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Topic: Exhaust port (Read 1149 times) previous topic - next topic

Exhaust port

I decided it not hurt to clean up my engine so I've been cleaning the ports out with my dremel. I'm not trying to polish them or trying for any horsepower, just cleaning up. Just for the heck of it I started to read up on porting on this forum. One person made the comment that the exhaust is where the porting is most needed. When I went to look at them, I noticed they have what looks like a housing for another small valve (??). It has a small hole in it, but for what? Looks like it's only purpose is to block the exhaust. What is it and does it have a purpose?  Thanks!

Exhaust port

Reply #1 –
It is the The thermactor bump or hump. It is for emissions recirculating a portion of the exhaust gas back into the intake stream to reburn, suposedly helping emissions. If you are this far into your heads you should remove the hump with your dremel while your at it. It does help as the heads flow very poor on the exhaust side anyways because of the Ford design, and the thermactor hump only makes matters worse. ( this is why most aftermarket cams have a split duration to keep the exhaust valve open longer to help exhaust flow ) If you got the time do it, you will gain some power. I would remove your valves though and keep the dremel away from that area and then blow everything out and clean it before reassembly.
1985 Turbo Coupe
1988 Thunderbird Sport
1996 F150

Exhaust port

Reply #2 –
I took "thermactor bump" and did some reading on the internet. My problem is even though my car is a 1986 cougar with a 5.0 engine, I still have to take it through emissions. From every thing I read, all seem to agree that taking them off is the thing to do. I'm wondering if this will hurt my emissions test? Some issues that I read said it is an emissions "pump". If it is pumping exhaust or sucking exhaust then grinding it may not make any difference (just guessing). Then again, there would be more exhaust being there will be less restriction. I did read one that said to just smooth out the part of the "bump" between it and the valve. It said to shape it like a bicycle helmet. Thanks!

Exhaust port

Reply #3 –
What I'm thinking of doing is cutting the "bump" at a 45 degree angle on the valve side. This would make it more aerodynamic and it would open up the whole to take in more exhaust gas. Hopefully balancing the ratio out, yet more flow. Any thoughts?

Exhaust port

Reply #4 –
This whole thing has me wondering. When I took the heads off, I found the air crossover tube to be plugged on both heads. So, no air was being pumped through my thermactor bumps into my exhaust ports. So, it was not adding O2 and fresh air and not burning up any exhaust fumes, yet my car always passed emissions. What the bumps were doing is restricting exhaust and nothing more. I have unplugged my air crossover tube and so now hopefully it will help me with my emissions test. Most of what I read was from the "Vintage Mustang Forum" so, what I was reading applies to my 5.0 engine. What I also read was that removing the "bumps" would not effect the workings of the thermactor air system. Only one way to find out if it will cause my car to fail emissions and I don't think it's worth the gamble.

Exhaust port

Reply #5 –
It is the The thermactor bump or hump. It is for emissions recirculating a portion of the exhaust gas back into the intake stream to reburn, suposedly helping emissions

Totally apples and oranges. The thermac system is not EGR. You have them confused. The air pump injects air in to the exhaust ports to reduce HC & CO. The EGR or Exhaust gas recirculation is for NOX. EGR is  introduced in to the intake manifold. NOT THE EXHAUST MANIFOLD. The exhaust is already THEIR!!!!!!!

Removing an air pump will sky rocket your emissions
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Exhaust port

Reply #6 –
Quote from: 86cougar;401287
What I'm thinking of doing is cutting the "bump" at a 45 degree angle on the valve side. This would make it more aerodynamic and it would open up the whole to take in more exhaust gas. Hopefully balancing the ratio out, yet more flow. Any thoughts?

Once again TOTALLY WRONG!!!

The both of you dont understand what is going on and or how these totally separate systems work!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Exhaust port

Reply #7 –
This is an EGR system i Fabricated for a 347 ENGINE i built for a mustang. Without it this car would not pass EMISSIONS. EGR has nothing to do with AIR systems.

I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!

Exhaust port

Reply #8 –
Maybe this will help. Chevy uses external air manifolds. As ford incorporated them internally in the heads. Also every AIR system incorporates a check valve to prevent exhaust back flow in to the system. I am giving you basics about the system. But the EGR and Air system are two completely different systems. If you want to trim those bumps as you call it??? Go for it. As any restriction in the exhaust is just that!!

http://www.camaros.org/emissions.shtml
I spend money I don't have, To build  cars I don't need, To impress people I don't know

HAVE YOU DRIVEN A FORD LATELY!!
 

Exhaust port

Reply #9 –
Tom,
      I "Thank You" once again! When I took the heads off, I noticed that the smog pump was inoperable due to clogged air tube and heads. I had previously removed my EGR valve and noticed it was stuck (open or closed?) and the crankcase vent element was clogged as well. So, in reality I have never had either one since I bought this car. This really makes me wonder how my car will perform at emissions. Those thermactor bumps are huge on my 6e30 heads, so I will be taking them out. Thanks!