Need some edelbrock tuning help!

[bparsel]

Hey guys,

I have an Edelbrock 750 performer running on a 455Olds motor. I have adjusted everything and have the timing set perfect. Here is what is happening. In the driveway the boat runs perfect, however once on the water with a load (Jetboat) I have a great idle and it's running great at WOT. However my mid range is gone, the boat wont even come up on plane without going to wide open throttle. It seems like the the back 2 barrels are opening way too soon and its flooding the motor in the midrange. It is set up with the orange springs in the carb. It is also making an outrageously loud sucking noise when in the midrange as well but it eases off at WOT. The boat should come up easily on just the 2 front barrels, and my goal is to only have the back ones open with the last 1/4 throttle.

I'm used to tuning a quadrajet and this edelbrock has me puzzled. Any help or suggestions? I just switched out the quadrajet after getting a deal on this edelbrock.

 

[J. Mark]

Re: Need some edelbrock tuning help!

Edelbrock included a DVD with set up instructions with their new carbs. If you can't find one locally, let me know and I'll send you mine or try and burn a copy. There is a linkage at the rear that can be adjusted (there are three holes in it) Usually they are set in the middle, but you may need to move it to accommodate your motors needs.

I may also have the paper instructions with recommended metering rods, jets etc. If you still need it tonight I'll dig it off of my desk top.

 

[bparsel]

Re: Need some edelbrock tuning help!

Thank you very much for the offer. I didnt get a dvd with it. I've been trying to read through the manual on it, the spring adjusmtent based on the vacuum is where I was going to start first. I'm planning on just ordering all the different springs and seeing which works?

I have adjusted the linkage and needed to move back a hole, however I think I still need to adjust as the motor has a lot left when my throttle is tapped out.

 

[J. Mark]

Re: Need some edelbrock tuning help!

I found the DVD videos online here http://www.edelbrock.com/automotive_new/misc/tech_center/install/tech_vids.shtml

Hopefully they will be some help

 

[HT32BSX115]

Re: Need some edelbrock tuning help!

They also have a complete support site you can go to.

http://www.edelbrock.com/automotive_new/misc/tech_center/install/index.shtml

 

[J. Mark]

Re: Need some edelbrock tuning help!

http://www.edelbrock.com/automotive_new/mc/carbs_acc/pdf/carb_owners_manual.pdf

And here is the owner's manual

 

[bparsel]

Re: Need some edelbrock tuning help!

Thank you both very much, looks like I have some studying to do.

 

[Polar_Bus]

Re: Need some edelbrock tuning help!

Those Edelbrock carbs closely mimic the Carter AFB. I was a good Holley tuner for years, and then got the crazy idea to switch gears, and purchase an Edelbrock carb. BIGGEST MISTAKE OF MY LIFE. I could NOT get that Edelbrock to pull clean and hard. The method at which the Edlebrock metering systems function is completely oposite a Holley, and I realized you CAN'T use Holley tuning methods on the Edelbrock. Especially that funky Edelbrock pivoting secondary "weight" that opens via increased flow...

 

[bparsel]

Re: Need some edelbrock tuning help!

I'm glad someone else feels my pain. My Quadrajet took me about 10 minutes to dial in. I spent about 6 hrs last weekend messing with this Edelbrock and keep getting the same results. I have to be missing something stupid about it.

 

[wca_tim]

Re: Need some edelbrock tuning help!

I hear and echo some of the comments above regarding tuning these. but mine wound up working fine on my 383 after much hassle (maybe I'm just a slow learner?)... that carb has a very small idle circuit and often has a major off idle lean condition that is kind of hard to get rid of. the bug thing to work with first in your situation is experiment with the springs. What color spring are you running now? and what kind of vacuum are you pulling at idle?

You can play with the rods and jets all you want but until the right kick down spring is in there it is going to be lacking... or at least that has been my experience on both this carb and the analogous 600 version.

I wound up figuring it out after I tried all the springs and a number of jetting changes... then it was like OH, I get it...

 

[danond]

Re: Need some edelbrock tuning help!

In my experience, Edelbrock carbs work most of the time as a bolt-on-and-go carb, but when they don't, you get a Holley. Adjusting them just never made sense to me, and results weren't predictable.

 

[Polar_Bus]

Re: Need some edelbrock tuning help!

I hear and echo some of the comments above regarding tuning these. but mine wound up working fine on my 383 after much hassle (maybe I'm just a slow learner?)... that carb has a very small idle circuit and often has a major off idle lean condition that is kind of hard to get rid of. the bug thing to work with first in your situation is experiment with the springs. What color spring are you running now? and what kind of vacuum are you pulling at idle?

You can play with the rods and jets all you want but until the right kick down spring is in there it is going to be lacking... or at least that has been my experience on both this carb and the analogous 600 version.

I wound up figuring it out after I tried all the springs and a number of jetting changes... then it was like OH, I get it...

Now go bolt on a box stock Holley 600 CFM vac secondary and you will pull another 600 rpm's and gain another 20 hp....

All kidding aside, if those Edelbrock's were in fact the cats azz , they would be on top of all the weekend sprotsman drag race engines, but they are NOT....

 

[bparsel]

Re: Need some edelbrock tuning help!

I'm currently running the orange spring right now, which is the standard calibration spring set up for 5" vacuum.

So I'm hearing that my plan of just ordering the different springs and trying them is pretty much my best option? Or just go buy a Holley seems to be the other concensus

 

[wca_tim]

Re: Need some edelbrock tuning help!

I would try the springs. The edelbrock is a decent carb and should make just as much power on your set up as a holley... I'll look to see what spring I'm using... I think I'm using the silver one off the top, but haven't done anything with it in a while...

 

[wca_tim]

Re: Need some edelbrock tuning help!

Now go bolt on a box stock Holley 600 CFM vac secondary and you will pull another 600 rpm's and gain another 20 hp....

All kidding aside, if those Edelbrock's were in fact the cats azz , they would be on top of all the weekend sprotsman drag race engines, but they are NOT....

Straight up, the guy that built my current engine said they ran a baseline 383 build using off the shelf parts with several carb, intake and exhaust combinations and that the edelbrock (750) marine carb made great power off the shelf...

I had great results with an edelbrock 600 on my 4.3, with the current 383 the 750 edelbrock is working ok although it was a pita to get dialed in, but The next time the boat goes in the water it'll be a 750 holley square bore with mechanical secondaries on top the intake...

 

[bparsel]

Re: Need some edelbrock tuning help!

Geez, this thread isnt boosting my confidence in getting this thing tuned in.

 

[n2ostroker]

Re: Need some edelbrock tuning help!

I was hoping wca tim would chime in. I'm interested in what parts you're using in the Edelbrock.I'm going to attempt some tuning this weekend on my 750 Edelbrock carb.

I like the Edelbrocks cause they work similar to a motorcycle carb with the needles, springs and jets on vacuum secondaries. You can really dial them in for all throttle operation. At least Edelbrock tries to narrow down the selection of parts to get it right. Holleys are foreign to me and qjets have too wide an assortment of parts to guess at when tuning a completely new combo.

Also the Edelbrock is a rebadged carter/afb/weber carb.

 

[n2ostroker]

Re: Need some edelbrock tuning help!

Geez, this thread isnt boosting my confidence in getting this thing tuned in.

Just put in some time, write down what you've tried and how it worked. It'll start to come together then you'll be able to predict behavior of the parts you change. Then making changes will be easier and quicker. Just takes a little patience and trial and error.

 

[bparsel]

Re: Need some edelbrock tuning help!

I'm going to have to be patient I guess, of course the local shop by my house has to order the springs even though theyre an edelbrock distributor.

I guess I had dreams of grandeur when I got the carb originally that I would just bolt it on and it would perform. So all of this dialing in is frustrating.

 

[n2ostroker]

Re: Need some edelbrock tuning help!

Get the Edelbrock 1480 calibration kit. Then you'll have everything thing you need to tune it. Springs, jets and rods.