KW87GTA

I was taking of my runners from the plenum, while installing a new superram which is a major pain btw. And I noticed that all of the runner tubes had a large amount of carbon buildup in them, except the 1st one. It was almost totally clean. I found this to be a little odd. Does anyone have any idea if this indicates a problem somewhere else?? Thanks.

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87 GTA 350 L98
K&N filter, beefed up TH-700r4, Accel Manifold, Ported Plenum and Runners, Fuel Press. Regulator 49.5psi, air foil, modified MAF, SLP cold air box, Hypertech Thermomaster chip w/160 thermostat, MSD 6AL and Blaster 3, B&M shift kit & megashifter, Moser Ford 9in Rear with Richmond 3.50 and locker, Edlebrock TES headers and Cat Back,Gutted cat, removed emissions, Hotchkis setup in rear, Poly suspension and Koni in the front, relocated MAT, bypassed TB coolant, 300 lbs lighter

PETE

iTrader: (1)

semms to me you have a rich condition what runner was the cleanest?crbon is caused by the harmonic pulse when the tpi fires the exhaust valve closes causing a reversion of the air back into the runners causing a ram effect when the intake valve opens back up.try leaning out the fp you usually can tell of a rich condition by opening the tb blade and looking for a lot of buildup that way it should be relativly clean

Ed Maher

The carbon is not caused by reversion...at least not nearly as much so as it is caused by EGR and PCV gases that are introduced at the front of the plenum.
I have no idea why one runner would be clean though...

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Ed Maher - Moderator @ The Carb Board
92 Z28 Convertible - Quasar blue / Tan top
LB9 4L60 GU2 G80 - stock, soon to be sleeper
-=ICON Motorsports=-

- Definitely prototypes, high powered mutants of some kind. Too weird to live, too cool to die

88blkiroc

just a theory, but in a TPI nitrous setup if ur using a plate the nitrous tends to skip the front 2 cyclinders cause the plate is too close 2 the front 2 cylinders. maybe the same thing is happeneing with the EGR/PCV system , hence the clean 1st runner.

Synergy

Well the PCV system is out of the question... PCV enters in the intake directly, way past the runners. The only thing that could do that is the EGR gases that enter right behind the throtle body. I disable my EGR completely and my runners stay squeeky clean.

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92 Z28 5.7
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Trick Flow 23° heads, Comp Cams XR270HR-10 cam, Accel intake base + ported TPI,
TES headers, Flowmaster catback, MSD ignition, #24 SVO injectors, 1LE aluminum driveshaft.
[b]
Click here to see pics of my car !

Guest

If the valve isnt opening... it would be clean

I dont think thats it. Is it wet with fuel at all? That cleans them up in a hurry.

KW87GTA

To my knowledge there is no fuel in the runner, I just find it rather odd. The car appears to be running fine so I dunno.