Figured I might as well post a small update...
As you may know if you keep up with the misc thread, I nearly had an engine fire a couple days ago. 2nd gen RX7s (and most EFI vehicles, actually) have a device on the end of the fuel rail, called a Pulsation Damper, that uses an internal diaphragm to smooth out the flow of fuel throught the rail. It's is fairly common on Series 4 ('86-'88) FCs for this diaphragm to tear and allow fuel to drip out and onto the motor, often resulting in catastrophic engine fires (check your PD, kids!!)
So I'm just minding my own business a couple days ago, trying to figure out why the eff my idle still surges (I eventually figured out I had a vacuum leak from the throttle body gasket, new one on the way from Mazdatrix right now) and to give the exhaust I finally installed a good listen and a leak test (I think I have one at the Y-pipe too
) So I'm ricing out in the garage video taping the mad tyte flames that a catless rotary allows when I suddenly see smoke billowing out from the engine bay. I'm like "SHEEEIT!!" as I kill it and jump out. I took a look under the hood and saw this smoke/steam coming out from under the intake manifold. I immediately suspected the PD and sure enough, that shit was leaking when I checked it out the next day.
Rather than spending $150 on a new failtacular PD, I decided to tkae the high road and buy a $10 banjo bolt to totally eliminate the whole thing. This is a highly debated method, some arguing that the lack of smoothness in the fuel rail could cause the A/F ratio to lean out unexpectedly. That said, that really on matters on turbo cars and I doubt it will hurt much on a stock n/a. So now I have to pull off all the intakes to get to the primary fuel rail.
My +5 hp andonized blue banjo bolt (Summit had it to me in 2 days!
While I have all the intake stuff off I decided I'd do the throttle body mod as well. The throttle body mod consists of getting rid of the thermowax, which opens and closes a second set of throttle plates under cold conditions. I also lightly ported the throttle body while I was in there. I didn't go too crazy with it (since it doesn't do much for an n/a anyway) but it gave me something to do in the downtime.
Here's all the junk that comes out/off of the TB after the TB mod
Getting the second set of throttle plates out was a major bitch, since the screws holding the plates in completely stripped immediately.
Drilling out screws FTL
Here's the TB after all was said and done. I still need to smooth out the walls a little after the porting and clean it out.
I kept the dashpot (bulky thing on the lower left side) This slows down the closing of the throttle plates if the driver quickly lets off the gas pedal. I've heard elimination of the dashpot can cause stalling in those conditions (panic braking, ROC shifts, etc.)
I need to go out and finish tearing down the intake and fuel rails tomorrow and continue waiting for my TB gasket (should be here Monday or Tuesday)
Oh yeah, here's dramatic footage of the near-fire:http://www.youtube.com/watch?v=Mi0K0wZ6fUI
1986 Mazda RX-7 sport ^ blown engine
1986 Mazda RX-7 base > Project car