Carburetor Video
 

While dynoing a 555 I decided to play with my GoPro and took a video down into the carb on a pull. Kinda cool. What I find a bit surprising is that it appears to be pulling fuel from the secondary accelerator pump nozzle at higher rpm. You can't see the primary side because of the choke plate. This seems odd to me. I've searched for other videos and found a couple that seem to show the same thing
.www.youtube.com/watch?v=ceBRps8kqCI

Bob

I guess I should add the engine is 9.5:1 compression, 555 ci, Canfield heads, 246/256 .640ish cam on 114 LSA and Gil exhaust. It made 650 HP at 5900 RPM. I didn't build it, just tuned it. Seems to be pretty good power, so the heads must be working well. Full marine trim and wet exhaust on the run. Also, the builder installed the cam at 110 deg. centerline and it made 630 HP, I retarded it to 113 and picked up 20 hp, moving peak tq and hp up about 200 rpm

Bob

not surprising that it pulls fuel out the squirters, that system is set to only flow one way and with enough air flow past it I can see it pulling it in. the real question then is if that happens how much does the squirter size effect air fuel ratios? maybe not much but who knows. would like to see both the front and rear squirters blocked off and then make a pull to see the change. would have to bring it up slow with out them but probably doable.

Good stuff Bobl.

I cannot remember where I read about this.Itmay have been speedtalk.com or https://www.tapatalk.com/groups/raci...ms/holley-f25/
Couple of really sharp carb guys on both.One named Tuner and other jmarkaudio

That is neat bob. You ever see the video Mild Thunder posted with the clear float bowls on the dyno. That's another interesting one. Amazing the things we don't see.

bob,i also noticed that on a dyno video taken at the place i used to do my dynoing at,i think it happens whenever a carb goes wot so i would say it is part of the fuel being use.if one never viewed the video you would never know.

And seems so many concern with fuel atomization. Shoot you can barely see the fuel at wot. Imagine by the time it hits the int valve. Any mini cams installed in intake port close to head. SB will find one. Lol... I gotta go shovel snow.

http://www.mtfca.com/discus/messages/118802/169553.jpg

http://www.mtfca.com/discus/messages/118802/169554.jpg

Nice gain from 3 degrees of retard. Im sure it would have made some more with different exhaust and cam. Those canfields were good heads.

really cool....something you would never see without the camera...interesting for sure

been meaning to tk u for posting forum. I've got some helpful info that you don't just get anywhere!

I saw this way back in the day (early/mid 80's) when I had tunnel ram motors. Holley had "anti pullover" nozzles. Tried them, didn't work.

Under the screw that holds the nozzles in there is a check valve. I wound up drilling the bottom of the screw and putting some little tiny springs in there to hold the valves closed. It took a bit of trimming to get just the right amount of tension so that the accell pump still worked OK. We didn't have an AFR meter back then so I can't tell you how much difference it really made but I sure felt better eliminating the pull-over.

I am such a pack-rat that I still have a bunch of the springs around if anyone is interested.

I found this pretty interesting in the link you provided. As long as it remains simple, I could see an application for a boat: https://www.tapatalk.com/groups/raci...eci-t1602.html
This idea really shows some promise in addressing a carbs only drawback - in performance applications anyway...(IMHO)

Pretty clever and may fill in a nice niche. I personally have my QF850 at about 12.5:1 across the board except at 4K - the peak torque (13:1) where it needs fuel the most.