Let's discuss knocking. I have a 68 350-2 engine with a Poston intake, Hooker headers, 800cfm q-jet, and I swapped the points dist. for an HEI. Other than that, it's stock. According to TA performance, this engine has a compression ratio of 9.0:1 which would indicate I can use 87 octane without knocking. BTW: I know there's something wrong with the distributor because I set initial timing at 10* and it only advances to 16*. This test is done with the vacuum disconnected and the port plugged. I had the initial set higher but backed it down to 10* to resolve knocking noise. It didn't help. I hear the knocking when I am at a dead stop and push on the gas to go. I don't even have to push that hard to hear the knocking. It's kind of annoying. Any troubleshooting tips? MARK
Hmmm, how can I describe what it sounds like? I think of a ping as a higher pitch noise. This sounds like someone tapping their knuckles real fast on a door.o No: Would that be a ping or knock? Oh, yes. I'm running 87. MARK
Does it knock at idle and off idle then disaper at higher rpm if so, with my own experance it could be a rod maybe at low speeds oil pump is not oilling properly, and as it speeds up it oils better. Any time ive ever heard pinging was at wide open throttle or pulling a hill at part thottle. I would think that if it was advaced to much at idle it would not run at all or at least smooth. i hope this helps a little i dont want to say its a rod or main because i cant hear it. Does it sound hollow. deep knocking does car take gas good josh
Hmmmmmmmm, sounds like a rod or main bearing. Usually mains will thump at idle, and you'll notice a big drop in idle oil pressure. To tell if its a rod bearing, rev the motor, and as its comming back to idle, a bad rod bearing will knock, thats from the rod becoming suddenly "unloaded" as the motor comes back down to idle, this allows the rod to jump around on the rod journal on the crank. I know this isnt very scientific, but these are based on my own experiances with my 350. Hope this helps some, Mark
Come to think worn berings would help cause low oil pressure because there would be so much more clearence. I beleave ive read another thread where youve been having trouble with oil light and oil gauge going to zero after hot but lets still hope for the best Josh
Ok fellas, I'm with Shark. I've got an engine with less than 15K miles on it so I am going with the assumption (??) that the internals are all good. I have similar symptoms, though. The engine is basically stock with a TA performance RV12 cam. It idles fine but either pings or knocks at partial throttle (just off idle to just shy of the secondaries). Let's just say it sounds like your typical John Deere diesel! My initial timing is 12 degrees BTDC, with total at 28 (I think, it's been awhile since I checked), and my dwell at 30. All as advertised optimum for this cam. Couple thoughts here: the dieseling doesn't happen until about 5-10 minutes after start-up and gets worse with heat. As I noted earlier, if I stick my foot into the secondaries, the noise stops. I've wondered about two things...Does the car run too lean and possibly need more fuel at part throttle?..OR is my timing advance coming in too fast? If so, do I need stronger or weaker springs/weights in the distributer? I'm not very mechanically inclined so any thoughts would be appreciated! Thanks
Well from the descriptions I'm reading, I don't think it's a main or rods knocking after throttling down. I don't hear anything at idle and it runs real smooth at higher speeds. The only time I ever hear it is when I step on the gas from a dead stop. I did notice when I swapped my timing cover this weekend, that my distributor has some play in it. I can move the module? up and down about an 1/8" or more. I'm not sure if that's called the module, it's the white thing that spins around. Is it suppose to move? I'll put some good gas in it and see if it helps. MARK
I think you're talking about the rotor. The module is underneath it attached to the distributer body (if its an HEI). Points distributers don't have a module, but do have rotors. All the distributers I've had moved up and down a little, but I don't know about an 1/8". Sounds like a lot to me.
Yeah, it's an HEI and it's the rotor that I'm pulling on. I noticed when I pulled the one out of my V6 it barely moved at all. MARK
Mr. Goof, I was getting those symptoms when my choke was set too rich causing it to stick shut. You might check that.o No: For everyone else helping me out on this, get your pencils out! The answer was discovered last night when I made several start/stops on my way home from work. I finally pulled over in to an empty parking lot, set the emergency brake, put the car in drive, opened the hood, and revved the car by pushing the throttle linkage on the carb. I didn't hear a single noise. I sat in the car again with the hood up, took the emergency brake off and held the brake down and revved the car. No noise. I finally revved it again pushing the brake until the tires started spinning. No noise. Now completely confused, I looked under the hood again but stood in front of the car this time. When I leaned my gut on the fan shroud and revved the car a few times the noise came back!!! So do you know the answer... It's the freaking fargon foopa fan shroud! The engine twists under load and the fan hits the fan shroud when the hood is shut putting pressure on it. When I put the 350 in the Regal, I did the "cut the fan shroud back 3 inches" short cut. I also bent the fan blades down a little for clearance. I guess not enough! Did you write it down or are you laughing too hard? MARK
........hits the fan I'm laughing!:grin: Lots and lots of wrenching for just.......... This rely turned out to be a "when the **** hits the fan" story Sorry for the bad language, but I just cant help my self. Actually Im happy for you!:beer from here, start advance the timing and you soon bee flying away! There is just the lack of mecanical timing advance, non working vacuum advance and to get the oil warning light to work properly left.. The crane ign, advance kit i bought, also included the avcuum "canister" thing, just a litle hint. Lars :TU:
Too much distributor end play will cause problems, you can pull your distributor, take off the gear (knock the pin out), add shims. I've bought some old ones from the Chevrolet dealer or you can find washers that will work if your careful. BTW, I had a 9:1 Buick 350 and added a 4bbl intake, it wanted to ping unless I used mid-grade gas or better. A cooler thermostat will help as will blocking up the heat risers. The 350 has an open combustion chamber, in my opinion it contributes to spark knock. Also if your heads are carboned up on the inside, you will have to use a better grade fuel.
