Check your fuel pressure it should be no more than 6psi for the street, check for trash or dirt in fuel, check and make sure nothings blocking the vents. Other than that check your floats an needle & seats for sealing. Hope this helps.
Randy, I just upgraded my 3310-2 from a 134-21 metering plate to a secondary metering block conversion Holley kit. The factory metering plate had .039-.040 IFR’s. This new metering block has .030 IFR’s. Does that mean I have to drill them to .039-.040? Any advice would help. This carb has no secondary idle. Only the tiny drip holes under the secondary transition. Thank you and great video!
I think I would try it with the .030 thousandth ifrs and see. The metering block is absolutely better than the plate. If it causes problems then I would change it. Hope this helps
Yes they are thin and tend to warp just removing them. Most of the time I don't even reuse them because if they stick you just about have to peel them off.
Hey Randy, I'm trying t set a carb with 4 corner idle on a old Barry Grant 750 double pumper that was rebuilt. I'm not getting much change on the any of the mixture screws but the back left screw. If I turn the other three of them all the way in, it leans out but not kills the motor. The back left will kill all the way in. The funny part is at idle with all out 1 full turn I get an AFR around 12. What should I check? Thanks
Mike if the carb is in good shape, first you need to adjust your idle speed screw to close your transfer slots up, where there is no more than 010 to .020 of the transfer slot exposed, with a four corner idle circuit this is what it takes to help lean it,, then look to see if your carb has an adjustable idle air bypass if so adjust to get your proper idle speed without changing your idle screw much, if you don't have a adjustable bypass then it should have bypass holes drilled in your throttle butterflies , if not you will need to drill all four butterflies, starting at .080 thousandths and tune from there, the bigger the hole the higher the idle will be. Also open your idle air bleeds up .005 at a time no more than .010 max then readjust your idle mixture.hope this helps.careful not to drill your bypass holes to big. You may won't to look at some of my videos covering this, If you have problems let me know.
Hey does my basic Holley 1850 with stock metering plate.....Idle circuit actually do anything? There are no mixture screws. Does it meter any gas at idle?
Mike the primary metering block should have adjustable mixture screws, if your talking about the rear metering plate there are no mixture screws, but there is a idle circuit in the rear metering plate its usually around .030 it feeds the rear idle and the rear transfer slot the idle feed hole in the throttle plate is about .024 Hope this helps.
@@holleycarbshowtosadvice40y90 Yep I'm talking about the rear plate on my 4160 1850 600 carb. It's adjusted and working very well on my mild 350. I'm just struggling with the idea it's actually doing anything.
Hi Randy, I almost went and purchased a replacement metering plate with a bigger main hole but it looks like I can modify my current one in my 4160 2 corner 600cfm Holley carb. I got the carb mostly tuned right everywhere else and with regards to this video, I was wondering if there's a way to modify the metering plate to get rid of a ~1 second lean spot (15-16AFR) entering WOT (less than 1" vacuum). I think that's when my secondary throttle blades start opening. After that 1 second lean spot my AFR recovers to the 12.5-13AFR range as I stay at WOT for a few seconds more. I have my carb on a dual plane intake on a bone stock 302 with the yellow spring in the secondary diaphragm and it doesn't bog when I floor it to WOT. Please let me know if you have a solution for this issue. Thanks, Roland
Try changing from the yellow secondary spring to the brown spring, also make sure the secondary float level is set right. I think your secondaries are opening to quick. Hope this helps.
@@holleycarbshowtosadvice40y90 Thanks Randy. I actually tried the brown spring before the yellow and the lean duration was worse. Float level good set to trickle out of sight hole while shaking car like the primary sight hole. Should I try maybe raising the float level by a quarter turn of the adjuster?
Usually the secondaries are opening to fast but you could try richen up the secondaries. Make sure in the secondary diaphragm housing that the ball check is there and some have a office instead of the ball check, make sure which ever one you have isn't missing. I would keep the float level setting you have, I always run the pink accelerator pump cam on the 4160s because of its long duration of pump shot, let me know if your still having problems, one of these ought to take care of it. hope this helps.
@@holleycarbshowtosadvice40y90 I can try the brown spring one more time and record the data. Would it be okay for me to email you a graph plotting telemetry from a recent pull I did from cruise to WOT? I think I saw your email written here in some comments. The check ball is still in the secondary diaphragm housing. Will the pink accel pump cam still help even if I gradually get the throttle from cruise to WOT?
Before you do anything else check your secondary ifrs for blockage and if not blocked, richen your secondary ifr by.010 thousandths and see if that helps. Let me know.
Hi randy i can not find a answer anywhere. Do the Quick fuel plates have a idle circuit? They d9nt list any size of them if they do on any web listings. Also i am running a pair of 660s on a 468 bbc with a 671. And i have drilled the primaries and after watching yourvideos will be drilling the secondarys but should the secondarys be opened at .040 transfer size? Or closed
I have a quick fuel secondary plate and it has an idle circuit, some have a removable idle fuel restrictor and the question about the secondary transfer slot, it should be closed. Hope this helps.
Hi Randy !Thanks for all videos they are very helpful. Can you tell me how much the secondary transfer slots should be open? my primary ones are .040 open as you have said in another video but to get my idle speed to 900 RPM i need to open the rear up to .080 is this to much?my mixture screw are 3/4 turn out to get the best vacuum. Carb is 0-1850 600 CFM 2 corner idle, on performer RPM MANIFOLD 302 Windsor with a mild 220/235 @ 050 hyd cam. Thanks for any more help that you can suggest.
I usually drill bypass holes in the throttle plates but, if its not causing you any problems that will be ok but no further than .080, I would rather drill bypass holes its a better way with out opening the secondary plates. I usually start by drilling four .080 holes in the throttle plates , drill the holes in the throttle butterflies on the out board side , or the side nearest the transfer slots. I usually start with .080 holes and open up a little at a time using only your primaries until the primary transfer slots are correct and at proper idle speed, hope this helps, I have a video out there that shows this procedure. I believe its called tuning your idle circuit with high duration cams. Take care.
Well i thought i was missing that metering plate backing plate! I was concerned about how bad this old gasker was smashed into the metering cicuits BUT I suppose just clean it and slap a new big gasket on. Thank you man
Hi Randy, I installed a 750 DP on my 390 Ford. It was new in 2012 and is great shape. I had a Autolite 4100 on the truck and it ran great. Once I installed the Holley, I noticed I could not adjust the mixture screws. I could turn them all the way in the mixture would not change. When I drive the truck it drives fine but backfires through the exhaust when I decelerate. Any ideas where I should look first? Thanks!
You need to check the power valve for leaking, if pv is bad stop and replace and retest if your still having, then you need to look at your transfer slots how far there open at idle you won't about .020 to .030 thousandths exposed, if you have 2 or 3 timesthat much, you may need to drill some bypass holes in your throttle plates i start at .080. I have a video you need to watch, it called mods for the idle circuits with high duration camshafts, watch the video but close your transfer slots up to where there is only about .020 to .030 of your trans slots open, your may have to repeat removing carb and drilling bypass holes bigger several times to get it were it needs to be, each time you drill the holes bigger you will need to lower your idle speed, which intern closes up your transfer slots, again you only want to see .020 to .030 of your transfer slots exposed. Hope this helps.
If it sticks your going to bend it. I don't use the tin plate or the plate gasket, just use the metering plate on the rear gasket. If you won't to straighten the tin plate I use a flat anvil and a piece of wood.
I bought the same QFT plate. I am not sure whether or not to install the original thin plate when changing the metering plate. I seems the QFT is thicker but I wasn’t sure whether it goes gasket plate gasket QFT plate or gasket then QFT plate. Thanks! Great info on the channel. I have learned a lot!
The meter plate seems a pure waste vs a metering block. Why carburetor’s even have plates as compared to blocks must just be for cheapness😊. Performance reliability sucks, they warp and leak. The older zinc cast are far worse than the aluminum ones. Good presentation but need to tell guys plates vs blocks is a no contest,
Point being I’ve taken many, many zinc casting Holley apart and find the secondary meter plate is warp and way out of flat. That is primary reason they leak. Plenty of main housings also being warped. That needs to be made flat too. One will find the secondary bores wet when let set after engine shut down. Replacement with secondary meter block has better chance fixing problem. Sanding meter plates flat seldom fixes issue for good. A tuned Holley with meter blocks is a far superior running engine than what can be attains using cheap zinc cast meter plates. Warpage is the main issue with cast zinc Holleys in original 60’s cars.
Thanks Randy. Always good knowledge 🍻
Thanks
Hey I've got a new Holley carb that's pushing fuel out the vent the old carb was doing the same thing has new fuel pump and regulator
Check your fuel pressure it should be no more than 6psi for the street, check for trash or dirt in fuel, check and make sure nothings blocking the vents. Other than that check your floats an needle & seats for sealing. Hope this helps.
Randy, I just upgraded my 3310-2 from a 134-21 metering plate to a secondary metering block conversion Holley kit. The factory metering plate had .039-.040 IFR’s. This new metering block has .030 IFR’s. Does that mean I have to drill them to .039-.040? Any advice would help. This carb has no secondary idle. Only the tiny drip holes under the secondary transition. Thank you and great video!
I think I would try it with the .030 thousandth ifrs and see. The metering block is absolutely better than the plate. If it causes problems then I would change it. Hope this helps
Randy don,t forget to tell your viewer to check this plates for flatness Ive had issues being warped
Yes they are thin and tend to warp just removing them. Most of the time I don't even reuse them because if they stick you just about have to peel them off.
Great video thanks for uploading. Exactly the information I needed about the metering plate
Glad to help
Omg! I needed this video.. Hard to find information. Thanks for posting this and sharing your knowledge!
Your welcome
Hey Randy, I'm trying t set a carb with 4 corner idle on a old Barry Grant 750 double pumper that was rebuilt. I'm not getting much change on the any of the mixture screws but the back left screw. If I turn the other three of them all the way in, it leans out but not kills the motor. The back left will kill all the way in. The funny part is at idle with all out 1 full turn I get an AFR around 12. What should I check? Thanks
Mike if the carb is in good shape, first you need to adjust your idle speed screw to close your transfer slots up, where there is no more than 010 to .020 of the transfer slot exposed, with a four corner idle circuit this is what it takes to help lean it,, then look to see if your carb has an adjustable idle air bypass if so adjust to get your proper idle speed without changing your idle screw much, if you don't have a adjustable bypass then it should have bypass holes drilled in your throttle butterflies , if not you will need to drill all four butterflies, starting at .080 thousandths and tune from there, the bigger the hole the higher the idle will be. Also open your idle air bleeds up .005 at a time no more than .010 max then readjust your idle mixture.hope this helps.careful not to drill your bypass holes to big. You may won't to look at some of my videos covering this, If you have problems let me know.
How much thicker is the qft plate? Will it interfere with the float? I like the side hung bowl on my 1850. Liked your video. Keep it up.
Qft plate about the same thickness and yes it will interfere with a brass center hung float. Hope this helps.
Thanks for answering the question. On another note, would the qft plate interfere with the nitrophyl float in a side hung bowl?
How do you re move the plate
With a clutch head screw driver then gently remove plate.
Thanks for the content.
Your welcome.
Hey does my basic Holley 1850 with stock metering plate.....Idle circuit actually do anything?
There are no mixture screws. Does it meter any gas at idle?
Mike the primary metering block should have adjustable mixture screws, if your talking about the rear metering plate there are no mixture screws, but there is a idle circuit in the rear metering plate its usually around .030 it feeds the rear idle and the rear transfer slot the idle feed hole in the throttle plate is about .024 Hope this helps.
@@holleycarbshowtosadvice40y90 Yep I'm talking about the rear plate on my 4160 1850 600 carb. It's adjusted and working very well on my mild 350. I'm just struggling with the idea it's actually doing anything.
Take it easy
Great video!
Thanks
Thank you for answering my question about a missing plate in my carb.
Glad to help
Hi Randy,
I almost went and purchased a replacement metering plate with a bigger main hole but it looks like I can modify my current one in my 4160 2 corner 600cfm Holley carb. I got the carb mostly tuned right everywhere else and with regards to this video, I was wondering if there's a way to modify the metering plate to get rid of a ~1 second lean spot (15-16AFR) entering WOT (less than 1" vacuum). I think that's when my secondary throttle blades start opening. After that 1 second lean spot my AFR recovers to the 12.5-13AFR range as I stay at WOT for a few seconds more.
I have my carb on a dual plane intake on a bone stock 302 with the yellow spring in the secondary diaphragm and it doesn't bog when I floor it to WOT. Please let me know if you have a solution for this issue.
Thanks,
Roland
Try changing from the yellow secondary spring to the brown spring, also make sure the secondary float level is set right. I think your secondaries are opening to quick. Hope this helps.
@@holleycarbshowtosadvice40y90 Thanks Randy. I actually tried the brown spring before the yellow and the lean duration was worse. Float level good set to trickle out of sight hole while shaking car like the primary sight hole. Should I try maybe raising the float level by a quarter turn of the adjuster?
Usually the secondaries are opening to fast but you could try richen up the secondaries. Make sure in the secondary diaphragm housing that the ball check is there and some have a office instead of the ball check, make sure which ever one you have isn't missing. I would keep the float level setting you have, I always run the pink accelerator pump cam on the 4160s because of its long duration of pump shot, let me know if your still having problems, one of these ought to take care of it. hope this helps.
@@holleycarbshowtosadvice40y90 I can try the brown spring one more time and record the data. Would it be okay for me to email you a graph plotting telemetry from a recent pull I did from cruise to WOT? I think I saw your email written here in some comments.
The check ball is still in the secondary diaphragm housing. Will the pink accel pump cam still help even if I gradually get the throttle from cruise to WOT?
Before you do anything else check your secondary ifrs for blockage and if not blocked, richen your secondary ifr by.010 thousandths and see if that helps. Let me know.
Hi randy i can not find a answer anywhere. Do the Quick fuel plates have a idle circuit? They d9nt list any size of them if they do on any web listings.
Also i am running a pair of 660s on a 468 bbc with a 671. And i have drilled the primaries and after watching yourvideos will be drilling the secondarys but should the secondarys be opened at .040 transfer size? Or closed
I have a quick fuel secondary plate and it has an idle circuit, some have a removable idle fuel restrictor and the question about the secondary transfer slot, it should be closed. Hope this helps.
Hi Randy !Thanks for all videos they are very helpful. Can you tell me how much the secondary transfer slots should be open? my primary ones are .040 open as you have said in another video but to get my idle speed to 900 RPM i need to open the rear up to .080 is this to much?my mixture screw are 3/4 turn out to get the best vacuum. Carb is 0-1850 600 CFM 2 corner idle, on performer RPM MANIFOLD 302 Windsor with a mild 220/235 @ 050 hyd cam. Thanks for any more help that you can suggest.
I usually drill bypass holes in the throttle plates but, if its not causing you any problems that will be ok but no further than .080, I would rather drill bypass holes its a better way with out opening the secondary plates. I usually start by drilling four .080 holes in the throttle plates , drill the holes in the throttle butterflies on the out board side , or the side nearest the transfer slots. I usually start with .080 holes and open up a little at a time using only your primaries until the primary transfer slots are correct and at proper idle speed, hope this helps, I have a video out there that shows this procedure. I believe its called tuning your idle circuit with high duration cams. Take care.
Well i thought i was missing that metering plate backing plate! I was concerned about how bad this old gasker was smashed into the metering cicuits BUT I suppose just clean it and slap a new big gasket on. Thank you man
Thanks.
Hi Randy, I installed a 750 DP on my 390 Ford. It was new in 2012 and is great shape. I had a Autolite 4100 on the truck and it ran great. Once I installed the Holley, I noticed I could not adjust the mixture screws. I could turn them all the way in the mixture would not change. When I drive the truck it drives fine but backfires through the exhaust when I decelerate. Any ideas where I should look first? Thanks!
You need to check the power valve for leaking, if pv is bad stop and replace and retest if your still having, then you need to look at your transfer slots how far there open at idle you won't about .020 to .030 thousandths exposed, if you have 2 or 3 timesthat much, you may need to drill some bypass holes in your throttle plates i start at .080. I have a video you need to watch, it called mods for the idle circuits with high duration camshafts, watch the video but close your transfer slots up to where there is only about .020 to .030 of your trans slots open, your may have to repeat removing carb and drilling bypass holes bigger several times to get it were it needs to be, each time you drill the holes bigger you will need to lower your idle speed, which intern closes up your transfer slots, again you only want to see .020 to .030 of your transfer slots exposed. Hope this helps.
@@holleycarbshowtosadvice40y90 Thanks so much for your detailed reply and support Randy!
How you get that tin plate off without bending the heck out of it?
If it sticks your going to bend it. I don't use the tin plate or the plate gasket, just use the metering plate on the rear gasket. If you won't to straighten the tin plate I use a flat anvil and a piece of wood.
I bought the same QFT plate. I am not sure whether or not to install the original thin plate when changing the metering plate. I seems the QFT is thicker but I wasn’t sure whether it goes gasket plate gasket QFT plate or gasket then QFT plate. Thanks! Great info on the channel. I have learned a lot!
I just run gasket and plate. Hope this helps.
Yes it does. Thanks again!
The meter plate seems a pure waste vs a metering block. Why carburetor’s even have plates as compared to blocks must just be for cheapness😊. Performance reliability sucks, they warp and leak. The older zinc cast are far worse than the aluminum ones. Good presentation but need to tell guys plates vs blocks is a no contest,
The metering plates are cheap,a metering block is much better. But the plate does work. Everybody to there on.
Point being I’ve taken many, many zinc casting Holley apart and find the secondary meter plate is warp and way out of flat. That is primary reason they leak. Plenty of main housings also being warped. That needs to be made flat too. One will find the secondary bores wet when let set after engine shut down. Replacement with secondary meter block has better chance fixing problem. Sanding meter plates flat seldom fixes issue for good. A tuned Holley with meter blocks is a far superior running engine than what can be attains using cheap zinc cast meter plates. Warpage is the main issue with cast zinc Holleys in original 60’s cars.