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Old 03-16-2017, 09:51 AM   #26
68post
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Re: Headers and exhaust?

I agree with longhorn, the side exit vs. rear exit is mandatory with a rear facing opening.
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Old 03-16-2017, 10:31 AM   #27
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Re: Headers and exhaust?

Currently the exhaust exits behind the rear wheels, both sides, right before the bumper.

I got the broken manifold bolt cut off, drilled out and tapped last night. Since everyone keeps saying stay with manifolds, my question is how much performance loss is there in that? Is there a mani that is 'better'...I've seen talk about 'vette mani's but I'm sure those will be hard to find.

My motor is about a 330hp street motor. 600cfm eddy 4 barrel with performer manifold, flat tops 60 over, stock heads with valve job, isky 270/280 cam.

I know it's not am overly hot motor, but a few extra hp is always nice if it can be had. Maybe not enough to worry about if i do some other exhaust changes after she's running.

Part of my concern was that broken stud on mani to tail pipe flange and I have cut to fit plug wires....don't want to custom fit them to manifold and then have to change to header and have it look bad.
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Old 03-16-2017, 10:42 AM   #28
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Re: Headers and exhaust?

I never keep manifolds on V8's, always headers. I need the mileage and torque increases, even with a stock engine.
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Old 03-16-2017, 07:20 PM   #29
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Re: Headers and exhaust?

What kind of manifolds are on there now? IMO, 2-1/2" ramhorns versus headers are splitting hairs on anything less than 350 hp and spends most time under 4500 RPMs. I'm running truck ramhorns on a 383 and like it better than headers. I get excellent low-end torque with them which is what I want...and I imagine with your specs, that's what you want too.

Other types of manifolds (logs, 70s and 80s smog stuff, etc) are a different story. I won't ever recommend those.

If I want manifolds, my goto is ramhorns -- either the angled dump truck ones or "Corvette" 2-1/2" center dumps (preferred) if they fit. I've also been known to use 94-96 LT1 manifolds, which also flow very well, but need port matched for other SBC applications. However, the driver's side ones are no longer available new or aftermarket, so that ended that trick. For higher dollar, higher performance applications, definitely a good Thorley (Tri-Y is good for tight clearance) or Sanderson. There are other high-end brands available like Kooks, etc., some target modern cars and restomods, just never had any personal experience with those, so can't recommend. The low dollar headers aren't worth the hassle IMO.
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Old 03-16-2017, 07:46 PM   #30
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Re: Headers and exhaust?

Apparently I do have ramhorns, but 2". Are those ok?
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Old 03-16-2017, 07:48 PM   #31
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Re: Headers and exhaust?

71-75 350 RH
Corvette and Passenger 165, 195, 200, 205 & 270 HP 2.0" Outlet with and without A.I.R.
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Old 03-16-2017, 09:08 PM   #32
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Re: Headers and exhaust?

I agree with the 2 1/2" rams horns @ your power level....try Speedway motors, for the pair (around 115 bones). if you dig around in the site, you can also find some mandrel bent down pipes. I would keep it 2 1/2" to the muffs/ H pipe (you can go a size smaller, for an easier weld fit). Out the muffs, you can go a little smaller (2 1/4") , for a mellower sound & not loose any performance. Best of fun....Longhorn
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Old 03-16-2017, 09:17 PM   #33
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Re: Headers and exhaust?

So ditch my 2" manifolds. Is there a huge gain or is it something that could wait and not mess with my spark plug wire layout if/when I change later?
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Old 03-16-2017, 11:23 PM   #34
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Re: Headers and exhaust?

You have only 1 ram horn manifold there in the pic. The left manifold is a typical '73+ manifold. The 2-1/2" Corvette ram horn manifolds are readily available thru the aftermarket. I think Dorman may even offer them.
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Old 03-16-2017, 11:46 PM   #35
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Re: Headers and exhaust?

I guess I'll have to find the date code and model no on the LH unit. It appears some things say the RH is 2-3/8", so I'll caliper it tomorrow. I suppose that means I'd only need one for Lh side, BUT I'm betting they used a different style because of a clearance issue. Hmmm
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Old 03-18-2017, 06:34 PM   #36
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Re: Headers and exhaust?

Only the bottom pic is a ramhorn that we are talking about. For the price of the 2.5", I'd just replace 'em. The 2" will work too, but if what's in the pic is what you have, they are mismatched. So if you need to buy a new ramhorn to replace the top one, then might as well buy 2 of 'em and get the 2.5" version. You'll be good to go and never have to worry about them again.

Note about Dorman -- they do make the 2.5" Corvette version but it will have the generator bracket. You will have to cut/grind this off if you don't like or want it. Can't beat the price... about $100-$120 for the pair. For that price, it's worth spending an hour with a sawzall and angle grinder.
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Chevy by day...
1969 Chevy C30 Rollback Tow Truck -- 383 stroker, 4L80E
2011 Chevy Caprice PPV 9C3 6.0L (6K miles)
1995 Chevy Caprice 9C1 (177K miles)
1994 Chevy Caprice 9C1 #3 (99K miles)
1995 Chevy Caprice Wagon #2 (60K miles)
1995 Chevy Impala SS (20K miles)
Mopar by night...
1969 Dodge Charger
1972 Chrysler Newport 2dr Hardtop (27K miles)

Plus others...

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Old 03-18-2017, 09:56 PM   #37
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Re: Headers and exhaust?

I have absolutely no issue ordering a new set, but can someone answer the following....

- is there any reason those won't clear on the driver side with the torsion bar front suspension on my '60? I'm winding why they would have mismatched....I don't have my brake lines in yet, so no clue if there will be a clearance issue with them. Fyi....ordered cpp's stainless front brake line kit.
-what about tying the new 2-1/2" manifolds to my current exhaust? I'm not wanting to replace everything just yet, so if I can cut and lengthen the driver side with a new piece and maybe same for the passenger side flange, then I'm good to go.

Most of my exhaust pipe looks good, but I would like to add h pipe and the mufflers are rusting out, so I'll likely replace them soon, but trying to not spend more on this type of stuff until I'm up and running.
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