got a question on my 4 barrel Edelbrock carb. I have a stock 350, cam, turbo 350 trans, 2200 stall. I don;t have a kickdown cable installed (not sure if that is necessary, or pertains to the issue at hand). The coughing through the carb only happens when driving, it can rev while stationary without any issues. Between 1500-1800 rpm it pops (coughs) through the carb 4-6 times as I go through that rpm range and then it is fine once out of it. I have tried driving very easy, I have tried stomping on it and it doesn't matter, both ways it does it. I have been told by a mechanic that I took it to for tuning that Edelbrocks are not that tunable. We installed a fuel pressure gauge and regulator. it is runnin 7psi. We turned it up and down and nothing changed it. The timing is spot on...just have this issue that can't be tuned out.
Edelbrocks are as tunable as any other carb. Get an owners manual and a calibration kit for your carb. I'd probably start with stouter power valve springs and if that didn't work richen up the low speed jetting. You'll need to look at the chart in the manual for that. Larry T
thanks for the advice, I was at a car show yesterday and saw tons of edelbrock and was thinking... there is no way this many are used and not able to be adjusted... Guess I need to look for another mechanic when it comes to tuning a carb. I'll take the advice on the owners manual and kit.
Which Edelbrock carb are you talking about? They reproduce more than just the AFB version (I prefer the Quadrajet repro they make). They are all tunable. Edelbrock even sells kits that contain jets, needles, springs and so on for each model they reproduce. Most times, a backfire through the intake means it's lean or you have a valve that isn't shutting.
the calibration kit is a definite must to get the carb right. by following the chart for leaning in the owner's manual that comes with each carb, you can lean 4% by simply changing the rods and 8% by also changing the jets. it has been my experience that all the carbs are received "rich", and that leaning to 8% was a big improvement. also, the owners manual specifically states that fuel pressure should not exceed 6.5 psi, or the carbs tend to flood.
A quick test for the pop would be to advance the timing and see if it goes away. If it goes away have the dist. re-curved to match your engine combo. If it still pops look at the accel. pump operation.
I had a set of edlebrocks on my car for a bit and they did the same thing. It probably is your timing, thats what it was for me. Mine popped around 1500-2000 rpms when but once it warmed up it ran fine. I retarded my timing a little and it made all the difference. Play around with advancing and retarding it to se what is best for your specific setup.
If you have 7psi then the needle & seat is being overwhelmed and raw fuel is running into the engine, those carbs can take about 5 1/2psi
would the popping be lean or rich? I'll fiddle with the distributor a couple degrees each way to see if anything changes. The problem occurs no matter if it is hot or cold. One other thing I forgot to mention was there is a vacuum advance on the distributor that is not hooked up...should it be? I will also turn back the fuel pressure to 5psi. So it could be timing/fuel pressure and not carb issue at all?
you might try what mustang 9093 said...i have been running my edelbrock for about 5 yrs now...about 3 yrs ago was having a similar problem,and went to the edelbrock trailer...the guy went inside,gave me a new upper gasket and a new accelerator pump....like he knew there was a problem with them...never had a problem since...price was right too...free!
Call up Edelbrock and speak to one of there tech guys. They are preety helpful. I know that when it cam time to tune mine. I called them up a few times and in the end they sent me a set of metering rods and all the things I needed for FREE! It was awesome! J
Well, it -could- be. We don't have all of the information about your issue to make a accurate call. Was the carb just installed? Did it run fine before that? Did you have the distributor out and mix-up the firing order? Is the camshaft flat? Did you adjust your valves incorrectly? The list goes on and on... What's the entire story of the engine?
loudpedal pretty much nailed it... a lot more info is needed. But like was said back the pressure down to 5ish regardless. IF it's not a problem now it will be later...
It is popping because it is LEAN!!! in that range. Smaller needles may cure it or a bigger jet to over come the LEAN condition.
as already asked...which one? a 1405 is jetted for performance , a 1406 is jetted for economy and sometimes needs to be fattened up
Edelbrock carbs have to be really off to start changing jets, most improvements are through rod and spring changes. The springs are rated by vaccume and the rods like was said earlier control the amount of fuel flowing through the jet. I'm surprised you are not getting a surging feeling as well and those rpms are right in the transition mode of the carb. The carb has three modes, idle, cruise and power. Like also stated earlier each model of the carb, is set up different according to rod/jet size. Each rod is stamped with a number which indicates the size and step of it, the springs which the rod sits in is color matched to a certain vaccume. Here is the pdf owners/tuning manual http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf .
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