273 with 340 exhaust manifolds

-
cudafish65

cudafish65

Well-Known Member
Joined
Jul 27, 2016
Messages
79
Reaction score
23
Location
long island NY
I've heard that 340 exhaust manifolds will fit on a 273, which have higher flow than stock. Can anyone agree with this? The car is a 65 barracuda
 
Yes, i believe the driver will work but not sure about the passenger side. I had a set of later 340 manifolds but traded for a set for 360 magnum manifolds from TREBLIG in my 63 and its tight but works.

Jake
 
They will bolt on, but the angle of the dump on the drivers side does not work well, steering linkage interference. Can be made to work, but you butcher the manifold. IMOP, better to sell the 340 manifolds to some one who needs them and buy a set of Tri-y's from Laysons......work the deal right and almost even money.

Good luck!
 
You need the 60s 340 driver's manifold to get it to clear the steering shaft and box. Do you have 60s or 70s 340 manifolds...PICS???
Treblig
 
I wouldn't waste my money your probably gonna gain 5 hp at best.
 
There have been a few early A owners who have installed a 60s 340 driver's manifold paired with a 360 magnum manifold on the passenger's side. I sell these manifold sets to FABO members, been doing it for years. I also sell the 70's 340 manifold paired with a 360 magnum passenger's manifold for use on 67 and up A bodies.

Treblig
 
273 said:
I wouldn't waste my money your probably gonna gain 5 hp at best.
Click to expand...


I would respectfully disagree, the 340 manifolds were used specifically on 340 6 pack cars. The 340 6 pack engine produced much more power than a 273 or 318. So depending on your cam, heads and exhaust pipes the larger 340 manifolds can make quite a difference.

Treblig
 
There's 2 manifold dyno shoot outs floating around 318/340/360/magnum and headers
On a 300 plus hp 360 the difference between 318 and 340 manifolds was like 5 hp.
 
The 273 had a rated HP of 190-200. The 340 had a rated HP of 290. These HP ratings are pretty much tested and proven. The 273 came from the factory with 273 manifolds while the 340 came with 340 manifolds. The 273 manifold had a 1 5/8" exhaust exit hole while the 340 had a 2 1/4" exit hole.
If there is such a small difference (5 HP) between the 273 and the 340 manifolds how do you account for the 90 HP difference???

Mopar designed and manufactured the 340 manifolds to allow the 340 to produce all the extra HP. "cudfish65" is asking if the 340 manifolds will fit on his 273. I answered his question, yes...but it depends on which 340 manifolds he's talking about. As far as horse power gains, if "cudafish65" has a stock motor then he won't see much gain in HP. That's why I stated earlier "depending on your cam, heads and exhaust pipes the larger 340 manifolds can make quite a difference."
Are you saying that if "cudafish65" has a wild cam, great flowing heads, 340 manifolds and 2 1/2" exhaust pipes he won't see a dramatic increase in HP???

Treblig
 
340 has more cam, better flowing heads (which would be most of the gain), better intake and bigger carb over a 273. even long tube headers only give 15-20 hp on mild combos and shorties even less.
 
The early 273 drivers side manifold had a near 90 degree crook cast in. Quoting what someone else once said "Like trying to poop through a straw". I suppose it was engineered adequate for the stock 273. They only changed the Y pipe diameter for the commando with 4 brl and more. Anyway...
If you're upgrading the air in, you probably should upgrade air out one way or another.
From what I have read... Some have successfully installed Dakota manifolds with numbers ending 618/619. Others have failed too. I don't know if their heads were different ( 302s maybe) or different Dakota manifolds, or just what led to their failure. Those Dakota manifolds run very close to firewall thus they heat up the sheet metal.
 
Treblig said:
The 273 had a rated HP of 190-200. The 340 had a rated HP of 290. These HP ratings are pretty much tested and proven. The 273 came from the factory with 273 manifolds while the 340 came with 340 manifolds. The 273 manifold had a 1 5/8" exhaust exit hole while the 340 had a 2 1/4" exit hole.
If there is such a small difference (5 HP) between the 273 and the 340 manifolds how do you account for the 90 HP difference???

Mopar designed and manufactured the 340 manifolds to allow the 340 to produce all the extra HP. "cudfish65" is asking if the 340 manifolds will fit on his 273. I answered his question, yes...but it depends on which 340 manifolds he's talking about. As far as horse power gains, if "cudafish65" has a stock motor then he won't see much gain in HP. That's why I stated earlier "depending on your cam, heads and exhaust pipes the larger 340 manifolds can make quite a difference."
Are you saying that if "cudafish65" has a wild cam, great flowing heads, 340 manifolds and 2 1/2" exhaust pipes he won't see a dramatic increase in HP???

Treblig[/QUOTE

Great point made in whole post. I am in fact adding a few upgrades which is why I think it may be worth changing manifolds. I am upgrading to a 600cfm 4 bbl carb. more a gressive cam and lifters, Hei ignition, custom dual exhaust. so I figure I will see some gains with the higher flowing manifolds. headers are a pain on these cars and expensive. plus I want to keep a stock look as much as possible
Click to expand...
 
I would offer to say that Treblig's suggestions and help would be most beneficial here! He has done the math and made them work for early A's, and he is making them available here!! Or, you could do things the hard way and buy a bunch of different stuff that people have tried and "might" work, or stick with the stock units!! Personally, I would go with Treblig!!
 
Depending on cost of 340 manifolds, I would think better off spending $$ elsewhere for HP.
I have a set of 340 Hipo manis in the shop. My 67 273 cuda has factory manifolds.
Jmo
 
The only slight drawback is the fact that the early 273 and 318 heads have a smaller exhaust port. This smaller exhaust port might give you some sealing problems. Some FABO members have got the manifolds to seal and some have trouble. I (69 318 Barracuda) swapped over to 302 heads to get the larger exhaust port and to avoid any sealing problems. If you place a 273/318 exhaust gasket next to a 340/360 mag gasket you'll see the difference right away (318 is the blue one). Also don't forget, the 70's 340 driver won't fit nearly as easy as the 60s 340 driver:


DSC01769.JPG
DSC01770.JPG

Treblig
 
Treblig said:
There have been a few early A owners who have installed a 60s 340 driver's manifold paired with a 360 magnum manifold on the passenger's side. I sell these manifold sets to FABO members, been doing it for years. I also sell the 70's 340 manifold paired with a 360 magnum passenger's manifold for use on 67 and up A bodies.

Treblig
Click to expand...
I am installing a ATK 360 engine in my ‘65 Barracuda which now has the 273 commando engine. Would you suggest to put a 60’s drivers side manifold and a 360 magnum passenger side on that set up? Will my stock Formula S exhaust pipe bolt up to them? What’s your cost for the pair?
 
Vinnie said:
I am installing a ATK 360 engine in my ‘65 Barracuda which now has the 273 commando engine. Would you suggest to put a 60’s drivers side manifold and a 360 magnum passenger side on that set up? Will my stock Formula S exhaust pipe bolt up to them? What’s your cost for the pair?
Click to expand...
If you'll notice the date on my post (# 16 above), it's dated 2016. As such I stopped selling the manifolds years ago. But to answer your question, there are FABO members who have used the late 60s 340 driver and the 96/97/98 Jeep Grand Cherokee passenger's manifold on '65 A bodies. But they had manual steering and had to make some steering shaft adjustments/modifications. I don't know if the 340 side will clear manual trans clutch linkages. I have even ground the casting numbers off of the Jeep manifold to create clearance for the passenger's side fender well for the early As. I have no idea if your exhaust pipes will fit up to the 340/360 manifolds, I would recommend 2 1/4" dual exhaust pipes to get the benefit of the larger exhaust manifolds, (don't know what you currently have in your car?). You should do a search on FABO, I'm sure you'll find numerous threads about using the 340/360 combo on an early A. Treblig
 
Treblig said:
If you'll notice the date on my post (# 16 above), it's dated 2016. As such I stopped selling the manifolds years ago. But to answer your question, there are FABO members who have used the late 60s 340 driver and the 96/97/98 Jeep Grand Cherokee passenger's manifold on '65 A bodies. But they had manual steering and had to make some steering shaft adjustments/modifications. I don't know if the 340 side will clear manual trans clutch linkages. I have even ground the casting numbers off of the Jeep manifold to create clearance for the passenger's side fender well for the early As. I have no idea if your exhaust pipes will fit up to the 340/360 manifolds, I would recommend 2 1/4" dual exhaust pipes to get the benefit of the larger exhaust manifolds, (don't know what you currently have in your car?). You should do a search on FABO, I'm sure you'll find numerous threads about using the 340/360 combo on an early A. Treblig
Click to expand...
Thanks for the info.
 
273 said:
There's 2 manifold dyno shoot outs floating around 318/340/360/magnum and headers
On a 300 plus hp 360 the difference between 318 and 340 manifolds was like 5 hp.
Click to expand...
This type of info is too limited to be of much use, IMHO. This is probably just a peak HP number; no info is given about the effects at lower/middle RPM's, and what the actual limiting factor was for peak HP.
 
Treblig said:
If you'll notice the date on my post (# 16 above), it's dated 2016. As such I stopped selling the manifolds years ago. But to answer your question, there are FABO members who have used the late 60s 340 driver and the 96/97/98 Jeep Grand Cherokee passenger's manifold on '65 A bodies. But they had manual steering and had to make some steering shaft adjustments/modifications. I don't know if the 340 side will clear manual trans clutch linkages. I have even ground the casting numbers off of the Jeep manifold to create clearance for the passenger's side fender well for the early As. I have no idea if your exhaust pipes will fit up to the 340/360 manifolds, I would recommend 2 1/4" dual exhaust pipes to get the benefit of the larger exhaust manifolds, (don't know what you currently have in your car?). You should do a search on FABO, I'm sure you'll find numerous threads about using the 340/360 combo on an early A. Treblig
Click to expand...

I have a 65 Dart which I didn't build, it has a 360 in it and manual steering, if I posted some pics of the exhaust manifolds do You and others think You could ID them?
 
Avispa said:
I have a 65 Dart which I didn't build, it has a 360 in it and manual steering, if I posted some pics of the exhaust manifolds do You and others think You could ID them?
Click to expand...
Need the numbers on them
 
Avispa said:
I have a 65 Dart which I didn't build, it has a 360 in it and manual steering, if I posted some pics of the exhaust manifolds do You and others think You could ID them?
Click to expand...
Numbers would help but a good pic might do it??
 
nm9stheham said:
This type of info is too limited to be of much use, IMHO. This is probably just a peak HP number; no info is given about the effects at lower/middle RPM's, and what the actual limiting factor was for peak HP.
Click to expand...
Ok. Thanks
 
You must log in or register to reply here.
-

Back
Top