Re: 340 question.......
[Re: Russ H.]
#1385695
02/11/13 07:12 PM
02/11/13 07:12 PM
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Weddington, N.C.
Streetwize
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Yes, easlily with good porting and the right cam. The shortblock would also benefit (not required to hit 400 but it makes it a bunch easier on all things) from a lighter bobweight via aftermarket pistons, pins and rods. When you think about it, 400 hp is only 50 horsepower from each 44-ish cube cylinder.  360's do get there a little eaiser. (less RPM) 
Last edited by Streetwize; 02/11/13 07:14 PM.
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Re: 340 question.......
[Re: RobX4406]
#1385699
02/12/13 11:20 AM
02/12/13 11:20 AM
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Aar, PM me and we'll talk. The question was can you make a 400 hp 340 with a stock stroke and OEM heads and manifolds. The answer is Yes. X or j heads can be ported to flow at least 260-270 CFM with a fair amount (and a 2.055 or 2.08 and a thinner/lighter stem valve is a big help) but not a TON of port work and with very good mid lift flows which are the key to torque. A performer RPM and ported heads on a lighter bob weight shortblock will be a very stout package, even at Only 340 cubes. Bullet makes some awesome hydraulic roller lobes, the key to 340's is (more than any other Mopar IMO) is you gotta synch the cam and converter and give it some gear to work with.
Last edited by Streetwize; 02/12/13 11:52 AM.
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Re: 340 question.......
[Re: Streetwize]
#1385701
02/12/13 02:43 PM
02/12/13 02:43 PM
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Russ H.
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Quote:
Aar,
PM me and we'll talk.
The question was can you make a 400 hp 340 with a stock stroke and OEM heads and manifolds. The answer is Yes.
X or j heads can be ported to flow at least 260-270 CFM with a fair amount (and a 2.055 or 2.08 and a thinner/lighter stem valve is a big help) but not a TON of port work and with very good mid lift flows which are the key to torque. A performer RPM and ported heads on a lighter bob weight shortblock will be a very stout package, even at Only 340 cubes. Bullet makes some awesome hydraulic roller lobes, the key to 340's is (more than any other Mopar IMO) is you gotta synch the cam and converter and give it some gear to work with.
WIZE,
Do you have a specific roller cam in mind considering a 4 speed car with 391 SG?
Russ
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Re: 340 question.......
[Re: Russ H.]
#1385702
02/12/13 02:47 PM
02/12/13 02:47 PM
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Posts: 27,467
So Cal
autoxcuda
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Quote:
Quote:
Aar,
PM me and we'll talk.
The question was can you make a 400 hp 340 with a stock stroke and OEM heads and manifolds. The answer is Yes.
X or j heads can be ported to flow at least 260-270 CFM with a fair amount (and a 2.055 or 2.08 and a thinner/lighter stem valve is a big help) but not a TON of port work and with very good mid lift flows which are the key to torque. A performer RPM and ported heads on a lighter bob weight shortblock will be a very stout package, even at Only 340 cubes. Bullet makes some awesome hydraulic roller lobes, the key to 340's is (more than any other Mopar IMO) is you gotta synch the cam and converter and give it some gear to work with.
WIZE,
Do you have a specific roller cam in mind considering a 4 speed car with 391 SG?
Russ
What do you consider "decent street manners" that you would be happy living with are?
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Re: 340 question.......
[Re: RobX4406]
#1385704
02/12/13 03:19 PM
02/12/13 03:19 PM
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AutoX, For an A body with at least 3.91-4.30 gears with a 3200-3400 stall 9.5" vert and a HR cam in the 232-236 @.050 range on a 110 split in no later than 106. Performer RPM or AG intake is your best bet and a tweaked downleg 650-700dp. A 10.5:1 340 with at least 255 cfm of intake port will get you right at 400 hp in a very streetable low 6000 power range. That's plenty of airflow potential for that 400 hp range. Bullet lobe HR12 is 234@.050 and 155@.200 and .565 lift with a 1.6 rocker, I'd look at that one really close in a single pattern for what you want. Bullet HR's work really nice and rev QUICK. Heads are really key, the old iron can be pretty darn good if you know where to whittle.
Last edited by Streetwize; 02/12/13 03:52 PM.
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Re: 340 question.......
[Re: Streetwize]
#1385705
02/12/13 03:49 PM
02/12/13 03:49 PM
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RobX4406
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Quote:
AutoX,
For an A body with at least 3.91-4.30 gears with a 3200-3400 stall 9.5" vert and a HR cam in the 236 @.050 range on a 110 split in no later than 106. Performer RPM or AG intake is your best bet and a tweaked downleg 650-700dp. A 10.5:1 340 with at least 255 cfm of intake port will get you right at 400 hp in a very streetable low 6000 power range. That's plenty of airflow potential for that 400 hp range.
Heads are really key, the old iron can be pretty darn good if you know where to whittle.
Yep, not too far off from each others recipe!
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Re: 340 question.......
[Re: Streetwize]
#1385706
02/12/13 03:52 PM
02/12/13 03:52 PM
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Joined: Jan 2003
Posts: 27,467
So Cal
autoxcuda
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Quote:
AutoX,
For an A body with at least 3.91-4.30 gears with a 3200-3400 stall 9.5" vert and a HR cam in the 236 @.050 range on a 110 split in no later than 106. Performer RPM or AG intake is your best bet and a tweaked downleg 650-700dp. A 10.5:1 340 with at least 255 cfm of intake port will get you right at 400 hp in a very streetable low 6000 power range. That's plenty of airflow potential for that 400 hp range.
Heads are really key, the old iron can be pretty darn good if you know where to whittle.
I'm sure that is streetable and you can drive it on the street. No doubt.
But what I was getting at is that some people don't like a rumpity loud cam, like a low idle speed, enough vacuum for power brakes, etc.
Each person has a different threshhold or expectation for that. IMHO, that many times is more of a constraint than the parts you can put in it.
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Re: 340 question.......
[Re: autoxcuda]
#1385707
02/12/13 04:01 PM
02/12/13 04:01 PM
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Streetwize
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AutoX, I agree but the intake closing event with a good HR lobe combined with a smallish (but adequate) carb Venturi and a VERY good dual plane, you will be streetable. )Acceptable manifold vacuum in gear no lugging in the 35-45 range in high gear, that's my definition of streetable. The RIGHT cam can lope at idle and be Plenty streetable too, IMHO. I would venture to be a little milder you could knock the cam down ~ 4-6 degrees @ .050 and go to a 2800 stall 10" vert with 3.55 gears and still be right in the 400 range and that much more streetable....if I built it anyway  A blueprinted 340 can make about 310-315hp, especially if you use the '68 only manual cam profile advanced 4 degrees. And that's with a too small carb and an undersized intake manifold cross section. Back in the day the old LD340 and a 68-69 440 AVS of a New Yorker and a distributor spring tweak was a Huge step up on a 340, maybe 35-40 hp with no other mods...except you needed new valve springs if it was an old long block. The old Ultradyne 231/239 @.050 hydraulic is a beast in an otherwise stock 340 stick A body car with good valve springs.
Last edited by Streetwize; 02/12/13 04:09 PM.
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Re: 340 question.......
[Re: Sublime70]
#1385709
02/12/13 09:12 PM
02/12/13 09:12 PM
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Streetwize
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Russ, I'd look at that H12 bullet lobe I mention above, single pattern on 110 in at 106. The key with manifolds is you #1 need Velocity so don't go too big on the duration and #2 you really can't get very much in the way of upper RPM scavenging so the better the intake tract works on its own, the better the motor is gonna pull up high. The RPM intake can do pretty well with filling that short stroke motor. More duration will kill torque, less will limit the RPM you need above the mid range. Opinions always vary though
Last edited by Streetwize; 02/12/13 10:43 PM.
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Re: 340 question.......
[Re: Sublime70]
#1385710
02/12/13 09:31 PM
02/12/13 09:31 PM
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RobX4406
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Quote:
Umm.. the OP asked if you could get 400HP out of a 340. The answer is yes, where do you come off saying that he wouldn't be happy that wasn't the question. 
And the build YOU referenced from that article won't get close. Just pointing that out. Build that engine expecting that power output (390+) and you'll be unhappy
I posted what I'd use and mods to make it get there... how about you? 
Have fun in here. 
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