I am installing a racing beat header on a stock 12a. After removing the exhaust manifold, at the exhaust ports inside the aluminum rotor housings it looks like steel inserts. Do you remove these steel inserts prior to installing the header?

 

Not clear on what you're taking about?

 

No, they stay

 

You can't get them out anyway. Even when the engine is all apart they can be a little tough to remove.

 

Once you remove the stock exhaust manifold. If you look at the exhaust ports there is a steel insert in the rotor housing My question was do you remove this prior to installing the header?

 

No, those stay inside. Replace the exhaust gasket if it looks shady.

 

i think they are to help tone down exhaust noise cant rember maybe that was the t2 housings

 

2nd gen NA housings have diffusers in the exhaust sleeves to tone down the noise. Reason being both 2nd gen exhaust systems, whether NA or turbo, are about the same. We all know how much a turbo can quiet the powerful exhaust of a rotary, so what was to be done about the untamed NA exhaust? Add diffusers of course!

Another function of any exhaust sleeve, from '76 to '02, is to expand quickly right out of the port. This quiets the exhaust pretty dramatically as well. The earlier sleeves were smaller and expanded less, and if ported, end up louder than '76+ with the exact same port timing.

I just experienced this first hand the other day when I got my '74 REPU running on a vintage '74 engine with a port job. Let's just say the exhaust system was incomplete at best, and totally inadequate at worst. The funny thing is the same muffler was used in the GLC with a '76+ engine under similar circumstances and the total exhaust noise/volume level was substantially less. Port timing was similar. The only difference was the GLC had a cast iron manifold while the REPU had a header. A header can make things louder, so maybe it's a combination of things.