Troubleshooting Holley Vacuum Secondary Function

[@Bige4u]

Great way to test with compressed air over the ventury hole.... another way i've seen here on YT, there was a gentleman that used a very powerful shop vac, he turned the vacuum on, then placed the end of the hose to the bottom side of the carburetor primary side that has the vacsec draw hole, and it opened right up, it was like seeing a simulated high vacuum load of an engine.

[@holleycarbshowtosadvice40y90]

Absolutely, creating a depression. Take care.

[@TheSaxon25]

Thanks Randy! Need more of these vacuum secondary videos. 🍻

[@holleycarbshowtosadvice40y90]

Coming up.

[@NightWrencher]

Hey man! Great to see you back on youtube! I watched all your old videos last year and it really helped jump start my curiosity with carburetors. Just wanted to drop in and thank you for all the great info you put up here for us!

[@holleycarbshowtosadvice40y90]

Thank you, your channel is very good too.

[@scottdavis6463]

Keep them coming. Love your work

[@holleycarbshowtosadvice40y90]

Thanks Scott

[@erikturner5073]

I like double pumpers for the track. But lately I'm leaning towards hot STREET performance so I'm looking towards the Vacuum secondaries for for all around performance and help with mpg as well. Appreciate the videos! 👍

[@holleycarbshowtosadvice40y90]

Thanks Eric

[@halfzacstunts]

Got a 460 jet boat not getting into the secondaries. Thank you for the video. Going to pull my diaphragm off as soon as I’m off work and check it out.

[@holleycarbshowtosadvice40y90]

That 460 will come alive .

[@halfzacstunts]

@@holleycarbshowtosadvice40y90 it sure did!! Picked up over 10 mph on the water

[@Mynextproject_74]

I really enjoy all your videos. I appreciate any Vacuum Secondary info as well as the Double Pumper info.

[@holleycarbshowtosadvice40y90]

Thank you ,let me know if there is a video you would like to see.

[@dondavies2447]

Great videos Randy. Would be great to see something on the Mopar 6 pack setup

[@holleycarbshowtosadvice40y90]

Six.packs are hard to run across , but you never know.

[@reevesautomotivefarm9614]

great video thanks.

[@holleycarbshowtosadvice40y90]

Thank you.

[@smitteninthemitten3777]

Great video. Extremely helpful. How do you open that clean out port that you showed? Mine has what appears to be a ball bearing in it.

[@holleycarbshowtosadvice40y90]

The clean out should be a lead plug it resembles a ball, I drill it out and close it up with a piece of lead or tap some threads and install a threaded plug. If somebody managed to drive a steel ball in there it would be difficult to remove. Hope this helps.

[@TheCanadianBubba]

Thank you 👍

[@holleycarbshowtosadvice40y90]

Your welcome

[@gregpratt1007]

Thank you Randy I do have a question is there any difference in the metering plate from say a 390 4 Barrel or 600 or 750 if you got a 600 and that's what you're trying to build but you have a metering polite from a 390 and a 750 would you gain anything from putting the metering plate in it. Also do you gain anything bye Milling off the choke horn.

[@holleycarbshowtosadvice40y90]

You gain a few cfm by milling the choke horn, as far as a metering plate they are predrilled , they can be modified it's better to stay with the original metering plate unless you are racing , never put a smaller plate like a 390 plate on a 600 it will be to lean.

[@cuda6496]

I have a holley 750 vaccum secondary it has 2 vaccum passages one to primary and to one to the secondaries I read somewhere that if you plug the passage for the secondary it will open faster ?

[@holleycarbshowtosadvice40y90]

Most holleys do have both holes, if you block the secondary hole it will open the secondaries early, sometimes it will cause a stumble because the secondaries open to fast initially.

[@cuda6496]

@@holleycarbshowtosadvice40y90 got it !!!! Thank you 👍👍👍

[@artjones2498]

im doing a 3310-4 right now...got it for free.. i took it off the engine myself a non runner it had a lot of crap in the throttle blade and they did not open...i soaked it for 2wks.. in a solution i made...got them free with out having to force them...made sure i didnt bend the blades....the secondary blade dont open as easily as the primary blades...its not together yet...will it work properly or should i relace the whole throttle blade assy...apolligize for so long....but i wanted to make sure you under stand my question....that i worded it properly??...any reply will help thank you

[@holleycarbshowtosadvice40y90]

If the bowls and metering blocks are good , then it's worth repairing , the throttle plates have to work very smoothly , if not the carb will never perform properly , there is a lot of 750 parts around , hope this helps.

[@custom-ok8pd]

Hello Randy, thank you for the videos. I have an off topic question. Can I plug the choke vacuum port on my 670 street avenger? Seems like a vacuum leak there and I cant find any info it. Thanks in advance,

[@holleycarbshowtosadvice40y90]

If it's a full electric choke leave it open .the older cars had a electric choke assist cap and a vacuum tube that ran to a exhaust chamber and back to the carb , it would draw cool filtered air through the exhaust chamber that heated the air back to the choke cap spring and open the choke , the heated air would make the spring in the cap unwind and open , I'm feel sure yours is a controlled leak and you should have a full electric cap , your ok.

[@custom-ok8pd]

@@holleycarbshowtosadvice40y90 Thank you!

[@pierre-yveslavigne9688]

Hi, my 80457-8 (600cfm) does not have that hole at the bottom of the ventury...i look like the secondary have vaccum troughs ventury circuit inside the main body.🤔

[@holleycarbshowtosadvice40y90]

If there's no feed hole in the primary venturi to feed the secondary diaphragm it will be a first for me and the secondaries will not open. You need to look closely, the hole is hard to see and most have a hole in the secondary venturi too. If you can't find the hole remove your sec. vacuum diaphragm housing and squirt some WD in the feed hole and follow the spray to the venturi. Hope this helps.

[@SupermanBPR9]

Have you ever seen a primary metering block with no emulsion holes? I have one and not sure if I need to get a different one or use it for my 670 cfm Holley.

[@holleycarbshowtosadvice40y90]

Yes I have, do you have the list number of the carb it came off of?Some of the ford factory holley's had them .

[@SupermanBPR9]

@@holleycarbshowtosadvice40y90 no sorry, it was in a box of Holley parts I got at auction. Trying to get a circle track carb together and wasn’t sure about it.