put pressure on this choice in the 70’s. Sadly GM used little flair or imagination in the use of these engines over the years. There were myriads of possibilities and very little done to make the most of what they had….

First the L4…. and the engine capacity variations available:

• 120 cid, 1960cc, (90.49 x 76.2)*
• 130 cid, 2123cc, (90.49 x 82.55)*
• 141 cid, 2319cc, (98.425 x 76.2)
• 143cid, 2352cc (90.49 x 91.44)*
• 153 cid, 2512cc, (98.425 x 82.55*)
• 151 cid, 2471cc, (101.6 x 76.2)*
• 163 cid, 2677cc, (101.6 x 82.55)*
• 170 cid, 2783cc, (98.425 x 91.44)*
• 181cid, 2965cc, (101.6 x 91.44)*

* Engine block available with V8 SB bell housing pattern with starter low on right (Ranger type) or small bell housing pattern with starter high on left (Firenza, 1900, 2300)

All engines were viable as vehicle production units with some limitations:

1. The small engines 120&130cid suffered from high internal friction and rotating mass relative to the engine capacity. This made them subjectively lazy. These engines should have been built with smaller crank journals and lighter flywheels and clutch assemblies to give them that additional snap and better fuel consumption.
2. The 170 and 181 were longer stroke versions and had high levels of primary vibration deemed too high for production saloons. I could personally not tell the difference in a subjective evaluation but ancilliaries like air con pumps did get a bit of a pounding.

The ‘2.1’ was nevertheless a great choice for the Opel and Vauxhall sedans of the mid sixties and surprisingly, gave GM a bit of a market niche at the time. Performance was better than the smaller European engine equivalents and fuel cons about the same. The arrival of the 2,5 was great because whilst not a screamer of any note, this was one engine with ‘snap’. One negative was simply the fact that GM engineering refused to move away from the Carter YF carburetor that literally used to fall apart along with its aircleaner assembly. It had a terrible reputation as fitted to Rangers and Rekords. The pig- headedness of the engineers refusing to acknowledge a crappy application when it bit them in the butt was absolutely staggering.

In one of the earlier posts I referred to the carb change on the Firenza at launch. Well I support my above comment by telling you exactly how that happened. Bob Price conducted an early viewing of the Firenza with selected dealers shortly after he arrived & prior to the original proposed launch. At one dealer group meeting one of the dealers, upon opening the bonnet of the car, took a look at the carb arrangement and slammed the bonnet down and said in words to this effect: “hierdie ding sal nie op my perseel verkoop word met daie stik XXX nie” Bob was standing nearby and asked the question….He came back to the factory and did the necessary with the service dept…. to find a hugely corroborating story there. The carbs were changed…… ! If that does not indicate to you just how insensitive to market forces GM were at the time then nothing will.

Making them Go….tomorrow….. including a 302 V8 head bolted to a 2.7…..

[Johann65]

Hullo Paul,
Great to mention the L4 engine and the L6 engine that you talked about.
I remember the Canada (McKinnon) connection that lead to the establishment of our local engines. I had the tedious job of updating the specifications as the new sheets came in.

I looked at a 5 Liter L6 with Mexico casting numbers here in Meyerton. Perhaps you can tell about this 5 litre.
I have its inlet manifold on my L6.

The Aluminium tappet on my L6 cover comes from a Blue Flame motor( 1982) Last Chev Commodore's

My 65 and 69 engines have the (M) casting marks and the 75 L6 GM? with a Mexico inlett manifold.

Cast: A 23 5 (Jan 23 1975)
Cast No; 348675 GM 65

VIN 273988 LAE (LAE hand punched)


My 1973 Ranger SS had the HO 2.5 engine and the Weber 36DCD with local inlet manifold. That SS was capable of easily doing the ton up on the back road between Vereeniging and Henley on Klip. Was the last SS to be sold in Meyerton by Williams Hunt.

[ZA Perana]

Great post as always. Would it be possible for you to elaborate on what the main problem with the Viva GT was, I hear stories that dealers had no idea how to look after them, cambelts breaking. Just seems to me the Viva GT was the forgotten GM performance car, or maybe in 1970 more people were interested in the Monaro, which if I recall correctly caused GM a certain number of problems because the car was launched too soon and not enough CKD kits had been brought in, meaning people has to wait ages for their cars. My info circa CAR magazines of the era.

[993 Kadett]

Hi Guys,
Johann, The 292 engines were made in both the USA and Mexico. If my memory serves me right it was Mexican production only from the early 80's to 1984. Sounds like you have located one so hang on to it, the crank is worth lots of torque & can drop into a standard 230/250 block... but check to see which rear main seal it has so it can be matched to an equivalent block. It also has larger big end journals. Recommended rod lenth is 5.8 to 5.9 inches. Basically to build a 292 from a 230/250 block the only problem is the L/R ratio. Stock length rods 5.7 with 4.125 stroke makes a ratio of 1.38 which is just OK for a 'torquer' but not too bright if you want to rev it. Max rpm for a 292 crank in 230 block is around 6500 even with long rods and trick High Pin pistons..

The aluminium rocker covers were needed in later years on the L's simply because market forces dictated it. A tin rocker cover really did smack of 1965!
Inlet manifolds were all roughly the same, though I do remember the 292 having slightly larger bores and a bigger carb venturi. I do not have casting # detail but am sure we could determine more detailed info if we need to.

John Jacques, The Viva GTwas something of a orphan simply because of the culture that existed in the company. I thought it was a lovely car and far more refined than the Fords of the day. It handled and stopped well and the engine was reasonable for its time in terms of power and reliability. From memory, the cam belt issue had more to do with service than a design fault and as VMX pointed out in an earlier post I do think that this being the first proper OHC in the system, it came as a bit of a culture shock to the techies. The engine was awkward to get better power out of too, mainly because good hot cams were difficult to come by… but a very strong engine nonetheless. It was the last Vauxhall to be marketed in the country and the dealers at that time were also very wary of the brand.
Something worth mentioning is the fact that the engine was heavy and if compared to the new generation Opel 2 Litre designs very much over-engineered. That stems from the fact that as a design concept it started out as a V8. The test programme for the V8 happened in the UK around ’67 and engines were fitted to Bedford trucks for testing purposes. This to see how the motors performed under constant high load conditions and to keep the project a little more under wraps. That project was halted for various reasons associated to the conservative nature of the greater GM and it continued as a slant 4 instead. One of the ex Vauxhall chaps in the Dyno cells at GMSA in the early years told a great story of the OHC V8 Bedfords running flat out down the M1 at 80-90 mph seriously confusing the cops and other road users at the time! (Think Army Bedford and 90Mph – boggles the mind!)

Perhaps also worth mentioning, is the fact that the 1600 engine “hole” in the product line up was a problem worldwide for GM although they may not have appreciate exactly why at the time. The 1600 version of the Vauxhall slant 4 was a heavy beast, as was the equivalent CIH Opel. Both were intended to grow to 2.3 and 2.4 Litres respectively and they had exactly the same problem as the “small” Chevy 4’s…..too much bearing area and too much rotating and physical mass. I will never forget driving the first Opel 1700 delivery van in 1967 and truly thinking that the timing must be hugely retarded….it was’nt… but that is exactly how it felt. The 1600 Opel Manta had a very similar subjective feel. Ford and others at that time had what I would describe as smaller and lighter 1600’s, the Kent as an example. Whilst these engines did not produce the max power of the GM equivalents, they were of much lighter construction with vastly smaller rotating mass and most had mechanically operated secondaries as well. This made the engines feel vastly more responsive.

GM again lost a golden opportunity in enlarging the OHV Viva engine range to plug the hole. I recall a study to modify the block to a five main config (a La Ford 1200 to 1500) and taking the stroke to 72mm. That was a mod, the cost of which was for nothing and the theoretical engine studies indicated power figures not far short of the 1600 “porkers” with fantastic engine response. Just as an aside, the cost of a 1600 Slant 4 or CIH was exorbitant compared to a Kent or a five bearing version of the Viva engine and that limited the Generals ability to maximise their potential in this sector.

Been very busy on the new project in the last few days so apologise for the delay on Chevy 4... will get to it over the week end… P

[zahistorics]

Yes, those Vauxhall slant 4 engines are incredibly heavy. I bought one for the flared Firenza and was absolutely stunned at the weight when I went to load it up. The weight is the reason it is still sitting on the floor and not in the car (and also some bastard stole my engine hoist).

[993 Kadett]

My apologies to you Jacques, I must pay more attention. A little more info on the Slant four. As you will remember Lotus used the engine in their cars with the Lotus 4V head. Something that is significant is that when casting the alloy version of the block, changes to the basic design had more to do with the manufacturing process and Bore Sleeve installation than changes required to beef up the part in it's alloy role. That is just how strong the original block design is. How sad that GM did not do a 'Lotus Cortina" using the Alloy Lotus engine in full production in their product. They did silly things like design their own 16V cyl head, different to the Lotus one yet tried to use the Lotus part for rallying and were, from memory stopped from doing so. P

[zahistorics]

The Lotus engine is interesting. Originally Lotus were doing their own thing, but when it was discovered they were very similar to the Vauxhall (same bore centres at least) the Lotus block was 'Vauxhallised'

A Lotus-Firenza would have been great, but the alloy block Lotus 501 in its early variants (in Firenza time) was not famed for reliability. Of course Lotus got it sorted eventually some years later and eventally made a good turbo engine out of it.

It is another GM mystery why they just didn't homologate the 16V Lotus head on the iron block, it obviously worked well as the rally cars proved before they were disquallified for using a non-homologated head.

Anyway we a are digressing further and further from the GMSA iron block... Back to you Paul.

[993 Kadett]

L4 Power

Asking what power can be extracted from an L4 Chevy is much like asking how long is a piece of string. Power outputs on this basic engine can run as high as 420 bhp with engine capacities of up to 3.5 Litres…..
The engine is a sister powerplant to the Pontiac Iron Duke which ran in the states from 1977 through to the 90’s and although the same configuration, this engine was updated to meet emission and FWD engine installations of the time and part interchangeabilty was affected .

Some Typical power outputs attainable from the Chevy version in the early years just as an example:

2.5 Six port 225BHP
2.5 Marine 8 port 210
2.5 Marine Plugged ports 240
3.0 Six port 250
2.7 302 V8 Head 265
3.2 302 V8 Head 310

For interest, the Pontiac Iron duke ran power up to 370 bhp off a 3 litre base in Cosworth 16V form in the 80’s
Iron Duke tooling was sold to a private tuner who now manufactures the bottom end assembly to fit any V8 head with 4.4 inch bore spacing, Chevy, Ford or Mopar.
Engine capacity has even been stretched to 3.5l using the 4.125 inch bore of the 400 V8 small block and a 4.00 inch stroke. Over 400Bhp.
The above indicates the natural transition of the engine over the years and the fundamentally good design, again stemming from the SBC heritage. One good thing on the Pontiac version is that it retained the Chevy SB bell housing in many of its configurations and can make a great transplant into a Ranger for street or track.

Tuning the stock 2.5 L4 in 1970, however, was a bit of a steep learning curve because being a four cylinder, one was always tempted to do the std mod of the time…“head, cam and sidedraughts”… . Unfortunately for those that tried this route, the results were rarely good.
Throughout the years I have heard many simply resort to Turbocharging as the simple solution to getting power and not bothering with the finer task of normal aspiration. Most professionally done turbo applications worked well, with very good durability - Louis Cloete’s Firenza and Bob Althoff’s Nomad just a few from the early years.

So….My scribblings here cover the Chevy as produced in the 60’s and 70’s in SA and what was done at that time on normally aspirated engines.

First, some of the cylinder heads available at the time (1970’s)

Six port small chamber (2.1)
Six port large chamber (2.5)
Brazilian 8 port small chamber (1.9)
Brazilian 8 port large chamber (2.3)
Mercury Marine 8 port (Large port)
Pontiac 151 8 port.

In 1970, our engineering division had done a lot of work using the 8 port (181cid) Mercury Marine cylinder head (which was basically a 2,5 head with extremely large intake and exhaust ports) but had met with very limited success. Max power was around 160… They had used a 2.7 with V8 pop up forged pistons, isky cams, sidedraughts and a wild exhaust system…all with little luck.

Our venture, by comparison, looked like a poor mans show and I guess that is why it was so successful in the end.

I had only two basic starting requirements for our engine and that was that we would use flat top forged pistons (+0,5mm) and longer inlet tracts using a single 48IDA downdraught. The thinking on those two was A) to avoid any flame path hassles with the use of V8 pistons and to B) to maintain inlet gas velocities and to take advantage of pulsing to help the lower revving nature of the engine. On paper we would sacrifice compression (12.0 :1 vs 10.8:1) and reduced venturi area but a few thumb sucks indicated that the engine would produce good torque, something the engineering engines seemed to lack.

When it came to choosing a cylinder head I opted for the six port, small chamber 2.1 Litre unit to get the best compression for the application. The 2.5 chamber is far too large to run with flat tops & the 2.1 chamber design was compact and ideal for opening out around valve areas for larger valves. Valve sizes were 1.9 and 1.55. Inlet ports received the serious surgery of removing the cylinder head bolt posts..... and head bolts were countersunk into the bottom of the inlet ports instead. At this point we did something completely by chance that was to have a marked effect on power. The tapered Alan capscrew head bolt protruded above the inlet port floor by about 3mm, so, in our inexperience to make the mod “look” correct, we screwed two plates into the bottom of the port to smooth the lower entry on either side of the exposed bolt head. That was to be a head scratcher later in the project because we removed the plates being worried about them loosening at one time and lost power in the process. It took a while to sus out what had happened….
The rest of the head took about 100hrs of work to clean up exhaust ports and match chambers to bores and a very careful valve throat and seat job. Inlet ports were opened in the roof area only.

Camshaft was not a US part and we decided on a ‘known’ local BVR profile which had worked brilliantly on the Kadett. With rocker ratios at 1.75, Kadett 1.5, I was prepared to take a chance on the increased valve acceleration (that was to hurt us in the beginning) but the extra valve lift would cater for the larger displacement & as a first shot, the cam was a known quantity and something we could use as a baseline.

We only had a rolling road to test the engine but……after sorting some valve train hassles, BHP would initially move up from a stock 86 @ 4200 to 188 @ 6200. The engine would literally pull tree stumps out of the ground at anything above 4000 rpm and despite cam duration of around 295°, the engine could have been run on the street! This did not come on our first dyno run though. At that stage I was still learning about the vagaries of valve train harmonics and the engine literally would not run above 5300rpm even with solid lifters. That was a Friday afternoon and we had to compete for the first time on the Saturday. We did….. and Trevor shifted the Ranger at 5000 rpm & ran the ¼ in 15.2 sec nailing the 3 litre class 1st time out. I will not tell you what language and laughter came from the Ford contingent at scrutineering at GT motors that friday evening........ More tomorrow including a ‘Can Am 2.7’
Have included a pic of the Thomas Viva GT at Kyalami - This must have been 70 or 71 do not know who is in the Datsun.

[993 Kadett]

Back.....A bit about the Ranger Sprint car;

The attached pic may give you some idea as to why the Ford guys had the chuckles at scrutineering that Friday night. It did not look too much like a racing or sprint car did it?….. A few pointers….. what you see is not always what is going on under the skin:

The gearbox was a close ratio Opel. Built into the same casing as the Nomad (Commodore) gearbox, close gears from Opel did the trick.
Rear axle was a prototype 3800 with B-Warner L/S same as Can Am……. But with a 4:1 final drive. (The Ranger has the same basic floorpan as a 3800 which, at that time, was still 18 months or so from production)
Rear wheels and tyres were from a Holden Monaro…. 14" Dunlop SP68’s specifically chosen for soft compound and longer footprint than stock 13”.
From the pic you will also see that the car was not a lightweight. All glass was in place and the heavier 3800 axle and gearbox made for a weighty machine. It still had its vinyl top and heavy rear decklid spoiler!
Fastest ¼ mile 13.9 @ 162.2km/h.

But at this point I would like to take you to the pic which was taken just off the start line. I mentioned the fact that the engine, in addition to good power, had massive mid range torque and therein lay the secret of good sprint times. Have a look at how the car is leaning to the right. We had kept the standard spring package and just uprated the shocks (did not even lower the car) and the engine torque always got the body shell twisting clockwise as it took the holeshot, the thing felt like it had a V8 under the bonnet!

To get to the 13.9 sprint time above we simply continued refining the engine package. The carburetor increased to 50mm Bores with choke tubes @ 47 mm! …yes 47mm… a 305°cam (same 1.5:1 rocker ratio philosophy) and mods to the exhaust manifold. The earlier valve train problem was cured by using stock 302 solid lifters, tightening up pushrod to cyl head lateral clearances ( we did not use guide plates) and reduced valve spring pressures. The engine would buzz to 7000 cleanly but best shift points were at 6500.

The car ran essentially unchallenged in the 3.0 litre class from 1971 to 1974 when it was called to duty as a racer. The best Ford managed, were a few triple carbed V6 Capris done by Ford engineering and ran around the 14.5 mark. These attempts were sporadic and I knew that if handled properly, would chase us down, so plan B was in the cupboard:

• Car lowered 55mm & 40 mm front /rear
• Weight reduced by 200Kg
• 181 cid (2994 cc up from 2538cc)
12.5:1 CR up from 10.8
• Two 46 IDA Webers
• Bhp 210 to 250
• Projected time 12.3 @ 180+

This never materialized, but it was extremely interesting that at a recent (Nov2009) historic meeting in PE I bumped into one of the ‘70s Ford motorsport guys who, for the first time ever asked the question “what did you really do to the Ranger” and intimated that we were running a big engine. The facts are above and I would have given my eye teeth for Ford to have responded at the time…..

The 2,7 Firenza. 1975.

The following paragraph could be interpreted as being unreasonably critical but bear with me because it comes from the simple motivation that I care. I care primarily that we try to understand what happened, this seen against the opportunity that existed at the time….. and that this is simply recorded for posterity if nothing else.

I could not believe that the factory had, after the fuel crisis, simply abandoned the magnificent brand of the Can Am. Sure, the Can Am and all it stood for, was a bit of an embarrassing pimple on the nose of an otherwise perfectly conservative and professionally run organization, ……but to leave the racing cars to the likes of dealers and privateers, however well intentioned they were, was in my opinion not very responsible. The thing was moving toward a slow and painful death the instant the factory took their hand off the tiller. I fully accept that the conservative response GM had to the crisis was perfectly OK, those are the type of choices companies have to make…..but those cars should have been technically managed directly from the factory at all times and kept to a sharp standard or locked up in a museum, nothing in between.
I do not understand how the cars were allowed to be raced at all if the policy was to show a responsible corporate face on the Fuel Issue. Just how was the man in the street to know that the cars running around tracks ….post 1973…were not works cars. One cannot be half pregnant on issues such as these. Finally, for those of you that were around in those days, did you see just how tatty the cars became compared to their original splendour as the years went by? … being a PE guy at the time I remember well taking a good look at the flag car at Scribante in later years and simply just walking away….

Despite the situation & in the midst of the changes, I finished an engine project just started prior to leaving for the dealer team most of it in my private time. With no hope of the package making it to any form of production it was great to just do it. We had had thoughts of creating a mini Can Am by building a lightweight L4 Coupe, I mean why not…. the thing was just screaming…… “do something”.

By using the 151 4” bore Pontiac block and stock 2.5 crank, we built a 2.7 L4 with a large chamber six port head. Inlet ports were machined to take a capscrew in the port and pillar removed (a-la Ranger). The inlet manifold was a dual plane four barrel with the secondary barrels furthest from the engine. Designed to take a Quadrajet or a Holley, the primary runners were short and above the secondaries through separate runners. The secondary lengths were 14” from carb butterfly to valve and had an upward angle of attack to the inlet ports. Compression was 9.6:1 and camshaft an Isky hydraulic with about 265°of duration. Valve sizes 1.94 and 1.6. Exhaust was a tubular short 4 into 1 with no specific tuned pipe lengths.
The engine was not run on the engine Dyno but rolling road figures indicated 160 bhp at 5400 rpm. That is 70 bhp up on a stock (weber) 2.5. Gearbox was a close ratio Opel 4 speed and Final drive of 3.08:1.
The package ran quietly in my very stock looking 2,5 company 4 door sedan for a short while, and although a stillborn project, could quite easily have been “productionised” for a short run in a 4 cyl version of the Can Am. Weight would have been 880Kg. and original Can am wheels, bonnet and livery. The only change from the exterior would have been colour (GM Blue corporate) , ride height lowered by 40mm from stock Can Am height….and the 1900 grill and front end*

Stock power to weight: 23,5 lbs per bhp
Firenza 2.7 HO: 12.4 lbs per bhp
Can Am: 8.64 lbs per bhp

Geared speeds @ 6000

1st : 2.63 86
2nd : 1.63 136
3rd : 1.28 176
4th 1:1 210 @ 5600
0-100: 7.1 sec

In a direct comparison to the Thomas racing car The HO would have been 90Kg lighter, had a close ratio box and in racing form about 70bhp more. Engine and gearbox aside, a racing version would have been copied from the Blydenstein 2300 ‘old nail’ without the droop snoot. Estimated lap times as follows:

Scribante 1: 11
Kyalami: 1: 36.5
Killarney: 1: 25.5

Again the 3 litre option was available using a locally cast 4 cyl version of the Argentinian L6 head @ 315Bhp……… That would have matched V8 Perana times, particularly on the shorter tracks and as mentioned in an earlier post, the world would have been our oyster for aftermarket quick parts…..

I attach a very old and not quite legible copy of the South American cylinder head porting and combustion arrangement. It would have been so easy to do….. but for the will to do it…….. more on fitting a SB ‘head to the L4 tomorrow……P

[Johann65]

That realy brings some memories back!!!. Remember the Opel Gt that we had for evaluation before deciding on the Manta??
I personnaly think that the Manta and Kadette was the death of the Viva GT. Ladies car Iso of some performance.
Standardation was the name of the game no innovation or innitiatives!!!
I still recall Re-trimming a red Vauxhall Viva with black trim specially for the MD's wife! Must says it was good looking!!!