What Size Exhaust-Went with 2" Pipes- Sounds great!

[MercuryMarc]

I am going to replace my "original" exhaust system on my 1963 Comet. It originally came with a 170 I6 but now I have a 250 in it. I need to replace it since the muffler is really old and the pipes rub agains my ebrake cables and are too close to the axle and new 16Gal gas tank. I am not using headers and have a stock 250 (from a 70 Falcon) with a 1 barrel Carter RBS carb w/pretonix and duraspark. The current original pipes look very narrow- I wonder if thery should be larger for the 250. Any suggstions about diameter and muffler choices? (for more details check out my web site URL below).
Thanks-

 

[matt1967]

1/3/4" originally, but 2" is what u should have for the 250

 

[66200i6]

This is a huge debate. A stock 250 is running what?..aprox 200 cfm. Why would you want to invest in something other than stock? There are good reasons to keep the diameter small if you are just idling about town or running constant highway speed.

Back pressure is not all bad. Keep the pressure from the head to the muffler constant. If the exhaust pipe dia is too large for the flow/pressure the exhaust will cool (relatively) and create backpressure as well. The stock system will keep your torque curve at low RPM and the mileage up.

Keep it simple and install a good quality stock system. You may want to invest in a stainless tail pipe. The tail pipe (aft of muffler) is usually the first to rot due to moisture.

Apply the K.I.S.S. principle here.

Have fun, Ric.

 

[Mercury Mike]

KISS? \m/

 

[mugsy]

KISS = Keep It Simple, Stupid!

 

[Geezer 300]

Explain to me why back pressure isn't bad...

 

[grocery getter]

the cubic inches are 50% more than the '63. i'd go at least one step larger.

 

[CZLN6]

Howdy Marc and all:

I'd definitely go with a 2" system and a turbo type muffler.

I don't subscribe to the belief that back pressure has some benefits. The stock log exhaust manifold will give your engine all the back pressure it will ever need. Your stock '63 system is probably adding to engine heat and lower mileage. Who'd want that?

I do agree with Ric that velocity and heat, to some extent, in the exhaust system is good. Condensation is bad, and heat and velocity combat it.

A 2" system will be neither obtrusive. If you want a bit of a performance sound, but still civilized I'd suggest the DynoMax turbo type muffler.

Let us know what you decide to do and how it works out.

Adios, David

 

[wallaka]

Explain to me why back pressure isn't bad...

'Coz some guy said that cars need backpressure to make power one time and everybody heard about it.

A properly sized exhaust minimizes backpressure and maximizes exhaust velocity. Too big of a pipe will reduce the exhaust velocity too much and create more backpressure. Too little of a pipe will restrict the exhaust flow, creating more backpressure.

I'd go for a 2 1/4" or so. It won't be too big. A 2" would work too, and be a couple bucks cheaper. These engines were way undercarbed and restricted from the factory.

 

[MercuryMarc]

Thanks for the great responses! I am taking my car to the shop in the morning and I'll see what they say.

 

[ludwig]

I am taking my car to the shop in the morning and I'll see what they say.

Betcha they say, "I dunno. It's not in the book. Lemmie see if I can find sombody who knows." Then you'll wait a while, the phone will ring a couple of times. Then the guy will come back in and say, "Nah, he doesn't know either." Oh yeah. It doesn't matter what you ask.

 

[MercuryMarc]

Went with the 2" set up, oval muffler in front of the tank, and a chrome tip.
Nice low pitch rumble, not too loud...
Check out the sound at:

http://www.angelfire.com/falcon/comet0/muffler.html

Thanks!!

 

[Mercury Mike]

Sounds good. I want that sound, but a lot louder. =D

 

[michael_cini]

sounds good, what kind of muffler did they use?

 

[michael_cini]

what is the volume level of the dynomax muffler compared to a stock muffler?

If you want a bit of a performance sound, but still civilized I'd suggest the DynoMax turbo type muffler.

 

[MercuryMarc]

sounds good, what kind of muffler did they use?

They used a standard oval muffler - $30 + labor.

 

[jim reese]

It does sound good.

I thought long and hard about my 250 and finally went with dual outlet headers and 2.25 dual exhaust the entire way to the back then went into chrome GT dual tips.

It has two very small mufflers.

It sounds so much like a small v8 at idle that must folks think it is. I am very happy with it.

Jim Reese

 

[jahearne]

Sounds great, Marc.

Where did you get the gas tank?

 

[MercuryMarc]

Hi John-
I got it (the gas tank and sending unit) on eBay from Northcoast Mustang- there is one available now:

http://cgi.ebay.com/ebaymotors/1960...ameZWDVWQQrdZ1QQcmdZViewItem#ebayphotohosting

Works great!