Roadrunner1

Hi all

I have a 1970 roadrunner with a 440. Recently it has developed an exhaust blow from what I think is the exhaust manifold. I have changed the manifold gasket and resealed the manifold bolts but it is still blowing. To be honest it sounds like a top end engine knock but engine runs strong with no problems. I have been assured that it is an exhaust manifold problem but I don't seem to be able to get rid of it. I don't really want to remove the headers again unless I have to due to the water from the headers bolts etc Any ideas ?

RacerHog

You try the Ultra Seal header gaskets?
Also Make sure the headers did not get bent. If they are. You are going to play hell to getting them to seal..
Also Make sure the motor mounts are in great shape.. If they sag to much, the header can hit other components and not allow you to get the header butted up to the head properly...

https://www.summitracing.com/parts/mrg-5936/overview/

Keep us posted...

Archer

RR! -

If you're sure it's the header gaskets, get a set of Remflex gaskets and be done with it. The can compress almost 1/8" and will contour themselves to any flange deformity. If the header is cracked, you'll have to replace it.

Archer

matt1967

check to see if the header is cracked.. it was on the last set i got for my 440. made the same noise that you're describing.

Iowan

Just for kicks and giggles make sure you don't have a loose spark plug, I've had it happen.

Roadrunner1

Thanks chaps I will try all your suggestions and will keep you informed

MoparNoCar

+1 for cracked runner in the header.

Quite common.