Just some simple questions that i have... The popping sound from the exhaust, or backfire i think its called, what is that caused from? I cant stand that noise, its embarressing... Second, the 3" flowmaster american thunder series cat-back, is it bad-*** sound? Lets disreguard the fact it was 400 bucks, im just asking for quality of it. Third, what is the difference between my stock converter (86 z-28 iroc 305 4bbl.) and a high flow converter? And what is a good brand and price range for one? Would it fit to a 3" exhaust set up?

 

dual or single exhaust? dual 3" would be to much for your 305, go with a 2.5"

i am probably wrong here, but isn't backfiring caused from back-presure.. the piston trying to be forced down cuz of to much air?? hmm something like that i think.

-fly

 

WEll, first off, check the 3rd gen meet link in my sig out.

2nd, that popping or backfire, if it's real loud that is not normal,and since you have stock exhaust I would say it's not normal. Cause sometimes people with flows say they get a small backfire sound.

Do you have any exhaust leaks?

I'd get the Hooker cat-back for $200, sound clip of mine is in the sig.

A hi flo cat will free up some HP over the stock one, and you can get a Catco one for about $90.

 

sometimes backfiring is due to loss of backpressure.

 

I already bought the flowmaster cat back, i have a Y-pipe to the converter, then a pipe back to the muffler, and then 2 pipes out the side of that, i have no idea what thats called, oh and its not a stock muffler its a terminator that the previous owner put on. I want headers but are they worth putting them on a 305?

 

lemme put it this way.... the headers and intake is what makes a 305 worthless. Headers and an intake manifold are the best thing you can do for a 305, after that comes lots of TBI mods (or buy the holley TBI, probably cheaper) and port the heads, then you'll have a beast of a 305 for relitively cheap (around 600 bucks)

 

by holley tbi do you mean a carb? If so mine is a rochester q-jet hunk of crap as it is, and its computerized, i cant take that out without taking the computer out...Dont know all these terms like porting heads so maybe go a little bit more detailed with that ???? thanks

 

Don't you mean manifolds?

It's not really worth portin the stock swirl port TBI heads , they suck.

 

Actually, a well tuned q-jet is hard to beat.
Basically, heads are what the air flows out of the engine thru into the exhaust. The more ported the heads are the more easily air can be pushed out, creating HP. Don't worry about porting the stock L03 heads.

 

The pipe from the cat to the muffler, is called an intermediate pipe or I pipe for short.

Yes, headers are worth putting on a 305, and they'll bolt up to any SBC, like a 350 if you get one later on.

 

he has a 4bbl carburetor, not TBI.

 

Get the american Thunder. Its worth it. A nice deep rumbly exhaust.

 

He said he already bought it, in a later post.

 

A well tuned q-jet is hard to beat??? Really??? This i must know! Can i get it professionaly done or do i have to do this myself? I saw a website about it but it didnt make any sense to me...... What are good headers? Will they fit into my car?? There appears to be only a few inches from the ports to the wheel well... would i have to cut those or something?

 

I'd suggest some Hooker headers unless you can afford SLP.

 

If you want to get some good performance from your Q-Jet, go here in the ThirdGen Tech Articals. You should be able to get all you need from a carb out of this artical. The headers, if made specifically for a thirdgen, should fit right in, even right up to the Y-pipe, if im not mistaken. I will be hopefully bolting a set on this weekend if all goes well, I'll let you know what kind of difference I see, hopefully quite a bit!

I know this is not related to your topic, but while your at it, if your looking for performance, you may as well throw on a new intake manifold and possibly a cam. Im thinking you got the LG4 in your '86 right? Very low performace cam with those...

 

Don't forget the cam like in my situation

 

What gives the most power??? There's american thunder which sounds nice but what gives the most power? I know there's borla but that's out of the picture sorry $600 is out of my price range. I was looking at Flowmaster, random technology, and slp. Does anyone know about the slp loudmouth for our cars I couldn't find anything. Also I have a 305 TPI not 4bbl is that comment about 3'' being two big actually true? I mean most exhaust system's for our cars will give a 3'' to the manifold then dual 2.5's out. If it's 3'' to the manifold anyways does it really matter wiether or not the last 2 feet of pipe on both sides are 3'' or 2.5''. Also right now I have no exhaust it's been completely ripped off past the cat. You guy's think this is actually hurting my power??? And Boring out the cat, I know it's illegal and makes the car louder but how much does it help? Thanks a lot.

 

All the cat-backs give about the same amount of power, so basically it's a decision on what sound you like. Personally, I like hooker, it's $200 from summit or jegs. The slp will fit, but you will have to make some modifications. Single 3" is is fine for a 305, 4" would be excessive. The two 2.5" pipes coming out of hte muffler won't hurt it, dual 2.5" flows more than 3" anyways. Your power probably went up after you tore the tiny stock stuff off a little, but it will by a lot once you put headers and a real y-pipe on. Gutting the cat flows more especially if yours is clogged, but I would get either a hi-flow cat or put a pipe in place of the cat. Some people around here don't like the sound of a gutted cat, I can't say for myself becasue I've never heard one, but I'll take their word for it.

 

is the "backfiring"

a real consistant sound.... not too loud but easily heard?

kinda like a chug...chug...chug sound?

if it is like that, you just have an exhaust leak.

just make sure that the leak isn't coming from the exhaust manifolds or you will suck a valve.

other than that an exhaust leak isn't "really" harming anything

 

When i rev it doesnt pop, but while the rpms are decreasing the popping sound happens, how do i fix a leaky exhaust? I have a new one being put on as we speak, would that fix it? I was talking to Mark and he suggest i get hooker shorty headers and a Y and a catco high-flow catalytic coverter. Sounds good to me, i just dont like the sound of 400 bucks for someone to install headers. If i knew what i was doing i would do it myself, but im just a kid Also, i dont know if i can get a better manifold, i dont know to much about them , but the carb that i have on it that has to be there because its computerized, i think the guy said its spreadbore flanged. its 2small circles and the 2 larger circles on the back half. And, has anyone out there tuned up there q-jet and have it successful? If so please tell me the details on the performance and all the little things that you had to do! I read that tech article over and over again, but i have no clue on what the hell they are talking about.... Hopefully my car will have some ***** by the time school is out....:lala:

 

Yeah i read about those cams, it drops the horses down by 20 or something like that, I want a roller cam, but yet again, i have dont know about quality of cams and whats good/bad. Dont i have to put new bushings if i put a new cam in or something along the lines of that? Anyone know prices of nice cam for mine??

 

What about cam losing 20hp?

No, youu don't need to install new bearings, unless you think they're no good. Sliding the cam out slowly and carefully is important not to nick the bearings.

 

[QUOTE]Originally posted by Mark A Shields

>I'd get the Hooker cat-back for $200, sound clip of mine is in the sig.<

Mark, where do you get that cat back for 200 bucks?? Everywhere I look they want 270-300 for it?

 

#1) Mark is a huge Hooker fan. Yes there products are nice, and yes the Hooker cat-back is my favorite sounding exhaust, but if you can't afford $400 for Hooker headers, just get some Heddman ones for like $200.

#2) I believe that Mark bought a slightly earlier model of the Hooker and just cut off a flange, so that's how he only spent $200.

#3) If you really want an intake manifold, just call up Edelbrock and explain what you have to them. However, I don't suggest changing the intake manifold yet, unless you want to keep your stock cam :nono: If you plan on putting a new cam in, then I recommend doing the timing chain and intake manifold then, so as to save you some labor cost.

#4) The 305 heads can be ported to flow pretty well. Sitting Bull ported his and came out with the magic rating of 305 HP.:hail: I will probably end up porting mine, but it depends on my money flow.

#5) If you do all this without upgrading your suspension, you are going to do nothing but smoke your tires off......which is actually a pretty good excuse to get your parents to buy you another set of tires. But anyways, spinning in place is cool to impress your friends, but while your doing that during a race, the other guy will be gone.

#6) Before any of this, you should do a tune-up if your car requires one. I recommend MSD parts, but it's your call. Also, maybe you could bump up the timing a little to get some more umph....and of course tune your q-jet.

Hope this helps.

-The Gunny

 

Probly what he means by this is that the LG4 cam (along with a few other slight differences) produced roughly 20HP less than the L69 (basically same motor, diff cam and manifold i think?). They were both the same motors, we were just the unfortunate ones to get crappy cam....

 

#1 Yes,I love Hookers, he isn't saying $400 is too much for headers, just too much for an install charge.
#2 Yes, I bought the Hooker for an HO car that has a 4bolt flange so it was only $200, required some fab work.
#4 You're confusing 305 heads from TPI and Carb, they are decent heads, but if you have TBI then those heads suck no matter what.

 

Jaboski yo where at in Philly man??? Im in Phila 2 maybe we can tackle the header project together???? IM me on AIM

 

what suspension upgrades are necessary? im a learning teenager too .

 

Sfc's are a great start.

 

Here's a link to another post that I was involved in. You should find it useful.

https://www.thirdgen.org/techbb2/sho...threadid=132075


Hope it helps.

-The Gunny

 

Well, nevermind. The link doesn't work. I'll figure something out this evening for ya.