Edelbrock carb tuning question.

Posted By: Six Popper

Edelbrock carb tuning question. - 03/05/10 01:59 AM

I have a mild built 360 with a 650 Edelbrock carb it runs pretty good while only in the front two barrels, but when you step on it it stumbles puffs a little smoke then picks up and goes. The engine is not a fresh build but isn't wore out by any means. I am going tomorrow to get a vacuum gauge but I won't lie I am clueless as to how I need to tune it properly. I would like for it to run crisp if that means running a smaller carb then thats what I'll do, but I'm positive this carb should be tunable to acomodate this engine. Thanks in advance Chris.

Posted By: RapidRobert

Re: Edelbrock carb tuning question. - 03/05/10 02:18 AM

Well I have an eddy 1406 (elec choke) on a stock 318 and it stumbles/runs lean and I have not got it worked it out. float level is right and the AP squirts immediately. Gonna play w rods/jets/springs and the choke some more. Plus try my 1805 (600 cfm) holley

Posted By: scratchnfotraction

Re: Edelbrock carb tuning question. - 03/05/10 02:26 AM

bump up the timing and use tha vac gauge to get the highest vac reading

that will get you in the ball park

I can stomp mine on the 318 from an 850 idle and it wont skip a beat all the way to 5000rpms

never got the eddie 750 to do that

adjust the rod for the biggest pump shot on the AP

Posted By: RapidRobert

Re: Edelbrock carb tuning question. - 03/05/10 02:32 AM

Quote:

I can stomp mine on the 318 from an 850 idle and it wont skip a beat all the way to 5000rpms

Thanks Scratch, it sounds like I have some work to do

Posted By: Lefty

Re: Edelbrock carb tuning question. - 03/05/10 06:35 PM

I would try to increase the accelerator pump shot first. Also, make sure the accelerator pump diaphragm is not leaking or torn by removing it and looking.

Edelbrock sells calibration kits for the carbs they sell as well as having a good tuning guide in the manuals.

http://www.edelbrock.com/automotive_new/mc/carbs_acc/access_calibrate.shtml

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

Posted By: MileHighDart

Re: Edelbrock carb tuning question. - 03/05/10 07:06 PM

Quote:

I would try to increase the accelerator pump shot first. Also, make sure the accelerator pump diaphragm is not leaking or torn by removing it and looking.

Edelbrock sells calibration kits for the carbs they sell as well as having a good tuning guide in the manuals.

http://www.edelbrock.com/automotive_new/mc/carbs_acc/access_calibrate.shtml

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

Bingo, I bought one of their tuning kits, that comes with different size jets and metering rods, and a tuning guide to help you figure it all out. I had to tune for high elevation.
I had the same "stumble" problem your talking about, and cured it my changing jets and rods and studying the tuning guide.

You of course have to take the top off the carb to change the jets/rods. Just remember to reconnect your fuel line before firing up the engine, you could set your engine on fire ! dont ask how I know

Posted By: scratchnfotraction

Re: Edelbrock carb tuning question. - 03/05/10 07:17 PM

set yourself on fire

I have had that happen,now I use an old dish soap bottle to safely prime one

Posted By: patrick

Re: Edelbrock carb tuning question. - 03/05/10 07:20 PM

Quote:

Quote:

I would try to increase the accelerator pump shot first. Also, make sure the accelerator pump diaphragm is not leaking or torn by removing it and looking.

Edelbrock sells calibration kits for the carbs they sell as well as having a good tuning guide in the manuals.

http://www.edelbrock.com/automotive_new/mc/carbs_acc/access_calibrate.shtml

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

Bingo, I bought one of their tuning kits, that comes with different size jets and metering rods, and a tuning guide to help you figure it all out. I had to tune for high elevation.
I had the same "stumble" problem your talking about, and cured it my changing jets and rods and studying the tuning guide.

You of course have to take the top off the carb to change the jets/rods. Just remember to reconnect your fuel line before firing up the engine, you could set your engine on fire ! dont ask how I know

top can stay on for rod/spring changes(loosen cover screws and rotate cover out of the way), not jets....mine, I have a 6-8" rubber hose from the fuel hard line, so I don't need to disconnect it.

check and make sure the floats are the right height, and play with the acc pump positions. the nearest hole to the body gives the biggest pump shot. what is your idle and cruise vaccuum? odds are, you'll need to swap out the step up springs to the stiffest ones.

Posted By: Six Popper

Re: Edelbrock carb tuning question. - 03/05/10 11:22 PM

I didn't get a chance to work on the carb today, I spent most of my day after work putting a injector harness on my father in laws F250 Yuck. I did fix my header leak though. I will get a vacuum gauge tomorrow and start there, I will also look into getting one of Edelbrocks tuning kits. I like the idea of haveg a assortment of metering rods springs and jets. We don't have a local dealer so if I were to buy them one at a time guessing what I needed I would spend a fortune in shipping. Thanks for the help guys.

Posted By: volaredon

Re: Edelbrock carb tuning question. - 03/06/10 12:01 AM

as long as it's over 30*F out (or the engine is completely warm) I can stomp mine and it GOES! '83 318. Only trouble with my Eddy on my truck is the tuning of the choke. if I crank the elec choke tighter it lopes like it has a full race cam in it; It's like it needs less tension (easy to do) but come off "slower" (not as easy)

Posted By: Anonymous

Re: Edelbrock carb tuning question. - 03/06/10 12:15 AM

Quote:

I didn't get a chance to work on the carb today, I spent most of my day after work putting a injector harness on my father in laws F250 Yuck. I did fix my header leak though. I will get a vacuum gauge tomorrow and start there, I will also look into getting one of Edelbrocks tuning kits. I like the idea of haveg a assortment of metering rods springs and jets. We don't have a local dealer so if I were to buy them one at a time guessing what I needed I would spend a fortune in shipping. Thanks for the help guys.

change your metering rods to a smaller number like a 6552, that will richen you up off of tge primaries gradually progressing into your secondaries. you also need to find out what metering jets you have in there. also put the accelerator pump in the top hole.for more pump squirt.

Attached picture 5847478-CARTER750CARBS9755S.SUSHI007.JPG

Attached picture 5847478-CARTER750CARBS9755S.SUSHI007.JPG

Posted By: Six Popper

Re: Edelbrock carb tuning question. - 03/06/10 01:27 AM

I moved the pump up for more fuel first hole next to carb it helped alot, but the transition to WOT is still not as smoth as it should be. I will inspect the metering jets and get vacuum readings and go from there.

Posted By: 383man

Re: Edelbrock carb tuning question. - 03/06/10 07:08 AM

I dont remember if that is an air valve secondary but if it is you need to tighten the spring a little. If it is to loose it will open to quick when you nail the back barrels and stumble only when you hit it hard. Ron

Posted By: 451Mopar

Re: Edelbrock carb tuning question. - 03/06/10 08:08 AM

Correct float level is the most important, if the fuel level in the bowls is too low, all the other changes won't make much difference. Start car/fuel pump to make sure fuel bowl is full, shut off car/fuel pump and pull top of carb and fuel level should be about the same height as the notch in the fuel bowl baffels. If fuel level is lower, adjust the floats.