Originally Posted by
PhydeauX
I'm just toying around with an idea that I'm not sure will work yet but I'll throw it out here anyway. I remember a few people talking about making a performance manifold for the Weber DGV I got thinking and started looking into things. Making a new manifold wouldn't really be practical. It would be harder to make, i.e. cost more, then a DCOE manifold. The way I see it if people could afford the DCOE manifold why would they bother with a DGV. Basically what I'm doing is modifying the stock manifold to have a larger plenum and accept a Weber carb without an adapter. I making this with the DGS in mind but a DGV will be able to work on it with no problems. Basically I'm grinding out the plenum area. Not just the dividing walls but also the whole plenum area, removing the top and all reshaping it for max volume. Then I plan to weld a new top on the plenum ready to accept the DGV series carb. This manifold should give the car better breathing up top and be good on a stock or mild cam engine. I have no idea on pricing yet. Most likely it will be less then $200. I just started making the prototype and I'll have a better feel once that’s done. I'll probably also put a $50 core on it so those who buy one will send me their old manifold. Manifolds are such a pain in the ass to get off at the junkyard.
A few updates. I might consider making the manifold to fit a DCNF if the interest so arises. The DCNF is a 2 barrel down draft carb usually found on Italian V configured engines, Lambo, Ferrari, etc. The common bore sizes on e-bay are 40 or 42mm, though they came in 36, 40, 42, and 44mm versions. Used they don’t tend to cost any more then a DGV. The carbs are performance carbs and are fully tunable. The available choke sizes range from 23-38mm. The DGV uses a 26 and 27 mm choke, not changeable, and the DGS uses 2 27mm chokes, also not changeable. This could prove to be a rather potent setup.
It should clear the hood using a short stack. It’s no taller then a DGV, which is why I'm thinking about it instead of an IDF or IDA series carb. The bores are also closer spaced making it fit the plenum better. The way I am setting this up there will be no adapter plate so the carb will sit closer to the manifold to help with clearance issues as well. The only major concern I have is that the carb will be sitting sideways. The throttle shaft is supposed to sit parallel to the crankshaft on an inline engine; the DCNF will be sitting perpendicular. I've read that this can cause issues with uneven distribution of mixture to the cylinders, but I don't think it will be an issue here with the enlarged plenum. Though the only way to find out is going to be when I finish building it and test it out. I already have a manifold that I'm using as a prototype but thanks anyway.
The throttles sit sideways. When they are only partially open fuel only comes through the side that is tipped down. That puts it closer to the 1-2 half of the manifold then the 3-4 half. That could pose a problem with cylinders 3 and 4 getting a weaker mixture at partial throttle. I'm not sure how much of a problem this will be. As you can see in those pics the plenum is now cavernous compared to what it was before. I think that will cancel out some of the effects. I want to stick with the DCNF because of its tunability and compact size. Ideally I'd like to use an IDA but that’s not feasible. I saw a carb on e-bay labeled 40 DFO. It looks like a cross between a DCNF and a DGS. I can't find any info on it; it doesn't even make it into my Weber book. If its what I think it is then this carb would be perfect. The one on e-bay is in sad shape and way over priced so I'm not going to bother, besides its too rare. I'm going to give it a shot with the DCNF and see what happens. If it doesn’t work out then I'll settle for a 38/38 DGS. There's probably a chance that I'll make some for the DGV anyway just because I think I'll have a better chance of selling them.
My DCNF came today. I must say it fits the manifold like a glove. The outside dimensions are almost the same as a DGV carb. I have just a bit of work left to do before the prototype manifold is complete. Then its testing time.
The manifold still isn’t completed. I drilled one of the holes crooked when I was doing the studs. I've made a plug for it but I haven't got around to actually plugging and redrilling the hole. I'm going to wait until I can either get access to or just finally buy a drill press to finish it.
I'll assume it will give some sort of gain with a DGV. The whole reason I started this was to fit a DCNF carb to the car to offer a cheaper performance alternative that was some where in between a DGV and a DCOE conversion. I toyed around with making some studs for the DGV because theoretically it should give some gains in the upper rpm. I never ran the numbers to see if it was worth it though. It would also eliminate the need for an adapter plate, which can be the source for numerous vacuum leaks. The car would also sit about half and inch lower allowing you to run the taller air filter, which may or may not make a difference. I always ran a taller one, but then a gen2 doesn't have the clearance issues a gen3 does.
I'm not sure if I'm even going to test this setup on my car anyway. I know it will be a step down from what I have now, but I might like a comparison as to how close it comes. I already have a tester lined up to run it on a stock motor when ever I get it done so don't even ask ;-b.
Andy
Custom, Performance Carb Intake Manifolds ( 2bbl / 4bbl )
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What kind of fuel pump would you need for a quadrajet? Or one of those 2 barrel holleys? I was arranging to buy a carter fuel pump for my weber carb but I wont buy it if I wouldnt be able to use it with a bigger carb.
Keeping the dream alive!
*Weber 32/36*Pacesetter Header*2.25 in. Cat Back exhaust*SE-i rear disk brakes
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