I'd use the 340 manifolds simply because I'll bet they are lighter. (I assume)
...musical exhaust manifolds...
4
Ok folks - for my mild 360 magnum 'truck' engine...I'm looking at two versions of center dump small block manifolds (for both sides of my engine), and I've narrowed it down to these two: '71 340 p-side, and the later 70's 318/360 truck manifolds.
Both manifolds have similar port sizes, and the same 1-7/8" i.d. exhaust outlet diameter. I was going to use the magnum manifolds that were on the engine, but they aim way way back and frankly make 'getting in there' to access the transmission linkage and such pretty difficult, plus making things pretty toasty and requiring more shields, etc. The magnum manifolds also have the same outlet size of 1-7/8", and with that in mind I'm looking at center dump exhaust manifolds, so back to the 340 or later 318/360 units. The 340's flow good, and I think the 318/360 units probably flow the same, so I doubt there's not much of a flow difference that I would ever notice, and I don't care about gaining/losing 5 hp at 5000 rpm. The later units have more 'cooling fins' and a bigger internal core...but I don't know if that has any bearing.
My brain tells me these (below) both flow about the same, and will flow plenty well enough for my mild 360, again built to be 'done' by 4500 rpm - I'll just be adding gears - not for high rpms - for low rpm grunt work.
So, that said, am I missing something, or would either of these suit me just fine - I'm leaning towards the 340 units...and unless someone convinces me otherwise I'll be picking up a set of the 340 manifolds from a local club buddy tomorrow morning. But if the later truck units would be better...well tell me why.
71 340 -
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70's pre-smog small block (318 and 360 I think) -
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Both manifolds have similar port sizes, and the same 1-7/8" i.d. exhaust outlet diameter. I was going to use the magnum manifolds that were on the engine, but they aim way way back and frankly make 'getting in there' to access the transmission linkage and such pretty difficult, plus making things pretty toasty and requiring more shields, etc. The magnum manifolds also have the same outlet size of 1-7/8", and with that in mind I'm looking at center dump exhaust manifolds, so back to the 340 or later 318/360 units. The 340's flow good, and I think the 318/360 units probably flow the same, so I doubt there's not much of a flow difference that I would ever notice, and I don't care about gaining/losing 5 hp at 5000 rpm. The later units have more 'cooling fins' and a bigger internal core...but I don't know if that has any bearing.
My brain tells me these (below) both flow about the same, and will flow plenty well enough for my mild 360, again built to be 'done' by 4500 rpm - I'll just be adding gears - not for high rpms - for low rpm grunt work.
So, that said, am I missing something, or would either of these suit me just fine - I'm leaning towards the 340 units...and unless someone convinces me otherwise I'll be picking up a set of the 340 manifolds from a local club buddy tomorrow morning. But if the later truck units would be better...well tell me why.
71 340 -
70's pre-smog small block (318 and 360 I think) -
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The 340's do flow better than any of the truck manifolds for sure but so do the Magnum manifolds. Actually the best manifold combo is the drivers side 340 manifold and the passenger side Magnum manifold. The 340 manifolds on both sides exit in between cyl#'s 5 and 7 and 6 and 8, so they are in between the Magnum manifolds and the 318/360 manifolds. Why not just get some shorty block hugger headers from Summit?
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well like I said in my first post, because of potential clearance/heat/access issues the magnum manifolds are a non-starter - otherwise I'd use them; I even tried a set of the Grand Cherokee manifolds but they weren't any better. Nope, my goal is to find a set of center dump manifolds that will flow plenty well enough for a truck engine. Headers are out for several reasons, all of which have nothing to do with flow. Sounds like the 340 manifolds are a perfect blend of everything I want, and need, and my Mopar buddy offered a set to me for the same price as what a set of the truck 360 manifolds are going for on ebay, so "340 manifolds" it is.
Thanks guys - always a pleasure
- Sam
Thanks guys - always a pleasure
- Sam
1 - 20 of 46 Posts
