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#1
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Factory 4 barrel intake question
Is there a difference between the factory 4 barrel intakes from a 340 to a 360? In one of my old Mopar magazines, they built up a 360 horsepower 318. At one point while testing it on the dyno, they swapped the 340 intake for a 360 intake and it made more power.
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#2
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I not sure but I believe the 340 piece was a special casting only, it was a higher high rise. the reason the power would have been better is that the ports where smaller and would have flowed better with the smaller ports. the only compar. I have is an early 2 bbl. and it is lower than a 340 piece. and the later 4 bbl. 360 mani's where all smoggers, i.e.,egr ports etc.
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#3
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I don't know if it was any taller than other intakes, but a 360 intake is more than likely a spreadbore T-Q intake and the 340 a squarebore intake. The intakes abilty to make more power or better power is one suggested by the old head engineer of MoPar Performance, Larry Shepard.
He has writin this before in his books. Also, the T-Q carb was probably larger than the "Other" carb they were useing if such is the case of swapping carbs. A big block T-Q off a 440 is right about 850 cfm. The 340 and 360 share intake port size windows. Even if the 360 had a 2 bbl. However a 318 and/or a 273 share the smaller window. I generally do not suggest a smaller intake port size for the larger engines. But makeing more power with a smaller window is possible though not likely for higher HP levels. Some early 318 2bbl. intakes were VERY low and even single plane. |
#4
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[QUOTE=B.Tallent]I not sure but I believe the 340 piece was a special casting only, it was a higher high rise. the reason the power would have been better is that the ports where smaller and would have flowed better with the smaller ports.QUOTE]
I think you are correct on the height being taller but I don't think the ports were smaller on the 340. They were smaller on the 273/318 manifolds though. The reason it made more power was due to the taller height and resulting better approach angle. |
#5
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Rumble is right. The 340 and 360 use the same ports. What 340 intake were they using? There was a cast square bore, the stock edel LD340 aluminum, and the speadbore thermoquad intake which is the same intake used on stock 360's. Also what carb was they using on which intake. The thermoquad will make more hp than the other carbs.
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#6
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Intakes
Rumblefish is right on again.
My 2 cents, I have had the Edelbrock Performer, Edelbrock SP2P, and the old style cast 340 intake on my 360..also had a Thermoquad, 2 different Edelbrocks, and a Qudrajet carb on it. I tried everything I could afford to get the results I wanted. The Stock cast iron 360 Intake made the best power. The Thermoquad made the best power (but is out of my league to tune right). The Quadrajet is about the same as a Thermoqaud (in my Opinion). I now run a 600 cfm Holly and I get easier starts, no bog, and better milage than the others. Were I to race I would prefer a well tuned Thermoquad. Just my little test conclusions so I hope I don't ruffle any feathers. |
#7
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Isnt it true that after 71 that even the 340 head was changed to the small port. and that being the case the man. would have been changed. I guess I was misunderstood. with the 360 late model mani. being smaller ports. I might be wrong again but I have never seen a 360 4 bbl. made before 72 which would have mde it a small port just like the 340 late production. maybe I need to dig out my mopar engine prod. book and refresh my memory.and I know for sure that the early prod. 360 2bbl is lower than my early prod. 340 mani. but it does have the same size ports . the x heads are the same as my j heads. I just figured since the changed to a smaller head window they would also change port size in the mani. to match
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#8
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Intake
It is ALL relative...depends on your combo..my 360 is probably one of a kind the way I put it together.I was advised not to use the heads I have, and was advised to use different rings etc.
I used what I could afford at the time, and got lucky,I like the way it runs and it exceeds what I expected.Never uses any oil between changes. It is an 87 360 block, Speed pro stock size pistons (block only had 30k on it). Summit K6901 Cam kit,1991 Dodge Dakota heads (positive valve seals), Crane timing set advanced 4', FBO ignition kit, 600 cfm Holly w/67 main jets,. It holds 16 inches of Vac at idle in gear. Idles real smooth and really cooks on the freeway (2.73 diff). Passes smog great. I have no idea how many HP I have as I cannot afford to dyno. Sure moves my 73 Swinger nicely though. |
#9
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Quote:
Quote:
When dealing with intake to head runner port windows, it is best to match it with each other. It's OK to use a 318 intake with a 360 head, but the reverse is not good. The smaller window of the head against the larger port window of the intake will cause a bad match. The air and fuel hit the surrounding area of the small port head and 1, puddle. This will cause the fuel to condense and when the cyl. fills, it fills with big drops of fuel which do not completely burn up. Result, bad mileage and tail pipe readings. 2. It will cause turbulance. Like stuffing a garden hose on high into a straw. Not good. Speeding the the velocity is a very good thing to do. However, there are limits with current offerings and that is combined with the way it works on engine size. If you can speed the air and fuel up on an engine, the result should be more power. |
#10
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Excellent reply Rumblefish
Sorry I didn't see on your post that you had already stated that the port size hadn't changed. I have a habit of just skimming over posts sometimes.
Anyway, B.Tallent, there was a very good article a while back, not sure if it was Mopar Action or Mopar Muscle, but they ran various intakes on a 340 and showed how the higher approach angle really helped the engine. I'll try and dig it out of my 5 bazillion magazines I have since it does list the different heights of the manifolds and that cast iron 340 was one of them I believe. I think the Aluminum LD340 is the same as the cast iron 340 with the square bore carb. |
#11
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Thanks James.
I also just skim sometimes. I own a LD-340. It is a bit taller than a stock T-Q intake. I dont recall the 340 being any taller, though I have never directly compared the 2. Also, the LD-340 came in 2, count them, 2 flavors. 1 was what you described 2. The other had 2 special things on them. 1. A choke well for the T-Q and a Chrysler part number. Order thru Direct Connection. I am fuzzy on if it did or did not have a T-Q carb pad though. Mine is a heavy moded intake. I think I got a pic here on line someplace. I'll look for it. |
#12
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I've never seen a stock LD340 with TQ carb, but there is room to mod one for a TQ and I have seen thosae before.
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#13
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Scroll down some for various clickable pics. I think you'll find this thread very good.
http://www.moparchat.com/forums/show...threadid=63965 |
#14
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I believe the LD340 and the Cast Iron 340 square flange intakes are the same height. I've got a cast iron one but no LD340. I also have a victor 340, a performer rpm, a torker II 360, and a slew of old cast iron 318 and 360 intakes.
The cast iron 340 is definitly a nice intake, just a bit heavy but taller than the 360. |
#15
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I'll be back in a few min.'s. I'm going outside to measure up a few things.
I'll start with a stock 360 T-Q intake and go on to the LD-340. The Torker II, Peromer and RPM are listed at Edelbrocks web site. A few min.'s later..........Front.......Rear...... Stock T-Q 4bbl height, ..3-30/32 ...4-30/32 My LD-340's height, ......4-1/2 ......5-1/2 |
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