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#1059257 - 09/30/18 01:29 AM Exhaust port shape  
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2ndss Offline
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2ndss  Offline
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Evansville in.
Hello. I am wanting to put headers on my stock 87 ss. What shape are the exhaust ports and do the header ports need to be the same shape? Thanks

#1059258 - 09/30/18 02:04 AM Re: Exhaust port shape [Re: 2ndss]  
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86ttop Offline
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Brooksville, Fl
square/rectangle ports


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#1059262 - 09/30/18 06:56 PM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
I bought Flowtech 31104 headers and Mr gasket square header gaskets from summit. When I received the Flowtech headers they have oval ports. Has anyone encountered this problem?

#1059264 - 09/30/18 09:25 PM Re: Exhaust port shape [Re: 2ndss]  
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BadSS Offline
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Pearl, MS, 39208
That's a very common issue. For the headers to match up to the heads, you would need to order headers with Same As Port (SAP) or Square/Rectangle flanges - even then there's no guarantee they won't overlap the ports (especially on aftermarket heads), The last time I looked there wasn't many available and when you can find them, they're typically higher than "oval" headers.

Technically you would want the header flange opening to be larger than the head port, or at the least not overlap the port. Most, not all, of the oval 1.625" that I've seen cover the corners a bit even on the stock head opening.

Long story short, as long as they don't overlap the port and the headers can seal off with whatever gasket you use, you'll be fine.

#1059266 - 09/30/18 10:54 PM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
Ok. Thank you Badss.

#1059276 - 10/02/18 09:01 PM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
Also I plan on running true dual exhaust. What are your opinions on modifying the existing trans. crossmember or buying a new one? l am thinking about welding a steel pipe in there.

#1059281 - 10/03/18 03:47 AM Re: Exhaust port shape [Re: 2ndss]  
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BadSS Offline
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Pearl, MS, 39208
Originally Posted by 2ndss
Also I plan on running true dual exhaust. What are your opinions on modifying the existing trans. crossmember or buying a new one? l am thinking about welding a steel pipe in there.


Folks have been modifying the stock crossmember for years and if they're cut and welded by a competent person, then there shouldn't be a problem.

That said, I had mine welded up by one of the highest recommended welding companies in my area. Either they didn't clean the area properly, pawned it off on the new guy, or the guy drank too much the night before and the welds on mine came loose and literally dumped the transmission from the car when I shifted into third gear at approximately 100 mph. It busted the transmission housing, bent the flexplate so the converter ear hit the block and cracked it. The transmission fluid caught fire and if a passing off duty fireman had not stopped with a large fire extinguisher the car would have likely burned to the ground (the small one I had was to weak to put out the fire).

I now have the beefiest aftermarket crossmember in the car that I could find and feel the $140 for it is well spent insurance.

#1059288 - 10/04/18 12:14 AM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
I went ahead and ordered a new one. I think 200$ is worth not having to worry about my buddies welds holding up.

#1059329 - 10/08/18 11:46 AM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
I got the drivers side header in, switched crossmembers and deleted all the smog crap. I had to relocate the oil pressure sending unit. Next weekend mini starter, passenger side header and 2.5'' pipes w/ flowmaster 44's.

#1059443 - 10/16/18 08:52 PM Re: Exhaust port shape [Re: 2ndss]  
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Fred SS Offline
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Glassboro, NJ
2ndss, which brand crossmember did you get?


87 SS, Harwood cowl induction hood, UMI trailing arms. Edelbrock TES Headers (Jet Hot Coated). GM Goodwrench 350, TPI & Trick Flow 56cc alum heads, SLP runners, ported plenum, Comp Cams 260AH-12 cam, Trick Flow 1.5 roller rockers, Bilsteins, TCI 2400 stall converter, Ramcharger fans, SLP ZR1 rims.
#1059445 - 10/16/18 09:07 PM Re: Exhaust port shape [Re: 2ndss]  
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2ndss Offline
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Evansville in.
I got the crossmember and the header back exhaust from summit but the exhaust doesn't fit under the crossmember.It hits in the middle on both sides. I'm going to have to cut the corners out to give the pipes room to make it through. I wish I would have got the iceman!

#1059511 - 10/20/18 01:55 PM Re: Exhaust port shape [Re: 2ndss]  
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BadSS Offline
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Pearl, MS, 39208
I think I'd be looking at having the exhaust modified to fit the cross-member.or send the summit one back. They're typically pretty good about taking back something that doesn't work out for the customer, especially when it's their brand.


Original owner of 1985 SS black hardtop w/gray interior. Frame-on restoration - 406 sleeper w/ heavily ported FIRST TPI. However the 1.875" headers, 3.5" duals, TH400, Ford 9", notched frame, and 10-point cage w/swing-out bars might tip you off it's not a lil' ole 305 TPI. Other mods: 2" drop, 18" wheels, f/r disk brakes, and custom stereo system.

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