By polishing up the inners of my upper intake and runners on my 305 tpi? In other words is it worth the time? The only things done to the car so far is hooker 2055' 3 in y pipe and smog/cat delete. I do plan on a bigger cam, and a better rear. The 2:77 rear has got to go. lol. Right now the car is running good, timing at 6*BTDC. I do need to get a set of header style plug wires, and better plugs. I don't like how the rapid fires are performing.

 

to be honest in a 305 i dont think so. porting out the EGR walls by the TB might be ok, but even with that dont expect much more than some better throtle responce.

 

Polishing? Probably not. Removing EGR walls and siamesing the plenum to the runners? Maybe. It's one of those jobs that I would hold off on until you have to take off the intake for a reason.

 

That's what I have thought. I don't think I'm gonna bother then. K&N's will be next then.

 

well at this point the biggest bottleneck in your engine is the stock cam. You can port until your heart's content and you will still not notice much becaue the cam wont allow the engine to draw the extra air in. Get rid of your crappy cam and maybe do something with the heads and you'll be happy with the gain. see the sig.

 

where did you get a lingenfelter motor from

 

yeah you can see all my mods I did to my 305, it runs pretty good.

 

What did your car put down power wise tenpin842?

 

ok. im looking into the smog pump delete, and i was wondering what the EGR walls are. second what is siamensing the plenum? would taht be helpful in my 350?

 

3rd° Tech Tips~Porting the Plenum

 

The EGR walls are the walls located right behind where hte throttle body sits. There is one on the bottom of each inlet hole.

Siamesing is when you basically blend two runner inlets together so that they form one figure 8 shaped (without the middle part) hole.

 

siamensing the plenum seems like a lot of work, and a high risk for the gain. anyone out there have any dyno runs to prove if its worth it?

 

Dave, most people will tell you that porting the plenum is useless and/or a waste of time, but in all reality you are making the incoming air direct itself towards the runners faster and smoother so I don't see why not? It's a free mod so I'd do it if I had the choice.

When I ported my plenum it literally took about 20mins for each side. Carbide bit and a dremel is all you need. Along with a few sanding discs to smooth it all out. To me, it's worth the time. I need to get cracking on my base to match my new AS&M runners now...

Oh and I don't have any real dyno proof if it effects anything, it's more piece of mind really.

 

yea.. thats helpful, someone said before that you should jsut do it when your plenum is off, so i think i might do that when i take my smog **** out. oh about that, i was reading the tech article on this, but it erally does not give me any info about it. for those of you who have done it, and tips on what i should look for?

 

I kept my EGR in place but I removed the smog pump and all the tubing that went with it. My car being an '87, I didn't need to get a smog pump delete pulley.