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Showing results for tags '4.0l'.
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The timing cover on a 4.2L is different than the 4.0L. TDC mark is many degrees away from the 4.0L damper mark, which is typically the damper used in a Mopar EFI conversion. Use true TDC for #1 piston when referencing TDC. If your damper mark does not match up with #1 piston TDC, place the #1 piston at true TDC and scribe a timing mark on the damper to match the timing cover TDC. This is one builder’s 4.0L/4.6L experience. He has a 4.0L in a ’98 TJ Wrangler and installed an OE 4.2L/258 crankshaft. The 4.2L crankshaft keyway did not match his OE 4.0L crankshaft keyway position: “I had stashed away parts from the 4.2 that I stole the crankshaft from to build my Stroker. Last night I dug out the timing cover and put it next to the one from my 4.0. Now I see why the notch in the harmonic balancer doesn’t line up with the tab on the 4.0 cover! The woodruff key slot on the 4.2 is cut in a different location than the key slot on the 4.0 course crank… This might be one for the forums- probably most people never even look since the timing marks won’t be used to set distributor timing but some people like me will be very confused if they do.” 4.2L Crankshaft with 4.0L damper and timing cover. 4.2L timing cover (top) and 4.0L timing cover (bottom). Know which parts you have and always index the timing cover TDC mark with precise TDC of #1 piston. Follow-up/Footnote: The 258/4.2L timing cover and crankshaft source was early seventies I-H 4.2L (AMC) inline six. The I-H/AMC 4.2L crankshaft with the unique key-way offset is a holy grail 12-counterweight type. When you're sourcing parts, know the origins of the crankshaft and the original timing cover's TDC and advance/retard tab location on the cover...Moses Moses -
The timing cover on a 4.2L is different than the 4.0L. TDC mark is many degrees away from the 4.0L damper mark, which is typically the damper used in a Mopar EFI conversion. Use true TDC for #1 piston when referencing TDC. If your damper mark does not match up with #1 piston TDC, place the #1 piston at true TDC and scribe a timing mark on the damper to match the timing cover TDC. This is one builder’s 4.0L/4.6L experience. He has a 4.0L in a ’98 TJ Wrangler and installed an OE 4.2L/258 crankshaft. The 4.2L crankshaft keyway did not match his OE 4.0L crankshaft keyway position: “I had stashed away parts from the 4.2 that I stole the crankshaft from to build my Stroker. Last night I dug out the timing cover and put it next to the one from my 4.0. Now I see why the notch in the harmonic balancer doesn’t line up with the tab on the 4.0 cover! The woodruff key slot on the 4.2 is cut in a different location than the key slot on the 4.0 course crank… This might be one for the forums- probably most people never even look since the timing marks won’t be used to set distributor timing but some people like me will be very confused if they do.” 4.2L Crankshaft with 4.0L damper and timing cover. 4.2L timing cover (top) and 4.0L timing cover (bottom). Know which parts you have and always index the timing cover TDC mark with precise TDC of #1 piston. Moses
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For finding TDC on the compression stroke without the starter functioning, a time-honored approach is a whistle that fits into the spark plug hole for #1 piston. Spark plugs removed to ease crankshaft rotation, this device allows rotating the crankshaft by hand in the normal direction of rotation while listening for the whistle as the piston rises on the compression stroke. Note: If you have brazing or soldering equipment, you can make this tool using an old spark plug shell with the porcelain, electrode and ground strap removed. Braze or solder a metal whistle to the metal plug shell. Remove any burrs or debris from the "tool", then thread it into the spark plug hole for #1 plug in this case. For a pre-made type, here's a popular and inexpensive example that uses a rubber stopper instead of a threaded base. You'll get the idea: https://www.amazon.com/Innovative-Products-7894-Flexible-Compression/dp/B000TQ16HG. An alternative is to use a compression gauge installed in #1 cylinder spark plug hole. Plugs removed, rotate the crankshaft and watch for the bump in compression as the piston rises on the #1 compression stroke. Simultaneously watch the crankshaft damper timing mark to make sure you're rising to #1 TDC. Once the piston is at TDC (look down the #1 spark plug opening and confirm that the piston is at its peak with the TDC mark aligned on the crank pulley/damper), you can decide where you want to place the #1 spark plug wire in the cap rotation. Allow enough room for the distributor's vacuum canister to rotate back and forth without interference when you set the spark timing. Lift the distributor away from the camshaft drive to align the distributor shaft and rotor with a selected distributor cap position for the #1 spark lead. Then you can hook up the remaining spark leads in clockwise rotation, following the firing order: 1-5-3-6-2-4. There is a preferred position for #1 wire in the cap, traditionally around the 5:30 to 6-o'clock position on a CJ Jeep inline six. Without EFI and using a conventional HEI/DUI distributor like you're doing, you can select whatever cap position you want for #1 wire lead. Just make sure the rotor points to that position at TDC for #1 piston on the compression stroke. Allow enough room for distributor movement to fine tune the spark timing. Install spark leads following the 1-5-3-6-2-4 Jeep inline six firing order. Moses
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Well Moses I took your advice. I found a Cherokee Sport. It's a 2001 with little rust and 39,168 original miles on it. The information I have basically points to it last being registered in Vermont in 2007. Of course with every good thing comes a problem. I find a "barn find" in a manner of speaking, but I have yet to get it to start and run. I will post the pictures I took this evening after it got into my driveway. Yes, it was raining here this evening. To tell you what I'm thinking, I think it is a problem with ignition or the NPS. It turns over just fine, but there is no hint of firing. I've tried to start it in Park and Neutral without success. What do you think? $1500.00 was what I paid for it. The rust is at the very rear of the quarter panels and the drivers side rear wheel well, but I don't know just how extensive it is.
