lbody headers...

[IsaacHayes]

I'm going to guess 3500/3400 are same gasket...

[MY91GT(Z)]

yes they are

[Forced_Firebird]

3400 and 3500 exhaust gaskets are NOT the same. The 3400's have smaller port openings, and the 3500's have a flat bottom on the "D" shape. Look at the carbon marks on a set of 3500 heads, and you'll see what I mean In fact, probably have some 3500 and 3400 gaskets at the shop, see if memory doesn't fail me and I'll take pics.

[IsaacHayes]

hmm. So will this cause an issue when using the 3400 gaskets on 3500 heads? (that's what I have). Or are they still big enough openings that it doesn't cause an issue?

[Forced_Firebird]

3400 gasket opening more than cover the 3500 heads. The 3500 openings follow the tubular manifold openings.

[Money pit Beretta]

Hey, thanks for making the headers! Love your avatar on 60*.

[IsaacHayes]

So the 3400 gasket opening is larger than the 3500 port for anti-reversion? My ports are opened up some. I need to find some spare gaskets to compare... hmm.

[Money pit Beretta]

I think what he said was that the 3400's are smaller. I still have stock 3100 heads.

[3X00-Modified]

05 3400 have the same gasket as the 3500... I know because I bought both a 05 3400 and 04 3400 and the gaskets were the same... Except for the fact that the Malibu 3500 ones were setup with lower heat shields to protect the block since its a dual down pipe system and no cross over.

I'm assuming they took the 3400 crossover exhaust system and made it the same as the 3500 in 04 so they were only producing one set and they used them on both motors, because IIRC my manifolds were also slightly larger than the standard 3400 ones. But I could be wrong on that part.

[IsaacHayes]

Can you get 3500/large 3400 felpro exhaust gaskets?

[3X00-Modified]

Um, that I do not know... I would have to see at the store what set they are giving you... But I know the 05 3400 set that came on my motor was the same size as the 3500 ones on that engine. IIRC I'm using a 3400 front one and a 3500 rear one and they are the same port size.

[IsaacHayes]

I like the factory style gaskets, look re-useable to me and you said you've done that before. I wonder how much they run at the dealer.

[3X00-Modified]

I've had my front header off MULTIPLE times... its still the same gasket I used when I built the motor back for ole red... Before pinky existed.

[IsaacHayes]

Yeah, looks like thin stainless that seals it with a spring type seal/connection. The WOT/TNC ones look like they'd compress and use once.. (maybe twice! haha)

[3X00-Modified]

What are the WOT/TNC ones made out of? Graphite style like a header collector flange gasket? If so those are typically 1 timers