Idle problem, transfer slots

[BelvedereSatellite1966]

850 dp is not to big. When I was in high school my friend had one on his 68 roadrunner. Ran fine. Seemed like every big block had a 850 dp.
Stumbles when the secondaries open. What does your gauge say when this happens? With a big cam and big shooters you might be using up the shot to quick. Smaller shooters lenghten the duration of the shot. That spring on the linkage can compress and then extend keeping the shot going after the pedal reaches wot. Have you looked at your gauge while its stumbling? What color is the exhaust when it stumbles? Rich or lean can cause a stumble. A combination of both can cause a stumble too. Big shooters and not enough duration.
Your actually doing pretty good for having no experiance with carbs. But I think you can benefit from some good reference books. SA design publications has some good ones. Supertuning holley carbs by David Vizard is a good book. How to make horsepower by David Vizard is another one. Reasonably priced and easy to get. Try em.

Guage says leeeeeean when the stumble occurs, hitting max 22 AFR and stays there.
Primary runs perfect now with a 31 shot and white cam.
The biggest problem i have is to determine if i give to much or to little gasoline on the secondary pumps as the engine miss i can't get a correct AFR-reading.
Exhaust do not tell me much either, it gives me no smoke but i'm not convinced that i'm to lean on the secondary-pumps even if there is no smoke present.


35 on secondary have gave me the smallest amount of hesitation yesterday, 40 and 31 gave me the exact same behavior.
It starts to jump and cough for about two-three seconds and then takes of if i have rolling tires and keeping my foot on the gas not letting of.

I think i will drill out my 40 to about 45 just to test.

I will do some research on this books, thank you for the tip!

The funny thing i still that day when i accidental turned the blue cam backwards and almost removed the stumble completely.
Still having sleepless nights over that i destroyed the pump-arm

Another thing is that when i had the 31 squirt with the blue cam on the secondary it backfired several times when doing throttle in park, have not this backfires on 40 squirt with blue cam.
But the hesitation is identical in gear with both 31 and 40.

How much effect gives the screw on the squirt, the hollow vs the solid?
When i had the solid screw with 31 squirt and blue cam i could see leaking at the top of the screw on secondary because of the high pressure.
Maybe the leaking on the squirt affected the backfiring.

I will try to make a movie so you can see how it behaves.
Maybe you more experienced can tell much of the behavior .


Br.

 

[BelvedereSatellite1966]

Guage says leeeeeean when the stumble occurs, hitting max 22 AFR and stays there.
Primary runs perfect now with a 31 shot and white cam.
The biggest problem i have is to determine if i give to much or to little gasoline on the secondary pumps as the engine miss i can't get a correct AFR-reading.
Exhaust do not tell me much either, it gives me no smoke but i'm not convinced that i'm to lean on the secondary-pumps even if there is no smoke present.


35 on secondary have gave me the smallest amount of hesitation yesterday, 40 and 31 gave me the exact same behavior.
It starts to jump and cough for about two-three seconds and then takes of if i have rolling tires and keeping my foot on the gas not letting of.

I think i will drill out my 40 to about 45 just to test.

I will do some research on this books, thank you for the tip!

The funny thing i still that day when i accidental turned the blue cam backwards and almost removed the stumble completely.
Still having sleepless nights over that i destroyed the pump-arm

Another thing is that when i had the 31 squirt with the blue cam on the secondary it backfired several times when doing throttle in park, have not this backfires on 40 squirt with blue cam.
But the hesitation is identical in gear with both 31 and 40.

How much effect gives the screw on the squirt, the hollow vs the solid?
When i had the solid screw with 31 squirt and blue cam i could see leaking at the top of the screw on secondary because of the high pressure.
Maybe the leaking on the squirt affected the backfiring.

I will try to make a movie so you can see how it behaves.
Maybe you more experienced can tell much of the behavior .


Br.

Too clarify this:
"35 on secondary have gave me the smallest amount of hesitation yesterday, 40 and 31 gave me the exact same behavior.
It starts to jump and cough for about two-three seconds and then takes of if i have rolling tires and keeping my foot on the gas not letting of."

35 shortens the coughing with about one second, but the coughing is still for about two seconds with the 35 squirt on the secondary.

 

[BelvedereSatellite1966]

So i have had my carb inside for the last two days, watching exploaded views on holleys.
I was pretty sure i checked it already, but if you look at the picture im missing the checkvalve under the squirters on both side.
I've always thoght that especially the secondary with 40 squirt is to "bubbely", too much air in the jet.

As my primary works fine and also lacks the checkvalve i do not want to get my hopes up, but i will order the checkvalve today.

What do you guys think, can this be a part of the problem?

 

[Bigal75]

You need that little pin in there for sure.

 

[hangn0ut]

Yeah,both of them. You probably want to go back to original cams and shooters.

 

[BelvedereSatellite1966]

I don't know what year my carb is as the choke-horn is gone.
Its a 4781 with listnumber 6r3738b.

It came with either the pin or ball+weight.
The ball+weight is imposible for me to grab here in Sweden if i do not find a older Holley nobody is using.
Do you guys know if i can run with the pin even if the carb came with ball+weight?
The pin have articlenumber 121-5 at Holley.

You can se both versions on this exploded view:
http://documents.holley.com/techlibrary_4150_4160_exploded_view.pdf

 

[Bigal75]

Can you get those parts at Summit?

 

[hangn0ut]

Your probably good with the pins. 1975 was a long time ago.

 

[Bigal75]

Doesn't the ball and weight just preven5 siphoning? I don't think it's preventing fuel from coming out.

 

[BelvedereSatellite1966]

Doesn't the ball and weight just preven5 siphoning? I don't think it's preventing fuel from coming out.

What i understand it also prevent air from filling the pumps, delaying the shot.
Read about a guy with the same 2-3 second bog, fixed the problem when installed the pins.

 

[BelvedereSatellite1966]

Yes, it was a big difference with the pins in. Still a bog when opening secondaries but it runs much better.

Will try some different squirter and cams tomorrow!

 

[BelvedereSatellite1966]

Sorry for not updating, have not had so much time to work at the Satellite.

40 squirt with blue cam did not work perfect, there was no stumble at all on Cruise to wot but from idle to wot i still did have moderate stumble, it was not perfect, but alot better with the pins in.

Today i drilled up a squirter to about 50-55, put in the green cam as i read it was the most aggressive.
Magic, completely new car.
No hesitation at all almost.
Only in big uphill at dead stop from idle to wot there is a small amount of hesitation.
Maybe im a little rich or still little to lean, but now im down to fine tuning.

Just want to thank you all for your help. Learned alot by all the tips and guidness i got from you all.
I made a movie doing a really smoky burnout just for you guys, sadly i only got the first three seconds.
Promise i will make a new one if i do not forget.

Br.