Single weber manifold ID help

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sideshow
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Single weber manifold ID help

Post by sideshow » Sun Feb 22, 2015 9:56 pm

Is this the “good single” weber IDF manifold? The other runner is some where and I am not sure where the heat riser were new from. I have all ways assumed Redline made the proper preheat'ed version, but never knew for certain.

And the other side looks suspiciously like;
http://vwparts.aircooled.net/Deluxe-Cen ... 04.315.htm
As in the cast in linkage boss and existing linkage bits.

In the day MB was Mr Bug, now?
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Piledriver
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Re: Single weber manifold ID help

Post by Piledriver » Sun Feb 22, 2015 11:22 pm

looks right.
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buildabiggerboxer
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Re: Single weber manifold ID help

Post by buildabiggerboxer » Fri May 01, 2015 2:44 pm

The quality is certainly there, Correct me if I'm wrong, but it looks like isolated runner, fuel standoff can be a broblem, as apposed to a plenum type which eliminates standoff, ultimately, I found the plenum type to outperform the isolated runner type, ie more power, We had too big a spec cam in my view, but hey ho, we all had the same, it was easier to tune out difficult corner exit flat spots as far as racing is concerned, I made these plenum end castings for isolated runner intakes, they were a big help smoothing out the uneven pulses that generate standoff, then I modified an isolated manifold to a plenum, and found gobbs of extra power, the jet sizes went way up and the motor was burning all the fuel, the balance pipe fitting was then not required, it was a pre plenum attempt at softening standoff, I ran it blanked of with the plenum, we binned the pre heat, but they do help stabilise the centre section, there is always unbalanced cylinder filling with the stock end castings, the plenum end castings even out the odd cylinder charges, ultimately they were banned in my series by the have nots moaning instead of making their own, I just found a way round it that fooled them, then I found the biggest moaner of all was running a FV flywheel which was clearly on the taboo list...
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Marc
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Re: Single weber manifold ID help

Post by Marc » Fri May 01, 2015 4:22 pm

As a general rule top end performance is aided by the larger plenum volume(s); for the proggys the isolated-runner is the better deal IMO for street use since it also helps reduce their infamous low-end flat spot.
Another example is the Zenith 32NDIX (356 carb) and the Holley Bug Spray - they'll bolt to the same manifold - the Zenith likes the open plenum, but the Bug Spray requires only the little slot milled into the base of the carb between the bores, with a plenum it's a pig for anything but WOT use. Here again, manifold heat is needed for street driveability in cool/humid weather; that's true for ANY single centermounted carb, but I've found Bug Sprays to be particularly problematic - I've had them develop ice plugs in the venturii so bad that the engine wouldn't even run, at ~45° on a rainy day.

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Re: Single weber manifold ID help

Post by buildabiggerboxer » Sat May 02, 2015 7:11 am

Marc wrote:As a general rule top end performance is aided by the larger plenum volume(s); for the proggys the isolated-runner is the better deal IMO for street use since it also helps reduce their infamous low-end flat spot.
Another example is the Zenith 32NDIX (356 carb) and the Holley Bug Spray - they'll bolt to the same manifold - the Zenith likes the open plenum, but the Bug Spray requires only the little slot milled into the base of the carb between the bores, with a plenum it's a pig for anything but WOT use. Here again, manifold heat is needed for street driveability in cool/humid weather; that's true for ANY single centermounted carb, but I've found Bug Sprays to be particularly problematic - I've had them develop ice plugs in the venturii so bad that the engine wouldn't even run, at ~45° on a rainy day.
It's true enough, icing is a centre mount problem, we got it bad in our autumn events, given time I would flip the belt off and get as hot as I dare to heat soak on the grid, at least we got off the start, hot air pipe systems appeared about September time on most runners, without precautions some dropped out with a dead motor immediately, the no air filter runners mainly, what drives these folk to not run filters? they swear power gains, I'm damed if I could ever find any over a K&N set up. BBB.

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