Which adjustment on Edelbrock chart for rich at WOT?

[evan]

To adjust wide open throttle air fuel ratio do I need to adjust the main jet and metering rods based on the chart or the secondary metering that is noted to the side of the chart?

After rebuilding and re-jet here are my results:
Idle: mid 12's
Part throttle acceleration: mid 12's
Highway cruising: mid 14's
Letting off the accelator: mid 12's
Wide open throttle: low 10's.

According to the manual I'm in the ballpark for everything except the wide open throttle.

[AcampoDave]

I would change the secondary jets. If you change the main rod/jet combo you will lean out the WOT along with all the rest. Doing the secondary only should not affect the other parameters.

[burnin oil]

If the motor isn't a race engine I would say you are rich across the board. 12.5:1 is the WOT ratio. Idle should be closer to 14 without the choke. Now your ratios look good for a wild cam that's run on the street. Every motor has different AFR requirements but slightly lean usually makes more power. Rich is a safety margin that kills mpg and sparkplugs.

[AcampoDave]

So I'm assuming you have an AFR guage. I'm going to do one this winter. If I may ask, Which one do you have?

[evan]

Originally Posted by AcampoDave

So I'm assuming you have an AFR guage. I'm going to do one this winter. If I may ask, Which one do you have?

I’m using an older version of this one.
https://www.innovatemotorsports.com/...-kit-8-ft.html

[geezer#99]

When you re-jetted do you go richer or leaner than the stock set up?

[evan]

Originally Posted by burnin oil

If the motor isn't a race engine I would say you are rich across the board. 12.5:1 is the WOT ratio. Idle should be closer to 14 without the choke. Now your ratios look good for a wild cam that's run on the street. Every motor has different AFR requirements but slightly lean usually makes more power. Rich is a safety margin that kills mpg and sparkplugs.

I agree. I’d like to get it leaned out closer to 14 everywhere.

I went for a quick drive tonight and it was shooting up to 17-18 on part throttle cruising. I’m leaving town for a week but when I get back I’ll let it warm up fully, do another test drive and if it’s still doing weird things I’ll pull it off again to make sure I didn’t screw it up the first time. I’ll double check the metering rod spring strength too.

[evan]

Originally Posted by geezer#99

When you re-jetted do you go richer or leaner than the stock set up?

Leaner. I went to setting 7 and one stage leaner on the secondary jet.

[burnin oil]

If this was a holley I would say the air bleeds were off causing the lean out. It sounds like the idle circuit is running out of fuel before the primary sides main jets are coming in. I have a feeling that the main jet is to large also. I just don't know how to adjust this on the edelbrock carb.

[Dead Parrot]

The Doug Roe Rochester Carb books shows 16 as the ideal A/F for economy on part throttle cruise with 15~17 as being OK. For power he has 12.5 as ideal with 11~14 as OK.

For idle, you want as lean as possible while still getting a smooth idle. (Assuming a OEM cam). The shade tree mechanic method was set timing and idle rpm, then adjust idle mix for max rpm, then lean a 1/4 turn on each screw. Then readjust idle rpm to desired.

What initial timing are you using?
Do you have one of the Eddy calibration kits with the variety of jets, rods and springs?

[evan]

Originally Posted by Dead Parrot

The Doug Roe Rochester Carb books shows 16 as the ideal A/F for economy on part throttle cruise with 15~17 as being OK. For power he has 12.5 as ideal with 11~14 as OK.

For idle, you want as lean as possible while still getting a smooth idle. (Assuming a OEM cam). The shade tree mechanic method was set timing and idle rpm, then adjust idle mix for max rpm, then lean a 1/4 turn on each screw. Then readjust idle rpm to desired.

What initial timing are you using?
Do you have one of the Eddy calibration kits with the variety of jets, rods and springs?

Yes, I have the Edelbrock 1487 calibration kit. That gets me the rods and jets to achieve the black circles on the chart I posted above. I'm at the #7 with 1425 secondary jets as well (one stage lean).

Here are the specs from my cam. It's got a bit of a choppy idle.
Duration at 050 inch Lift: 227 int./241 exh.
Advertised Duration: 279 int./297 exh.

[geezer#99]

What’s your initial timing?

[Dead Parrot]

Do you have a vacuum gauge? Wonder if the cam is keeping vacuum a bit low and causing the power pistons to lift and run rich? Might try one spring level difference and see what that changes. At least those can be swapped without lifting the carb top.

[evan]

Originally Posted by geezer#99

What’s your initial timing?

10 degrees at idle. 31 at 4100rpm.

[geezer#99]

Originally Posted by evan

10 degrees at idle. 31 at 4100rpm.

Not nearly enough.
You should be running up close to 18 to 20 degrees.
At your elevation you need to start the burn earlier.
More initial also let’s you turn down the idle on your carb getting it back idling on the idle circuit.
Right now you’re likely idling on the power circuit.

[evan]

Originally Posted by geezer#99

Not nearly enough.
You should be running up close to 18 to 20 degrees.
At your elevation you need to start the burn earlier.
More initial also let’s you turn down the idle on your carb getting it back idling on the idle circuit.
Right now you’re likely idling on the power circuit.

Thanks! I'll adjust it as soon as I get back from the family camping trip.

[geezer#99]

Sneak up on the max initial. Try 14 first and see if that changes your afr’ s. Then bump it 2 degrees.
Listen closely for pinging though.
A good way to see if you’re idling on the power circuit is to adjust either mixture screw in slowly to see if the motor wants to quit.
Where do you go camping?

[evan]

Originally Posted by geezer#99

Sneak up on the max initial. Try 14 first and see if that changes your afr’ s. Then bump it 2 degrees.
Listen closely for pinging though.
A good way to see if you’re idling on the power circuit is to adjust either mixture screw in slowly to see if the motor wants to quit.
Where do you go camping?

When you say watch AFR’s, is it likely to be going more lean or more rich?

We’re heading to Jasper, AB. I’ve been through a few times but never stayed. Looking forward to it.

[geezer#99]

It’ll go lean.
Good place to go to.
Stayed there a few times.
Went up on the ski hill gondola and to Miette hot springs.
One of my old trucks is still around there. A white 56.
Have a good time.

[evan]

Originally Posted by geezer#99

It’ll go lean.
Good place to go to.
Stayed there a few times.
Went up on the ski hill gondola and to Miette hot springs.
One of my old trucks is still around there. A white 56.
Have a good time.

We’re back that was a great trip. Went up the gondola and hiked the rest of the way to the summit. Amazing experience. Didn’t make it to the hot springs but the whole family had a great time.

Ok, I set the initial timing with the vacuum advance hose disconnected. It gained idle rpm and smoothed out more and more the higher I went. Stopped at 18 degrees and figured I’d check total timing. Tightened down the distributor, set idle to 800 rpm, plugged the vacuum advance hose, and the rpm jumped up a few hundred rpm. Checked timing and it was at 37 degrees.

Is it normal to have the timing jump 19 degrees when the vacuum advance is plugged in?

[geezer#99]

Yup.
But your 19 degrees from vac pot might be partly mechanical timing starting to kick in. Most start to kick in near 800 anyway.
Get it to idle down as low as you can then check timing.

[evan]

Originally Posted by geezer#99

Yup.
But your 19 degrees from vac pot might be partly mechanical timing starting to kick in. Most start to kick in near 800 anyway.
Get it to idle down as low as you can then check timing.

I set idle to 650 and it’s about 33 degrees at idle (vac line still plugged into the distributor).

[evan]

And at 2500 rpm it’s at 48 degrees advance.

[evan]

https://youtu.be/TF03snllO_A

Seems to start fine.

[geezer#99]

You can’t count the vac advance until it starts, so you’re only starting with 18 initial.
I had a rowdy 350 once. More cam than yours. 10 to 1 compression, trick flow heads.
I ran 22 initial, 12 from mechanical plus a limited 10 degrees from vac pot.
Used a limiter like this one in the link.
I can tell from the way yours starts that you’re close with timing.
Sounds good.


https://www.summitracing.com/parts/m...yABEgKeI_D_BwE