Edelbrock problems

[69greenleaf]

hello all. I have been having hesitation issues when snapping throttle open quickly. I have a 1406 series 750cfm edelbrock on a almost stock (headers and slight cam) 440. I have already rebuilt the accelerator pump and adjusted it as well hoping to fix this problem. But it never fails to lag and hesitate when the throttle is quickly opened. I had bought the carb used, and do not know what cid engine it originaly came off of, but I can only assume it was a sbc, and that the metering and jetting are just too far off for my large cubic inch engine. I am wanting to go through and put new jets and metering rods, the only problem is I don’t know enough about sizing them to just dive into it. If anyone has any suggestions or tip please send them my way, they will be greatly appreciated!

 

[Bill Monk]

Before you do that, are you absolutely sure your timing is right?

 

[Charged440]

The factory book says a 1406 is a 600 performer carb that has a .098 primary jet and a .095 secondary with the .075 x .047 metering rod with orange springs, the manual is available online and has lots of good info. I just went through the same thing for a 1407.

 

[lewtot184]

The factory book says a 1406 is a 600 performer carb that has a .098 primary jet and a .095 secondary with the .075 x .047 metering rod, the manual is available online and has lots of good info. I just went through the same thing for a 1407.

this is correct. i'd try a 70x47 metering rod. of course there may be other issues than the carb.

 

[69greenleaf]

Before you do that, are you absolutely sure your timing is right?

I am fairly certain. I had fought with it for a while though. Just when I thought it was right I would kill the car and it would be too advanced to start back up. I believe it is correct now at about 12-14befor tdc and either way I adjust will start to stumble the engine, and will fire right up even when dead cold. Car will Cruze and idle smooth and if I roll into the throttle it acts fine, only having problems when the throttle is rapidly opened.

 

[69greenleaf]

The factory book says a 1406 is a 600 performer carb that has a .098 primary jet and a .095 secondary with the .075 x .047 metering rod with orange springs, the manual is available online and has lots of good info. I just went through the same thing for a 1407.

The carb is a 1407 750cfm lol pardon my fat fingers.

 

[lewtot184]

some of those larger edelbrocks are jetted too fat OOTB. i'd take a que from the factory jetting for those carbs. the '67 375hp 440 had a carb that was identical to the 750 edelbrock in venturi and bore size.

 

[Charged440]

Ha haha, me too! specs for the 750s are different, everything you need to know is here

http://www.edelbrock.com/automotive/misc/tech-center/dl/carb-owners-manual.pdf

 

[moes]

I have been having hesitation issues when snapping throttle open quickly.

Does this happen when the car is just sitting in the driveway and you snap the throtle open or when you are driving it and you step on the gas? When you say you adjusted the accelerator pump what did you do? You need a big squirt of fuel for a big CID motor. Did you place the rod in the top of the three holes on the accelerator pump to give the carb the biggest shot of fuel? Next I would check the floats out to see if they are adjusted to the correct height (you want 7/16 of and inch for the height), you will have to take the top off the carb and flip it upside down to check this (I use a 7/16 drill bit for the measurement). For a carb everything has to be done in stages. I would check these two things first and then go on to the jets and metering rods next. Come back and lets us know after those two adjustments to see if they help and then we can work from there.

 

[Ranger16]

Read up on CALIBRATING THE POWER MODE STAGING in the link Charged440 posted regarding the "step up springs". It sounds like that may be your problem.
Then check the troubleshooting chart lower down.

 

[khryslerkid]

You said you rebuilt the accelerator pump. Looking in the carb, do you get a good shot when pulling back on the throttle? I've heard that the blue one doest work very well and the orange or brownish colored one is better.

Here's a good article for troubleshooting the Edelbrock for hesitation...
http://jgronoj.weebly.com/hesitation-or-bog.html

 

[lewtot184]

blue pumps are rubbish. also the check valve may be missing.

 

[khryslerkid]

blue pumps are rubbish. also the check valve may be missing.

Yep. The rebuild kits for my 600's came with blue ones. I didn't hear about the orange ones until after I rebuilt them. I've noticed the rear carb is weak on the squirt. It's on my list!

 

[Johnpat]

Is your timing advancing when you snap
the throttle.
Check your advance???

 

[rlem1977]

I am fairly certain. I had fought with it for a while though. Just when I thought it was right I would kill the car and it would be too advanced to start back up. I believe it is correct now at about 12-14befor tdc and either way I adjust will start to stumble the engine, and will fire right up even when dead cold. Car will Cruze and idle smooth and if I roll into the throttle it acts fine, only having problems when the throttle is rapidly opened.

If you bought it used, and you believe the previous owner changed jets or metering rods, you should buy jet gauge and Edelbrock's 1480 kit and get the carb back to factory. Make sure the step-up spring is the orange 5"Hg spring.

Did you use a vacuum gauge when timing the engine? If not, you should do so. Once properly timed, and the car idles where it should, then you can tackle any stumbling/hesitation issues and adjust jets and rods and springs (oh my!) to fine tune. Don't go messin' with other stuff yet until you're sure the carb is in order.