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Volvo 122s “Georgia Peach” Station Wagon Restoration – Part VII

The last feature on the “Georgia Peach” was in late April of 2017, so an update on progress of the rebuild is in order. The engine, transmission, and overdrive were removed for a complete rebuild in mid-April, and all three were dissembled and all of the pieces where cleaned up for an inspection. At that point, the search for needed replacement parts began.

Since the 1800cc B18 engine is now over forty-nine years old, most of the stock of quality original OEM and aftermarket parts has dried up, although after a prolonged search here in the US, in the UK, and Europe all of the needed parts have been sourced. The largest issue was finding pistons that could withstand the increased horsepower and added heat produced by the boost from the vintage Judson supercharger.

  • The original engine before being dissembled for cleaning, inspection and measurement for rebuilding. The lead photo in the post shows a 1967 to ’68 Vermont license plate with a unique number found for the 1968 Volvo 122s project car.

In the end, after not being able to find any high-quality Mahle (German) OEM pistons, CP-Carello located in Irvine, California was chosen to make a set of forged lightweight aluminum pistons and supply modern narrow wrist pins, and state-of-the-art treated steel low friction piston rings for the engine. The Company was the only piston maker found in the US that had forged piston blanks of the correct length needed, and is regarded as one of the best in the business and also manufactures the famed Carrello forged steel and aluminum connecting rods.

  • The CP-Carrilo Volvo B18 forged aluminum pistons, and wrist pins are finely CNC machined inside and out and will be able to withstand the higher combustion pressure and resulting heat due to the use of the Judson supercharger. 

An earlier cast iron B18B ohv rocker arm and push rod actuated cylinder head is being used with a lower 8.7:1 compression ratio that better suits the use of a supercharger and will help to control spark knock with boost pressures of up to 7 psi. The original 1968 head has a 10.0:1 compression ratio that is actually to high to use with today’s premium pump gasoline without octane boosters.

This head is being slightly modified to take advantage of some of the Volvo cylinder head advancements made up until the last ones were manufactured in 1975 before the change to a SOHC head for 1976. To increase flow through the intake and exhaust ports new conversion valve guides for later B20 valves were machined here in the shop from cast iron. The later (1969 to ’75) valves have smaller .312-inch (5/16″) diameter stems; the earlier stems measure .343-inch (11/32″). The new intake valve guides are shorter and have tapered instead of blunt ends on the bottom end of the guide where it projects into the intake valve port. Both changes will increase air flow into the engine. The top of the new valve guides also were machined to use later B20 valve guide seals.

  • New and original valves and valve guides side-by side, exhaust on the left, intakes on the right. The heads of both new valves will later have a second angle machined where the 45-degree angle face meets the swirl polished head to improve airflow.

After the valve guides were finished, attention turned to the new B20 intake and exhaust valves. The image below shows how the valve stem thickens were it meets the head; in the interest of better airflow flow this area was machined smooth (see the changes in the photo above) on the lathe and then swirl polished. This form of polishing promotes a twisting motion of the incoming air and fuel as it enters the combustion chamber and cylinder, resulting in a better mixture of both which increases engine power.

The heads of the 42 MM B20 intake valve heads were machined down to 41 MM in diameter that is larger than the original 40MM B18 valves; the valve seat, combustion chamber and port will be opened up to accommodate this change. The exhaust valves on both the early and later engines are 35 MM (1.375″) in diameter and the only the changes here will be some very minor porting of the valve seat area.

  • Standard B20 intake valve before being modified, they have hard chromed stems that prevent wear and are compatible with the cast iron guides that were finished off with a very smooth honed interior bore.

Photos below show machining operations on the new valve guides, and a 1975 Volvo B20 cylinder head being used as a model for valve, guide, seat and port improvements. When we return more of the engine rebuild will be covered.

Thanks go out to Swedish VP Autoparts US branch for many of the parts being used on this project. For advice on modern Volvo 122s aftermarket and performance parts Cameron Lovre of Swedish Relics and Eric and Ian at Hi Performance Auto Service for original parts, advice, and vintage Volvo Competition Services factory racing parts.

View the first six parts of this feature covering The Old Motor Volvo 122s.

  • After being cut and machined to length the valve guide bores are drilled and the reamed in the lathe followed a smooth final finish by honing – the image below shows the top of a guide being machined to accommodate modern valve stem seals to keep excess oil out of the air and fuel mixture. The bottom image shows a similar valve guide precision finished here on a Sunnen honing machine. 

  • 1975 B20 fuel injected cylinder head used as a model for valve, guide, and seat improvements for the earlier B18b head.


18 responses to “Volvo 122s “Georgia Peach” Station Wagon Restoration – Part VII

  1. It’s a wonderful coda to the petroleum combustion era that Volvo has just announced that their gas engines will be phased out beginning in 2019 in favor of hybrids & all-electric power plants.

    Speaking as one who has long admired the rugged, powerful and long-lived engines that Volvo produced, I’m sorry to see them go. Everyday I wake up missing the late Volvo wagon that ran up over 365,000 miles on conventional motor oils until the Ex finally managed to kill it by overheating it . Rolls Royce may have laid claim to being the “Best Car Ever Built” but based on experience, I’d submit to you that it was in fact the overhead cam B230 engined 240 Volvo.

  2. I read today that the Chinese company that owns Volvo is in the electric battery business. Might this this bear on Volvo’s hybrid decision?

  3. Those pistons are a work of art! It’s interesting to me that a fifty year old car is being transformed into a daily driver. Not unusual, but think of doing that in 1967. A 1917 machine would be undrivable day to day. Thanks and keep us posted. ( My dd is a 93! )

  4. “The original 1968 head has a 10.0:1 compression ratio that is actually to high to use with today’s premium pump gasoline without octane boosters.”
    What? Are you saying 10:1 is too high for 91-93 octane gas without the Judson?
    I beg to differ, my Chevy LS-2, 10.9:1 runs fine on today’s gas.
    Of course adding 7.2 psi boost changes the equation, so I built my Blown Chevy 350 with 8:1 compression.
    It seems you could buy quite an expensive new car for what you’re spending on the Volvo, so thank you for carrying the torch, keeping the old car spirit alive and well.

    • The Chevy LS-2 is a modern engine computerized w/fuel and air management and ignition controls and because of them can run higher compression ratios – the Volvo B18 is and early-1960s design w/a squish combustion chamber, carburetors, and a coil and points ignition system which does not make for a fair comparison with the higher compression ratios used in recent times.

      “It seems you could buy quite an expensive new car for what you’re spending on the Volvo” Actually that is not the case here since I am doing all of the work and the cost of the car and the parts will end up being less than what a used five-year-old Toyota sedan costs. The fun of doing it though is priceless.

  5. Interesting to stick with the b18, why not go with with a b20 and take advantage of the enlarged combustion chamber etc? Will you be measuring the rocker ratio? With the exhaust ports, raising them prices to gain torque.

    Which camshaft shall be used? Given you’re down 200ccs to start with over what most people do.

    • Alex, The car is being restored with its original engine with the addition of period correct high performance parts instead of using more modern pieces except where it is un-avoidable.

      • It’s your right to do whatever you want, but I have the same question as Alex since the valves are from a B20 E/F and the pistons are 21st century CNC jobs…To each his own I guess- I updated my 1968 using a 1974 block bored to 2130 CC with a 1975 double sprung head.
        That said, it’s still enjoyable to read the thread and consider all the infinite choices in these customized resto-mods. Best of luck with the rebuild.

        • The valves are actually are non/FI B20 valves, and installing them is much like what could have been done as early as 1969 for a performance gain. Could not find any off the shelf pistons that I would be comfortable using w/the supercharger. Have been rebuilding antique engines for years and quite often need to have custom pistons like this made because nothing else is available.

          The other reason for using the original B18 engine is the blower is sized to a 1800CC capacity engine and would not work well on a larger 2000cc engine.

          I am well aware of all of the modifications that can be done to B18 and later B20 engines, but have chosen to use all period parts (except the pistons, valves, and camshaft) and am including some original Volvo Competition Services parts so that when it is finished it will represent what could have been done in the 1968 to ’72 period.

    • It is as milled in a CNC turning machine, I do not know the exact figure on the RA scale, but would estimate it to be about RA 1.5 -1.0.

      In layman’s terms it is not quite a perfect mirror finish but on a 1 to 10 scale with ten representing a mirror finish I would rate it at about 6-7.

    • At the end of the day, this set of pistons cost about 30% more than what other companies charge for their custom made pieces, but the due to investing in top notch CNC (computer controlled) machinery and the best piston engineers around, CP-Carillo’s quality level and added features that prolong engine life is superior to its competitions products. The companies pistons and connecting rods are used by many serious competitors in a number different types of high-level motor sports in the US and elsewhere which speaks volumes about their quality.

      When all is said and done, the extra cost to use these pistons in a high-quality engine rebuild works out to about 5% of the total cost, but a piston breakage issue down the road or on the track can at times lead to total destruction of an engine. To myself and my customers that is a small price to pay to obtain better performance and help to preserve a vintage engine.

  6. Do you happen to have an old Mercedes- Benz – 4- Banger Diesel — that needs its: Mechanically- driven Pierburg Vacuum Pump rebuilt??? Not to worry — it happens to have an (also old )Volvo repair kit
    parts number (for a fraction of the M-B parts price!) The early Volvo designs: —(Looks like a mini ’48 Ford Sedan ) Austin -4- Banger engine, — floor shift trans = bulletproof! Edwin W.

    • Ed – Volvo never used an English Austin engine, it always produced its on engines. The first of the new era cars the 444, first released in 1944 was equipped w/a B4B 4-cyl. ohv engine that displaced 1,414cc or 86 ci.

  7. As I recall, “Sports Car Graphic” magazine built a racing P1800 with the B-20 back in the sixties. As I was a confirmed Volvo fanatic at the time (’60 PV544, B16B), I read the series with great interest. They found that elevated RPM’s the intake charge would actually REVERSE course and be forced back thru the manifold into the carburetors! They speculated that this was due to the design of the intake channels inside the head. They blended together just downstream of the manifold inlet and this caused the effect. While this served as an effective guard against over-revving, it also limited the amount of power and speed the engine could produce. I do not remember what or if there was a solution found to the problem.

    • David, It is called air reversion and most times it is caused by exhaust gas pressure in the cylinder at the end of exhaust stroke when the intake valve opens.

      It is not a problem that is suffered only by the Volvo pushrod engine and can happen in any racing engine and can be changed for the good by reducing back pressure and changes in the shape of the backside of the exhaust valve and ports.

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