Re: 340's Rule, 360's Drool !!
[Re: pittsburghracer]
#2722424
12/07/19 11:08 PM
12/07/19 11:08 PM
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Joined: Jan 2003
Posts: 1,237 North Central, Indiana
Roughbird72
pro stock
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pro stock
Joined: Jan 2003
Posts: 1,237
North Central, Indiana
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It means if they're factory stock there's a difference, due EPA restrictions. IMO, If you build either with premium parts I don't think .040" more bore is going to be a much of difference.
72 Plymouth Roadrunner 11.08@123.25
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Re: 340's Rule, 360's Drool !!
[Re: Brian Hafliger]
#2722495
12/08/19 11:06 AM
12/08/19 11:06 AM
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Joined: Jan 2003
Posts: 1,908 Nebraska
4406bbl
top fuel
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top fuel
Joined: Jan 2003
Posts: 1,908
Nebraska
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Until you sonic test a 340 and realize they can be paper thin! THIS!! I have sonic checked 3 360 magnum blocks and the thinnest thrust was .190, down low close to the mains. along with the roller cam, .020 shorter deck, and the fact that the deck on all 3 was square within .003. The oil passages to mains and pump are also already big, no need to do that step. 4" steel crank and eagle h-beams go in with a small eyebrow notch. Only bad thing I found was main bore diameter being to the high side of spec, but still in spec. Even the chevy machinists commented how well machined, and thick they are compared to a chevy.
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Re: 340's Rule, 360's Drool !!
[Re: jwb123]
#2722572
12/08/19 04:09 PM
12/08/19 04:09 PM
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Joined: Jan 2003
Posts: 3,122 Auburn WA
Dave_J
master
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master
Joined: Jan 2003
Posts: 3,122
Auburn WA
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back when I was in high school, 1974, my first mopar was a 1970 340 4 speed dart. I had a buddy that had a 71 340 automatic duster and his brother had a 1972 duster with a 360 4 speed, we drag raced on HwyY just outside of town and I could always beat the 340 auto by a car length, the 360 duster just depended on what side of the road I got, we were neck and neck. I currently have a 69 cuda with a 408 stoked 360 with a procharger, 4 speed and man is it fun to drive. Have built several of the 360/408 engines for others and they all really like them. With the reasonable stroker kits today, a 350 or 340 is really a mute point, unless you are restoring for numbers correct vehicles. I have seen so many dead stock 340 Darts go head to head with 360 Darts and it was always so close, mostly driver. From my observation, the 340 cars would 60 foot the 360 cars but the 360 cars had more MPH in the top end. But I bet if your buddy with the 340 Auto had yanked that A727 and put in a good shift kit'ed A904 it would have been a whole different outcome. With no other changes, my 1979 Cop car 360 E58 in a 66 Dart Wagon with the A727 that came with the engine, the A727 was going south so I put my TransGo shift kitted 1978 LeBarron A904 in it with just the trans and driveshft changes and that Dart wagon came alive.
Retired, US ARMY 1973-1994 ASE mechanic, Electrical 1994-1997 Retired GTE/VERIZON/FRONTIER 1997-2015
Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.
03 Suzuki Burgman 650(Burger King) Scooter 65 Formula S Cuda 78 Little Red Express Truck 98 Buick Regal (wifes car)
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Re: 340's Rule, 360's Drool !!
[Re: 4406bbl]
#2722597
12/08/19 05:57 PM
12/08/19 05:57 PM
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Joined: Apr 2014
Posts: 129 SE Indiana
kowalski440
member
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member
Joined: Apr 2014
Posts: 129
SE Indiana
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And ironically enough, they were made and machined in Mexico (the 360 Magnum blocks)! Until you sonic test a 340 and realize they can be paper thin! THIS!! I have sonic checked 3 360 magnum blocks and the thinnest thrust was .190, down low close to the mains. along with the roller cam, .020 shorter deck, and the fact that the deck on all 3 was square within .003. The oil passages to mains and pump are also already big, no need to do that step. 4" steel crank and eagle h-beams go in with a small eyebrow notch. Only bad thing I found was main bore diameter being to the high side of spec, but still in spec. Even the chevy machinists commented how well machined, and thick they are compared to a chevy.
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Re: 340's Rule, 360's Drool !!
[Re: J_BODY]
#2723089
12/10/19 09:28 PM
12/10/19 09:28 PM
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Joined: Jul 2019
Posts: 194 Springtown Pa
Ray408G3Hemi
member
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member
Joined: Jul 2019
Posts: 194
Springtown Pa
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360 wasn’t nothing but a truck motor.... forgive this Ford guys , lack of SBM knowledge , but the 2 lines running to the valve covers,........Oil to the rocker shaft ?
1963 Thunderbolt 496FE 10.80 (still a work in progress) 1968 Mustang slow a$$ 428 FE 1971 Boss 351 Mustang 11.20@115mph 1993 Lightning 10.61 @ 129mph 408Ci A3 headed NA 1996 Viper GTS 2001 Lightning 8.99 @ 155MPH 5.4 Mod Motor 2009 Ram 9.65@144MPH 463CI G3 NA 2010 Challenger 9.91 @ 139MPH 408CI G3ci NA 2019 F150 (local dealer's Lightning package) ..11.90s
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Re: 340's Rule, 360's Drool !!
[Re: Ray408G3Hemi]
#2723101
12/10/19 10:18 PM
12/10/19 10:18 PM
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Joined: May 2015
Posts: 259 n.c.
geo.
enthusiast
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enthusiast
Joined: May 2015
Posts: 259
n.c.
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360 wasn’t nothing but a truck motor.... forgive this Ford guys , lack of SBM knowledge , but the 2 lines running to the valve covers,........Oil to the rocker shaft ? Looks like a nascar "truck" motor, probably oil spray rails to cool the valve springs.
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Re: 340's Rule, 360's Drool !!
[Re: STEFF]
#2745405
02/22/20 08:57 AM
02/22/20 08:57 AM
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Joined: Jan 2004
Posts: 169 orange city,FL
Demon340GSS
member
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member
Joined: Jan 2004
Posts: 169
orange city,FL
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Pull this topic out of mothballs!! This is an oldie but goodie topic that used to get plenty of blood boiling!! 340 based Small Blocks will always reign supreme as the Tru HiPo Small Block, Where as the 360 based Small Blocks were nothing but 340 Wannabe's!!
Let the fight begin!! I agree!!! I have owned and raced 42 different small block Chryslers so far. In my opinion the 340 is better if its the 67 to early 72 motors for the forged crank, Higher rpm more reliably Better heads from the factory. Higher compression Pistons, on and on... , The cast crank 340's are the same as all the 360 4 barrel motors and hard to tell when racing stock ver stock. But in racing if you change everything around the 360s are a dime a dozen and if you blow it up the stuff is easy to find. The 340's are desired for doing restorations and racing. If mopar had been smart and offered in stock form a 360 with a factory forged crank then I would buy them. You go ahead and bring your 360 powered car around and make my 340 motor match the same and I will show you why the 340 is better. ( same cam, Same heads, Same intake/carb etc and I will out rev you. Out horsepower you, and beat you to the end of the track. The 340 X, U, O heads all are 2.02 intake valve sized. The 360 heads only came with 188 valves. Sure you can upgrade? and that is another reason why the early 340's rule in drag racing. The only reason the 360 motors are so popular as most cant find a 340 instead. Emissions and Cost was why the 360 stayed. Performance was not much of a though at mopar anymore. Fuel crunch and fuel embargo's caused it. in my humble and educated opinion. Grant Eaton
Owner of Original collector and restored original mopars from Mr Norms Grand Spaulding Dodge.
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Re: 340's Rule, 360's Drool !!
[Re: Demon340GSS]
#2745523
02/22/20 04:12 PM
02/22/20 04:12 PM
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Joined: Dec 2005
Posts: 11,408 Fulton County, PA
CMcAllister
Mr. Helpful
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Mr. Helpful
Joined: Dec 2005
Posts: 11,408
Fulton County, PA
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I much prefer the smaller main bearing bores/smaller crank. The rod ratio was an advantage, even with the resulting shorter stroke. The early, thick wall block is the one to use if you can find one.
If the results don't match the theory, change the theory.
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Re: 340's Rule, 360's Drool !!
[Re: geo.]
#2745636
02/22/20 10:24 PM
02/22/20 10:24 PM
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Joined: May 2003
Posts: 13,182 aZLiViN
J_BODY
I Live Here
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I Live Here
Joined: May 2003
Posts: 13,182
aZLiViN
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360 wasn’t nothing but a truck motor.... forgive this Ford guys , lack of SBM knowledge , but the 2 lines running to the valve covers,........Oil to the rocker shaft ? Looks like a nascar "truck" motor, probably oil spray rails to cool the valve springs. Revamped for dry lake bed racing.... yes, spray oiling for the valve springs. Not sure what I’m going to do with it. Supposedly 11 dyno pulls on it.
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Re: 340's Rule, 360's Drool !!
[Re: dvw]
#2745667
02/23/20 02:22 AM
02/23/20 02:22 AM
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Joined: Jan 2003
Posts: 3,122 Auburn WA
Dave_J
master
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master
Joined: Jan 2003
Posts: 3,122
Auburn WA
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Dead bone stock yes a 340 crushes the 360, on paper. Any one that thinks a 1978 Little Red Express only had a MAX of 225 HP, can I call you stupid and get away with it? Mid 1980's I had a 1965 Dart GT. I put a 1974 4bb 360 HP in it with the only mods done was a 'True deck' milled the block 0.020", a 340 Resto cam and a Weian aluminum intake. I used 340 Iron exhaust manifolds. A727 with TransGo shift kit. 8 /34 with 3.91:1 SG 225/60 14 tires. I had a Heath Kit CD ignition triggered by my Prestolite Dual Point. My buddy had a 1964 Valiant 2 door. He had a stock 340 from a Duster. Mallory YL dual point dizzy. He also used the 340 iron manifolds. A727. 8 3/4 with 4.10 SG but he ran a taller 235/65 14 tire. We weighed within 35 pounds with us in the cars, mine was heavier. Best 3-4 out of 5 he would beat me by a door.... until I put a set of 2.02" X heads that had been milled a bit. 5 out of 5 I'd win. Yes he 60 footed me every time but I'd run him down between 1000' and 1320' marks. The only way he could beat me was by removing the passenger and back seats and the front bumper. I raced with my spare tire and jack in the trunk. Many runs at test and tune nights at Seattle International Raceway.
Last edited by Dave_J; 02/23/20 02:51 AM.
Retired, US ARMY 1973-1994 ASE mechanic, Electrical 1994-1997 Retired GTE/VERIZON/FRONTIER 1997-2015
Posting cheap tech help (CRAP) here since Nov 97, 1000's of posts, some may be good.
03 Suzuki Burgman 650(Burger King) Scooter 65 Formula S Cuda 78 Little Red Express Truck 98 Buick Regal (wifes car)
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