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Discussion in '1970 - 1973 Specific' started by john Gialanella, Mar 21, 2020.
I'm in the exhaust category
In my younger days (mid 70s) that’s all we had!
I use Bosch Platinum +4 spark plugs, I can feel the difference. Tried NGK Platinums and Iridiums but my SBC 350 runs best with the +4s.
I took the SS 396 out today for 20 mile run. When it started to make noise I gave it gas and it went away, same as when I put it in neutral. I checked under the car from the side and the two mufflers had about a 1/2 inch clearance from the floor pan. In warmer weather I will go under the Camaro (I am getting to old for that) and see if a hanger is broken. Camaro has headers on it (I have the correct BB exhaust manifolds) I will check to make sure the bolts are all tight. As for the torque converter wouldn't it also cause vibration when I am on the Highway. I have no vibration on highway.
I think some part of the exhaust system is hitting resonance like I was saying in an earlier post.
Is this something new? Could be a hanger is broken, so the stiffness of the system changed and now the resonant frequency of the system is in band with with the engine at that rpm.
I had a 76 type LT with a 350 and I had a vibration that drove me nuts, come to find out it was one of the exhaust pipe hangers. Just give a little tug on all exhaust components and see if anything is not secured.
You mentioned in post #24 about checking under the car and having a half inch clearance in neutral you really probably need to pit the car on 4 jack stands and put car into gear and see if the exhaust system shifts just enough to cause the rubbing vibration. Could be a worn motor mount shifting the engine just enough to cause what you are feeling.
John in post one from what I understand you shift to park and the vibration goes away. That’s telling me the fluid pressure on the vanes changed , causing the vibration to stop. Same when on rolling along under light load you are getting the vibration, then load up the pressure it goes away , From post 24 it seams to be more of a noise than a vibration . Somebody else must be an trans guy that would know better. It just sounds like torque shudder to me .
In warmer weather I will check hangers on mufflers. Also I have been meaning to take Camaro to Transmission place to replace trans fluid. I can ask about Torque converter. But I am concerned that guy can say that that is what it is (when it is not) to make money. I will search on internet for problems caused with bad torque converter.