Hi All, All of a sudden my car starts missing, so I replaced the plugs and it seems ok. Does anyone see anything wrong with these plugs?? They were wet and very dark except one. Your thought please. Its a pump gas 462 with a mild cam. Carb built by SMI I
The ground strap should be parallel to the center electrode. Those look like extended reach plugs and are usually gapped at .055-.060. with MSD or HEI ignition like these...
2x on rich. Did you check the gaps? One doesn't appear to be firing... Check the wire on that one, or the ceramics. I've cracked many a plug ceramic and spent weeks trying to figure out the engine problem.
You should change oil and filter. Looks like it has been loading with raw fuel (with the deposits) and that will dilute oil and cause rapid breakdown of oil's ability to function with bearings. If it takes time to sort out the over rich condition, after you sort it out, change the oil and filter again. $100 in oil and filters is better than thousands on rebuild.
Someone else recently posted this on here: https://www.dragstuff.com/techarticles/how-to-read-plugs.html
More questions, the oil does seem to get dirty quickly, a dark brown. Also if the car sits a couple days there is no gas left in the carb. To start the car it requires cranking and pumping the accelerator. If the car sits a few hours most times when started it will puff a blue grey smoke when you start it. Last when sitting it smells of raw gas. I think I have a carb issue but I am not an engine tuning expert. Your help is appreciated. Jim
I hate to harp on the oil, but with a float bowl draining that fast, you are adding a great deal of fuel to the oil, and one of the things that can lead to is cylinder washdown of oil film and "dry start", rapid wear on walls/rings. That can explain the puff of blue smoke. Diluted or oil that is broken down from fuel can also lead to rapid wear of valve guides, and also the blue smoke on start. Back when I was a younger monkey, seeing "blue haired ladies driving blue aired cars" was the norm. And cars hitting 100k miles was almost like hitting the lottery.
Make sure the power piston is held down with engine vacuum. With the engine off, you can stick a thin screwdriver down the vent and push the power piston down, then let go and it should spring up. If the piston is stuck in the up position, the rods will be out of the jets. The only other thing is extreme nozzle drip at idle. The engine is running excessively rich, you need to fix that.
Larry, you are over my head already, but I can catch up. I have a book by Doug Roe on Rochester Carbs. I am reading about the power piston tonight and will try to move it tomorrow and post the results. The plugs have around 1,000 miles as does the engine and the carb. It has a stage 1 fuel pump. The engine was built by Mike Phillips I will change the oil and filter also as I do not want to wipe bearings Just guessing the only way to check the float adjustment is to open the carb up and manually check it setting?? Thanks for your patience and help
Yes a SMI rebuilt. the engine is all iron Stage 1 462 with a TA 284-88H cam. The carb is a SMI Stage 2 QJet jet is 77, rod 46K sec AU
when my car started fouling plugs, I didn't realize it until I took the air filter off and looked at the carb when the engine was running, fuel was pouring into the carb because an o ring had hardened up and wasn't sealing. I was running a quick fuel at the time.
Heads are not ported, just Stage 1. Yes on the headers, TA shorty. The compression ratio is 9.8 to 1 it was built to run on 93 pump gas. the combustion chamber is 68cc, the deck height is .020, the dome volume is -23cc and the gasket is 4.380 (gasket doesn't sound right, typo I think) I have never had a QJet apart can I change the rods and jets out? I do have an extensive mechanical background. I live in rural central Illinois and there are no carb people around here any more. Thanks Jim
