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Old 10-16-2007, 06:20 AM
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Tuning tips edelbrock 1406


I`m a newbie here on the forum, been reading a good portion of the posts here, and this seems like the place to be :-)
Since I`m from Norway my language is so and so, please be patient with me..

I have a 1965 Chevrolet El Camino with original 327 engine and 4speed.

It runs good at idle and at WOT.

At very low throttle openings it has a tendency to have a small stumble. I`ve checked the plugs at that very opening, running about a steady 30mph. They where white indicating lean mixture.

As this my second american car, the other one being a 1971 Red Camaro with Holley, I have yet to understand the tuning procedure of the Edelbrock carb in full. Although I`ve snapped up the three stages being idle, primary and secondary stage.

Wrote an email to Edelbrock to get the basic setting of the carb to this engine, put in new needles and springs according to their recommondations. Got a little better but still being on the lean side I`m searching this forum for help.

Can someone please describe the basic functions of the needles, jets and the springs?
Wich number is richer than the other?
When should I change jets and when should I change needles?
Also I have not got a clue of what that spring strength has to do with it.. haha

Puh this was a long post.

Any hints to any of the questions are appreciated.

Thanks in advance guys !

oh, and it`s electric choke by the way.

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Old 10-16-2007, 06:57 AM
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Do you have the manual for the carb? You can download it from the Edelbrock web site. Has pretty much everything in it that you are asking about.
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Old 10-16-2007, 11:30 AM
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This is the URL for the 1406 manual.

The stock calibration of the 1406 is supposed to be relatively lean to help fuel economy, but someone may have already swapped components. Once you verify what you have, you can use the chart on page 12 to determine how to make it slightly richer.

Edelbrock sells a calibration kit #1487 for your carb, which provides different metering rods and jets that you can try.

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Old 10-16-2007, 05:01 PM
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Thanks guys, I had the manual already, but had not realised how to read the chart. Sat down for a while today and finally figured it out.

Say that I`m at number 8 now, I will have to move to number 1 to get a richer cruise mode. without changing the power mode. These two stages I referred to as primary stage and secondary stage in my earlier post.

I was thinking that the jet where controlling wot throttle and the rod cruise/primary stage. Although it seems like this is not wrong, after studying the chart I see that they are working more together than I thought at first - depending on eachother and influenced by eachother. Right?

So is the spring then controlling for how long rod will be in the jet. Weaker needle: rod stays in the jet for a shorter period making the jet come to work faster and vice versa?

Where can I find information in the manual about the functions of the spring, and how to pick the right one?

A long Example:
Say I have a rich power mode (for hp) and an on the weak side cruise (for mpg), both very driveable and not hurting either the performance or the engine (pinging, knocking).

If I`m travelling at a steady 30 (yeah right???) it`s on the lean side but yet ok and good for fuel economy

If travelling at a steady 80 (that`s more like it ;-) with a fair amount of throttle. It`s getting too lean and plugs are white.
Will a weakener spring make the rod go out of the jet faster making the carb go faster in to power mode with and thereby enrichening the mixture?

I`m defintely getting my self an innovative system so I can monitor this on the road and get both good mpg and good power when flooring it.

Thanks for helping out a newbie....
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Old 10-16-2007, 05:42 PM
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I think of the JET as just a hole that lets fuel go through it. The Rod just moves up and down in that hole and allows more or less fuel go through the JET.

The Rods are slightly cone shaped so the deeper they go into the Jet, the more it "plugs up" the hole (Jet), and the less fuel that is able to get through the Jet. when The Rod is raised (like is WOT) more Fuel is able to pass through the jet.

Springs.....The springs are what hold the Rods in a raised (more fuel) position or a dropped (allowing less fuel) position.

A weaker spring will put less tension on the Rods when It is trying to drop deeper into the Jet. Thus allowing the Rod to Lean out the A/F ratio.

A Stronger spring will hold the Rods up, keeping the Jets unplugged and causing the A/F to be richer.

When you buy a pack of springs they come in assorted colors for different strenghs. Just remember that the more tension a spring has, the richer the A/F will be.

Read the manual very thoroughly. I drew it out on paper when I read it. Also make sure that the floats are adjusted correctly. I didnt understand a lot of the stuff in the manual untill I actually took the top half of the Carb off and did some explorer. Im more of a hands on learner. I'm doing the same thing right now because I cant get my 70' el camino to idle.
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Old 10-16-2007, 06:48 PM
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I think for the springs you just have to play around abit and try various different ones.. it only takes 1 minute to change springs so its not too big of a hassle. I too have a 1406 with a low rpm stumble
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