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<x-charset iso-8859-1>> Y'know, it's always something. > My car is running poorly. Doesn't want to hold idle, bucks and pops at all > RPM ranges, painfully slow. Check the fuel pressure to make sure it isn't running lean (possibly the reason it's backfiring through the intake). This could also cause bucking or surging. It sounds like there may be a problem in the idle circuit of your fuel system, or there your carbs may not be accelerating at the same rate. (you do have carbs right? if not maybe one of the other FI specialists in the group can help). > Fiddling with idle, mixture, advance, retard produces no desireable effect. > Valves, gap, dwell all within spec. Plugs firing correctly. > Compression on #2,3,4 all bteween 100-105. #1 down around 90lb.... > #1 plug is a little dark, but NOT completely fouled. No blue smoke, so this > pretty much eliminates pistons, rings, cylinder walls - right? Your compression isn't too far off (10# is acceptable) in number 1, but to be sure have you run a wet compression test as well? To determine if the problem is in the cylinders or in the heads, squirt some oil down the cylinders and re-record the results. Remember to make sure all the plugs are out in all four cylinders before running the compression test, and turn the engine over at least 3 or 4 revolutions per cylinder - otherwise your readings may be inaccurate. If a wet test doesn't make a substantial difference in the compression, there could be a head problem, but don't just assume so. > Fire - yes, actual bursts of flame - occasionally issuing from both exhaust > pipe and carburetor. Which means it ain't just one stuck lifter, flattened > lobe, or mangled pushrod, right? If you can isolate one problem at a time, you may find several smaller problems causing multiple symptoms. Usually you won't get misfiring through both the intake and the exhuast unless multiple problems are present. Perform a power-balance test to see if #1 makes any noticeable change in the RPMs. : Power-Balance Test This test provides a good indication of how much each cylinder contributes to the overall power output of the engine. In addition, it also isolates which cylinders contribute little to manifold vacuum. You can perform a power-balance test at home on any air-cooled engine except those with electronic ignition. To perform a power-balance test, a.. Remove all the spark plug leads from the spark plugs. b.. Set the leads lightly back on the tops of the spark plugs. c.. This will enable the lifting of each lead off its plug without using too much force. d.. The procedure is to pull the lead away from the plug and ground the lead against the cylinder head. This will prevent that plug from firing - this is called open-firing. e.. The engine will now be running on only three cylinders. f.. By comparing how the rpm drops for each cylinder as it is disabled g.. If a cylinder is faulty, then as it is disabled it will have little if no effect on the engines rpm, as it will not be contributing fully to the overall engine power. h.. If there is a suspected burned valve or other major problem, a quick, ear-calibrated power- balance test will indicate which cylinder it is. i.. Because VWs have only four cylinders, a faulty one will show up relatively quickly. However, if you are looking for a more subtle problem, use a Tach Dwell Meter or Tachometer to measure the exact rpm drop for each cylinder. > So, what are my best & worst-case scenarios here? What have I overlooked? > What else to check before I assume a cracked head, pull it and get new? Exhaust as many possible tests on the engine in the car before you pull the engine and/or a head. Otherwise, it will be more difficult to isolate the problems. Jason 68 Notch (Nadine) I proudly buy my aircooled parts and service from... The Bug Stop in Arlington (DFW), Texas www.texasbugstop.com ------------------------------------------------------------------- Search old messages on the Web! Visit http://www.vwtype3.org/list/ </x-charset>