PONTIAC ZONE TECH FORUMS
 

Go Back   PONTIAC ZONE TECH FORUMS >
Restoration and General Tech
> 1958 - 1981 Pontiac Tech & Restoration
User Name
Password

1958 - 1981 Pontiac Tech & Restoration Firebird - GTO - Fullsize

sponser links

Reply
 
Thread Tools
Old 03-15-07, 12:07PM   #1
Greystone75
Registered User
 
Join Date: May 2006
Location: somewhere
Posts: 28
Default Stock Cat removal

Hi everyone, I have a 1975 Formula 350 all stock. I was wondering if it would be beneficial to remove the cat and just put a piece of straight pipe in it's place. Has anyone done this to this year and model? Any tips, suggestions? Thanks,
Greystone75 is offline   Reply With Quote
Old 03-15-07, 05:55PM   #2
Ron Genovese
Drag Racer
 
Ron Genovese's Avatar
 
Join Date: Mar 2007
Location: Hopewell Junction, NY
Posts: 612
Default

I remember back in the 80s I hollowed out the catalytic converter on my 83 trans am & it made a huge difference in power.
Ron Genovese is offline   Reply With Quote
Old 03-15-07, 08:50PM   #3
region warrior
Drag Racer
 
Join Date: Feb 2007
Location: valparasio, in.
Posts: 420
Default

Yes, but do you have to have it tested?
If so, just do what Ron said. It should still pass emissions as long as it's in good tune.
Dual exhaust would make the best single improvement.
region warrior is offline   Reply With Quote
Old 03-16-07, 11:41AM   #4
A. X.
 
Posts: n/a
Default

You don't see too many stock 75 exhaust systems still in tact.
  Reply With Quote
Old 03-16-07, 02:47PM   #5
Greystone75
Registered User
 
Join Date: May 2006
Location: somewhere
Posts: 28
Default

It is exempt from any sort of smog or emissions related testing due to the year. And ya, stock exhaust is still intact, the whole car is stock, pretty sweet! Only 28,000 original miles!
Greystone75 is offline   Reply With Quote
Old 03-16-07, 02:53PM   #6
tweety
the blue canary
 
tweety's Avatar
 
Join Date: Sep 2005
Location: somewhere in the twilight zone
Posts: 785
Default

Quote:
Originally Posted by A. X. View Post
You don't see too many stock 75 exhaust systems still in tact.
True, you don't. When I bought my 75 back in 2000, it still had the stock exhaust on it, but I was the third owner. The second owner only had it for 2 years,and he didn't play with it much. For some reason, when I swapped out the 350 - 2 barrel for the first 455 I put in the car, I kept the stock exhaust. I never did try it without the cat though. Figured I'd pick up more power with a bigger engine.
__________________
Why do we never have enough time to do it right, but we always have enough time to do it over?
tweety is offline   Reply With Quote
Old 03-16-07, 04:04PM   #7
A. X.
 
Posts: n/a
Default

That was usually the first thing ripped out and replaced with dual exhaust. I think I'd leave it alone, but that's just my opinion.
  Reply With Quote
Old 03-16-07, 05:30PM   #8
tweety
the blue canary
 
tweety's Avatar
 
Join Date: Sep 2005
Location: somewhere in the twilight zone
Posts: 785
Default

Yeah, I hear that. The first year or so I had the car, I put about 4000 miles on it with the stock set up. Power was good for a cruiser, and I thought the gas milage was fine. Sometimes I regret pumping it up just from the loss of originality. It was just a base model car with no options though, so overall I didn't feel like I was loosing anything from building it. If it was a Formula, I may have felt different. But then, I'm really partial to Formulas. I've had a few of them. When I'm done this build, hopefully I'm looking at low 12's - high 11's and to me that's more than worth it. It's all about priorities though.
__________________
Why do we never have enough time to do it right, but we always have enough time to do it over?
tweety is offline   Reply With Quote
Old 03-16-07, 10:07PM   #9
Chuck
 
Posts: n/a
Default

Quote:
Originally Posted by A. X. View Post
You don't see too many stock 75 exhaust systems still in tact.
Excatly what I was thinking. You real aint going to get that much more power by removing it usless its plugged. I'd leave it.
  Reply With Quote
Old 03-17-07, 11:57AM   #10
Greystone75
Registered User
 
Join Date: May 2006
Location: somewhere
Posts: 28
Default

thanks for the responses everyone, I will probably just leave it to keep the originality, I was just thinking that if I could remove it to replace it with a piece that could easily be swapped on an off, and pick up some ponies, it may be worthwhile.
Greystone75 is offline   Reply With Quote
Old 03-17-07, 02:33PM   #11
strickrodt70
Registered User
 
strickrodt70's Avatar
 
Join Date: Aug 2006
Location: Ft. Campbell
Posts: 59
Cool 75 Formula 350

Quote:
Originally Posted by Greystone75 View Post
It is exempt from any sort of smog or emissions related testing due to the year. And ya, stock exhaust is still intact, the whole car is stock, pretty sweet! Only 28,000 original miles!
Sounds like a nice car. I'd really get a kick out of seeing some pics if you can post any or send them to me pm. Thanks.
I'd leave the cat too, unless it's plugged. The originalness of your car is rare and if it was mine I'd keep it that way.
I still own lots of parts of my 1975 Formula 350 (lost the body due to major rust in Michigan) and someday I hope to put it all back together. So far it has been my favorite car. I've owned 4 Firebirds and one Camaro, but that 75 was the most fun. Mine was nearly all original (the rust was an aftermarket feature).
strickrodt70 is offline   Reply With Quote
Old 03-19-07, 03:16PM   #12
Greystone75
Registered User
 
Join Date: May 2006
Location: somewhere
Posts: 28
Default

http://img236.imageshack.us/img236/366/pontiac42ix9.jpg
http://img396.imageshack.us/img396/5...ntiac13sl2.jpg

Heres a few quick shots, sorry they are kind of far away. I'll try to get some better ones!
Greystone75 is offline   Reply With Quote
Old 03-19-07, 04:42PM   #13
abarone300
Registered User
 
abarone300's Avatar
 
Join Date: Jul 2005
Location: Brooklyn, NY
Posts: 20
Default

Mike's right! Why mess with something nice and stock. I realize that you want to retain the catalic converter and install a test pipe in its place, and later reinstall the cat, but why would you want to cruise down the boulevard with a noisy exhaust... yes, because I know from experience! I did the same with my '79 T/A, and it was much louder! Although you might have the one large muffler behind the axle instead of the two small resonators I had, and therefore your car won't quite as loud as mine.
abarone300 is offline   Reply With Quote
Old 03-20-07, 12:37AM   #14
billygoatii
Registered User
 
billygoatii's Avatar
 
Join Date: Mar 2006
Location: Slinger, WI
Posts: 311
Default

You would gain quite a bit just by replacing the convertor with a straight pipe. My bone stock engine in my CanAm ran a best of 15.19 sec. with no mods except a straight pipe in place of the computer. It still retained the rest of the factory single exhaust.
__________________


"Been waitin' all week to get my wheels on the street
Get my hands on the wheel, slide down in the seat"
Foreigner
billygoatii is offline   Reply With Quote
Old 05-02-07, 11:43AM   #15
Greystone75
Registered User
 
Join Date: May 2006
Location: somewhere
Posts: 28
Default

Aside from just custom making a test pipe, is there anyone that makes one for this application?
Greystone75 is offline   Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

vB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Forum Jump

Similar Threads
Thread Thread Starter Forum Replies Last Post
RIP Grumpy Jenkins Zedo Grape Vine - General Discussion 2 06-04-12 12:56AM
it's the banks Zedo Grape Vine - General Discussion 8 08-12-10 09:20AM
Recommendations for 650 to 700 HP blown nostalgic looking Pontiac engine Glenn Lever Engine Tech Discussion - Street or Strip 6 06-06-10 12:04PM
Next Saturday June 14th Stock Appearing Drags Englishtown GONZO Races - Shows - Swaps - Events 0 06-06-08 03:48PM


All times are GMT -3. The time now is 01:26AM.

Featured Ads
Ken's Speed & Machine
Mayhem Turbocharging

Carter Cryogenics.  What can we freeze for you?

Pacific Performance Racing

Central Virginia Machine Service.  Home of the Injun Engine!

All Pontiac Engine Kits

Larry's Auto Machine.  Full serivce auto, marine machine shop, domestic and foreign.

Powered by vBulletin® Version 3.6.8
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.
2001 - 2007 PontiacZone.com
Page generated in 0.13580 seconds with 43 queries