Thanks for the info! I've never had to do a compression test before so this is very useful. What is the optimal PSI range for the cylinders? 110-120 PSI, 120-130 PSI? I'm not sure what could be causing my problems at this point. That's why it's been helpful to get on here and see what you guys have to say. Yeah, you couldn't PAY me to go back there to that shop. I would take it to the guy who did the actual motor rebuild, since he's been helpful and not associated with that shop anymore (he didn't even get paid for doing my rebuild from that shop).
Depends on a lot of things, especially your compression ratio. Should be at least those numbers but the important thing is the readings should be pretty consistent on a new rebuild. Not sure what the spec would be but if any cyl is 10% below the average that would be a concern to me. I'd be happy with a 5% variation. But, if they're all at least 80 PSI I wouldn't expect that to be the cause of your misfire. When you do the test, spin the engine thru a few compression strokes till you get the maximum reading. Takes about three compression strokes to max out my gauge. A remote starter switch similar to this [ame="http://www.amazon.com/gp/product/B000EVU8MK/ref=pd_lpo_k2_dp_sr_2?pf_rd_p=486539851&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B0009XQUKW&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=090DSGC4M2TJW6PJJKQS"]Amazon.com: Equus 3630 Remote Starter Switch: Automotive[/ame] will make the job easier. Also lets you crank the engine without the ignition being on and high voltage jumping around under the hood. Whoever sells the compression tester should also have the remote starter switch.
the occasional rough idle problem you describe sounds like the carb float level may be too high. this can cause fuel to slowly dribble out the veturi boosters when there is supposed to be no fuel flowing from them when at idle. ive been able to look down a carb with this problem and see the drops falling off the venturi in go into the motor in time with the stumble it would cause in the idle speed.
I couldn't see anything before when I looked, but it was getting a little dim out. I'll look again when I have some better light and see if that's happening. Would this have any effect on cylinder #8 in particular?
it may. i would doubt it but i could see how it could in the perfect storm of circumstances. i still feel that you are getting oil into the cylinder that is fouling the plug.
Looked again at the carb with some good light and couldn't see any carb dripping. I DID notice that my voltage is going all over the place between 14V -16V while driving. At around 60mph or so, it looks like a clock ticking between those voltages. Could a bad voltage regulator be my culprit?
Ok, I replaced my voltage regulator since it was causing some erratic voltage changes....I still have my misfire though but hopefully saved some of my electronics and battery. I pulled all the plugs on the driver side and cylinder #8 now isn't black with the grainy/sooty deposits on it...it is now white, as are cylinders 5, 6 and 7. They are all about the same whiteness and texture. They all fall somewhere between the arrows shown in my attached picture. What could cause this? Imbalance between the two idle mixture screws? Blown head gasket? Vacuum leak? They all appear like they are running lean, but only on the driver side. The passenger side plugs are all beautiful. What do you think? It would sure be nice if this was something stupid and easy to fix.
Just by reading the causes on the plug chart it looks like maybe a gap issue.. Where do you get your fuel? I go tothe same location where they only have 100% fuel (no ethenol).
Right now I have all my plugs gapped at 0.035". I usually get my fuel at a local QT so there's no telling the quality of the gas and I'm not sure if they use ethenol or not. If it was the fuel, wouldn't all the plugs look this way, not just the driver side?
