What can we do to keep our aging high compression motors alive and efficient in this era of reduced fuel octane ratings? Various correspondents have suggested a number of solutions including using octane booster, lead substitute, thicker head gaskets, retarded ignition timing and what-not. None of these will do you any harm except maybe in the wallet. Here's a summary of the pros and cons of each:

   OCTANE BOOSTER: These products really work but the good ones are not cheap. They greatly reduce knock (detonation) as well as dieseling (run-on after the engine has been shut off). Using the typical product at half the maximum recommended strength will add something on the order of 10¢/gallon to your fuel costs. With the location of the fuel filler on pre-70 1800s, it is very easy to spill the stuff on your paint, which will leave a permanent stain in most cases. Also, many octane boosters are methanol based. If you haven't been using some son of fuel detergent (e.g. carburetor cleaner, STP gas treatment, etc.) after 14-26 years, there are probably deposits of crud in your gas tank. These are occasionally lifted up in clumps by the methanol, clogging the gas line screen fuel pump or whatever.

   LEAD SUBSTITUTE: Most of these products provide valve seat protection, not retarded combustion. Besides costing money, they are probably unnecessary for Volvos. When my father bought a 144S new in 1969. it came with a dealer (Volvo Freeport, Freeport, NY) recommendation to use unleaded premium. then available only from Amoco. This advice was followed and 170K miles later it is safe to say it caused no great harm.

   THICKER HEAD GASKET. There is no doubt that installing a lower compression head gasket will reduce your motor's octane requirements. These gaskets, as offered on B18A. B18D and B20A motors are reliable lifetime parts that are widely available. On the other hand. they reduce both the volumetric and thermal efficiency of the motor compared to normal (knock free) combustion with the original head gasket.

The reduction in volumetric efficiency will in theory yield an improvement in gas mileage at the expense of full throttle torque (a commodity somewhat lacking in these cars in the first place) as if you had a slightly smaller motor. The lowered thermal efficiency will negatively affect both economy and power (once again, compared to knock-free operation of the stock engine) though perhaps negligibly.

These disadvantages may seem entirely acceptable to many an owner whose motor clatters like an AK-47 when confronted by the slightest upgrade.

   RETARDED IGNITION TIMING: This will greatly limit octane knock though it will not have much effect on dieseling. It costs nothing to set the timing back a couple of degrees, but your gas mileage will suffer. More than a very small adjustment will also cause the car to feel sluggish. I consider this to be more in the line of a temporary, emergency modification to be made, say, when out of gas in the middle of nowhere with only 87 octane fuel available. It would only be fair to point out that I have known of people who have run their Volvo for years with retarded timing and who swear that the loss in efficiency is entirely offset by being able to buy cheaper fuel. The following steps may be of interest:

   Do A Valve Job. Pulling the head off one of these motors is within the ability of the most abject mechanical novice. If you don't need parts (valves, guides, seats, etc.) typical machine shop price in this part of the country runs about $50. This includes disassembly, inspection, boiling out the head, relapping in the valves and reassembly with new guide seals. Cleaning the head thoroughly like this will make knock and dieseling go away for at least 10K miles and is good for the motor in general. Be sure to clean off the piston crowns while the head is off. Don't scratch the soft aluminum alloy. (Keep bits of crud from dropping down around the rings when you do this. Many people set an old ring in the bore to keep it clean. I just scrape the pistons with a vacuum cleaner sucking up the scrapings.) If you need to install new valves or other parts, the job could conceivably cost as much as $250, but if you needed parts it would be false economy not to do a valve job, and new parts will last 100K miles or so. Reinstallation of the head will cost, say $25 which goes for gaskets, antifreeze, oil, etc. If your water pump is on the way out (i.e., loose bearing, leak) there'll never be a better time to replace it: $20 more.

   Install a Hot Cam. Stock duration, high lift cams such as IPD's 700 1 cam are just the ticket for Volvo motors as detailed in Sports Car Graphic's "Project Volvo" series in 1963. An advantage of this type of modification that is rarely mentioned is that volumetric efficiency. Therefore, tendency to knock is reduced at lower engine speeds, say below 3,000 rpm. This is precisely when most knocking problems occur. Once you get above 300 rpm, you also enjoy the expected benefits in performance. 

If the motor is otherwise stock, the main improvement will be that the engine will wind out freely, without running out of breath until  well past the red line.

   Also, the cam will allow you to exploit the advantages of other breathing modifications such as a header or Weber carbs. Although installation of such a cam will not cause instant self-destruction of the motor, I recommend installing it only after replacing valves and guides as it will overstroke the wear pattern on used valves, causing much more rapid than normal stem wear. Depending on your driving habits, you may actually get more miles from a gallon of gas, due to the reduced low speed breathing. Of course, use of such a cam will make the car a smidge less convenient to drive around town: a higher idle speed (around 1,000 or so) and a bit more clutch slip when engaging from a stop will probably be necessary .If you are driving hard, the generally higher rpm made possible by the cam may adversely affect the longevity of the engine. Ring loads (as well as combustion loading on the bearings) are proportional to torque (hence greatest at full throttle@ 3,800 rpm in stock B18B's, 3,500 rpm for B20's, a little higher with a tweaked cam). Colin Campbell (The Sports Car, 1969, p.98) reports, however, that the life of rod bearings is principally limited by inertial loads, (not combustion loads) which increase with engine speed. In any case, if your motor knocks as badly as some I've heard, you will probably break a ring long before your rod bearings fail.

   So what should you do? As far as I can see, the only unmixed blessing you can confer on your car is to give it a regular valve job every 50K to 75K miles. If you don't wait until it needs it, it probably won't require much in the way of new parts and it may well extend the life of the bottom end. If you feel you must use a thicker head gasket this would be the time to swap it in, but don't complain to me when your car goes slow. You might as well do a valve job if you are changing the cam, too. Boiling out the head will result in better cooling and the elimination of carbon hot spots in the combustion chamber. A fresh sealing surface on the valves and seats can't hurt either.

Well, I must surely have run on long enough. I hope to see as many of you as possible at Rippling River. If you haven't seen this part of the country maybe the thought of all those1800s lined up will get you out here.

  MATT DELSON

  Portland, OR