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#1
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Help with Edelbrock sq bore
I've installed a 600cfm edelbrock carb on my 318. It's the 1405 carb with a square bore. I've wired the manual choke in the open position (it's not very cold here in San Diego).
I've also installed the Edelbrock performer intake manifold with the square bore to spreadbore adapter plate. I've got no headers (yet) and stock heads. This was a 2bl setup before. I think it's running a bit rich, I do need to check the plugs, but one stab of the throttle in the morning, and she starts right up. It seems to be getting a lot of fuel, and mileage is bad 10 to 13 mpg. Edelbrock says it was shipped with the follwing configuration: Metering Jets: Primary .100, Secondary .095; Metering Rods: .070 x .047. Step-Up Spring: orange (5" Hg) Now I'm a little green with carbs so bear with me. Can someone explain how each of these components work and what I might change to lean out the mixture. I've seen kits that contain different jets and rods, so I might need to make a change but to what? |
#2
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use a fatter rod (like a .072 X .049)When the rods are "in the hole" aka. when the vacuum is high enough to keep the rod down in the jet by pulling down on the power pistons that the rods are attached too. , (idle- normal cruise), the difference between the size of the jet and the size of the rod (trying to fill the jet orofice) is the total amount of "jet" you have ( or in Holley speak...100 jet orifice - .070 rod size = .030 total jet area.) If you were to go to a fatter jet in the larger measurement (.072), itll lean out at idle and cruise (assuming the idle circuit is good) if you were to go fatter at the smaller (tip .049)) measurement, itll lean out at WOT and acceleration (low vacuum) times. Rods are easy to change and are pretty cheap. Get yourself a few and experiment.
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#3
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The easiest way on that carb to change jetting is to change the metering rods. The large part @ .070" combined with the primary jet is basically your main metering system. The small part @ .047" is your enrichment or power valve equivalent. By changing the rod you effectively change the main metering and/or the power enrichment. You will need to buy a strip kit which contains various jets and metering rods so you can tune the carb. Also get a spring kit because i find the stock springs usually aren't the right ones. You can lean the main system out by going to a metering rod with a larger top section. Don't make to big a jump a one time, just sneak up on it. If you driving down a flat road at say 30-35 mph(just an example) at light throttle and the engine surges then you are probably too lean.
Pishta beat me to it. |
#4
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the edelbrock 600 we put on sons 318 ran rich....but not all that bad.Helped a bit when he dumped the cats,and freed up the exhaust by installing duals.From what ive read,those carbs are tuned up to run better on chevys,outta the box.Try getting the metering rod kit like they mentioned.Theyre real simple to change.
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#5
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Ok, I guess I'll mess with the rods.
I've already got duals and I have a set of cheap headers, but I've been putting off installing them cause I know on A-bodies it's a bear. |
#6
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The instructions that came with the carb are pretty good on operation and tuning. They should be online as well. Also, there is a book out there on Carter carbs. Everything you wanted to know and didn't about Carter carbs from the WC4bbl to the T-Q. All 4 Carter carbs are covered.
Carter and Edel. carbs are the same in operation and tuning. Click here for info on carb; http://edelbrock.com/automotive/eps_intro.html |
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