70 roadrunner knock noise when driving ?

[70phoenix]

I'm working on a 70 roadrunner, 440 727 automatic, 8 3/4 rear.  I'm just getting the car back together.  I just went and drove it down the street and at in town speeds it has a aggressive knocking noise.  When I slow down 5 mph or less it goes away.  I can put it in park and rev it up and it doesn't make the noise. So it shouldn't be in the motor.  It has new u joints and I just went through the rearend. The transmission seems to be working normal as well.  Any ideas ?

[cudaken]

First thing I would check is bell housing and flex plate bolts. Around 30 years ago my 68 Road Runner started knocking and I thought it was a rod. While I was pulling the motor, I found the bell housing bolts had backed out. Tighten everything back up, knock was gone.

I still have the Road Runner I will add.

     Cuda Ken

[firefighter3931]

As Ken mentioned ; the converter bolts could be loose. When thry back off a bit the noise is nasty as the bolts hit the block. 

If they are loose i would retighten and add some loctite to the threads. 


Ron

[70phoenix]

thanks for the help

[cudaken]

Was it the problem? 

[SRT-440]

I agree with the converter bolts...I too have a 70 RR and had the wrong sized bolts. Changed them and prob was gone.

[1974dodgecharger]

Are you in Phoenix?

Mine knocks on cold mornings then warms up its gone, I'm thinking piston slap.