what are those things?

[tc1959]

If cutting down these fittings is good, then wouldn't eliminating them be better?

Pretty much. I cut mine down, then just decided to eliminate em completely one day. Made no noticable difference with them removed compared to cut down, but it certainly seemed like it would be better and you don't have to worry about them coming loose. Now with my EGR removed, I have them plugged up with allen headed pipe plugs.

The real question of course is why in the hell did Oldsmobile put them there to begin with?

to reburn exahust to reduce NOX emmisions also to reduce pinging.

 

[Bonnewagon]

EGR is there to reduce the total combustion temperature, nothing more. At high combustion temps Oxides of Nitrogen are formed, a major component of air pollution. By recirculating inert gas (exhaust) into the incoming air/fuel mixture NOX is defeated. The reason you get pinging when the EGR is malfunctioning or disabled is because to regain some of the lost power, the factory added loads of timing advance. Since the prm range NOX is formed is from off-idle through part throttle, that is when it is introduced.

 

[hankthecrank]

You know, I think it's weird that I've never come across these ports being mentioned anywhere when looking for people building up 307's (except one guy on his website who mentioned the deep crosshatch bump/pattern at the bottom of the plenum). I started this post up just out of curiousity, and now look what I learned. I'm rebuilding my carb to get my 307 driveable. In the meantime, I'm prepping a 403 longblock to take the 307s place, so I'll be posting lots of questions.

 

[DoubleV]

I wasn't asking why the EGR system was in place, I was asking why those stupid tubes were installed. I can't see any advantage those tubes offer over the old proven method of just having 2 holes.

 

[FE3X CLONE]

My guess is that they were trying to get the exhaust gas released higher so that it had time to mix with the incoming air/fuel mix before entering the cylinders.

 

[tc1959]

My guess is that they were trying to get the exhaust gas released higher so that it had time to mix with the incoming air/fuel mix before entering the cylinders.

You got it.

 

[DoubleV]

My guess is that they were trying to get the exhaust gas released higher so that it had time to mix with the incoming air/fuel mix before entering the cylinders.

That would be my guess too ( even though I really don't know why it would effect anything ) but there was a guy on Oldspower a while back who actually tested his car at the E-check place with and without the tubes. Car ran much cleaner without the tubes. :shock: