hey guys......... I've been tuning my 455 with no success for the past two days. I'm not good. Anyways, as i am adjusting the idle needles (750 holley dp) and the float levels, I get this ticking/tapping sound that can get very audible and noticeable. It's definitelly an internal engine sound that goes to the pace of my timing light. Is this simply a bad gas/air ratio, or is one of the lifters going south? The lifters are new, and I haven't even gotten the car on the road yet. I pulled the number one spark plug wire out, zapped myself *ouch!*, and it stopped, but it does reappear every so often when I'm monkeying around with the carb. what causes this sound? I'm sure it's the mixture in the cylinders, but some guy claims that it could be a lifter going to sh_t. *groan* I hope not! any opinions? o No: Thanks ~Mark
Too lean an idle mixture would be my first thought, since that's what you're working on, but of course since I can't hear it for myself, it could be any number of unrelated things...Although if it stopped when you pulled the wire, that should be a telling sign. I had two or three things happen that might be related, once upon a time: One of the snorkels on my air cleaner wore away a pulg wire, somehow, and that wire was discharging partly through the aircleaner. I heard a faint tapping type of noise I had a very small leak in an exhaust manifold gasket that I could have sworn was coming from deep in the engine, one time, but it was just an exhaust leak. Depending on how hot or cold the engine was, it changed volume. I had a rocker shaft arm bolt come partly loose. This one seemed really bad. No matter what i did, I had this tapping noise intermittently. I pulled the valve cover off to begine pulling the head, and the first thing I was going to do was remove the rocker shaft. Well, the first bolt I put a wrench on wasn't tightened all the way to begin with! The slop it had was enough to cause clatter. who's this "some guy", by the way?
well, he's my neighbor's friend, who is a mechanic by trade. He's good with cars, but he isn't God, so therefore he doesn't have to be correct. I figure it's gotta be a bad mixture, simply because I never heard this sound before until I started monkeying around with the carb. I hope I'm right. Thanks for the input though. oh yeah, another question. What's your experience with newly gasketed heads and intake manifold? Do the bolts get loose after a while, since the gaskets were new? I'm always told this about oil pan or water pump bolts.
OMG Thank you Chris and Mark for the posts in this thread, and to you Mark for leading me to it! I was so upset at the 70GS that I haven't touched it in days. After reading this thread I went out and raised the float levels, and "riched" the idle mixture, and the knocking went away!! I was so sure that the engine was ready to explode, I had given up on it for the summer. Now I wish I would have read this a few days ago. I could have taken the 70 to Norwalk today along with the 2 cars we did take. ou: Anyways.... Now it's running pretty good again, but idling very rich (in my opinion). A friend stopped by while I was tinkering with it, and he said he didn't think it was too awfully rich. Maybe a little on the rich side, but not too bad. I think I'll just leave it like it is and drive it to work for a few days and see how dependable it's going to be. :beer
Rick Glad to hear! :beer Can you do me a favor? When you feel that your car is tuned, can you let me know what your vacuum gauge reads at idle? I was trying to get my carb tuned but ran out of sunlight. 3 broken bulbs later and I said "saturday!". I have to say it scared the crap outa me to hear that sound. I have been trying to get this car together and on the street this summer, and couldn't imagine having to take it apart! Then the "mechanic" says, "eh. sounds like a lifter."
Here is a thought.. Take a spray bottle, and with the engine running, spray the entire length of the spark plug wires with a light mist. I am willing to bet that considering you have been "zapped" by a plug wire, that under load, the wires are finding a way to ground, other than thru the spark plugs. You should be able to spray the ignition system until is is pretty wet, before it affects the way the engine runs. Give that a try, and see what happens. JW
