My issue is unless your pushing 300-400 HP or NOS or lots of psi, I would NOT run locked dist. One module you ground, one you run power to, one gives retard other gives advance. way for most people to set the timing, and is not a good procedure for optimum performance. It ran low 7's till the found article using retard on distributor module. So they built up ol Duece Nova he had, 13.5 -1 roller cammed 327, solid can, 4 SPD factory 4.10 gears. His old neighbor had garage filled with old car mags, old car parts, the didn't have much cash but old man willed all his stuff and garage and land to them. Had one guy with no extra cash want to take kids racing. And its easy if you have right module to get a start retard. Most SBCs run very good with around 34-36 total ignition timing at WOT - usually 20-22 degrees mechanical advance + base timing set at around 12-14. So far can't find it.īut the distributors fit, work well and are very reliable. If you need more advance at idle just shorten the mech advance slots to reduce the number of degrees available - then set the base timing a little advanced to make up for it. I used to have list of hei modules that advance or retard the timing. As a result, the timing moves to 32 degrees before top dead center which allows the fuel to be ignited early enough so that it is burning while the piston is rising and completely burnt when the piston reaches top dead center.Had a few guys use CCC locked hei's the ones from the elctronc carb engines. In order to have the same result, the fuel must be ignited much sooner in the compression stroke.
This would equate to 10 degrees of crankshaft rotation before reaching top dead center to give the fuel sufficient time for a complete burn.Īs the engine rpm increases to 3,000 rpm, the fuel, - still requiring the same time to burn - would never have sufficient time to burn if ignited at the same 10-degree timing. Using an engine idling at 900 rpm further illustration, the piston is moving upward at a speed that the fuel, given the time it takes to burn completely, is ignited 1/16-inch from the top. I have a Petronix HEI and thats about it for ignition mods. Id like to run as high as possible inital timing and get very little advance out of it and have the advance come in quick. This would mean that the fuel is still igniting while the piston is descending in the power stroke and would result in a massive loss of power. On a blower engine,BBC or SBC,roots,centrifugal,twin squrew,etc.whats the best timing curve for a street/strip motor. It would not be efficient having a small percentage of the fuel consumed before the piston hits top dead center. As the piston rises, the ignition spark plug ignites the fuel and the process begins again.Ĭonsider that the fuel must be burnt as completely as possible before the piston reaches the top of the compression stroke in order to force the piston downward in the power stroke. This is the fourth or compression stroke. The crankshaft turns again and the piston begins to move upward, compressing the raw fuel and air in the process. Just prior to reaching the bottom of this stroke the intake valve closes. As the piston reaches top dead center and continues downward once again it creates a vacuum sucking more fuel into the cylinder. Just before the piston rises completely in the exhaust stroke the intake valve opens, using the vacuum produced by the rapidly exiting exhaust gases to help draw in more fuel from the intake valve. The upward moving piston forces the burnt gases out of the cylinder. As the crankshaft turns, the piston begins to go back up and the camshaft opens the exhaust valve. The burning fuel expanding forces the piston downward. The piston begins all the way up at top dead center. The crankshaft turns two revolutions, which moves the pistons up and down to one turn of the camshaft that opens and closes the valves. Let's use a single cylinder in an engine as an illustration to demonstrate how all four strokes work. of the valuation provisions in clause 52. The SBC timing is advanced by turning the wheel to the right, and the timing is set backward by turning the wheel to the left. All automotive engines today have four strokes. of variations in advance of the formal instruction of such variations.
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