![]() ![]() ![]() However, cams with a big overlap window (intake open point plus exhaust close point) also tend to have big TDC lift numbers, and this is what Stroke, thus getting it moving before the piston even starts pulling on it. Overlap can be a wonderful thing in a set of cams, as it effectively connects the exhaust system to the intake tract and gives the exhaust an opportunity to pull on the intake charge at the front of the intake It's exactly as the name implies, how much the valves are open at top deadĬenter (TDC), in this case overlap TDC, not compression TDC (overlap TDC occurs between the exhaust and intake strokes). Not a set of cams is going to get you in trouble on valve-to-piston clearance, TDC lift is the spec you're interested it. TDC Lift: Contrary to popular belief, maximum lift has no bearing on valve-to-piston clearance, because max lift occurs with the piston well down the bore. Here's what to look for on the spec sheet: The complexity level is directly related to the cams you're trying to install, and for that information, Swapping your cams can be very simple or very complex or anywhere in between. You have any questions, don't hesitate to contact us, we're happy to help. We want your project to be a success, so this article is provided to show all the ins and outs of swapping cams on an XL motor. When you start leaving power on the table by virtue of your stock cams, it's time to change them. Cylinder fill is the name of the game, and cams play a huge role in that, by both the timing of when they open and close 1987 Use on EVO 1984-present 4 5/8” 3 5/8” +.010 8 1/2” *9.Cam Specs and How They Affect InstallationĬhanging cams is part of almost every high performance project, simply because the factory cams generally start limiting you before you make it very far down the path of modifying your motor. Use on EVO 1984-present Use on EVO 1984-present Use on EVO 1984-presentĨ7” EVOLUTION ® STROKER KITS WITH FLAT TOP PISTONSĨ9” EVOLUTION ® STROKER KITS WITH FLAT TOP PISTONSĩ6” EVOLUTION ® STROKER KITS WITH FLAT TOP PISTONS (SEE JIMS ® CASE BORING TOOL NO.1409) PART NO. Pressed Plug For Increased Flywheel RetentionĨ0” EVOLUTION ® STROKER KITS WITH DOMED PISTONS For more details see No.1972-IS instructions Parts not available separately, except piston sets.See JIMS ® Evo case bore tool No.1409 on page 168. For 3-5/8” bore pistons, motor cases will have to be bored to install 3-5/8” cylinders. 24628-87 pinion bearings may also be used. ![]() ![]() These kits can be installed into 1984-99 cases with standard pinion shaft races (24599-58B, 24599-58A, etc.). These kits are shipped with standard length sprocket and pinion shafts. JIMS ® new EVO crankshaft goes a long way to narrow the difference in strength between the two engines. This greater rigidity and load capacity is perhaps the greatest advantage of the Twin Cam ® engine over the EVO. Harley choose to enlarge the pin diameter and make it a press fit in flywheels of the Twin Cam ® engine. The taper-fit crank pin flexes at high rpm and can often shift, even in normal use. The bolt together EVO crankshaft has some limits when run at high rpm in powerful engines. This is the strongest and most rigid EVO crankshaft made. Of course, we use the proven JIMS ® “H” beam 4340 chromoly connecting rods for the ultimate in strength and stability. Each left flywheel and shaft is forged as a unit to maxi- mize stiffness and reliability. We have integrated the strength and stiffness of the genuine Harley ® Twin Cam ® crank pin and bearings into our new Evo crankshaft assembly. Unmatched strength for your EVO! Your next high performance EVO engine build will be more reliable with JIMS ® new EVO/Twin Cam ® hybrid crank assembly. ![]()
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