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#1
09-17-2013, 10:22 PM
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exhaust help
'71 lemans stock 350/2bbl. stock exhaust manifolds w/2.25 inch down tubes. i was looking to do Pypes 2.5inch w/ x pipe and street pro kit. i was ordering w/ opgi and sales rep said i would not benefit from this upgrade because of stock 2 bbl/ ex. manifold. said i should go w/4bbl and shorty hedman headers because of automatic floor shift linkage[long tubes would inter fear w/linkage] if i was to do 2.5 inch dual exhaust. suggested to go w/ single muffler if keeping 2 bbl. does this sound right? need exhaust now plan on doing carb when the $$ is available. i'm not trying to be cheap but i'm on a budget. any help is greatly appreciated
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#2
09-17-2013, 10:28 PM
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Your car will benefit from the dual exhaust off the stock manifolds, even with the stock 2-barrel carb.
After upgrading to a 4-barrel later on you'll extract even more power. Shorty headers aren't much better than your exhaust manifolds and are a lot more trouble. Buy what you want, the sales rep's opinion wouldn't matter to me. |
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#3
09-17-2013, 11:04 PM
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i was thinking 2.5 inch down tube off the manifold into an x-pipe set up. i figured it could only help. i was just looking for some reassurance on my decision.
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#4
09-17-2013, 11:50 PM
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Summit Racing carries PYPES, should be cheaper than OPGI, especially the shipping cost.
The 2.5" downpipes are a great idea. The stock exhaust manifolds aren't as bad as many of the uninformed make them out to be, especially for milder street combinations. |
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#5
09-18-2013, 07:46 AM
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Listen to b-man. He's giving you good advice.
Don't listen to the dippy working OPGI!
__________________
1966 GTO 1969 Lemans Convertible- F.A.S.T. legal family cruiser. 12.59 on G70-14 Polyglas tires. 1.78 60' 1969 Bonneville Safari- cross country family cruiser. . 1979 Trans Am 400, 4-speed, 4 wheel disc. View from the drivers seat racing down Atco Raceway- http://www.youtube.com/watch?v=GhYDMdOEC7A Ride along in the other lane-http://www.youtube.com/watch?v=mIzgpLtF_uw |
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#6
09-18-2013, 08:06 AM
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You will love the sound of the Pypes Street Pro system. I have it on my 1971 GT-37.
 Click here to the Pypes website to see my car
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1971 Pontiac GT-37 Car is a junk yard dog and maybe one day will be restored. 
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#7
09-18-2013, 05:22 PM
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Quote:
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#8
09-19-2013, 12:09 AM
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The stock manifolds are only made for 2 inch head pipes. You will have to have a head pipe made of 2 pieces to go from the 2 inch to the 2.5 inch pipe. If your planning on upgrading later I would go with the headers. Headers will go on your car as far as fit with very little problem at all the only thing you have to worry about is if your heads have all the needed bolt holes in them to install the headers. Some of the 71 heads don't have the bolt hole in the ends of the heads , but if you have 6 holes in the heads your fine. Go ahead & put the headers on you will be farther ahead in the long run when you start builkding up for a stronger engine in the future.
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#9
09-19-2013, 12:38 AM
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PYPES already sells a 2.5" headpipe that fits the log manifolds, it is 2.25" at the flange. The stock logs will accept a 2.25" headpipe as-is, the inside diameter of the passenger side manifold on earlier versions with the heat riser valve matches up perfectly with that size. The driver's side manifold outlet can be opened up to match.
Modified log manifolds and 2.5" headpipes can be seen here: http://forums.maxperformanceinc.com/...d.php?t=630943 |
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#10
09-19-2013, 10:48 PM
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"Headers will go on your car as far as fit with very little problem at all " ??What?? Not something I have ever heard about Pontiac headers!!
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#11
09-20-2013, 11:47 PM
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350 engine 2bbl carb doesnt need a 2 1/2 pipes. that said as your are going to a 400 or larger motor 2 1/4 will suffice. Only if you are going to have a strip/street car with more race than street would I go larger. Im running a 496 bbc 282 286 510 lift roller cam 10:1 compression ported big valve heads with 2 2/18 in primary tube super comp headers with a 2 1/2 inch exhaust. pypes x pipe cutouts and full length tail pipes and violators. the problem is is the larger the pipes the more ground clearance you use.Decide how much you want to lower the car and if you want ton scrape at every speed bump and worry about wacking the exhaust every time you go over a rail road track. Headers also are ground scrapers also and nothing is more fun than hitting hard enough that you scrape the exhaust off the car and it wraps around the rear axle and you have to sleep in the car all nite with the windows up cause the skeaters are big enough to carry you away.just saying
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connman |
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#12
09-20-2013, 11:57 PM
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I saved a lot of money by buying thru summit and if you ask they will have it dropped shipped from pypes whse so it will cut the deliver time. They can also check if it is in stock or not. I would recommend you use the stock manifolds if it is a street machine except it takes away the wow factor
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connman |
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#13
09-21-2013, 12:44 AM
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dont know where you live but if you live in warm climate take the heat riser out or lock it open. or make sure it works freely and lube it good. if it locks shut it will give you all kinds of hot starting problems. use to work for a Pontiac dealer lite years ago.................
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connman |
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#14
09-21-2013, 02:04 AM
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Hey gtome,,,, putting on headers is not really that big of a deal if you know what you working with. Headers on any A-body Pontiac only take about 1.5 hours if you remember which bolts have to come out & how to riase the engine up & which bolt to put in the head so the header will hang in place while you working on them. I have over the years bent a few end wrenchs so they will work just so to be able to tighten up the bolts on the head. All it takes is the right tools & the right state of mind & have put several set in, 100 plus sets over the years. Just like anything else pratice makes perfect. The very first set I put on was in 1971 on my then new to me 69 bird whci only took about 2 hours on my back in my parents garage. By the time I got my new 73 GTO It only took the 2 of us about 1.5 hours to put them on & join them to the cut exhaust. Yes the bolts were all brand new as the car only had about 60 miles on it when we put them on but again knowing that you have to take off more bolt then you think in the begining help. But headers on a Pontiac are really no harder to install then any other car, except headers on a B-body chevy with a small block in it. Those cars give you lots of room & are proberly the easyist to put on.
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#15
11-06-2013, 09:20 PM
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Thanx for all the input. i took the b-mans advise and some others and went with the pypes 2.5 inch w/x-pipe street pro kit and used the old log manifolds. it sounds great and i got a little more power. install wasn't too bad, but an extra pair of hands would have helped but i couldn't wait to put 'em on. a bit of a drone but nothing intolerable. thanx again
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