85t5mcss

iTrader: (1)

After searching what seems for hours I have not been able to find the answer I am looking for. So....

Is there a difference in 305 and 350 factory 3rd gen exhaust manifolds? I need the best flowing manifolds for a SBC 3rd gen. Headers are out of the question. Everything behind the manifold is open to whatever I decide to use. So, from 82-92 what is the best flowing manifold? Casting numbers would be great as well. Not to worried about A.I.R. since I can take care of that. Any help is appreciated.

Info from an 8 year old thread:

2" outlet manifolds with single 2 1/4" y-pipe
82-87 305 LG4 (VIN H)
88-92 305 L03 (VIN E)
82-83 305 Crossfire
90-92 305 LB9 w/o G92 axle (VIN F)

2 1/4" outlet manifolds with single 3" y-pipe
83-86 305 L69 (VIN G)
85-89 305 LB9 (VIN F)
88 350 L98 (VIN 8)
89 350 L98 w/o G92 axle (VIN 8)

2 1/4" outlet manifolds with dual 2 1/4" cats
89 350 L98 w/G92 axle (VIN 8)
90-92 350 L98 (VIN 8)
89 305 LB9 w/G92 Axle (VIN F)
90-92 305 LB9 w/G92 (Vin F)

Does this still sound right? The lower 2 being interchangeable. Kinda sucks because as of right now I have the 1985 305 "H" Engine.

ninetyone

iTrader: (2)

Not sure if they would bolt up to the 85 heads you have, but if find out for sure. I have a set of L98 350 TPI exhaust manifolds off of a 91. Would sell em for $25.

JamesC

iTrader: (5)

Shouldn't be a problem. Long ago, I swapped out my 85 Vin H manifolds (2") for the Vin G manifolds (2 1/4), along with the latter's Y pipe, cat, and intermediate pipe. The differences in pipe size is significant (even the OE intermediate pipe was larger than the after market which I'd swapped in previously). Note the pic in post #7:

https://www.thirdgen.org/forums/exha...-question.html

Oh, Vin H and G are both carbed cars so the swap was easy. IIRC, the TPI cars have at least one air tube that faces the wrong way--sorry, it was a number of years ago. Carbed cars use a butterfly valve between the manifold and Y pipe on the pass side, while the TPI cars use a simple spacer, essentially the same piece without the butterfly.

JamesC

85t5mcss

iTrader: (1)

I bought some that were supposed to be L98 350 TPI, but were 2" outlet. Not 2.25 unless I cant use a mic or tape measure. I'm going to recheck them anyways then ask the seller what we can work out if they truly are 2". Does anyone have pics of the 2.25" so that I can share them when I look for more 2.25" manifolds?

JamesC

iTrader: (5)

IIRC (and I may not as I haven't looked at an OE manifold in some time), there's a part number cast into the manifold.

90-91 5.7L V8 (L98):

LH GM 14094063
RH GM 14094064

EDIT: Somewhere in the deep recesses of my foggy old brain, I seem to recall that the 2" doesn't quite measure that and neither does the 2 1/4.

The following link is interesting especially the last post:

https://www.thirdgen.org/forums/exha...manifolds.html

JamesC

ninetyone

iTrader: (2)

B.S. , those manifolds i sold you were bolted directly up to my stock 2 1/4 inch dual ypipe. I even sent you the cut ends off of the dual ypipe with the flanges so you could use those to weld up to your stock ypipe if need be. I am not a scammer!

ninetyone

iTrader: (2)

FYI, the motor is an L98. Those are the stock manifolds off of it.

ninetyone

iTrader: (2)

You better get out your measuring tape and look closer 85t5mcss.

JamesC

iTrader: (5)

Since links are often overlooked, a poster above says that the 2 1/4" outlet really only has an ID of 2.18 and 2.19"--another case of rounding up, like calling OE 1LE front brakes 12" (11.7) or an OE intermediate pipe 3" (2.75).

JamesC

ninetyone

iTrader: (2)

Run those numbers on the side of each manifold and then you will see.

85t5mcss

iTrader: (1)

WOW! Never mentioned who they came from and even asked for clarification what the actual measurements were from other members. Never accused u of being a scammer, yes you did send the ends of the Y-Pipe. Re-read my post. And try some Ritalin.

Never said they weren't

Planned on it after finding out what others measured to see if it was a case of rounding. Re-read my post.

I will and thank you for the suggestion.

85t5mcss

iTrader: (1)

This could have simply been someone posting a difference in size, I would have remeasured and assuming they measure roughly 2.18 I would have posted that I mismeasured and no harm done and NO public attacks that I certainly don't appreciate. I didn't put names to avoid conflict until I found where the discrepancy was.

End of rant.

ninetyone

iTrader: (2)

Well, i responded cause whatever you posted that time came directly to my personal e-mail.

ninetyone

iTrader: (2)

You got what i advertised for sale ,stock L98 manifolds

85t5mcss

iTrader: (1)

600+ posts and u haven't noticed that when u post and subsribe to a post it goes to your personal E-Mail? Really. Look at "Additional Options" when posting. Don't blame me for it going to your E-Mail, I cannot control that part of the forum.

I said I will double check. I will knock the carbon off the inside of the manifold and remeasure. Chill. U made a big deal out of this by letting the entire forum know that it was you. I often forget why I dislike forums. Thank you for reminding me.

And, when I remeasure I will let everyone know what I find. 2", 2.18", or 2.25". If I am wrong, I can admit it. I will post what I find.

Due to an extremely busy day at work, I did not get them measured. Tomorrow I will be at a meeting but will try to swing by for a measurement.

85t5mcss

iTrader: (1)

Correct, they are. Thanks for the info on this.
Measured 2.10" and 2.17"-1 is closer to 2" than 2.25" and the other is just the opposite. I guess tolerances weren't so tight on this type of item especially sine they were on the same car as stated by seller earlier.

Thank you all for the help because I would have considered this 2" (and wrongfully did) due to the fact that aren't truly 2.25".

ninetyone

iTrader: (2)

It's all good dude.

85_ZED28

Edit

chazman

iTrader: (4)

Can we assume that the 2" manifolds may be more like 1.93" or something?

88fastgta

iTrader: (9)

no offense dude but i dont see why anyone would want to go through all the trouble to swap out their factory manifolds for other factory manifolds that might be just a tad better but still suck compared to any header out there.... all third gen manifolds are horrible regardless of which engine they came from and if your looking for performance then manifold swapping would be the last thing to do.. imo you just wasted alot of time and money just to swap out to "better" factory manifold that are a quarter of an inch bigger... why complain over manifolds that still suck..... you were way better off getting shorty headers at the least...

chazman

iTrader: (4)

Well, I guess that depends on what you want. Sure, on a stock car, you probably get another 15-20 hp from headers. But some people just want something better than what they have, with a stock look and without the hassle of headers. I just put a set of L69 manifolds on my LU5, so I guess I'm one of those folks.

eseibel67

For some, performance is the only consideration so headers are the only way to go. For the rest of us, there are more things to consider. Headers have a lot of negative drawbacks, so we use manifolds.

By the way, I just did some exhaust work on an 88 LB9 5 speed. Used the Magnaflow 16450 Y pipe, a Walker 15622 Converter, and a DynoMax 3" catback. I highly endorse this setup if you want to keep stock manifolds. It fits great, sounds great, and I can feel a bump in performance at all RPM's.

chazman

iTrader: (4)

Just curious, how much does a set up like that cost?

eseibel67

I'm in Canada, so it cost a fortune.

My estimate would be approximately $350 for the Y pipe and converter. Not sure on the catback because the one I got is used. Any 3" mandrel bent catback would be the way to go on this setup. Personally, I prefer the sound of a Flowmaster, but this DynoMax sounds better than I expected.

Mr Froman

Seems like too many problems are caused by them. I don't race and this is my daily driver so I'm not even going to bother putting new headers on the bird.

Lucid

iTrader: (4)

Did you notice any appreciable difference between the stockers and the high output manifolds? I have been wanting to upgrade the LG4 manifolds to L69 manifolds for some time now.

chazman

iTrader: (4)

Yes.

I already had a a 2.25" Y-pipe into 3" exhaust made for it and attached to the stock 2" LG4/LU5 manifolds. The L69 exhaust manifolds changed the way the car sounds, (for the better), and gave a perceptable increase in performance and driveability. It feels freer revving now, like it really wants some more gear, like a 3.42. I think if Crossfires came from the factory with the full L69 exhaust, (let alone it's gearing and 5 speed), people would look at them differently today.

Lucid

iTrader: (4)

Thats good to hear. It seems like these engines have a bit more potential than most people give them credit for.

When we had our LG4 rebuilt, my dad opted to install the L69 camshaft (because thats what I did on my 86 LB9) and eventually upgraded to a 3" catback exhaust. It definitely has some pep to it, but it feels as if its been choked somewhere.

I just converted the alternator to a 140amp CS-144 and its running really well. I guess the next step is to hunt down some high output manifolds, an EFE valve and a nice Y-pipe.

JamesC

iTrader: (5)

Don't neglect the intermediate pipe, which is considerably larger than the LG4 version.

JamesC

1986BANDIT

dont jump the gun,you should use your eyes and your brain in equal parts and leave the mouth out of it

T.L.

What are you talking about? This is an eight year-old thread...