Holley Carburetor Tuning: Idle Circuit Mods for High Duration Camshafts
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- Опубліковано 12 вер 2016
- Part 1 of 2: In this video we take a in depth look at the Idle Circuit. We're going to explain how to properly check, adjust, and modify the idle circuit.
Drilling a .070" hole in the butterflies works for long duration camshafts, for example, a mechanical camshaft that has 260* or more @ .050". My 460 CID has a very moderate Iskenderian custom ground flat tappet mechanical camshaft, Int. 240* @ .050" Exh. 246* @ .050", 108* LSA with 104* ICL. In order to get my engine to idle correctly I had to re-set the secondary butterfly adjustment screw on the underside of the carburetor as well as make sure the idle transfer slot only has .025" exposure on the primary side. Works great. Cool videos.
Iv looked ever where for information on 1050 4500 dominator. I tried to run power vales. This not working on mine.on ly plugs work for me if you have info please post to keep some one else from a hard ache.
After following these instructions and doing this to my Holley 670 carb with vacuum secondaries. With the engine warm and the choke open. When revving up the engine with the throttle and then releasing the gas pedal, what would cause the idle to get stuck at 1400 rpm and then take 20 to 30 seconds to drop down to 900 rpm idle?
If I quickly stab the gas on my holley and let the engine settle back down to idle it will idle slowly. If I slowly press the gas the engine will idle high. Every holley i have ever owned does this. What's the reason?
Probably the best and most understandable explanations I've ever heard. Great job! Thank you!
Hi Randy, love the videos. On a 4412 do all of these principals apply? Also friend has a circle track car and it's been a while since he ran it. Ran and idled fine, now goes to fire it up and it won't idle. Cleaned it all out, but still won't idle. Any thoughts? Thanks.
nicely done
This video Finaly solved why my engine wasnt idling. It has a high duration comp cams that runs perfectly fine when steping on the gas, but when I let go of the throttle it dies because there is not enough air going into the engine, because the low engine vacuum cant pull it though.
I have a 289 sbf w/ a big cam and it idles between 1200-1400 rpm. Anything lower than that and engine stalls. Any idea how I can bring down the idle between 1000-1200 rpm? Thanks in advance 🙂
I have a problem with one idle screw adjustment makes no difference, other one screwed all the way in it dies. I'm thinking I have a blockage some where. I'm going to try a different metering block. Thanks
I’ve been working on these for years and you gave me more information than I ever got on a Holley Carburetor. Thank you!!
I love how well described and explained these videos are.
The best explanation I've seen so far on this adjustment! Thank you!
I've been putting off addressing a very rich condition on my Quick Fuel 650 DP with 4 corner idle air adjustment! After seeing this video I decided to add the .070" holes in the butterflies also, since I was going to have it apart. I knew I'd need to reduce the power valve size as my cam makes just 10" of vacuum, and it turned out to be a #6.5, so I also dropped it to a #4.5.
You the man, thanks for the refresher course. I'm working a 6 pack and forgot all about the transfer slot on the center at idle setting.....on all 3 carbs. I appreciate this video!
felt I had to let you know on your advice , following what you said I picked up 2 tenths and 3 miles per hr on my drag car and was really happy , keep up the great advice thank you !!
This is the BEST instruction i have ever had,Thank You !!!!
My new favorite channel.
Thanks Randy! I’m pretty confident this is the problem with mine. When I slowly press on the throttle backing out of the driveway it wants to smother out and die at 1/8 throttle or less. If I push the throttle fast activating the pump it does fine but whe the pump isn’t involved it won’t take fuel and die. I’ve been trying to remedy this with the lower vacuum power valve but I though I’ve seen improvements I think I’ve done all I can. Time to drill holes.
Your videos are VERY informative. Thanks.