Thread: Mechanical secondaries question, 305 sbc

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I have another problem with my car

the 600 cfm (1406) edel. carb has mechanical secondaries (i think!!) and i believe they are opening too early, it seems like they open just after half throttle

up to just under half throttle i have plenty of torque, but just over it seems like it just bogs out too much and the engine loses some power


my question is:

when should the secondaries open (and how do i adjust them)?

Your 1406 is a vacuum operated secondary carburetor. Air flow through the secondary circuit is controlled by a pair of air valves that are located in the secondary bores above the throttle blades. They are balanced against a counter weight and open to admit additional air flow only if there is enough air velocity (vacuum) to allow the proper operation of the secondary circuit. In all likelihood, your jetted rich, but we need a bit more info first.

A few questions to allow help us address the problem:

What year is your 305 and what type of car/truck are you working on?

Standard or automatic transmission? If automatic, do you have a stock stall converter?

Stock rear end?

Is your 305 stock? If not, what else has been done to the engine?

What manifold are you running?

Did you buy the car with the 1406 installed or did you replace a stock configuration?

Fill us in and let’s see what we can do for you!

Regards,
Glenn

1982 camaro, 1983 305 motor and 700r auto trans, as far as i know stock converter, rear end is stock, but not for the motor and trans (3.08 airplane gears in it, supposed to be something like 3.55 or 3.73 i think) as far as i know, the car has an edelprock performer intake with stock cy. heads (heads never confirmed), shorty headers, the aforementioned carb, bought it like this but never got around to tuning it

i was going to have my mechanic tune it but im running a tight budget now for college so im doing it myself

as for the secondaries, i would never have known they were vaccume, i just assumed... shows how little i pay attention

anyways i posted before about the carb running a bit rich but after slighly advancing the timing and moving the vaccume line from the part time to the full time vaccume fitting (driver's side) it seemed to fix that problem, but i still have the boging down at over-half-throttle

If you go to the Edelbrock website you can download the tuning guide for your Carb and print it out,I am sure it will answer your questions.

Alrighty then – My insides tell me that you’re rich on the 1406. Edelbrocks tend to be rich from the box on stock (or nearly stock in your case) applications. If you don’t already have it, download the manual from: http://www.edelbrock.com/automotive_...ers_manual.pdf

Read the whole thing- really. It will give you a lot of insight and help you understand what I’m saying here. After you read the manual, go to page 22 and 23 to determine exactly where your bog down condition is occurring. My guess is you’ll want to change jets and metering rods to meet number 7 (red annotation below). This requires a 1426 jet set and 1456 metering rods. Check your local go-fast parts store. If they do not have them, both parts are available from Summit, under part number EDL-1426 (jets) and EDL-1456 (metering rods). The jets are $3.99 and the metering rods are $7.99. You will also need a new gasket set, EDL-1472 - $8.95.

You can do this yourself, but it’s a bit tricky and you need to study the pictures in the manual I told you to read. It can be done while the carburetor is on the car, but be very careful with the little parts. If you’ve not done this before, you may want to remove the carburetor and perform the “operation” on your workbench (or the kitchen table – like I did my first fifty or so – I have a very good, understanding, and loving wife!)

I'm sure others will chime in. Le us know what you come up with.

Regards,
Glenn

thanks glenns and everyone else!!

i hope im not getting annoying

i have another question,

if i get this carb. tuned right and i swap intakes, (trying to get an airgap) will it require some more tuning?

No problem with the questions. I think you'll find if you ask right and respect the opinions of those who respond you'll do just fine here.

As to the Air Gap - not sure what you're looking for. Your 305 will probably not see a lot of benefit from this manifold as you're probably out of motor about 5000RPM.

Get your current combination dialed in and drive it for a while. If you're not satisfied, a Performer RPM and a Q-jet would probably be a good fit.

whats the deal with the performer eps? i heard its supposed to give around 5 hp and 9 ft-lbs over the standart performer