RACING ENGINE INFORMATION
PLEASE read this information thoroughly. Mark what information pertains to your racing program. This is a basic guide of some of the most asked questions I answer for teams and helps put everyone on the same page.
INSTALLATION: The entry on the headers needs to be ground slightly bigger than the exhaust port exits in the cylinder heads. The cylinder heads have had so much critical attention that if this important transition area is crappy, well we might as well have put crappy heads on your engine. If your headers were run on the dyno then we already ported the headers. The bell housing to crankshaft centerline alignment must be checked. Put magnetic dial indicator on back flange of crankshaft. With bell housing installed over dowel pins, rotate engine while watching the sweep of the indicator around transmission mount hole. There are offset dowel pins to correct the alignment. After installing offset dowels in block, that block needs to be dedicated to that bell housing. Other blocks can be dialed in to that same bell housing, but if a different bell housing is used on block then procedure must be repeated. This misalignment could be from bell housing dowel holes, and or transmission mount hole location and from the block dowel locations where the actual correction was achieved.
Never run a belt drive or injector pump dry. Loosen fuel line at pump inlet. Remove return line on fuel cell and plug. Use air pressure in fuel cell return fitting with bypass pressure gauge and regulator to put in 2-3 psi. until fuel is at the pump. After fuel is bled to pump then tighten line, loosen line at barrel valve and bleed, and tighten line and finally to nozzles with lines disconnected or on carb until bowls are full. This should also be done to a block driven lever pump to lessen cranking time on initial start.
Throttle return spring works best if it is attached to throttle linkage on car and not on the throttle lever on carb. This will give the throttle bushings longer life. Make sure throttle pedal actually opens throttles all the way. Do not over tighten blower belts or crankshaft damage will result. Gilmer type belts are meant to run in a zero preload situation, this includes dry sump belts and belt-drive fuel pumps.
BREAK IN: Fill engine with oil, prefill filter and use a drill to drive oil pump shaft with a special tool. On dry sump systems put 2 quarts in oil pan and fill tank. Disconnect belt, or on a Sprint or rear belt drive system unbolt pump from mounting flange and spin the shaft with a drill or air ratchet leaving all the lines connected. Just turn until a good resistance is felt. There is no need to prime oil system if engine just came off dyno and oil system is complete.
If using a thermostat make sure the air is bled out of cooling system to keep from air-locking engine and wounding heads, valves, guides and rings, among other things. If running a non-modified thermostat, need to disconnect the highest hose or fitting under the height of the thermostat and fill system until coolant escapes. This insures the heads are full of coolant, then hook it back up and top off cooling system. Drill 2 or 3 holes 3/16 in size vertically around center control assembly on thermostat. The benefit of this modification is no special bleeding process is necessary and there will always be water circulating through system.
Warm the engine up(See oil section about preheating). If engine wasn’t dynoed and has a flat tappet cam, add 2 extra quarts of oil and ZDDP cam break-in supplement. Run engine at 1500-RPM minimum from startup (2000 is preferred once it’s warm) for 30 minutes minimum. Slowly cycle RPM up and down once every minute. Do not exceed 3500 RPM. Dedicate someone to always keep an eye on the oil pressure and water temperature until everything has been successfully verified. This is the opportunity to check header tubes for dead cylinders, look for leaks, set water level, rough tune ignition timing, injector, fuel pressure, and carburetors etc…
Always start new engine with air cleaner assemblies installed. Anytime the engine is off and a change in the timing, fuel pressure, jets, pills, bypasses, or re-hooked up spark plug wires etc… Always install air cleaner as a flame arrestor to avoid a fire from backfiring, and fuel spitting. When an engine belches it can throw flaming fuel on your racecar and you, or light any raw fuel on the intake manifold or rags. The air cleaners can be removed as soon as the engine is started. This is especially important safety precaution for alcohol, injected, or supercharged engines.
After 30-45 minutes shut off engine and change the oil and filter. This is especially important on flat tappet cams because the special cam lubricant that is used on camshaft will plug the oil filter. Pour in more ZDDP cam break-in supplement if using flat tappet cam along with new oil. Re-torque the heads to spec, mark all head fasteners with an alignment mark to verify how far each one moves, fasteners MUST MOVE. If they don’t, back off a little to break the thread set, then torque. They all should move 1/8 to 1/4 of a turn. If using head studs on aluminum heads allow time for engine to cool before re-torqueing. Reset lash, retorque intake manifold, check carb bolts, and headers, etc…
SETTING VALVE LASH: This is the ONLY acceptable technique for adjusting valves. Work cylinder by cylinder. Turn engine until exhaust valve just breaks open, then adjust intake valve. Open intake valve all the way to max. lift and almost closed, then adjust exhaust valve. Mark each rocker that is set so none is missed. Setting lash any other way (TDC method or two rollover method) may put lifter on a clearance ramp and cause misadjustment. Lash spec for a camshaft is not a starting point, it is a MAXIMUM. Adjustment can be tighter, but no more than .002 on tight lash cams normally. If lash is set cold, set .002 tight on iron heads, .003 tight for aluminum heads, and .006 tight for an all aluminum motor. ALWAYS RECHECK at operating temperature.
INTAKE MANIFOLD: Intake manifold leak is the number ONE cause for lean conditions causing blown head gaskets, burned pistons, spark plug tip melting, and numerous tuning problems. Re-torque manifold frequently, small block Chevy 25-30 pounds. Most common area for leak is at the bottom side of intake ports. To check remove carb and look down ports. If any look glossy down the runner with a flashlight, that is the oil coming up through gasket from the lifter valley. If the manifold is removed for any reason DO NOT put on without sealer on the gasket. Duplicate the way we installed it using 3M weather strip adhesive and silicone.
CARB SPACERS: Always use plastic or phenolic spacers as a temperature barrier because the less temperature the carb changes the more consistent the fuel curve for mixture control.
AIR CLEANERS: KEEP FILTERS CLEAN. A clean air filter is free horsepower. Having good filters with an inferior base seal is counter productive. The ones that come with the K & N kits are not good enough to use at all. We stock an air cleaner gasket with rubber on both sides with a steel girdle in the center. It will virtually last forever. If the air filter element is collapsed in any way (even a little bit) it will not seal properly and needs to be replaced. If your class allows air boxes use them! Box off hood to pull air from the topside of the hood, air under the hood is heated and less dense, cool air above hood is MORE horsepower.
OIL SYSTEMS: This is a slippery subject. Only use BRAD PENN or KENDALL GT-l oil along with PROLONG additive. Use the straight weight 50, or when it is cool around 60-70 degrees outside then use 40 weight. If any 30+ laps races are entered when it is cool use 50 weight with extra care taken on warm-ups. Don’t be last one in the pits five minutes before your turn on the track. Straight weight oil is very thick when cold, extra care in warm-ups is critical. DO NOT rev or load engine or race until OIL temp is 180 degrees.
On dry sump systems it is a MUST to preheat oil. The heaters that recirculate hot water to warm the block is a great investment and helps to insure that you make the race instead of hurting an engine without proper warm-up procedures. If you don’t have the Quick heat system then use a 110-volt oil heat pad to warm oil in tank. On wet sump systems, use ll0 volt magnetic heater to stick on oil pan. Preheating your investment will make your engine program have less issues, and will lengthen the life of engine as cold wear will be eliminated.
Aluminum blocks and rods need an additional warm-up period before any load is put on them, because of the greater expansion required to achieve proper bearing clearance. Dry sumps must have a vent of #12 line minimum for tank and at least two 1.25″ ID filters on engine and be clean at all times.
If an engine catastrophe in the bottom end has occurred, then the oiling system must be completely cleaned including the tank and lines. Remove the dry sump tank from the car, separate and clean thoroughly. Run solvent through all lines while they are removed from the chassis. Clean, blow, clean, blow….. until clean. Dry sump pumps must be disassembled for inspection. Any scoring on aluminum housings must be fixed or scavenge vacuum will not be sufficient, and can be bad enough to wound the next engine.
Prescreens from pan to pump will not save dry sump pump from damage. The meshing is wide enough to let particles of necessary size to slip through and damage the pump. All they do is restrict flow. An Oberg filter from pump to tank is advised. Use a coarser mesh than what came with the Oberg. It makes it easy to check for condition of bearings as part of regular maintenance and it saves debris from entering tank. Do not use as the only filter, always have a spin on filter somewhere else. Oil filters only flow about 10-20% of the oil required by an engine. When oil is cold and thick it barely flows any through filter material. So there must be filter bypass devices in system. Filters have bypasses built into them, but it is closer to the debris trapped in filter than the block bypass. DO NOT block by-pass valves in block as it is the preferred bypass location. Find oil filters that bypass on top of filter element, not from a valve and spring at bottom closer to where the particles are.
COOLING SYSTEMS: Bigger is better here, especially in the radiator department. Aluminum radiators transfer heat much more efficiently than copper or brass. Shrouds are a must, and proper fan spacing is critical. On gas, air boxes in front of radiator are necessary. Also use reduced ratio pulleys to slow water pump speed. Use a 5/8 – 3/4 water outlet restrictor in thermostat housing. Ask us about running thermostats, it may fit your situation. Dirt track racing has a bad habit of filling fins with dirt. Pressure washers and air pressure won’t clean these without damaging fins and ruining the radiator. It is better to clean a radiator by submerging it under water for a short time to penetrate all the dirt thoroughly and rinse with a garden hose and light air pressure.
TUNING: Most teams give up 10% horsepower because of incorrect tune on engine. That is 70 HP on an ASCS 360 motor or 90 HP on a 410. How can the outlaw teams be beat if that much power is being forfeited? They don’t give up that extra power because they have procedures for keeping their engine at close to maximum output. We have developed an even better more accurate way to achieve not close to maximum output but actual maximum output.
All engines we dyno are tuned for max power with an air density meter that will stay with the engine and be corrected to our dedicated dyno air density equipment. This will be the most accurate way of keeping the correct amount of fuel required by knowing the density altitude. Then a correction equation can be formulated for fuel adjustment at the race track, with no guess work. I have seen 3500 density altitude change from hot laps to feature. On a Holley carb that is about 3 ½ jet size difference to be at same fuel calibration. We dyno motors with air filters, and mufflers (if required by rules). Really does it matter how much HP the engine makes with no air filters? It is not ran at the track that way. If the fuel was set without filters the last time it was ran on dyno it now has the wrong fuel setting.
If the engine fuel is not set with air density meters then always start on rich side and then backup jets and bypasses. Always use new plugs in determining proper mixture. It may take a couple of sets of plugs so you are reading non contaminated colors. They can be cycled later as fresh plugs after tune has been achieved. Never use water temperature as a tattletale on mixture settings. The engine will burn up long before the temperature rises.
Timing indicator on damper has been marked for total advance. This is not a starting point it is a MAXIMUM. Make sure as engine is revved up it does not ever advance past this mark. Always have 2 timing lights available incase one wigs out or just to be confident that proper timing is achieved. Pressure regulators that have a throttle position activated “dump valve” that only has a few pounds of pressure at idle are not desirable. Set float level at racing pressure. Holley carbs typically can hold 9 psi on the track, they can hold more on the dyno and in the pits without the added motion. So set pressure 1 to 2 pounds below this at 7 to 8 psi. Change in pressure does change the float level which will change mixture!!!
All regulation should be after the carburetors in a constant flow system with a return line, this also keeps the pump from overheating.
RPM RECOMMENDATIONS: What I give is considering engine life and is a maximum safe limit determined by the highest stressed moment called critical tension at TDC which is affected by weight of reciprocating parts, rod length, and stroke of engine combination. Valve train is the where most of our designing technology is focused. The valve and spring material, spring specifications, lobe design, accuracy of the finished camshaft product, and total valve train weight are just part of the considerations taken to match the engine to your requirements. The engine can be turned slower. Many races have been won with less RPMs than expected depending on the driver preference, chassis, and track conditions.
MAINTENANCE: Drain tank on alcohol, loosen lines and blow out fuel system dry to lessen corrosion. Clean carburetor and lubricate every race. Use a choke cleaner to remove dirt and don’t forget air bleeds. If carb is disastrously dirty and the air bleeds are partially plugged, cleaning them will LEAN the mixture!!! After cleaning use CRC or WD 40 to lube shafts. We use only Holley parts on freshen-ups and on alcohol carbs special bullet nose needle and seats are installed. Carbs should be maintained every year, and absolutely no longer than 2 years. To store carb or fuel pump for more than one month, submerge in racing gasoline, even your alcohol carb. Do not leave out where air can dry out the gaskets.
Do not use fuel with heavy color dyes. Heavy dyes sometimes drop out of suspension thereby plugging fuel filters. It is best to buy fuel by the barrel to increase consistency of fuel, and keep it sealed so moisture doesn’t contaminate fuel. Rig up an air evacuation system on alcohol barrels and pull a slight vacuum. This keeps moisture from ruining the fuel. Always use bigger filters than what you think you need.
LEAKDOWN: A leakdown gauge is a must to keep track of engine condition. Single gauge units are much simpler and easier to use and the only ones we sell. It can also be used to set injector barrel valves. Engine should be leaked down and have results logged every night. Every race try to keep as much water out of the engine as possible when washing. Relight the engine, warm to operating temp, drain oil while hot that way all the particles are suspended and oil is thin. Add new oil and filter and re-start engine, set lash while engine is warm. Change spark plugs at least every four races to keep engine sharp.
On sprint cars if relighting engine is impossible pull all spark plugs, roll car at least two full revolutions of the engine like you would if it was flooded. Squirt WD 40 into cylinders making sure dome is out of the way so spray reaches far side of cylinder wall and roll engine at least 1 turn.
WINTERIZING: If motor doesn’t have enough races to be freshened and is going to be stored, follow weekly procedure including new oil and filter. Put WD 40 in cylinders, and roll engine over a few times afterwards. Loosen all springs, plug all holes, and re-insert spark plugs.
ENGINE LIFE: This is different for every type of engine we build. With the higher tech bearings and rings we are using, freshen-ups are extended on engines where heads need freshened before the bottom end to keep the engine sharp. Long-term engine life is extended because of new building and machining techniques and assembling with the highest quality of care. I have had winning 410 motors go over 40 shows with proper care. With this information on weekly maintenance and keeping track of leak down readings, lash movements, and oil filter inspections, it will be easy to determine when your engine needs to be freshened up. This will save you so much money on not freshening too often, or determining when to remove engine from service before real issues appear, which will save you thousands of dollars.
This is only a small list of information to help but, by no means all of them. I wrote this as a basic guide to put us more on the same page for your racing effort. Please call if there are any questions that I can possibly answer.
We extend our gratitude for your patronage and wish you a season of fun, excitement and the thrill of victory.
Only the LORD can fix a broken heart.
Go have FUN and good LUCK!!!
SRE ENGINE TECHNIQUES
6700 W Ina Rd, Tucson, AZ 85743