Hopefully an easy Edelbrock question

[crash89]

It has been a long time since I have had to work with a carb, so please keep that in mind...
I have a '69 RR with what seems to be a stock/mild 383. It still has the stock intake and exhaust on it. I have no history on the car. I bought it through a dealer who had little documentation.
When I got the car, it had an Edelbrock 750 on it. It ran like crap and ran very rich. Rich to the point that it ran stinky. Pulled the plugs and they were fuel-soaked. No real worries, I expected that.
I replaced the 750 with a 600. Runs much better but now has a miss when accelerating or cruising in the middle RPMs and is down on power at WOT. I pulled the plugs and it is running very lean. Being an Edelbrock 1406, I kind of expected that, as well.
My question is around jet size.. I assume someone that has more experience that I do has run into this. What size jets should I be running? I assume I have to go at least a step or two higher and am looking for some advice from someone who has run into this.
Thanks in advance.

 

[Lionized]

I'm running the 1405 on my 383 and I was actually considering stepping up to the Street Demon 750. I may just order the calibration kit from Edelbrock and mess around with this carb. I'm having pretty much the exact same problems as you are. Stumble/miss at part throttle, no real bottom end. I have a mild Comp Cam, Mopar dual plane intake, HP manifolds and a 2400 TCI stall with 3:55 gears.
In theory this car should run like a scolded cat.

 

[crash89]

I thought about down-jetting my 750.. But I figured up-jetting the 600 would be more efficient. I ordered the tuning kit already. I was just looking for a good place to start with the jets. The 750 was way too much carb for this motor.

 

[Lionized]

Do you have the specs for the 1406 already? That'll show you where to start.

I'm fairly certain there are guys on this board who'll let us know what they've found to work.

 

[crash89]

Do you have the specs for the 1406 already? That'll show you where to start.

I'm fairly certain there are guys on this board who'll let us know what they've found to work.

I do. And that's exactly what I am looking for.. Known working combinations. I can work with it from there. If I don't hear, I'll post my working combo when I am done with it.

 

[lewtot184]

the 750 and 800 edelbrocks are jetted stupid rich ootb. the 1406 probably needs a metering rod change. i'd try a .071x.047. using a factory style 383 fuel pump is usually an issue. they weren't any good in the '60's and nothing has got better since then. if you want to play with the 750 try a .104 primary jet with a .068x.047 metering rod. i always down size the squirters for driving, nothing bigger than a .028.

 

[crash89]

the 750 and 800 edelbrocks are jetted stupid rich ootb. the 1406 probably needs a metering rod change. i'd try a .071x.047. using a factory style 383 fuel pump is usually an issue. they weren't any good in the '60's and nothing has got better since then. if you want to play with the 750 try a .104 primary jet with a .068x.047 metering rod. i always down size the squirters for driving, nothing bigger than a .028.

Thanks for the info! The kit should be in tomorrow and I'll have some time later in the week to try it out.

 

[Darter6]

Not sure if it comes with the kit but Edelbrock has a booklet with many jetting/metering rod scenarios that may be helpful.

 

[crash89]

Not sure if it comes with the kit but Edelbrock has a booklet with many jetting/metering rod scenarios that may be helpful.

I do, but was also wondering if anyone had solved the same issue. I am going to try replacing the Metering Rods first, then go from there, if needed.

 

[SlinktRR]

I do, but was also wondering if anyone had solved the same issue. I am going to try replacing the Metering Rods first, then go from there, if needed.

Look in your owners manual for the carb it will have a chart for jet and rod sizes. it's going to be down on power because that is a small carb for a big block but you can certainly run it and be happy. find out what secondary jets are in there and go 1 to 2 sizes up first to see if that helps make it run smoother on the throttle. you can change those with just a screwdriver. you can also change metering rods (even easier), smaller number means richer. Probably want to go 1 size richer. small changes can make a big difference, take notes as you go.

 

[crash89]

Look in your owners manual for the carb it will have a chart for jet and rod sizes. it's going to be down on power because that is a small carb for a big block but you can certainly run it and be happy. find out what secondary jets are in there and go 1 to 2 sizes up first to see if that helps make it run smoother on the throttle. you can change those with just a screwdriver. you can also change metering rods (even easier), smaller number means richer. Probably want to go 1 size richer. small changes can make a big difference, take notes as you go.

Understood.. The first thing I need to solve for is the part-throttle issue. It is way too lean. So I am going 2 steps up on the rods to start. After that is solved, I'll work the secondaries. I'll be making small changes until it is right. It has been a long time since I have worked with carbs.. Thanks all for the input! If the 600 can't be made to work, I'll work with the 750 and see how that goes.

 

[lewtot184]

should have .095 jets in back, 600 or 750. wouldn't need anything bigger than .098. fuel pressure check is in order. if you look in the manual you'll notice that 4% changes are considered a step. what they are referring to is a step is 4% difference jet area not number or drill size.

 

[lewtot184]

thinking back when i had a stock 383 with the avs i used .093 jets square with a 68x52 rod. there isn't any big differences between the stock avs, 600's and 650's. looking back at all the afb's with the 1 9/16x1 11/16 secondary ( same as 600 and 750 edelbrocks) they used an .089 jet. there really isn't any need for something bigger than the .095.

 

[coloradodave]

You should be able to get your motor running perfectly fine with a 600. Jetting and metering rods will determine whether it's rich or lean at cruise or full throttle. Float level, float drop, idle mixture screws and accelerator pump adjustments all have to be right for a carburetor to function correctly. With stock intake and exhaust manifolds there really isn't any need to go to a 750. BTW, the same goes for the bigger carburetor. All adjustments need to be right in order to run smoothly.

 

[dvw]

We've run easy 12.80's with a 8-1 440 using the 600 Eddy so I doubt that power will be an issue on a mild 383. I've found the the accelerator pump link likes the hole closest to the arm pivot point. That may be all it needs. Make sure the floats are set right, air bleeds are clean and the seats a screwed in tight. My bet is the stock jets are very close. Possible with your combo it might need a metering spring change. The stronger the spring the early the metering rod will rise enriching the mix under load quicker.

Doug

 

[lglenn]

Hello to everyone on this thread. I'm new to the forum and found this conversation close to my issue. I have a 69RR and the conversation sounds similar to what I'm fighting. Off idle mild acceleration, and sometimes just cruising it will stumble and spit back through the carb. I have a 383 with 440 heads, Weiand 8008 intake, and the Edelbrock 1406. It's been frustrating for sure to try and figure this one out. Where you able to resolve your issue?

 

[crash89]

Hello to everyone on this thread. I'm new to the forum and found this conversation close to my issue. I have a 69RR and the conversation sounds similar to what I'm fighting. Off idle mild acceleration, and sometimes just cruising it will stumble and spit back through the carb. I have a 383 with 440 heads, Weiand 8008 intake, and the Edelbrock 1406. It's been frustrating for sure to try and figure this one out. Where you able to resolve your issue?

Still testing.. I am getting close. I have changed rods and springs. It has quieted a bit. I'll move up one more step this weekend and see how it goes.

 

[lewtot184]

Hello to everyone on this thread. I'm new to the forum and found this conversation close to my issue. I have a 69RR and the conversation sounds similar to what I'm fighting. Off idle mild acceleration, and sometimes just cruising it will stumble and spit back through the carb. I have a 383 with 440 heads, Weiand 8008 intake, and the Edelbrock 1406. It's been frustrating for sure to try and figure this one out. Where you able to resolve your issue?

spitting up thru the carb is either a lean condition or late timing or a combination of both.

 

[383man]

You should be able to get your motor running perfectly fine with a 600. Jetting and metering rods will determine whether it's rich or lean at cruise or full throttle. Float level, float drop, idle mixture screws and accelerator pump adjustments all have to be right for a carburetor to function correctly. With stock intake and exhaust manifolds there really isn't any need to go to a 750. BTW, the same goes for the bigger carburetor. All adjustments need to be right in order to run smoothly.

I agree as myself I like the Holley on my car but the Eddy AFB and AVS style carbs can really be tuned very well with using metering rods. You can do alot with them in tuning the idle , cruise and full throttle sytems and it may take some patience and time but they can work very good when tuned in. Good luck with yours , Ron

 

[crash89]

Okay.. Here's what worked on mine. YMMV. .101 on the main jet and 075x047 on the metering rod. I drove and it was close. I put 3 degrees of advance back in it and it really woke up! I am going to wait until the weather breaks until I test more. It is 19 degrees here today and salt on the road, so I don't want to drive it too much. But it is TONS better.