TuffSS

iTrader: (6)

Hi, I am going to go against the grain atleast initially and not jump right to LT headers.

I recently acquired my first late model muscle, an 00' SS M6.

I will be porting a spare set of low mileage take-off manifolds that I have for this.

I also have the OEM gaskets that came with this spare set of manifolds.

I will likely switch heads in the coming months but for now they will stay the untouched stockers

I need to know since I will be useing these used gaskets I got as my template/guide to porting the manifolds........well I need to know how close that OEM gasket matchs to the stock head exhaust port in size and shape????

Any help here is very very appreciated.

The gaskets surprissingly have openings much bigger than the manifolds. Indicating big room for improvement right there.

Really wish I had a set of stock heads off the engine to set these gaskets onto, but I don't. Hopeing somebody else can offer some help on this specific question.

A pic would really be awesome, but my hopes aren't up for that.

Thank you.

WILWAXU

iTrader: (6)

The manifold you have on your 2000 are the best factory setup for these cars. But I still recommend looking at a set of long headers instead of messing with the stock stuff.

TuffSS

iTrader: (6)

I will look further into headers. In about a year when the car is no longer my DD I may get serious enough about lowering the cars lap times down the 1320 to where I won't have any choice. For now though, that is not the case. Besides, if the old muscle guys in FAST (factory appearing stock tire) can bust out 12's 11's and some getting into the 10's while looking stock.........well I like the concept. Ultimate sleeper. I've jumped right to headers on every muscle car I've ever owned. I'm not going to do that on this late model muscle. Not going to follow the crowd this time. This bull is going to stray from the herd, LOL

TuffSS

iTrader: (6)

Anybody?

618HAWK

iTrader: (361)

I just put a set on the other day, prior to that I looked at that myself.
I would say they have about a 70-90 thousands larger diameter. This is what I saw just by the gasket sitting around the head port. Now I cant say any thing for the manifold to head port size difference.

TuffSS

iTrader: (6)

So, to clarify just so I understand right.

The gaskets were .070 to .090" larger than the port exiting the head? And I assume that would be all around the entire diameter of the exhaust port, from looking at the carbon buildup on these spare manifolds I got.

Considering how much bigger you often see the ports leading into the primary tubes on a set of given header flanges. I think I'll be pretty safe first matching the shape up on these manifolds first, then giving a minimum 1/16" step all the way around. With possibly a bigger step on the floor. Really, the casting limitations determine just how far you can try to perfect the castings flow wise. These will be easy compared to old school log manifolds. Heck, these are actually alot more shorty header like than most/many old muscle cars ever had. All part (one of many reasons) of the reason these lill 346"ers run so well stock.

I had some email correspondence over the weekend with Greg Gessler. He is the top guy porting exhaust manifolds, OEM head castings, and OEM intake manifolds for the FAST competitors. He basically confirmed my understanding of how to go about it, and what to do where. He was vague, but then he was giving away trade secrets so. I actually just in my initial email put what I thought needed to be done, and he confirmed with a few minimal additional comments. It can be hard to pry info out of guys who normaly get paid for that knowledge, so I try to make it easier on them. Good guy!

Gregs I think it is a 72...........Buick GS, has an official FAST record of ......oh I think its an 11.17, and recently ran an un-official 10.95 all through OEM castings ported by him. Ofcourse he does run a solid roller cam (specs unknown), but those numbers are on repro polyglass tires as per FAST rules. Freakin amazing. Absolutely amazing. Talk about a sleeper, wow

TuffSS

iTrader: (6)

Just thought of another question.

My 2000 is the first year of the better flowing manifolds, but if I understand correctly.........the last year for the Air Injection tubes attaching to the manifolds.

Is that correct???? 01 and 02 exhaust manifolds do not have the air tubes attaching to them???? Or am I wrong there?

Thanks