<h3>Today’s Gasoline Additives Silent Killers Of GM Engines, Joe Mondello, Engine Builder, June 2001</font></h3>
Over the past several years, I have answered hundreds of questions about engines: "Why does my engine ping? detonate? have its valves stick in their guides? have badly worn exhaust valve seats? Run hot? Make less power than it used to?" </font> The biggest problem engines face today is the fuel. It is unstable because of the additives: gasohol, ethanol, alcohol, etc., which cause fuel to oxygenate. When the fuel sits in the gas tank for seven to 10 days, it separates and accumulates water, in turn leaning out the fuel mixture.</font> Ever since the introduction of unleaded fuel, we lost tetraethyl lead, which lubricated the upper engine parts, and we lost octane, which used to eliminate pinging, detonation, upper cylinder head and engine wear. We now have to go back to square one to correct the problems.</font> The octane rating on the pump is not what goes into the gas tank – it is about one to two octane less. How can you correct this? In my experience, the use of Sta-bil fuel stabilizer, about two ounces per five gallons of fuel, and Marvel Mystery Oil, about four to six ounces per 20 gallons of fuel, is a good starting point.</font> The total fuel curve of the engine is very important and involves everything from the gas tank to the carburetor, so examine all of the components. Most people have never checked the condition of the fuel sock in the gas tank to see if it is clogged with sediment, rust and sludge. A dirty fuel sock is the most common reason for poor fuel delivery, low fuel pressure and a lean-running engine.</font> Steel fuel lines (5/16˝ and 3/8˝) can get pinched or dented, restricting fuel flow to the carburetor. The stock fuel pump (which is usually worn out, but even when new is i nadequate) can only hold 2-1/2 to 4-1/2 psi of pressure. This is hardly enough when you’re trying to run 4500 to 5000 rpm. I recommend a higher pressure, higher volume fuel pump for today’s gasoline. Holley, Edelbrock or Carter mechanical fuel pumps deliver up to 100 gallons per hour free flow with over 8 psi, but they will need a regulator for maximum street/strip performance. I prefer 6 to 6.5 psi of steady fuel pressure.</font> If your customer is running a Quadrajet, Edelbrock or Holley carburetor, always remove the paper fuel filter cartridge from the inlet side of the carburetor and replace it with a Barry Grant, System One, Moroso or equivalent in-line, free-flowing fuel filter. If you are running fuel additives, lead substitutes, octane boosters or carburetor cleaners, the paper cartridges will deteriorate.</font> Today’s gasoline is leaning your fuel mixture between 10 and 14 percent. For owners of motorhomes, this leaner mixture is really causing more problems than in a car, because of the 15,000 lbs. being moved, plus the excessive heat being generated in the engine compartment. The changing of jets and metering rods, both primary and secondary, is mandatory, especially on Edelbrock and Quadrajet carburetors. If the Quadrajet has a 72 primary jet and a .054˝ primary metering rod, you should go up two jet sizes (example: 74 primary jet and .047˝ primary metering rod) enrich the fuel mixture about five to eight percent. You should continue to enrich the fuel system until all signs of pinging and detonation are gone.</font> The easiest way to detect detonation is to install the Engine Knock Alert from MSD (p/n 8964). This device is easy to install and easy to use because it flashes a warning light along with an audible beep. </font> The MSD adjustable timing control (p/n 8782) works with all point type and electronic distributors. If your customer uses an MSD box 5, 6, 6-AL or similar in conjunction with one of the popular electronic distributors, I recommend an MSD-8680 adjustable timing control also be used. </font> Ignition timing set up is also critical with today’s gasoline problems. The H.E.I. is the most difficult to do correctly, especially if you are using it in a performance application. The stock GM H.E.I. distributor was made for 7.8:1 to 8.5:1 compression ratio, which used to require very high degrees of timing. The total timing on a stock 350, 403 or 455 Olds was about 46° to 52° with the vacuum advance connected. Some Chevy, Ford and Mopar engines in the ’70s also ran very high degrees of timing.</font> Most distributors that are set between 6° and 10° of initial timing always seem to have more throttle response for street driveability. </font> The H.E.I. needs to have the mechanical advance portion of the distributor reduced. The slot below the movable counterweights needs to be welded so the travel is shorter. Or, MSD makes a kit (p/n 8464) that includes counterweight springs and advance limit bushings which works well if you don’t weld the slot. The slot is also too long on some point-type trap door distributors and can be handled in the same manner as the H.E.I. distributor.</font> The Crane adjustable vacuum advance unit and vacuum timing limit is highly recommended to slow down the total vacuum advance (each notch adjustment of the limiter will shorten vacuum timing by 2°). This should only be used if you can’t reduce partial throttle-spark knock with the adjustable vacuum advance unit, movement on the H.E.I and point-type GM distributors. The Crane kit for HEI (p/n 99600-1) includes springs, timing limiter plate and adjustable vacuum advance unit. A kit for a GM trap door-type point distributors is also available (p/n 99601-1).</font> A good advance curve for Delco point type and H.E.I. distributors is as follows, but remember, this is only a starting point – fine tuning adjustments will sometimes be needed.</font> I recommend the use of MSD timing controls after you have reached a happy medium on initial mechanical and vacuum advance settings. On all point-type Delco trap door distributors, I recommend our electronic distributor modules for Oldsmobile (p/n EM-1181-LSCC) or Chevy (p/n EM-1181-LSC) V8s. The kits replace the points and condenser, giving more energy and spark through the coil and to the spark plug. It is a bolt-in item, easily installed. It retains the stock look of the distributor for show cars and works with all aftermarket ignition parts.</font> The stock HEI distributors send a very weak spark signal to the plug between 2000 and 4000 rpm, so I recommend an Accel Super Coil (p/n 140005) or a modified HEI dust cover by MSD (p/n 8401), which allows any good aftermarket coil to be run. These parts will eliminate poor spark complaints.</font> A good start for the ignition timing curve for an HEI or point distributor should be 10°-11° mechanical advance which is 20° to 22° in the engine, 6° to 10° initial advance and as little vacuum advance as possible. If you can get away without a vacuum advance, do it for performance street use. I like the use of a vacuum advance unit, because it gives far-better driveability under partial throttle acceleration and cruising speeds.</font> All Delco HEI and point type distributors need to be rotor phased. This is critical for street and racing applications and a free technical bulletin is available on how to perform it. Set the spark plug gap at .045˝ on the HEI and MSD. Rotor phasing puts the rotor, cap and module in tune with each other, giving up to 15 additional horsepower. </font> Now that the fuel delivery and ignition timing curves have been taken care of, the next most important thing is s park plug heat range and spark plug end gap. All point ignitions use .032˝ end gaps. If you’re working on a 173 Olds 455 with 8.5:1 compression, and you changed it to 10.25:1, do not run the AC 46-S spark plug that came with the car in 1973, because they are too hot. You should be using an AC 44-S plug, because a plug that is too hot will cause a lean mixture and detonation.</font> With today’s gasoline, do not run more than 9.5:1 compression with 92 and 94 octane unleaded fuel. You can run 10:1 compression on the street when using aluminum cylinder heads.</font> When rebuilding engines, and you expect them to live, I suggest you follow the tech tips I have recommended. Here are some others.</font> Do not use cast iron piston rings. Today’s fuel doesn’t have any lubrication, so you will experience very fast cylinder bore wear and short piston ring life. The use of a premium cast moly ring or a file-fit plasma moly ductile ring is my recommendation.</font> Because of the alcohol additives, today’s gasoline generates more internal engineheat with little lubrication. You must use more piston-to wall-clearance, valve-guide-to-valve-stem clearance and piston ring end gap. If your piston manufacturer wants .002˝ piston-to-wall clearance, I suggest you use .0025˝. The ring end gap must be increased by .002˝ to .004˝ over recommended end gaps for your cylinder bore size.</font> On the valve guides, whether they are cast iron, solid bronze or bronze guide liners, you must run .0015˝ to .002˝ intake valve guide clearance and .002˝ to .0025˝ on the exhaus t valve guide clearance. Less than these clearances will stick the exhaust valves and kill the engine.</font> I recommend a light knurl using U.T.P. (United Tool Processes) knurling equipment for both cast iron and solid bronze valve guides. I really like K-Line’s valve guide liners with the interrupted knurl finish. The guide holds oil for better lubrication and a cooler running valve stem.</font> The biggest failure area is exhaust valve seats, and many machine shops destroy a lot of Oldsmobile heads trying to install small block Chevrolet hardened exhaust valve seats in Olds heads. The A, B, C, D, E, F and H big block heads, and 1 through 7 and 7A small block heads need hardened exhaust valve seats. The replacement Chev-rolet exhaust valve seat is 7/32˝ (.21875˝) to 1/4˝ (.250˝) thick and will usually hit the water jacket in an Oldsmobile cylinder head.</font> We make two special size Oldsmobile exhaust valve seats which are both 3/16˝ (.1875˝) thick. The seats are available in 1.750˝ (p/n 1453) and 1.625˝ (p/n 2453) O.D., so they will not hit water, and are made of powder metal alloy which lubricates itself for long exhaust valve and seat life.</font> Good distributor blueprinting is one of the most difficult services to find. I have found through extensive testing that Pro-Blend 40-Below radiator coolant additive and Torco motor oil with MPZ will lower your engine and oil temperatures dramatically.</font> Remember that detonation and pinging aren’t always audible, but are the signs of a silent killer. If you follow these tips and do to your customers’ engines and tune up as I recommend, the engines will live a longer, happier life.</font> For more details about recommended part numbers or availability of parts noted in this column, or for a free technical bulletin on rotor phasing, contact Mondello Technical School at [img]chrome://skype_ff_toolbar_win/content/cb_transparent_l.gif[/img]</span>[img]chrome://skype_ff_toolbar_win/content/famfamfam/us.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/arrow.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img]</span></span>[img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img][img]chrome://skype_ff_toolbar_win/content/space.gif[/img]805-237-9185</span>[img]chrome://skype_ff_toolbar_win/content/cb_transparent_r.gif[/img]</span></span></span>; fax 805-237-9154; or email jmondello@engine-builder.com.</font> |
Good,but datedinfo. Andit wasn't all true even when he wrote it(especially about HEI usage and Accell parts). Joe used to be the only guy out there carrying the torch for Olds performance. There are a lot of really goodshops out there now that are surpassing him in products, priceand (more importantly) customer service. (Lesson #1: Don't let your weasel son-in-law take over your business!) C.J.Edited by: texasred |
How about posting a few of those links?
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http://www.btrperformance.com/ http://www.dickmillerracing.com/ http://www.fcrparts.com/ http://www.robbmcperformance.com/ http://www.rocketracingperformance.com/ Just to name a few. And if you are looking for a GREAT book on Olds buildups, let me throw out a hearty endorsement for Bob Gerometta' Oldsmobile Engine Modification and Tuning Guide. http://stores.ebay.com/Wild-About-Cars-and-Car-StuffBest $20 I have spent in a looooooong time! C.J. |
that is some great info! Thanks.
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RED . YOU GOTTA QUIT SHOWING OFF. W O W I AM OUTCLASSED. [img]smileys/smiley11.gif[/img]
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Not showing off, ilike. Just helping when I can. Showing off is empty post whoring, sniping at n00bs and being generally snarky. Not that I've never done that, but I'd like to think (for the most part) that my posts have some meatin them. C.J. |
So keeping with the meat in a post, What is everyone doing about the new CM certification of motor oil and your flat tappet cams?
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Rotella T synthetic. Royal Purple is the bomb, but way too expensive. C.J. |
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