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MG MGB Technical - Cold start problem and the less than $15 solution

Just thought I would pass this one on since I have been experiencing this problem recently and thought there may be others having the same problem.

My MGB engine is not a stock engine and is probably what would be called Stage 4 or 5 per the old factory race tuning books. Basically, it is about as "hot" a tune as you can do and still reliably drive the car on the street (including idling in traffic). The engine was built up about 4 years ago and has been running fine. Up until about 6 months ago, there was never a cold start problem, even if I did not run the car for a week or so, but recently it has been almost impossible to start the car from cold. Once started and warmed up, the car runs fine.

I did take the car into to my mechanic who built the engine and asked him to check everything to just make sure that I had not mis-adjusted anything (I do all my own engine tuning) and he said the car was in excellent tune. He did say that he thought that the gasoline might be a problem as he had several other customers who were having difficulties with cold starts. At first I thought there was no way that the gasoline could be causing the problem, but now that I have spent several times re-tuning the car since it will not cold start, I am beginning to think otherwise. Just to set the stage, I am a chemical engineer and work for a large engineering firm that does a lot of refinery work.

One of the things that has happened in California over the last 5 years has been extensive reformulation of gasoline to be less polluting. About 6 months ago California went to what is known as CARB 3 gasoline, which is a more stringent requirement than either the rest of the U.S. (which is pretty much at the old CARB 2 requirement) and Europe (which is somewhere between the old CARB 1 and CARB 2 requirements). CARB 3 gasoline is pretty much a sulfur free gasoline, but of more importance to us classic car enthusiasts, is that the RVP (Reid Vapor Pressure) has been significantly lowered to highly reduce pollution from gasoline evaporation. The reason why lowering RVP is critical to old cars is that the way to lower the RVP is to eliminate as much of the aromatic compounds from the gasoline that you can. Aromatic compounds are benzene, toluene, xylene, etc. These are also the compounds that give an octane kick to gasoline and one of the reasons why premium gas is now 91 octane in California.

So why is it bad for our cars to remove the aromatic compounds? Because these are the gasoline components that easily vaporize and therefore when you are trying to cold start a car, these are the bits that "fire" first and light the rest of the gasoline. Without these compounds present in the gasoline, it is very difficult to ignite the gasoline in CARB 3 formulation (As an aside, one of the changes in CARB 3 gasoline is that it is now to the point that on a cold day you can throw a match into a pool of CARB 3 gasoline and there is a very high probability that it will not ignite. DO NOT TRY THIS!! I have seen a demonstration film on this that was done under very controlled circumstances.).

So, with a cold block and head, a reformulated gasoline that does not want to vaporize on a cold day, a carbureted fuel system with weak air flow at start up, and a fairly weak coil by modern standards (modern coils are now getting in the 80,000 to 100,000 volt range), it is no surprise that our MG's don't want to start on cold days. Modern engines are now fuel injected, which does an excellent job of vaporizing the fuel, and use high energy ignition systems to overcome the new fuel formulations. And for all of you in the rest of the U.S. and Europe, CARB 3 equivalent gasoline formulations will be coming to you sometime in the future.

So, knowing that the gasoline is the problem, I decided to see if there was a relatively cheap way to solve the problem short of buying racing fuel all the time (which since it is "off road" fuel is not required to have the lower RVP and can keep all those nice aromatic compounds) or heating the garage all the time (which is definitely not a low cost option, even in California). My thoughts immediately went to the fact that the engine starts up fine when it is warm, since the CARB 3 gasoline will now vaporize correctly. Therefore, the key was to warming up the block and head in a cheap manner and that did not require modifications to the engine. My $15 or less solution was to buy a travelling type hair dryer (Sunbeam makes a nice one), set the dryer on high, set the dryer so that it blew on the spark plug side of the head (the Sumbeam dryer fits nicely between the leads) and then walk away for 10 minutes or so. Doing this, the engine kicks over nicely on the first crank, even without the choke (although I do set the choke once the engine starts up).

I just wanted to pass this on to all of you so that if you have hard starting problems and your car is in good tune, you don't waste a lot of time and effort trying to fix something that is out of your control, and to also offer a reasonable low cost solution to the problem.
Ron Kluwe

With my modified engine (with xr700 ignition and a hot coil) I widened the sparkplug gap out to about .070" and found it starts and runs cold much better. No apparent difference once it is warmed up.
Barry Parkinson

Ron, another solution may be to purchase an electric dip-stick (Oil) heater. I have seen them in the JC Whitney books. I had a Dodge Diesel truck which required plugging it up during cold whether. I plugged it into a timer and had it come on about two hours before I was going to drive the truck, this worked real well. Although I am not sure this would generate ample heat to the head in order to correct your problem. "Just a thought"
Steve C.

I personally would not walk away from a running hairdryer in an engine compartment in a garage. I watched a neigbors garage burn to the ground because he was useing a hairdryer as a heatgun to shrink wire-wrap on his motorcycle and he was standing right there when it went up. I like the plug gap idea the dipstick heater will just heat the oil which will do nothing to help atomize fuel. Just my $.02
J. T. White

I agree with JT, leaving a running hairdryer under the hood while you walk away is begging for trouble. The oil heating dipstick is not really designed to heat the block, just the oil so the engine will turn easier in real cold climates. Maybe a little heat would make it throughout the block for easier fuel vaporizing. I would rather try that than risk a fire that could damage or destroy the "B", garage or yourself. Have you tried a little starter fluid spray? Combined with the heated dipstick it might do the trick. How about using a gallon or so of race fuel to a tank of regular gas? Would that help? Let us know what works because if, as you say, we will all have that fuel in the future it would be nice to know what to do.

How about dosing your fuel with a little xylene? You can buy it (in NC, at least) as 3M General Purpose Adhesive remover. Also, I've heard that lower grades of gasoline tend to have higher vapor pressure, so perhaps dropping down to 89 (if you engine configuration will allow it) might help.

Rob Edwards

Having, at one time duiring my life, lived in the frigid wastelands of the upper midwest, I am aware of many diferent products to keep one's engine warm. There are tank heaters, that warm your coolant. There are headbolt heters, that actually replace a stud on your engine and keep the block warm. I've seen heated dipsticks, that keep the oil from turning into molasses on -40 mornings and even heated pads to keep the battery toasty warm and viable. Every car I saw back then, seemed to have a plug hanging out the grill that powered one or more of these gadgets. There are probably more variations on this that I haven't mentioned here that would keep the block warm. The fact to think about here, though,is the fact that as modern cars become more technologicaly advanced, the fuel industry will produce fuel suitable for them, leaving us Luddites hunting for suitable fuels. Those "octane boosters", of dubious value for raising the rating of our fuel, might be an answer to replacing some of the volatiles that we need.
R. L Carleen

Ron, thanks for the info. I too would suggest a block heater instead of the hair dryer. I had one on an Opel GT 1900 to use when I spent a lot of time in Colorado ski areas. Shouldn't take much time to warm up the head in SoCal.

Do you know whether the volatility goes down significantly over time or anything bad happens to the gas otherwise? Sometimes I don't drive my B for several weeks at a time. As it is a V8 conversion with hot-wire EFI, it starts well, but does crankover a bit more before it fires.

PS: whereabouts in Seal Beach?
Edd Weninger

I routinly add a pint of Xylene, available from Home Depot for less then $4.
Robert Dougherty

air filterIt seams that the main concern has been Fuel quality. Or strength. For initial start. I have been raking my brain for a solution that is safe and convenient. I just have taken my single zenith apart and cleaned it with some carb cleaner on a 77 mgb stock. After putting the carb back together and letting the car set for about
Gerry Groeber

Ever heard of starting fluid? $2 a at any parts store.Very volitile and an instant start. Don't get it anywhere near your eyes though.
John Agosti

This thread was discussed between 27/02/2005 and 08/03/2005

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