Secondaries no help

[fallguy]

1406 edelbrock. When my secondaries should be kicking in nothing additional happens. I have no power gains or ability to keep pullin to a higher speed. I'm wondering if my secondary jets are too rich (rich bog) or lean?

I can roll the tires off the line and it pulls hard up to the point of my throttle should be opening the secondaries and when they do open....nothing additional. No more power or performance. I can tell it's about wound out but the tyranny will give more if the engine would keep making power and with the new cam I should feel some top end too rather than nothing.

The question. Primary jets .98 down from .104 causing an increase in power....so I had a rich bog there. But the secondaries are .89 and fall flat. So too big or too small???

 

[rich weyand]

Stock is .098 primary and .095 secondary, so you are back to stock primaries, but the secondaries are lean compared to stock.

One problem I had: there is a lockout on the secondaries when the choke is engaged. As the electric widget shuts off the choke, it enables the secondaries by rotating a little widget. It's in tight quarters, too. So if it sticks, or if the little rotating thing catches on the cam next to it, no secondaries. I tinkered with it until I got it to work again.

You can check if this is it easily. Take off the air cleaner. Warm engine (choke off) but engine off. Just pull the throttle cable all the way and see if the secondaries open. No open, then that's the problem. Check that choke linkage lockout. You'll see it on the passenger side blocking the secondaries from opening. I think the secondaries lock cam that works the passenger side widget is actually on the drivers side in with all the throttle linkage stuff. Been a while since I had to fool with it. As I recall, it was wobbly on its shaft and caught some other cam on the same shaft. I put a thin washer in there to take out the wobble and space them apart and then it worked fine.

 

[fallguy]

Edelbrock tells me to plug vacuum advance into passenger side port (eventho I have no emission stuff) and put secondaries to .098 as well.

 

[rich weyand]

No. Manifold vacuum, per their documentation. I run .095 secondaries and you know when they're open!

Did you check to see if the choke secondaries lockout is stuck? Basically, do the secondaries open properly with the engine off (but warm) when you just floor the throttle all the way? There is no indication that this is happening other than you don't get secondaries. I mean, the throttle pedal doesn't feel any different or anything, you just don't have any secondaries.

For that matter, have you adjusted the choke properly? If it is not opening all the way, it will lock out the secondaries.

 

[fallguy]

I'll up my existing .089 to .095 first. I'll leave the vacuum advance where it is. I'll do that warm engine diagnostic as you describe....that part confuses me but I'll try. I'll ignore the edelbrock guys advice for now and try it your way first.

 

[rich weyand]

Shouldn't be confusing. On a warm engine, with the engine turned off, have somebody push the throttle pedal all the way down and see if the secondaries open. You don't even need to take the air cleaner off. Just watch the shaft of the secondary throttle plate on the passenger side and see if it turns.

In this pic, there are two shafts behind the choke canister. The second one (the one all the way to the left) is the secondary throttle shaft. This should turn almost 90*, beginning when the throttle pedal is 2/3 of the way down, and finishing its turn when the throttle pedal is all the way down. If it doesn't turn, the choke lockout is stuck.

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[fallguy]

Rich, thank you for the pic. I'm an idiot when it comes to this carb so I'm tryin to learn and not many seem able to help anymore.

 

[rich weyand]

So do the secondaries open or not?

 

[fallguy]

I am currently several hours from the truck and will not return until Sunday. I will find out and report back ASAP.

 

[fallguy]

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Ok, I have verified when truck is at operating temp that the secondaries DO open. The bottom mechanism does move about 90 degrees downward from the rotation.

I took off air cleaner, held open secondary top weighted flap to see the secondaries actually opening under full throttle.

Also I verified that at operating temp my choke flap is straight up and down in the vertical position so that the secondaries will be allowed to open. (Edelbrock tech support suggested that idea as the choke spring can become weak and then the choke cap needs to be wound counterclockwise until the choke flap sits perfectly vertical when at operating temp)

I removed my .089 secondary jets and replaced them with .095 as instructed.

I will test drive later to see if I notice a change. I have NOT switched my vacuum line to the timed vacuum side (passenger side port) and have kept it on the manifold vacuum side(driver side port)as I currently have it.

 

[rich weyand]

What rods are in the primaries?

 

[fallguy]

68/42 rods, pink springs and fuel pump shot at bottom hole for max shot.

The carb has always had a flat spot so Edelbrock recommended those rods and springs to eliminate that dead zone.

First I tried moving the pump shot arm from least, top hole, to most, bottom hole...but that did not solve the issue. When I switched the rods and springs to as stated....no more dead spot.

I was running 71/47 rods then tried 73/42 but that resulted in no helpful change.

 

[rich weyand]

.068 with .098 jets is about right on the cruise circuit, maybe a little lean, but .042 with .098 jets sounds awful rich on the power circuit. .065/.057 is closer. (Edelbrock #1461)

What is your base timing set at? Are you sure the mechanical advance is coming in?

To check the base timing, measure the timing with the vacuum advance disconnected.

To check that the vacuum advance is coming in, read the timing with the vacuum advance connected.

To check that the mechanical advance is coming in, read the timing with the vacuum advance disconnected and the engine running at 3000 rpm.

You should get numbers like 16* BTDC base, 31* BTDC base + vacuum, and 36* BTDC base + mechanical. You can also run 14/29/34 if you want more safety margin to the detonation limit.

 

[fallguy]

I have ordered the 65/57 rods and will put them in when they arrive. My timings is 16 and my vacuum advance is 12. I can roll the tires from a dead stop but i feel like the secondaries should be more help. Maybe the rods will trip that barrier....I'll report back next week when I know more.

 

[fallguy]

Rich Weyland....I have a question for you.

How do you know what rods and combo I need or which set is rich or lean or what ever? I'm a bone head about this stuff and have viewed the Edelbrock chart a million times but still can't get it and the rods I have or you've suggested, I don't see listed.

The metering rods arrived yesterday so when I get back I'll put them in, but my current configuration has made a difference, but under load with the secondaries I've seen slight improvement but there should be more (pulled a camper 120 miles to test it)...so I hope that the new suggested rods do the trick!