dual exhaust with stock 318 manifolds and no headers?

[Evan Frucht]

I have a 1964 Plymouth fury with the original poly 318 engine. 4 barrel, mild reground cam. The single exhaust currently on the car needs to be replaced because its falling apart.

Would it be ridiculous to put a dual exhaust setup on the car without upgrading the original exhaust manifolds? Would it defeat the purpose/benefit of the added flow?

How much of a difference would it make in performance and sound without headers? are headers a must when doing a dual exhaust on a small block like this?

I'm planning on fabricating a new exhaust system but I need to figure out what I want to do.

would 2.5 inch pipes be too big also?

 

[Darter6]

2 1/2'' are fine. Had them on my 64. Yes the manifolds with duals will help it run better and will sound MUCH better. Poly engines are happy with some up-grades however minor they may be.
Enclosed are photos of my 64 Belvedere 318 poly when I had it. Now the photos show TTI headers and exhaust. But like you I started out with duals,(I had a local shop make the exhaust)then intake and 600AFB carb and then the full headers with complete exhaust from TTI .Really made a difference from what I started out with. Photos are for reference.

 

[Evan Frucht]

I'm thinking of starting with these but they are a tad pricy for me but I may decide to buy anyway. I would rather find something cheaper that was mild steel but nothing seems available.

https://www.carid.com/1964-plymouth-fury-exhaust-systems/magnaflow-exhaust-pipe-179268403.html

also do people ever step down the I.D. of the exhaust system. those front pieces are 2.5" inch but I was thinking of maybe stepping down to 2" pipe. So I would weld together a custom dual exhaust system with X pipe to connect to front exhaust pieces I linked to.

so I would be going from STOCK CAST IRON MANIFOLD > 2.5" STAINLESS FRONT PIPES > 2.5"/2" REDUCERS > 2" MIDDLE SECTIONS > 2" 'X' PIPE > DUAL MUFFLERS W/ 2" CONNECTIONS > 2" REAR SECTIONS TO TAIL PIPES

Does that make sense?

 

[rumblefish360]

I have a 1964 Plymouth fury with the original poly 318 engine. 4 barrel, mild reground cam. The single exhaust currently on the car needs to be replaced because its falling apart.

Would it be ridiculous to put a dual exhaust setup on the car without upgrading the original exhaust manifolds? Would it defeat the purpose/benefit of the added flow?

No, it is a win - win. Consider that if you did a dual exhaust system with the same size pipe on it now it would be an approx. 50% increase in exhaust flow. Going up in size adds to this. Your gonna have to do the math.... LOL!

How much of a difference would it make in performance and sound without headers? are headers a must when doing a dual exhaust on a small block like this?
I'm planning on fabricating a new exhaust system but I need to figure out what I want to do.
would 2.5 inch pipes be too big also?

It will be quiter "INSIDE" the car with exhaust manifolds. Headers are not a must in any way shape or form on stock to mildy modified engines. Though they do help out nicely. Exhaust pipes should not exceed 2-1/2 inches on most street/street strip rides unless you start pumping out HP north of about (give or take, there is some good lee way here.....) 450 HP.

I'm thinking of starting with these but they are a tad pricy for me but I may decide to buy anyway. I would rather find something cheaper that was mild steel but nothing seems available.

https://www.carid.com/1964-plymouth-fury-exhaust-systems/magnaflow-exhaust-pipe-179268403.html

I think there is TTI and Accurate exhaust that has head pipes also.

also do people ever step down the I.D. of the exhaust system. those front pieces are 2.5" inch but I was thinking of maybe stepping down to 2" pipe. So I would weld together a custom dual exhaust system with X pipe to connect to front exhaust pieces I linked to.

I myslef would not use a 2 inch pipe for dual exhaust on a dead stock Poly 318 or even a dead stock low 180 HP 273. A waste IMO.
Use a 2-1/4 pipe at a min.!

so I would be going from STOCK CAST IRON MANIFOLD > 2.5" STAINLESS FRONT PIPES > 2.5"/2" REDUCERS > 2" MIDDLE SECTIONS > 2" 'X' PIPE > DUAL MUFFLERS W/ 2" CONNECTIONS > 2" REAR SECTIONS TO TAIL PIPES

Does that make sense?

No, not at all. Again, step down to a 2-1/4 exhaust pipe at the smallest.

How much HP does this engine have? (Approx. will do.)

 

[Evan Frucht]

No, it is a win - win. Consider that if you did a dual exhaust system with the same size pipe on it now it would be an approx. 50% increase in exhaust flow. Going up in size adds to this. Your gonna have to do the math.... LOL!

It will be quiter "INSIDE" the car with exhaust manifolds. Headers are not a must in any way shape or form on stock to mildy modified engines. Though they do help out nicely. Exhaust pipes should not exceed 2-1/2 inches on most street/street strip rides unless you start pumping out HP north of about (give or take, there is some good lee way here.....) 450 HP.



I think there is TTI and Accurate exhaust that has head pipes also.


I myslef would not use a 2 inch pipe for dual exhaust on a dead stock Poly 318 or even a dead stock low 180 HP 273. A waste IMO.
Use a 2-1/4 pipe at a min.!



No, not at all. Again, step down to a 2-1/4 exhaust pipe at the smallest.

How much HP does this engine have? (Approx. will do.)

I want to think my engine pushes 300 HP but in reality it may be closer to 250. The PO said he had the cam reground, I cannot verify that personally, so I must assume it's close to stock. It does seems have a little bit of a hotter feel/idle but I could be imaging that. It's a stock 318 poly except for the Carter AFB. Initial timing is set to 15.

The reason I though about stepping down to 2" was becuase the only front head pipes avalable for the stock manifolds i could find are 2.5" and that seemed overkill.

Currently the car has a 2" single exhaust setup currently (with a big hole blown out now) which I think might be stock. It didn't seem restrictive necessarily. So a double 2.5 seemed like a huge jump up

Stepping the exhaust to 2.25 after the headpipes may be what I do. The whole point in stepping down would be becuase the 2.5 headpipes are overkill.

 

[rumblefish360]

Did you look around Accurate exhaust for head pipes?

Never mind, I just check, that is a no go.

 

[Evan Frucht]

Did you look around Accurate exhaust for head pipes?

Never mind, I just check, that is a no go.

I checked the places that were mentioned. Accurate exhuast doesn't but TTI has aluminized head pipes that are $195. If that is 195+shipping it probably makes more sense to go with the stainless steel magnaflow brand head pipes which are 215 with free shipping. What would you do? Both head pipes are 2.5 inch

 

[tmaleck]

If you're looking for Magnaflow (which I like) www.hottexhaust.com has a 25% discount on top of free shipping. Best deal I've found so far on MF.

 

[Evan Frucht]

If you're looking for Magnaflow (which I like) www.hottexhaust.com has a 25% discount on top of free shipping. Best deal I've found so far on MF.

THANK YOU! I would of never found that, almost 60 bucks off. I'll probably get the head pipes from them, they look good and are made in USA.

 

[Evan Frucht]

For anyone who is curious. No one makes head pipes that fit the poly 318, all the ones advertised for 64 b bodies are actually only for the LA 318 engine. They are completely different, have different style flange and are for manifolds that dump off in different locations than the poly. Learned the hard way and bought the magnaflow headpipes. Luckily the return is going smoothly and I won't have to pay return shipping since it was "garenteed to fit" my 64 fury. Obviously a mistake in the parts database.

This information would have saved me some time so I'm passing it forward. Since the headpipe plan didnt work out I'm gonna try to make a pair of custom shorty headers.

 

[moparben]

I have a 1964 Plymouth fury with the original poly 318 engine. 4 barrel, mild reground cam. The single exhaust currently on the car needs to be replaced because its falling apart.

Would it be ridiculous to put a dual exhaust setup on the car without upgrading the original exhaust manifolds? Would it defeat the purpose/benefit of the added flow?

How much of a difference would it make in performance and sound without headers? are headers a must when doing a dual exhaust on a small block like this?

I'm planning on fabricating a new exhaust system but I need to figure out what I want to do.

would 2.5 inch pipes be too big also?

Hi Evan,
I'd like to give my 2¢ worth on the 318 poly. I got one out of a 64 Polara wreck that was bone stock with a 2 bbl and put it into a 64 Valiant with no changes except a duel point distributer and duel exhaust. However I did give the car a 4.11 suregrip 8 3/4". I live near Detroit Michigan and I took the car out on Woodward Avenue and raced it every chance I got. Even with the 2bbl carb I would only lose by about 1 car length to a 340 A or E body up to about 80mph. Kudos to the old cable shift Torqueflite: When that car hit 2nd it would leap 1 whole car length and the 340 guys could not believe it. Later I got in tight with the grandfather of the now famous Brad Keselowski, John Keselowski, and he had great things to say about that engine and he had a DUEL QUAD intake for it just sort of sitting around as a keepsake. Later I got myself a 4bbl intake & Holley 600 and ordered a cam from Sig Erson for it. But Erson screwed me and sent a cam for an LA 318, so it didn't work. I only had "flex tube" 2 1/4" exhaust, never headers but that engine was a solid lifter engine and revved up to 6,000rpm very nicely. But as John would say " it was all done making more power by 5,500rpm" but it sounded like a million bucks to scream it up to 6. I don't know how much my 64 Valient actually weighed, but it was probably around 500 to 750Lbs lighter than a 64 Fury. For visual, my car was a 2 door all Black lifted a few inches in the rear with a 7" high 24" long White Plymouth decal on the rear quarter panels. With F-70 front & H-70 14 rear raised white letter Good Year Poly Glass tires it looked tough, but it ran pretty tough too. I hope you find inspiration from my rant. ben [email protected]

 

[Kern Dog]

Uhhh....FIVE years have passed since this thread was started and abandoned. "Evan" never came back to this to provide any updates on how it turned out.