Misfire Diagnosis

Dear Madam Editor:

I have been a member of BSLOL in good standing for the past ten years and have

enjoyed the many benefits that membership does provide.  I especially look forward to the

wealth of information contained in each new issue of the Boat House.  There is however one

troubling aspect of the publication. That is, the shroud of apparent secrecy, the cloak of anonymity that obscures the true identity of Dr. Motorhead. Dr. Motorhead is certainly a pen name. I have checked the member rolls of the club and find no such person. The “Doctor” walks among us. In many articles, Dr Motorhead references contemporary events and persons. I have made it my job to closely observe the participants at club events in an effort to unmask “Motorhead”.  I can identify no one with the possible exception of Dr. Bob Johnson – I have wondered, but have satisfied myself through observation and detailed questioning, that it is not Dr. Bob. What is the cause of this self imposed anonymity? Is the “Doctor” hiding from the law; a violent husband; Child support; Advice gone terribly wrong? It then occurred to me, I may be guilty of gender bias? Is the “Doctor” (a non-gender specific title) a male or a female? There are a number of competent females among the BSLOL membership. Is Dr. Motorhead really Peggy Merjanian? She has many years of antique boat experience dealing with many intricacies of wooden boats as the Editor of the Boat House? How about Kathy Newman? Her fast action and superior knowledge of hydraulics prevented a near certain tragedy last year when a shaft log problem caused her beautiful and award winning Chris Craft Holiday to take on a threateningly large amount of water. I recall Nancy Stebbins jumped in and saved the day several years back at the Rendezvous and single handedly saved Paul Mickelson Falls Flyer from sinking for lack of a hull plug while the male membership in the area failed to recognize a problem and debated the correctness of the boot stripe. These are possible candidates that quickly come to mind, I am sure that there are other candidates among the

membership. I will continue my dogged pursuit of identifying “Doctor Motorhead” and eventually revealing that true identity to the world. In the meantime however,

I must seek the “Doctor’s” advice regarding a perplexing situation with my 95 horse power, post war, Hercules, model K.

My problem is that this typically reliable engine has developed what appears to be a misfire at approximately 1500 rpm. I have performed all of the usual diagnostics.  The compression measured 135 lbs and was within a couple of percent in all cylinders, as well, the cylinder leak test results were within 3% among all cylinders. Valve lash is set at .010 on the intake valves and .012 for the exhaust valves. I have replaced spark plugs, spark plug wires, coil, distributor cap, points and condenser.  I verified that the distributor was properly grounded and that the ignition timing was right on the money. I endured the expense and had the carburetor professionally rebuilt.  Additionally, I verified that the engine vacuum was steady at idle with 19 inches of mercury and that the fuel pressure maintained 4 pounds with good volume.  The engine idles perfectly but I detect the misfire when I increase the rpm’s to 1500, either at the dock or under way. Boat and engine have performed well all season.  I practically tore up Mt Dora and literally punished the Lake of the Ozarks at the annual ACBS meeting. I am sure that the “Doctor” can share in my profound disappointment of a now misfiring engine.

In closing, I have just one more observation. Over the years of reading Doctor Motorhead’s advice, I see a very weak feedback loop. That is, advice seekers seldom appear to follow up and comment on the quality of the dispensed advice in terms of whether or not it solved their problem. A cynical person might question whether this apparent lack of feedback is merely an edit function on the “Doctor’s” part. I prefer to think that our club membership is simply too busy in the conduct of ordinary life to double back with commentary. I pledge, that in the spring, after I have had the opportunity to implement the “Doctor’s” advice, I will provide a report card sorts that details the accuracy of the diagnosis and the quality of the advice in solving my problem.  Until then,warmest regards

Dear Warmest Regards,

Whoa! Talk about anonymity; you didn’t even sign your own letter with an alias or anything. No name at all, no one for sure will know who you are except perhaps Madame Editor. Are YOU trying to hide something? Are the authorities trying to locate you and perhaps your henchmen?

I smell a fish. I think you are trying to set me up. I hope you aren’t trying to impugn my advice and good judgment. If you say you are having trouble with a misfire, how in fact can you “tear up Mt. Dora” or “Literally pound Lake of the Qzarks”. Unless, you have in fact made the necessary repairs to your engine.  And besides how can you torture these lakes with a wimpy 95-horse power model “K” engine. Unless you brought it down to Milwaukee for a rebuild at Lou Brisity’s Speed Merchant and Transmission Shop. Perhaps this is Lou himself writing this letter not wanting to let anyone know he himself needs advise from the good Doctor. The more I think about it, not only is this Lou who wrote me this letter, you are very cleverly trying to give doubt to the readership that I even exist. Yes, this is a very clever plot to discredit my able-bodied assistant Piston and myself. How many others are involved in this conspiracy? Any more of you “CheeseHeads” out there? You suggested I answer your letter in the spring.

I have many things to do. Piston and I are very busy not only with BSLOL activities but with our continued consultation to the Pope. The Vatican fleet is aging and needs all the new technological conversions. Most importantly however, this conspiracy could not fester any longer. As I am sure the

trusted BSLOL members would agree.

Yes, only you Lou would have gone through all the trouble to try and discover your problem. The basic follower of this column wouldn’t even know the first thing about steady vacuum or how to measure 19 inches of mercury. For that matter, how to even perform a leak down test or let alone have the equipment for it. You are a clever one Mr. Brisity, but you can’t fool me, no sir!  So, I’ll solve your problem for you. I’ll even throw in a little additional advise for the sake of our readership if you don’t mind kind sir.

Here ya go. You did not make it very clear whether the problem persisted past 1,500 RPM or was intermittent misfire just at 1,500. Here is one thing everyone should know. If you have a fixed high-speed jet on your carburetor, at about 1,500 you may have a slight misfire. As you move from the low-speed jet to the high-speed jet, which determines the proper fuel and air mixture combination, this can occur. Don’t sweat, nothing to do here, just go a little slower or faster if it bugs you. How do you know if your high-speed jet is fixed or not? On the backside of the carburetor towards the bottom, if there is not an adjustment valve, it is a fixed jet. So, if you do not have one, it’s fixed and there’s nothing to worry about.

Second thought the “K” engine has a smaller distributor than the “M” engine. If you have converted your engine from 6 to 12 volts and have installed one of those chrome, high output mega flamethrower coils, you may get an occasional errant spark inside your distributor. This errant spark will send the high voltage to the wrong cylinder at the wrong time. This will more likely happen at lower speeds as well so less likely to be the problem. So, I won’t go any further except to tell the readers you don’t need that type of coil.

The last thought I have and a very unusual one is not even gas, spark or air related at all. I’m going to ask you to do two things for me. Please pull your spark plugs and visually inspect them for any unusual coloring or maybe even just wetness. You may have a combustion chamber problem. If one of your plugs looks fouled in any way, mark the cylinder from which it came. You are going to have to remove the engine head to go to the next step. Oh, one thing I am going to assume, you did not have any back firing in your carburetor, as you didn’t mention it. If you did you are withholding vital information. Remember; always be frank and truthful with your Doctor. Now I have only seen this malady a couple of times in my career. Because you were not getting a backfire in your carburetor, I would suggest that you have a problem with your exhaust valve on that one cylinder. Because you said the valve lash or gap between the valve and lifter was set properly I’ll accept that, you may have a bad or weak valve spring. If the engine is newly rebuilt you may not have any discoloration at all, so you will need to check all the valves and springs. Unfortunately, to do all this you need some very specific tools. Tools beyond the scope of your standard tool bag with the Dr. Motorhead seal of approval. You will more than likely need to pull the engine, remove the manifolds and begin removing one or all of the valves. Unless, you are working on a utility, then the engine can stay put. You will also need to then check the springs with a valve spring compression tester. Probably best left up to your engine rebuilder. Wait a minute you are an engine rebuilder.

You can do it Lou. Just remember your mantra. I trust my Doctor, I trust my Doctor. The engine ran fine at lower speeds because the weak spring could keep up with the rotations. Once you sped up the engine, the valve was not coming down fast enough to give you a tight seal at the seat as required. Remember, both valves need to be closed tight at the time of combustion. If you just rebuilt this engine shame on you for not checking the springs before reinstallation. If this happened after a long lay over a valve may have been fully extended keeping the spring compressed and loosing its strength.    

As to the question who am I? Am I really one of the fine ladies you reference? All of them models of quick thinkers, level headed and intuitive. I would be proud to fill their shoes. Alas, I am me, Dr. Fred Motorhead. Or, is it Frederica. Keep this in mind; regardless of gender I am the force, the spirit in which we all have inside us to take on the seemingly impossible projects. Like Greta Garbo I live a life without fan fair or, paparazzi. You mentioned my name was not in the ACBS directory. It is. Only the name in the directory is actually the one that is contrived to protect my anonymity. I walk among you, at annual meetings, BSLOL Rendezvous and Chapter Christmas parties. If the press knew I was at a party with you guys,  the evening would be ruined with reporters and photographers crashing in from all entrances. I owe it to my friends to remain anonymous and in seclusion. There are a few who know my alias. They however have been issued cyanide capsules. Don’t push their fate.

Dr. Fred (Frederica) Motorhead