I replaced my harmonic balancer here recently (due to the previous one becoming a flying frisbee) and since then it has started shaking at low rpms. At idle the shakes are very minute, but at around 1200-1500 rpm the engine feels like a jackhammer was put in its place. The fuel gauge on the engine bounces between 5-7 psi, and it sounds like it has developed a misfire. I've replaced the spark plugs and the wires, and the problem still prevails. Was wondering if anyone has had any similar issues, or any tips on what to look for. TIA

 

Carb ? Tbi ?

 

Edelbrock 4BBL (AVS2)

 

Sounds like the wrong harmonic balancer.

 

Didn't we just have another one of those recently?

Oh, yeah:

https://www.thirdgen.org/forums/tech...r-humming.html

 

What would be the right part number outside of Dorman? I can only find their parts when looking for the harmonic balancer

 

Look on RockAuto, summit or jegs. The balancer mark must match the pointer location.

 

What engine do you have? Does the new balancer look IDENTICAL to the old one?

 

It doesn't. The previous one had almost a "Channel" machined out of it going around the exterior. Its hard to explain, but I'll try to post photos tomorrow.

 

Disregard. I have come to realize the engine is a 400 SBC and not a 305. Thank you all for the help and advice!

 

https://www.jegs.com/i/Proform/778/66513/10002/-1

I bought this recently for my 400 seems to be good quality

 

Yep, the 400 takes a different HB then the others, it is externally balanced. It takes a different flex plate too.