Just completed FE390 build. .030 over, RV cam, straight up timing, sanderson headers, edelbrock performer intake and 1406 carb. Our goal was 9 to 9.5 CR. I am struggling with the carb. The carb was purchased used, and I had a local shop put a kit in it. I know the electric choke is not controlling the choke plate correctly. I need to remove the cap and troubleshoot it. It is all in my '76 Highboy. Timing is still a little retarded until I get 1000 miles on it. Awesome power. I can't shift the 4 speed fast enough to keep up with the motor. (It really needs an automatic.) My mechanic, as many mechanics, is geared towards putting new parts on vehicles. It's quick and it works. I'm a little slower. He says my carb is junk and wants me to buy new. He admits that he is not a 'carburetor guy'. So as I try to educate myself, and learn how to adjust and tune the edelbrock, what things would I look for that tells me this carb may be worn out and its time to consider a new one? Thanks. Kirt

 

The 1406 is a poor choice for that engine build. I would have gone with a vacuum secondary carb instead of a AVS carb. I also hate the Carter afb carbs which is what the edelbrock is. For the money and if budget is tight go with the summit brand 600cfm vac secondary carb.

 

Thanks. Now I need to double-check the model number. I was thinking this carb has vacuum secondaries. I'll look at it in the morning.

 

On a 390, I'd opt for a 750 cfm Vacuum secondary carb. Or Holley's list 80783 650 cfm VS carb.

 

You don't need an automatic transmission, you need to stop using 1st gear. This is a "granny gear" transmission. The only time you use 1st is on a really steep grade and/or have a really heavy load to get the truck moving from a dead stop. Otherwise 2nd gear is used for normal takeoffs.

 

I've been driving dentsides since I was 14 years old in 1973. I understand that 1st isn't typically used for routine take offs. I guess I put too much info in the original post. That is making the topic take an immediate left hand turn. Please re-read for my question.

 

Edelbrock Performer Series 1406 isn't a AVS carb, it based on the Carter AFB series, this is my least favorite carb but it works well as a basic stock replacement carb, getting one tuned for max performance is difficult.
The Edelbrock Thunder Series is based on the Cater AVS carb and is a much better carb with easily adjustable vacuum actuated secondary air door.
Even though the secondaries on both the AFB and AVS carbs are mechanical, the upper air door still makes these carbs operate in the same manner as a vacuum secondary Holley.
Neither of these carbs will perform at the level of a Holley double pumper, but then a 76 High Boy with a bulldog 4 spd isn't a race truck ether.

What is it doing that makes your mechanic think it's junk?
What do you mean by retarded timing until you get 1000 miles on it?
Retarded timing will effect how the carb performs.
Go to Edelbrocks web site, they have a 42 page guide on how to tune these carbs you can down load and print.

Like others here I prefer a Holley carb but I have friends running Edelbrocks everyday on daily drivers to 1 ton work trucks.

 

Retarded timing: I was advised that to promote rings to seat and for the engine to get a little 'broke in", during the first 1000 miles, I should a) drive easy, with a combination of acceleration and deceleration, no long sustained highway driving, b) keep the timing a couple degrees retarded, c) run mid-grade fuel to make sure there is no pinging, and d) use quality motor oil that we know has a good sulfur content plus use 1/2 qt break-in oil for the first 2-3 oil changes, and e) watch the oil pressure and temp gauges like a hawk. I changed oil + filter immediately after the 20 minute cam break-in, at 300 miles, and will again at 1000 miles. I saved oil samples and filters for documentation in case of a pending problem. I suspect this might be a little conservative/over-kill. But didn't think the protocol would do any harm.

Carb frustrations. I think my problems are pretty common issues to deal with. 1st problem I had to resolve was a vacuum leak around the base insulator. Simple. 2nd problem I resolved was an accelerator pump needed to be replaced. 15 minutes. 3rd problem I resolved is still a mystery. After replacing the accelerator pump, I could not get it to run right. I removed the the top plate to explore, and the only thing I could find was one of the little wire clips that hold the metering rod to the plunger was a little wonkey and may have been rubbing on the inside wall of the compartment. I got it back to normal position, replaced the top plate, and it ran much better. So I am assuming that was the problem. The 4th problem that I am currently working on is the electronic choke. I need to pull the cap and troubleshoot it. I haven't gotten to the point of recurving the distributor and playing with metering rods and springs. All problems are resolving, but my mechanic is a little impatient. Maybe I whine too much. But that is the source of the 'junk' conclusion. His, not mine. He likes shiny new stuff. Who doesn't. But I don't know what a carb looks like when it does need replacing. Hence, the post.

 

Oh, and I forgot one other symptom that may be important. I have an occasional drip of fuel that appears on the driver's side intake manifold, directly under the fast-idle mechanism. I think I get one drop when I shut the engine off, but I am not positive when it happens. That triggered a fairly strong response from the mechanic. "If the bushings are worn, it will cost more to press in new bushings than a new carb costs". So throw that in with the other data.

 

Wonkey ? that and dentsides tells me you're somewhere other than the US ! The only thing retarding the timing will do is make the engine work harder. The octane thing is spot on though. As for the rest ? I can't comment, not a fan of those carbs. Everybody who loves them claim they're simpler than a Holley, but everyone who lists their problems tells me otherwise. The only things that wear on a Holley are the power valve diaphragm and the accelerator pump diaphragm, both rubber parts that dry out if there's no fuel in the carb over long periods of time. And the throttle shafts wear into the bases if you use a return spring that's too stiff. The old complaint about them leaking stemmed from the old 1960's cork bowl and metering plate gaskets. That was corrected decades ago. As for the choke, unless you're in a cold climate and drive a lot in winter, they're pretty useless to me. I remove the whole assembly and baby the gas pedal a few minutes till it warms up. That mechanic sounds like he wants to sell you a new carb.

 

Every mechanic likes new shiny stuff as long as they aren't the ones paying for it.
Couple of things to look at.
Disconnect the throttle linkage and spring, then try to wiggle the throttle shaft, there should be little to no side movement at the base where the shaft go through the carb.
If there is your mechanic is right and the carb will never run correctly.
Take the air filter off and with the engine idling look down into the front of the carb to see if any fuel is dripping into the carb.
At idle all of the fuel should be going thru the idle circuits in the bottom of the carb and no fuel going in from the top, if there's any fuel entering from the top booster area ether the throttle blades are open to much or the float levels are to high.

There's hundreds of different recommended ways to break a engine in.
I like using the type of oil I'm going to run along with a bottle or two of zinc additive, no synthetics. After the initial cam break in I drive around 500 miles on secondary roads with stop and go traffic, no hot rodding. I live in hilly country so there's plenty of varying engine loads and rpm's.
After the 500 mile oil change I drive it like I would any other vehicle.

 

Sorry about my personal vocab. Instead of wonkey, I should have said the retaining clip/wire was disconnected and a little bent. Actually, I'm just a red neck dirt farm kid from the High Dessert of WA State. Go COUGS! (They wouldn't give me my diploma unless I promised to show some school pride)

Thanks, Destroked. Those evaluations were exactly what I need for my knowledge base. You have authored quite a file, already. Kirt

 

Hope it helps, i'm just a old dirt farmer from the hills of Ky, did spend a good amount of time herding diesel rigs around the country in the past.

 

I'm from New York, and been using "wonky" most of my life.

 

I've been drivin trucks for 41 years all over the country. And that's the first time I've heard "wonkey" :-missing Thought for sure he was from "down-under" with that word.