knocking noise, have idea but need opinions
 

Ok Ive had this knocking noise for a while now. I think I have it pin pointed, but Im not sure. With my ramhorn manifolds and 2.5" exaust tubes, the tubes come extremly close to the cross memeber/frame up front. I believe the knocking is the tube on one side hitting the frame. I came to this conclusion because it only happens when at a stop or slowing down. If I hit the gas, it goes away. I think when I hit the gas it torques the engine over and either puts the tube in constant contact or it moves to too far away to make contact. Also if Im at a stop or slowing down and give it a little gas the knocking will go away.

The other possability Im thinking is a bent flexplate/starter or somthing along those lines. The knocking only happens after the truck has warmed up a bit. Could be from the tubes expanding, or a flexplate. What do you guys think?

Damned if I know. :)

I guess you seen my post on my popping noise. Stuff like this drives me insane. :eek:

Does it sound like metal hitting metal? Is it loud and clean or does it sound incased? Is the exhuast making any marks on the cross member? Have you tried running over speedbumps to see how it acts then? How close is this pipe to the crossmember?

Tom, check for rocks jammed in small crevices (between crossmember and trans mount, etc) my buddy's Firebird had a rock stuck between the trans and the floorboard. dont ask how it got there, but sitting at a stoplight it would make a hell of a noise. replaced a bunch of parts before we got to poking around on the car one day, and saw it. not thinking, we removed it, and the noise was gone.

Well I dropped my truck to have the exaust re-welded so I can bolt down the tranny cross member and my exaust guy said he thought it sounded like the flywheel. Hes going to grind some clearnece into the cross members/frames where the tubes come close to se if it helps, if not the somehow my flywheel got bent and will need replacing. I just had the dam tranny out, and now its finally ready to drive I have to pull it again! :(

Tom , this is OT to your post but I can tell you are up on stick shifts so a question . On the middle to late 70'S short beds chevys what is an easy swap to replace a 3 speed stick , using the same drive shaft on a low displacement engine ? Will a camero t-5 drop right in ? This truck is not worth spending a lot of money on some thing like a munice.

Well, Im not sure as to what trannys have the same length as your currect one but:

a used T5 will run you about, what, $300? A rebuilt munice can be found for $400. While a T5 will also have the overdrive, its a weak tranny. If you get one out of a camaro, the shifter will be tilted to the side slightly.