Tech Talk with Steve Rolenc
Bud (Master Engine Tech)
Steve Rolenc (President)
SRE Engine Techniques
SRE Engine Techniques
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, we might as well have put crappy heads on your engine. If your headers were run on our dyno, we've already ported them for you.
Bell Housing - Proper bell housing to crankshaft centerline alignment is critical. Place a 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 must 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.
Torque Converter - Standard type converters need at least 1/8 inch at very minimum clearance between a straight (if it is bent or crooked it is junk) flex plate and converter. Stall converters need a bit more space as they grow in length due to the extra heat generated.
Procedure - Install converter bolts slightly finger tight. Spin converter around and verify everything remains finger tight. Now spin it again and snug the bolts a bit. At this point, you're not trying to lock it down rather sneaking up on tight, a little at a time. Spin it again and go a little tighter on each bolt. You may spin engine many times doing this procedure but it is best way to get converter centered up.
Note: When completed, regardless of a converter or a clutch, the end play on engine needs to be checked with a dial indicator. There should be about .005 That verifies nothing in driveline is binding up engine. Less is too little and a lot more indicates a problem that needs to be addressed
When using a thermostat, you must make sure the air is bled out of cooling system. This avoids air-locking engine and wounding heads, valves, guides and rings, among other things. When running a non-modified thermostat, 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.
Tip: 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 some water circulating through system even if thermostat is closed.
Bigger is better! 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 gasoline, 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.
If extra cooling is needed add 1 -2 qts of Below 40 additive, Water Wetter doesn’t work as well and it benefit fades away in a few weeks.
Tip: Run a rippled type suction hose (to water pump) that has the wire embedded inside the rubber. We've seen hoses suck closed on engines at speed and flow no water. Don’t use hose with the visible wire in them as they will end up in your water pump fins and destroy the pump and then your engine.
Cleaning your radiator - Dirt track racing has a bad habit of filling cooling 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.
This is a slippery subject! Only use BRAD PENN or KENDALL GT-l oil along with PROLONG additive. There may be oils that are comparable but I feel so strongly that BRAD PENN or KENDALL GT-l is the best that there is on the market, that there will be no warranty considerations if any other oil is used. 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.
Note: 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.
DO NOT block by-pass valves in block as it is the preferred bypass location. Filters have bypass valve in them, but they are usually at the bottom of the filter where the junk is accumulated, so we would rather bypass at top where the junk isn’t stirred up. Oil filters only flow about 10-20% of the oil required by an engine. So oil filters only filter 10% of the oil at a time, so 90% of unfiltered oil is being by passed to engine. When oil is cold and thick it barely flows any through filter material at all. So there must be filter bypass devices in system. You can find oil filters that bypass on top of filter element not from a valve and spring at bottom closer to where the particles are.
If an engine catastrophe in the bottom end has occurred, then the oiling system must be completely cleaned including the tank and lines. Oil cooler must be replaced as they cannot be cleaned completely. 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.
Always start new engines with air cleaner assemblies installed. Anytime the engine is off and a change in the timing, fuel pressure, jets, pills, bypasses, or reinstalled 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.
Warm the engine up (See oil section regarding preheating). If engine wasn’t dynoed and has a flat tappet cam, add 2 extra quarts of oil and ZDDP cam break-in supplement. Warm the engine up at idle or a little faster idle for 30 minutes minimum. Don’t run at 1500 rpm like they recommend as exhaust temperature will have about 1300 degree temp at that rpm. All that brutal heat on new not carboned(heat isolated ) parts is crazy! You can throttle motor up to set timing and initial tune engine, just don’t hold at a steady higher rpm for extended time (roller cams you don’t need to do this). Always keep an eye on the oil pressure! 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…
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 on until almost closed, then adjust the 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, costing you power at a minimum and risking possible engine damage.
Note: 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 as an initial setting. ALWAYS RECHECK at operating temperature.
Tip: Figure the exact correction factor for each valve as it shrinks to cold and you can then set cold and know exactly what it will warm up to. Measure all valves hot and document, let engine cool, recheck and you can calculate how much each one changes and then set cold lash to correct growth setting. Notice how they are not the same setting cold on each valve as the expansion is different on different parts of the head.
Check spring pressures and document on the spring sheet I supply weekly.
Other important information
Intake Manifold torque - Intake manifold leaks are the number ONE cause for lean conditions, causing blown head gaskets, burned pistons, spark plug tip melting, and numerous tuning problems.
Re-torque your 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.
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Tech Talk with Steve Rolenc