I just installed my rb streetable header and presilencer today and holy ****. As soon as i started it I shut it back off. I have NEVER EVER heard anything that loud before! I put in some ear plugs and started it back up. The car (81 gsl) runs like **** (misses half the time) and most of the noise seems to come from the engine compartment. Now what comes out of the muffler is only slightly louder than stock and has a good tone to it. I don't think that there are any leaks in the new exhaust. I believe what is making all the noise is the plate that blocks off the acv hole. Has this happened to anyone??
Dennis

 

Sounds to me like you have a leak at the engine/header gasket. You did replace all the old gaskets with new ones riiiiiight?

Another thing... what kind of muffler are you using? My setup was pretty loud with a rb presilencer and crappy muffler.

 

all og the old gaskets where in good shape. I did reuse the header to engine gasket. The sond coming from the muffler is fine. the noise coming from the engine bay sucks, gave me a headache WITH ear plugs in.

 

Always use new gaskets...The old gaskets will never seal correctly and will release gases and of course, noise...

Denny, from the 'ol corncrib...

 

And get some copper hi-temp silicone sealent.

To check for a leak between the header and silencers, stick your hand below and around (not too close) to that joint... The fisrt time I put the RB system on, it leaked there and I fixed it with some silicone and tightened the bolts tighter...

 

If your ACV is leaking that should not account for the noise. But get it fixed! I had a backfire that took out my water seal when I had a bad/leaky ACV plate.

Good Luck

 

heres a question. is your motor a 80 or 79?

the earlier motors had extra little ports coming out the bottom of the exhaust port and out of the housing right above the oil pan for the thermal reactor. these must be plugged or covered up or exhaust will spew out of them, accounting for the noise. I do no think the RB header will cover these holes completely.
You can use a later model gasket to cover the holes but I do not know how well this works. I plugged these ports up and used a leter exhaust gasket when I put the 83 manifold on my 80.

Hope this helps

 

RB will sell you "special" plugs for those...

 

It will be quite a bit louder, but not deafing loud. You might have an exhaust leak at the motor to header flange

 

make sure that you bolts are all tightened down.

the only time that my engine was loud was when i was running it without any exhaust... but good luck. once you get everything running right, you will love that exhaust