What is that little tube that goes down beside the exhaust manifold and connects to the cat? Also, is it bad if i run exhaust straight out of the y-pipe? I just ripped off the tore up system(wrapped around rear axle and pipe b4 cat was pinched off) off of my 89 project car and i was wondering if i can run it that way for a couple of weeks until i get an exhaust system for it.

 

The tube running down your manifold is the air tube, just take it off or plug it with something. It will hurt your engine valve train if you run your exhaust out of the Y. I ran 5 miles with my GTA with just cats cut off and it was loud as hell. Get yourself an exhaust before you drive it too much(two weeks is way too long).

 

that is crap, i get tired of people saying that running open exhaust will burn valves. it simply isn't true, you will be fine runnin out of your y-pipe till the cows come home, it will be loud, but won't hurt a thing.

------------------
86 IROC-Z
40,000 miles!!
305 TPI
gutted maf/airbox
k&n filters
manual cooling fan switch
headers, no cat, cat back flowmaster
700R4 tranny
shift kit
manual converter switch
BF Goodrich radial TAs
3.23 gears
georgous car repainted by my dad and assembled by me

FASTER THAN YOU THINK FOR A "STOCK" 305 hehe.

 

Eh i hate to interrupt this meeting but, there is an O2 sensor in your exaust right after your Y-pipe that uh, well put it this way, everdrop a steaming hot glass cup into a bucket of cold water? well let me tell you what happens... your O2 sensor is the glass cup, the steaming hot part of it is because its in your exuast, hence being quite hot. now the cold water is the air OUTSIDE the exaust... now considering your O2 sensor is glass or at least partly glass, imagine it sitting and being really hot inside of that exaust tube when suddenly a draft of cool air comes inside you exaust, say, after you shut your engine off, and kablash, you lose your O2 sensor. yes its that easy, and no i dont mean to sound retarded with this long as* explanation. this happened to me with my 1989 camaro after i cut the cat off and left it open, i had to purchase and have a new O2 sensor installed since my engine wouldnt run much at all after it was cracked. ruined. destroyed. $380.00 in parts and $220.00 in labor later, my 305 is back and running and im ready to sell the car. just a word of advice.

 

well he was talkin about the valves not being affected, not the O2 sensor. but what u said make sense.

------------------
86 IROCZ
T-Tops
700R4
305 TPI
3.23 gears
bought wrecked and repaired by dad and i. shift kit, manual TC switch, manual fan switch, flowmaster exhaust with edelbrock TES headers& hollow cat, drilled airbox and K&N filters, gutted MAF.

 

superz,

I must disagree with you. If you run an open exhaust like that with no muffler or anything there will be no backpressure and you WILL end up burning up your exhaust valves. Maybe not right away but it will happen. Not to mention all the fumes that could find themselves inside your car if you ever just sit there idling.

 

and is it just me or do superz and raging86 appear to be the same person?

 

the only way your are going to burnup a valve
is if you run lean from the open exhaust if you
have an ajustible fuel pressure regulator bump it up
maby that will keep you from running lean



------------------
388 SuperRam, DFI, Vortech R trim ,N.O.S.,alki injection,
Dart sportmansII heads,50 pound injectors, Headman full headers
duel 3' exhaust,and Flowmasters, Ford nine inch with 370's
Ronal rims with Nitto drad raidals.

 

The tube pumps air into the cat. This makes the cat burn hotter therefore burning off the "nasties" I have heard that without it you will quickly clog your cat.

------------------

• 89 Formula 305 WS6
  SFC's
  LCA's
  Spohn Panhard Bar
  Air Foil
  Flowmaster Cat Back
  Tranny Cooler
  A/F Ratio Meter (not a mod but it sure spurs interest)
  Trans Temp Gauge
  Most "Free" Mods
  3:73, Zexel Torsion Posi
• 90 Eagle Talon 2.0
  (Winter Beater)
  Mods? HA! Its A Rice Burner!

 

well if running open exhaust will burn exhaust valves i guess NASCAR teams, must have a heck of a time keeping their motors in exhaust valves. also what about all the cars at the drag strip running open headers, someone better tell them that they are gonna burn their exhaust valves too. i don't see how burning exhaust valves is possible unless it is like darcom said. when the mixture is lean it burns hotter and could get hot enought to mess up the valve. oh and by the way BTS88IROC i did change my name to hopefully ward off some of the jerks that flamed me in the post on the general tech board. i acted like an *** and so did they, so i'm changin my name and movin on. is that ok with you?

------------------
86 IROCZ
T-Tops
700R4
305 TPI
3.23 gears
shift kit, manual TC switch, manual fan switch, flowmaster exhaust with edelbrock TES headers& hollow cat, gutted MAF.

[This message has been edited by raging86 (edited April 04, 2001).]

 

hey, I can't say one way or the other for sure but comparing a street car to NASCAR racing is apples and oranges (more extreme than that really). I know for a fact these engines are rebuilt WAY more often than our cars get oil changes! (i.e. they don't care if it screws up a valve, it's gonna get replaced in another couple of hours anyway) plus the valves are titanium.

About that air tube to the cat, can I replace the one on mine? it kinked and broke when the engine was coming out. does the dealer have it?
thanks
Clem

 

the valves themselves are NOT titanium.
the only way to burn a valve is to run lean which may happen when you "uncork" the exhaust on a stock motor. however it is not the lack of backpressure that burns the valves its the extra heat from the lean combustion.

 

So how exactly can i even out my mixture and avoid burning a valve? where EXACTLY is the O2 sensor? Also, can i work around this?

 

Raging, like clem said those engines are rebuilt like every single race or a whole new engine is just dropped in, and the big guys running at the dragstrips, they rebuild their engines like every other pass down the 1/4, they aren't real worried about burning a valve up. If they had to, they could tear the thing out and rebuild it right there inbetween races, its been done before.

 

you are an idiot if you payed $380 for parts and labor for an 02 sensor!!its like a $30 part and takes a few minutes to change. no harder than a spark plug!

 

I have run open headers on my 55 chevy for years!!!!!!! I must have lead valves cause they still are fine The only way you are going to burn a valve is if your running really lean, or no headers or exhaust manifolds at all... Running them open doesnt do anything... I have run engines for year with open headers....Kevin

 

I think some of you are confusing burnt valves with warped valves. Run lean burn the valves, run with no exhaust manifolds warp the valves. Running open headers no problem if fuel is optimized, running off open y-pipe more loud and some loss of low end torque. Why not make something cheap to get you through till you can get new system like a peice of flexable exhaust tubing and a cheap turbo muffler for about 25 bucks total.

Steve



[This message has been edited by steve8586iroc (edited April 05, 2001).]

 

YEAH LIKE I SAID, A LEAN CONDITION WILL BURN VALVES, PLUGS, AND PISTONS. HOWEVER, RUNNING OPEN EXHAUST WILL NOT HURT THE VALVES, WHY WOULD OPEN EXHAUST CAUSE A LEAN CONDITION? I HAVE BEEN AROUND GUYS WHO RUN OPEN HEADERS AT THE TRACK ON THEIR STREET CARS WITH NO PROBLEMS. OPEN EXHAUST DOES NOT BURN VALVES PLAIN AND SIMPLE.

------------------
86 IROCZ
T-Tops
700R4
305 TPI
3.23 gears
shift kit, manual TC switch, manual fan switch, flowmaster exhaust with edelbrock TES headers& hollow cat, gutted MAF.

 

you are an idiot if you payed $380 for parts and labor for an 02 sensor!!its like a $30 part and takes a few minutes to change. no harder than a spark plug!

Um ok yeah O2 sensor=$25.00 right? what about all my electrical harnasseseseses?? those were lets see now.. wait heres the receipt... $225.00 with a whole new dash panel and fuses for my new fuse box. ok now whats wrong? ohhh my ignition! gee that mustv'e got fried too i dont know why... hey my trunk wont open what gives? oh look i spent $270.00 on a high torque mini starter thinking that was the problem what its the COLUMN thats ****ed wow i wouldn't of guessed. i guess thats all what happens when your O2 sensor goes and theres no 12V fuse when its wired directly and it fries your entire electrical board. hmmm... but this is another story, and im not sure if its directly related or not, since my starter, fuses, ignition, battery, harnass, and O2 sensor went all at once. maybe they are connected in some mysterious way.... who knows?

 

If Im correct the o2 sensor is on the exhaust manifold not after the Y-pipe. Even on my headers its on the header not the Y-pipe or after it. I dont think the exhaust would be hot enough to place it there. As for burning up valves, I my buddy has a Chevelle that he ran open headers on for at least a month with out any drawbacks. But anyway do it. Just avoid the fuzz, they love open headers.

 

Should be OK unless it is VERY cold outside.

 

so can we dispel the rumor of open exhaust burning vavles? it is nothing but a false rumor people spread, i want is stopped cuz it is a bull crap claim.

------------------
86 IROCZ
T-Tops
700R4
305 TPI
3.23 gears
shift kit, manual TC switch, manual fan switch, flowmaster exhaust with edelbrock TES headers& hollow cat, gutted MAF.

 

This subject was kind of making me nervous. I have heard both, Open headers will hurt your engine and Open headers Wont hurt a thing. I finally got my zz430 clone going and ran it with open headers. Good to hear more of you say it wont hurt anything. How do you tell if a valve is burnt?

 

A buddy of mine ran open for months didn't hurt a thing !! Was just louder!!!

 

I THINK, im not sure but I THINK a symptom of burnt valves is bad throttle response, poor fuel consumption, or seemingly running rich even though its not running rich. A friend of mine had burntvalves and im pretty sure those were the symptoms... its funny but those are the same symptoms as if your carbuerator is out of tune (baddly) although thats what he thought it was and he changed to a new carbeurator, and it didnt solve it. apparently, it was the valves. his symptoms, like i said, were crappy gas mileage due to poor fuel consumption (somhow thats connected.. i think..?) the engine seemed to run rich, black poof of smoke, and crappy throttle response. IM NOT Absolutely sure these are 100% correct, but those were the problems, and the valve change fixed it. he did however, while he had the heads off ported them and of course changed the gasgets and everything too.