The Classic Volvo Online Manual for Volvo B18 & B20 engines
This online Volvo Engine Manual is delivered to you out of 40 years hands-on experience and from studies of many sources. The main source is, and will always be, the original, green Volvo Service Manual made by AB Volvo. Thanks! |
| Chapter One - The Volvo Engine History |
| The Volvo B18 & B20 engine was fitted to Volvos during the long period; 1961 to 1974. It was installed in the following models; PV544, P210, P120, P130, P220, P1800 all models, all 140 models and in some of the very first 240 models in 1975. It is an four-cylinder, OHV (over head valve - with pushrods) engine. A very durable, strong construction, very overdimentioned for today's standards. Except for cars it was also used in Volvo-BM tractors, combined harvesters, army vehichles and lots of other machinery. The major change in construction which made it so much stronger then its predecessor, the B16, was (together with Swedish steel craftsmanship!) the crankshaft with its five main bearings (B16 had three). With a modern racing outfit it is possible to squeeze well over 220 horse powers out of the B18/B20 engine - three times its original force. All taken together has made this Volvo engine a big favorit for all kinds of automotive use and experiments. For the eye of the layman it is basically the same engine block and cylinder head during the whole reign, 1961 - 75, but for the expert there are, of course, a lot of minor and major alterations on many levels over all the years. Easy to spot are lots of different types of carburettors, fuel injection, alternators, dynamos and fuel pumps. More difficult to see are differences in the cast iron molding on the outside and, of course, all the changes on the inside. The 1,8 liter B18 model was in the 1969 year models replaced with the 2,0 liter B20. The outside of the engineblock was not changed much, only the cylinder bore. |
| The B18A or B20A was the basic, single carburettor engine that is mounted in most Swedish sold Volvos. The B18D, slightly stronger then the A model, was fitted to the "Sport" models of PV544 and P120/130. It had two SU-carburettors. This model was mainly for export markets. The B18B & B20B was the top of the line of the carburettor models fitted to the P1800 and the 123GT. With twin SU-carburettors. The B20E and B20F (F was mostly for the US market) had fuel injection and was used for later P1800´s and for the 140 GL models. |
| Click here for more detailed engine specifikations. |
| Some words on safety |
| Working on cars is fun and a car workshop can be a true, creative, artistic playground for adults. Working on your own car can save you a lot of money and make your car stay out of trouble. BUT it is to remember, at all times, when working with automobiles and auto maintenance that cars are heavy, insensitive creations that easily crush and destroy a human. In an auto workshop there are lots and lots of dangerous tools, machines, gadgets, gases, fluids and chemicals. In fact, almost everything in the car world is lethal to humans if used in the wrong way. One shall at all times have this aspect in the back of ones head and act accordingly. The number one danger in an auto workshop is fire. A car with a full petrol tank is a potential bomb even if they never burn the way they do in Hollywood movies. Gas tanks for welding are also potential bombs. So are thinner and most fluids used with cars. Car dirt, rags, dust and much of the debris generated in a workshop is also highly flammable. Another danger is weight. Jacking up a car (most amateurs do not have bridges) and climbing under is putting a ton of steel hovering over your body. Make sure it stays hovering! A third danger is, of course, that you perform the repair in an incorrect way and that this will make your car fail in an unsafe manner. ClassicVolvos have various short comings that do not give room for any mistakes. More about these in the coming Brake Manual. I will give more detailed safety instructions to be applied on the repair of the moment. Let us keep alert and stay away from hazards and keep car work as the fun thing it can be! |
| Specific dangers when working with the B18/B20 engine in the engine bay of a Volvo are mainly two: The first one is the FAN. The cooling fan for the radiator rotates, when the engine is running, at an enormous speed and its wings will cut off a finger or demolish a hand severely, in the split second. Extreme caution shall always be executed when working close to a rotating fan. You might not slash your body but your newly bought testing instrument might get tangled up and crushed. Bad enough! Another danger when working on the engine might occur if you use a remote starter tool and start up the engine standing beside the car. This tool is very useful BUT be 100% dead sure that the car is out of gear when using it. Cars have been known to hit the wall very hard when the engine is started and the gearbox was in first gear. Needless to say it gets a lot worse if you are standing in front of the car. Take care! |
| Down to shop floor basics |
| Belowe you can see the basics on the B18/B20. The picture shows a B18A with a Zenith 36 VN carburettor, probably 1964 model. |
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| Here is how it can look! This is a view from the bay on a P1800 1967. It has had its original engine replaced by a B20 block with modified cylinder head. The carburettors are SU HS6 (two-bolt filter type, originally mounted 1961-66) that has been modified for racing. Click for big! |
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| But this is maybe how it looks most of the time...? This is the bay on a 145 model from 1974 (Swedish market) with a B20B engine. Click on picture for bigger! |
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| If bad comes to worse it can look like this bay on a 1973 145 with a mileage reading: 370 000 kms. It is still the original engine, though with an enormous oil consumption! It has the single Stromberg 175CD2SE carburettor like most Volvos in Sweden has. |
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Replacing a B4B/B16 engine with a B18/B20 |
| From time to time I get questions about how to replace the older types of B4B/B16 engine (fitted up until 1960) with the more modern B18/B20 (fitted from 1961 and onwards). I have done this a couple of times so here are some advise on how to do this: First some words on sticking to the genuine line: All collectors items loose value as soon as they are touched and fiddled with. So also Volvo cars. If you have a nice Volvo with a good engine and everything works fine you shall think twice about changing anything away from the genuine look. If your car is a peerless collectors item and you any how decide to switch over to the B18/B20 engine, you shall keep all the old original parts/engine/items and store them carefully in your garage or up on your dry and well protected attic. Then, when times of separation comes, you can offer the new owner the choice of him/her altering it all back to normal. A well carried out engine replacement does, done in this fashion, increase the value and performance of your vehicle. If your engine is shot and the rest of the car has already swayed away from the genuine look, then go ahead, put in a B18/B20. Here is how to do it: |
| You need a complete B18/B20 engine/clutch/gearbox unit and ALL the electrical components from a 12V model. One can keep the old 6 volt electricity system IF one can find a 6 volt starter motor that fits the B18/B20. I have never managed to find one so all the engine replacements I have done has also included a switch over from 6 volt to 12 volt. Your B4B/B16 is definitely a carburettor engine so stick with carbs. You can, of course, switch over to fuel injection but that is a whole other story. You can, though, take a fuel injected engine, if you happen to find a nice one, and put on B18/B20 carbs. After a bit of tuning this can work very nice. Clean and do all the other workshop rituals carefully. Rip it all out and just swing in the B18/B20. Replace all electric components with 12V. Do not forget small bulbs in the speedometer (even if some seem to last long on double current....!?). Do not forget the wiper engine. 6 volt wind shield wipers on 12 volt is a sight for sore eyes, I promise! If you are working with models 1958 - 60, this operation is not so hard as if you are working on a mid-50:ies Volvos. If so, you must use your fantasy. Maybe some dashboard units have to be replaced with others since they are impossible to alter. Do it nicely! Once electric components are done, you get on to the real hard ware. On the PV and Duett you might have to adjust the clutch linkage a bit depending on which parts you stick with. This is not such a big deal. Bigger is the radiator problem. The B4B/B16 bottom hose comes in on the left side of the engine. On the B18/B20 it enters on the right. This means that you either must alter the radiator a bit or (cheating a bit...) make a "chikan" lower radiator hose. Moving the hose inlet on the radiator is not too much work if you are a bit familiar with soldering. Another problem might occur depending on what carburettor/s you settle for. On the PV & Duett the holder irons for the hood might touch the air filters. Usually it only needs a slight cutting-away job. Be careful the first time you close the hood after replacing. The best is of course if one can switch front and hood over from a B18/B20 model. Then the radiator- and hood problem disappears. Be observant, though, that the PV and the Duett fronts are different. It is hard to see, even for a professional and many are the stories in Sweden about Volvo workshops that did not find this out until it was time to fit the front chrome bumper (with the paint job already done!!). The holes for the bumper irons are situated lower on the Duett and the radiator is positioned an inch different height wise. So parts from the wrong model it will NOT fit. Get the right one for your model if you decide to do this operation. So, once all this has been carried out, you have to do some basic work on adjusting and hanging the exhaust pipe and then probably sorting out all the small adjustments. But this is what makes life in the Volvo workshop such a nice one, isn´t it? Once you are at it, why not fit an over drive gearbox to your ex-B4B/B16 Volvo? This story I will tell you another time! |
