zupmanZ28

alright i took the car to the track for the first time last night, expecting to see low 14's at least., but the best i could do was a 15.3@92.4, w/ a 2.43 sec 60'. And this is with a 350, 9.0:1 Comp. 454" lift cam, performer intake, and vaccume advance carb and dist., with a ram air intake and edelbrock cat back. The only logical weak link i can think of of the LG4 manifolds, y-pipe, and Cat. Could the exhuast actually be responsible for that much of a loss? My plug wires are getting bad too, could that account for anything? I just ordered new plugs and wires today so those will be on, im also gonna replace the fuel filter for next friday at Cecil. SO, with all that in mind, whats going on? and what would i gain from say TES headers(on a budget, cant afford SLP)? I didn't want to do them at all becuase its a PITA, but if it's hurting me that bad, then i guess i'll have to.

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My 1986 Z28 and more!!
Also, the proud new owner of an 85' IROC with 1364 miles!!!

R.I.P Dale Earnhardt

jbenge

iTrader: (2)

You definately need to upgrade your exhaust system. Your 350 needs to breath in order to make power at high RPM's. The stock manifolds and y-pipe are very restrictive. You should get into the mid 14's no problem if you get headers, 3in. cat back system and a high flow cat. Your 60' time is also pretty slow so you might want to get some sticky tires or try a different launch technique. The bad plug wires you mentioned might be causing some problems too if they are arching, so replace those first and see if that helps but you really need to upgrade the exhaust to get the maximum out of your 350.

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Ray87Z

A good full exhaust is worth 30ish hp on the stock LG4 even w/ it's peanut cam and crappy intake. The stock exhaust, especially the crappy exhaust manis, y-pipe and cat are choking the crap out of even that weak motor. I don't know what you thought they'd be good on your 350 for.

Your 2.4 sixty foot sucks as well, you'll get some high 14s just by getting that down where it needs to be.

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

[This message has been edited by Ray87Z (edited March 10, 2001).]

zupmanZ28

i know my 60' foot times suck, but hey, it was my first time to the track, so owell with that. Im gonna put the new plugs and wires on this week and run it again on Friday and we'll see what happens after that. Im not looking foward to putting headers on this thing at all, it's gonna be a pain. Can someone tell me the easiest way to go about doing it? also which part# TES should i be getting? #6871 is the replacement for an LG4, and 6874 is for the HO motor, or there's 6872 for the TPI motor. Whats the difference between these? I would think i would get the replacement for the LG4 exhuast, but is there a difference between them?

------------------
My 1986 Z28 and more!!
Also, the proud new owner of an 85' IROC with 1364 miles!!!

R.I.P Dale Earnhardt

Ray87Z

Well, the replacement for the LG4 is going to have a small diameter y-pipe, to work /w the stock cat. You don't want that if you want the best performance, but you'll have to use it if you're not going to change the cat at the same time. The one for TPI motors will work w/ the 3" cat, I don't know about the HO car, but I know the LG4 has a 2.5" or smaller y-pipe and cat.

Ideally, what you want to do is purchase the TES for 86-92 single cat TPIs, and get a 3" replacement cat for the TPI car (Catco unit, $99 in Summit), along w/ a cat-back to also fit the TPI car all at the same time (unless your current cat-back is a 3incher already). That will set you up w/ a nice full 3" exhaust. Which is also part of your problem, because you can't piece-part the system to spread out the cost...

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Ray87Z
-Vortec headed 350.
86 IROC w/ a cammed 305 TPI.
Formerly Ray86IROC.
www.inter-scape.com/Ray

zupmanZ28

thanks Ray,
thats what i thought. The LG4 y- pipe is only 2 1/4 inch, so i'll go with either the HO or the TPI headers. I was planning on replacing the Cat anyways, so that's not a big deal. i guess one good thing is that i already have the Edelbrock 3" cat back, it's just got a reducer on the end so it will fit the cat. I'll just take it to a muffler shop and have them knock the reducer off and weld the new cat in. It still sucks though, all together this is gonna cost me just under 500 bucks with shipping and all that, but owell, i guess thats what it takes to go fast!

------------------
My 1986 Z28 and more!!
Also, the proud new owner of an 85' IROC with 1364 miles!!!

R.I.P Dale Earnhardt

[This message has been edited by zupmanZ28 (edited March 10, 2001).]

RB83L69

Right... get the set for a L69 or L98, and the cat and cat-back for the same application. DO NOT get the one for the LG4 or you will be stuck with the biggest restriction of them all, the weenie Y-pipe.

The LG4 exhaust is terrible, gotta be the worst of the worst, it's a shame the factory did that to unsuspecting people thinking they were buying a performance car. It's junk all the way from the heads to the street.

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"So many Mustangs, so little time..."
ICON Motorsports

GMTech

zupman, not to rub it in, but the LG4 exhaust can't be that bad, considering that my mods, and BEST time is in the sig, and the engine and exhaust from manifolds back to the flowmaster is stock (except the flowmaster of course). BONE STOCK, including the "weenie" Y-pipe and 2-1/4 catalyst.

Chalk one up for the Fuel Injection guys.

But then on a side not, my "weenie" exhuast may be just right for the "weenie" motor its attached to, and may be acting differently with the 350, hard to say, but I would address the "tune-up" situation first.

And by no means am I sticking up the for LG4 exhaust, I agree, it really sucks.

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zupmanZ28

oh im definatley doing the tune up first, then we'll see what happens...

------------------
My 1986 Z28 and more!!
85 IROC w/ 1364 miles!

R.I.P Dale Earnhardt