Can anyone help me ?
I have a 1985 Z28 that has a 1986 body on it minus the 3rd brake light and "no on board computer of any kind"

I've had the motor rebuilt and done some extras to it. Flat head pistons, mild RV cam to give a little extra push ..... Edlebrock performance intake and carb and I do have headers on it right now with the stock Y pipe. I believe it's a LG4 ...... stock 305 that I beefed up a little and runs great without sucking more gas unless I'm heavy footed.

The Y pipe now has blown thru and GM no longer makes the thing !!!!!! A local shop want approx. $350 to make up a custom pipe, so I might as well look at a replacement - Only problem is NO ONE lists anything for a 1985 Z28, except for off-road - hence racing .....

On my car, because I changed the intake and carb, to took off the stock air cleaner and pipe setup and the headers on the car doesn't have the heating tube going up to the air cleaner or an EGR valve. I have a fully open K&N low profile (because of the low hood clearance) air filter sitting on a chromed Edelbrock top and bottom.

SO............. I BELIEVE THE HEADERS ARE FLOWMASTER, SO SHOULD PROBABLY BE REPLACED. CAN ANYONE TELL ME WHY THERE ISN'T ANYTHING LISTED FOR THE 1985 ? IS IT BECAUSE OF THE VENT TUBE AND THE VALVE THAT WAS IN THE PASSENGER SIDE STOCK MANIFOLD ? NOW THAT I DON'T HAVE ANY OF THOSE, SHOULD ANYTHING LISTED FOR 1986 WORK JUST FINE ????? SEEN POSTS SAYING I SHOULD GO FOR TPI VERSION AS IT WOULDN'T HAVE EXTRA ADD ON'S AND WOULD MAKE UP FOR THE EXTRA SPACE I HAVE BECAUSE OF REMOVING STOCK AIR CLEANER, HEAT TUBE, THERMA, ETC.

Any and all help is greatly appreciated !!! I've talked with may people right from GM & GM Heritage Center, to parts store and directly to some of the manufacturers or the aftermarket parts and "NO ONE" can tell my why the '85 is different, if it's different, or if any of these other combinations of parts will work.

Sorry for being long winded ...............

 

85 LG4 exhaust is no different from any other LG4 model. A replacement y-pipe is available from Walker and I've seen one listed on Rock Auto.

You don't want the factory y-pipe though especially if you have headers. The LG4 pipe was not much bigger than a garden hose and serious restriction. Search for a post by JamesC where he compared the LG4 pipe to the L69.

I was unaware that there were any headers that even fit the factory y-pipe? What kind were they? If it's a direct fit to the LG4 pipe, the L69 won't interchange since the right L69 manifold is slightly longer.

 

Thanks for your reply naf, but yes "Many" sites list pipes for sale - mostly Walker (Rockauto, Napa, O'Reilly's Auto parts just to name a few) but the part is no longer manufacturered !!!!!! Many, many sites still list parts as well as many listing the GM parts, but then when you go to order them, it says "No longer Available" or you call to talk to someone who then ends up telling you the same thing.

I believe the headers are Flowmaster and I'll be looking at changing them as most of what is out there need the headers and Y pipe to be from the same company to work.

The biggerst thing I'm trying to figure out is why there aren't any pipes made for a 1985 any more ? What is different ??? Is it the THERMAC and heat vent type things that I've already removed or is there something different that I'm not aware of .............

Still scratching my head ....... and if I keep this up, I'll have a hole in it !!!

 

Aftermarket headers for any model 82-92 will fit your 85. Hooker and Hedman provide headers and a matching y-pipe. I cannot say whether either system will bolt up to the factory catalytic converter though. Even if they did you wouldn't want to retain any single piece of the factory system. The LG4 exhaust pipes are just too small.

You may want to peruse some of the exhaust stickies for some ideas as to what may fit. If you're hard pressed to find a replacement y-pipe, you may find someone nearby that has one through the classified boards here.

I'm not surprised that replacement parts for the 85 LG4 are no longer available.

 

I got my lg4 walker y-pipe on e-bay,for 100 shipped

 

I've been searching, but haven't seen anything yet on top of the fact that in in Vancouver Canada, not where most of the people that do have parts are .............

Naf, why are you not surprised about the lack of parts for and '85 ?

There are lots of parts for '84 and prior and lots for '86 and newer ............ It seems that there is something different with the "85 that no one seems to know about to be able to tell me AND different that after market companies don't want to make the parts for that one year .............

I'm still baffled !!!!! Even messaging with GM and GM's Heritage Center I haven't got an answer - Anyone out there want to chime in with an answer ?

 

There is no exhaust difference for the LG4 from 82 through 87 (at least cat-forward) any piece from the 84 or 86 will bolt right in on the 85. I'm currently actually running an 85 y-pipe on my 84 FWIW.

 

That's good to know ............ Wish I knew why NONE of the after market companies will list for that year ............ I totally understand when they mention it's for "Off-Road Only" - obviously not for 4x4'ing it's for racing !

Just seems odd that even the message I received back from the GM Heritage Center has no answer ...... Not one person with any exhaust company, and GM dealer, GM itself ............ No One !!!!! There must be some difference, but hopefully with the fact I've already removed the normal exhaust pieces, whichever TPI system I chose will go on fairly easily ...........

Time will tell. Going to talk to the 2 best shops in my whole city - 1 is the only one with a mandrel machine and see what they say.. I'll post my results.

Cheers