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justus, pro systems, barry grant pictures
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so it's slow, and here a few pictures of the three carbs for comparison, hard to tell from the pics and jet size is not included, but i'll include a few observations.
in the order above, in the pic 2nd from the left the justus plate has the two holes lower in the plate, 3 spread emulsion bleeds, 2 with inserts, the pro systems has 3 e bleeds closer together with inserts, the bg has 5 e bleeds with inserts, bg block has threaded inserts and not all holes are used, pic on left of bg plate has extensions i added. |
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few more pics
justus carb on left has boosters epoxied with what appears to be modification to the inner diameter radius, i imagine the boosters were aligned then epoxied, throttle bores on justus carb have cnc'd diameter and an additional hole next to the idle bleed for what i'm not sure. |
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additional pics
bottom of the bg carb, and all three carbs together. looks like they all have plenty of adjustability and differences such as emulsion location and sizing. the justus carb has holes drilled in all the butterflies, the pro systems has holes drilled in the butterflies on the primary side only, the bg has no butterflies holes drilled. the justus carb is square jetted with pv caps on both blocks, i'm surprised there were no jet extensions. the pro systems carb was jetted different front to back with pv in front, bg was again square jetted with pv front and back. the bg is the rr 850 version, the pro systems was ordered for the jbl, the justus was bought used and presumeably for a "sporty" vehicle, not sure. |
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almost forgot, here is what efi looks like:D
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Thanks for the pictures.
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Re post#3
The Pro Systems carb appears to have the holes drilled in the secondary's only---just like mine. See photo in post #2 W/red billet baseplate. Craig |
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Just to clarify -- The "caps" you're referring to aren't a means of eliminating the power valves; they are baffles which keep the power valve's fuel entry ports from becoming uncovered during hard cornering. In the case of the carb in question, the PVCR's in both metering blocks are .063" in diameter, which equates to roughly nine jet #'s worth of fuel metered inlet area -- quite a bit to lose...even momentarily...when the PV's start sucking air. Jet extensions on a road car are almost never needed if fuel control issues in the float bowl are properly addressed. More to the point however, they often cause problems (engine stalling) of their own upon hard braking. For years, the "catch 22" was that if your engine made enough power...and your chassis and tires could hook that power to the ground...and your driver didn't run low on talent, then a car that truly benefited from jet extensions under acceleration would suffer a like amount from them on braking. The true solution to the problem -- metering blocks with lowered jet locations and float bowls designed with a "sump" to accommodate them -- didn't come around until just a few years ago. |
Remember when Barry Grant used to modify Holleys before he formed the Demon Carb product line.
[IMG]http://www.clubcobra.com/photopost/d...icture_181.jpg[/IMG] |
Re. the BG not having drilled throttle plates; remember that the BG has the center air bleed in the base plate between all the venturies (can't remember what it's called right now. Hey, it's early!) which obviates the need for the drilled plates.
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Can never be a problem on the primary since the primary main circuit under heavy neg g force (braking) is not operating. |
Of course you're right Gary but the OP's first set of pics included a BG Demon and that's why I mentioned the idle-ez:
http://www.clubcobra.com/forums/atta...8&d=1265473092 Steve |
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Dang man, that's what I get for thinking. Mine has it and I just made the leap that they all did. It's a great idea though.
Steve |
butterflies
What size are the holes in the butterflies and why are they there?
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vector 1- Have you used the BG FI ?
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Ok
I'll bite again, why would you need to drill holes in the first place and what would the symptoms be if someone needed to do this.
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Opening the butterflies to compensate exposes the transfer slots and makes the mixture screws less responsive to uncontrollable. It also shortens the idle/transition phase of the engine and produces off-idle flatspots etc. Drilling holes in the butterflies allows the extra air, but you need to drill in small increments to sneak up on the optimum. The transfer slots should have about .020 exposed when looking from underneath. |
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