Hi Randy, thanks much for your videos. 2 yrs ago I found you. later a few others said you did not know what you are doing when I referenced your info. I was working on my 1974 304 AMC jeep that I had since a teen ager. I have been wrenching for 50 yrs from mini bikes to big diesels. I built and modified a 4175 650 Holley to work on the 304 amc. many guys said and even holley said it wont work. I bought the carb used 1 time from a guy for 65.00. I knew I could make it work somehow. many guys said it never would because of the CFM. I watched all of your videos and bought the book. I tuned that carb in by doing many things I wanted to run pump gas and have performance and economy. the spreadbore was my choice because of the small primarys. I did it all even drilled the plates but did not have to mostlikley. It runs great used the white secondary spring, red ramp and modded the air bleeds. put on a secondary metering block etc. I did it all even modified the Thompsons power plate to work in the 4175. now I get about 17 TO 20 MPG I have tons of power out of the old 1974 AMC 304. GUYS THIS GUY RANDY IS FOR REAL. YOU CAN EVEN SEE THE TAN SMOKE RESIDUE ON THE INSIDE OF THE TURN OUTS ON THE PURPLE HORNIES thanks Randy
@@holleycarbshowtosadvice40y90 Thanks again Randy who ever those other guys who said that you dont know what you are doing Im sure you spanked them on the strip more than once. I was wondering why the new secondary metering block mix screws had no effect on the 4175 idle mixture. It runs too good right now to tear it off again. amazing 17 to 20 mpg if running conservative. also found out the 4175 has reverse idle mixture screws. the 4175 was a direct bolt on carb for a rottenchester replacement on emissions chevys. I just jetted it down to 55 on primarys and moved the 65s to the rear secondarys . not too lean but a nice tan color on plugs and you can even see a tan color inside turnouts on the new purple hornnies. crisp and clean. Youre the man Randy.
Man I sure wish you would tell us where the other metering plate came from? model number? what to use,... where to get it,.... what not to use. Great info thanks for sharing
Any old holley primary metering block from a 600 to a 750 double pumper, list#4779, 4778 ,4777 ,4776, just block the secondary power valve and jet up eight jet sizes, and if the idle circuit is to rich then change to a bigger idle air bleed. Hope this helps.
I know this thread is Old, however I figured you would receive my question... I have a metering block with a place for a power valve but with no pvcr. I guess my stupid question is: is that just a mistake?
Ryan when you receive your anti back fire kit it has instructions on how to install ,and mine came with the drill bit and drill collar make sure to set the drill collar to the correct length my kit shows 9/32" if you have any trouble let me know.
If my ifr is around .035 thousandths and I move the ifr to the top of the fuel circuit thats where I like it. Unless its a small carb. When you make sure your transfer slots are correct the last thing I do is tune with idle air bleeds. Now if your looking for fuel mileage thats different tune with afr guage but always follow this method. Always remember when you lean you ifr your leaning your transfer circuit and its easy to get into a lean stumble or a low speed surge from being to lean. Hope this helps
I've tried that but it's hard to drill the mixture screws straight , were they are perfectly aligned, I might try again , maybe try to make a jig to hold the block dead straight while drilling an tapping.
Randy, I have been trying to find info on converting a vacuum secondary Demon carb to a mechanical secondary. Everything I have read so far says that there are too many differences between the two carbs and you are better off just finding a mechanical secondary carb (unfortunately the 575 demon is no longer made, and hard to find used). My main question is, are the carb bodies different between vacuum and mechanical secondaries? I understand that the throttle plate assembly is different, and there is no secondary accelerator pump circuit. I appreciate your videos, as they have helped me learn a lot. Thank you for uploading your knowledge to help others out.
There is really to many parts involved to change , main body, throttle plate , metering block and rear fuel bowl and some small parts, I would try and find a mechanical secondary holley. Good luck.
Hi Randy been watching your videos. Great content a question on the 4 corner idle circut. The reason for this is so you can fattin up the idle air fuel ratio easier is that correct. Iam not really after fuel economy just tryin to dial this bad boy in. I installed a 2092 top end power kit from summit racing on a 351w engine. 1.6 rockers 1.75 long tube headers the carb is a 4160 600cfm. i installed a wideband o2 sensor in the exhaust. the exhaust is 3in from front to back with a y pipe installed. With a aod tranny and a 3.50 rear gear ratio for crussing capability. off idle problems were solved with a 50cc accelator pump with a 37 squirt nossel yellow cam. idle vacume is 10 power valve is 6.5 i got a preacy dial a jet installed on the primay side works amazing. Crussinr afr is 13-14 idle is 14-15 at 750 rpm engine under load is 12-13 afr reading i seem to have a lean bog around 1500- 1800 while the tranny is doin its thing. proably gonna jump to a 40 squirter nossel. The idle air mxture screws are turned out quite a few turns to richen things up. Primarys seem to be around the 70 mark secondaries are 74s. vaccume spring is a brown one. Thinkin the four corner process might help. Tell me what think
That is one of the reasons for a four corner idle circuit. You have an aod trans which usually is bad about shifting to early and slow to drop down a gear loading your engine heavily, all I can say is maybe try a larger carburetor with annular boosters and a lot of adjustability including , air bleeds , pvcr, idle fuel restrictors ect, hope this helps.
the next carbs going to tweak in are the old CARTER YH HORZIONTAL DRAFTS on my jetboat they used these on the old ford y blocks its a 1959 Beuhler Turbocraft jet boat the first jetboat ever made. putting in a 272 y block ford up from the old 256 ford dearborn interceptor
You know I don't remember the 256 but have worked on some 272, 292, 312 , but did not know much about them I was a kid, I worked for Ford for 30 years ,started at ford in 1973 only a few came in back then and I was in the learning stage ,but do remember the engine. Good luck to you.
Want to know if you can tell me how to change a 1050 Dominator from a 3 circuit to a 2 circuit, if you don't mind? Thank you, in advance! BTW I have learned a lot for your videos, we appreciate you sharing your knowledge! Thank you!
Enjoying your videos. I went with a large duration cam and lost a lot of vacuum and it seems to affected my torque converter also(it’s a cheaper one) I have a 750 dbl pump Holley it seems like my idle set screws have no adjustment. Any advice would be great
Scott if your idle mixture screws are not changing the idle speed when you turn them in and this happened after changing to a high duration camshaft, watch my video , (Holley carburetor tunning: Idle circuit mods for high duration camshafts.) This should fix it. If you have any questions or problems afterwards leave me a comment. Hope this helps.
Hi man awesome channel here just got into it again, awesome content. May i ask the idle mixture screws do they increase/decrease AIR or Fuel on a std holley 4150 or and 1850 ?? Thank you I think you mentioned it in one of your earlier videos a while back but cant remeber which one
Thank you so much I really appreciate your comment. May i ask at what point do they main jets get used while driving? Also do you have a patreon link ? I have a few more question and do not want to bother you for a lot of your time without compensation thankyou sir
I don't mind ,as to your question that will vary but usually anywhere from 1500 to 2000 is when they usually start ,a lot of factors including the load on the engine effects when the booster start to flow , size of engine verses small carb , float level and type of booster ect.hope this helps . PS are you after fuel mileage or performance? And you can ask me a question anytime. We are going to set up a patreon link soon but don't let that stop you from asking questions that would just help the channel grow, thanks for watching.
@@holleycarbshowtosadvice40y90 Hello thank you very much with your willingness to help i really appreciate it. Unfortunately i am after feul economy as gas in my country is about $4.5 a gallon and at 15.5 mpg it adds up very quickly. The set up on the vehecial is a 351c 2v, Frod c4 Tranny,Holley 1850 600cfm vacuum secondary, 16 inch of vacuum at idle when in gear and about 18 when in neutral. I have set up the carb just like you have done in your carb videos with the transfer slot set correctly etc. Who can i make it achive more Mpg in your opinion? And is my set up oky or would you change any thing. Thankyou if you need any other info please let me know thankyou
Hey Randy I am interested to know how you taper the Venturi on a 750 when you use a 850 throttle plate Also is there a modification on the main body idle circuit Thanks Stratos Melbourne Australia
Hi Randy, thanks much for your videos. 2 yrs ago I found you. later a few others said you did not know what you are doing when I referenced your info. I was working on my 1974 304 AMC jeep that I had since a teen ager. I have been wrenching for 50 yrs from mini bikes to big diesels. I built and modified a 4175 650 Holley to work on the 304 amc. many guys said and even holley said it wont work. I bought the carb used 1 time from a guy for 65.00. I knew I could make it work somehow. many guys said it never would because of the CFM. I watched all of your videos and bought the book. I tuned that carb in by doing many things I wanted to run pump gas and have performance and economy. the spreadbore was my choice because of the small primarys. I did it all even drilled the plates but did not have to mostlikley. It runs great used the white secondary spring, red ramp and modded the air bleeds. put on a secondary metering block etc. I did it all even modified the Thompsons power plate to work in the 4175. now I get about 17 TO 20 MPG I have tons of power out of the old 1974 AMC 304. GUYS THIS GUY RANDY IS FOR REAL.
YOU CAN EVEN SEE THE TAN SMOKE RESIDUE ON THE INSIDE OF THE TURN OUTS ON THE PURPLE HORNIES
thanks Randy
Your welcome.
@@holleycarbshowtosadvice40y90 Thanks again Randy who ever those other guys who said that you dont know what you are doing Im sure you spanked them on the strip more than once. I was wondering why the new secondary metering block mix screws had no effect on the 4175 idle mixture. It runs too good right now to tear it off again. amazing 17 to 20 mpg if running conservative. also found out the 4175 has reverse idle mixture screws. the 4175 was a direct bolt on carb for a rottenchester replacement on emissions chevys. I just jetted it down to 55 on primarys and moved the 65s to the rear secondarys . not too lean but a nice tan color on plugs and you can even see a tan color inside turnouts on the new purple hornnies. crisp and clean. Youre the man Randy.
Man I sure wish you would tell us where the other metering plate came from? model number? what to use,... where to get it,.... what not to use. Great info thanks for sharing
Any old holley primary metering block from a 600 to a 750 double pumper, list#4779, 4778 ,4777 ,4776, just block the secondary power valve and jet up eight jet sizes, and if the idle circuit is to rich then change to a bigger idle air bleed. Hope this helps.
thank you for the info.
Your welcome
Well Done.
Thanks Tim
Thank you Sir. for your help,getting closer all the time. You are awesome for giving us info that is hard to get
You are very welcome .
I'm trying to learn rent Randy I think your name is thanks for making us a video
Could be, lol.
FYI this stuff works I work on a lot of carbs
Glad this helps.
I can't wait till spring to try this shit out thank you.
Your absolutely welcome.
I know this thread is Old, however I figured you would receive my question... I have a metering block with a place for a power valve but with no pvcr. I guess my stupid question is: is that just a mistake?
If the power valve threads are there and has not been modified then I would say its miss built, you can always drill your pvcr. Hope this helps.
How do you install a backfire power valve saver check valve in the throttle plate?
Ryan when you receive your anti back fire kit it has instructions on how to install ,and mine came with the drill bit and drill collar make sure to set the drill collar to the correct length my kit shows 9/32" if you have any trouble let me know.
Thank you very much I appreciate this . I knew that this could be done but no idea how
Thanks for watching.
Is it possible to drill the hole for the idle air needle seat and tap the threads w/ 8-32 on a secondary block that doesn’t have idle air screws?
Are you trying to convert from a 2 circuit to a 4 circuit?
You didn't cover the idle feed restrictors though they have to be correct for the idle air bleed or it will run rich or lean
If my ifr is around .035 thousandths and I move the ifr to the top of the fuel circuit thats where I like it. Unless its a small carb. When you make sure your transfer slots are correct the last thing I do is tune with idle air bleeds. Now if your looking for fuel mileage thats different tune with afr guage but always follow this method. Always remember when you lean you ifr your leaning your transfer circuit and its easy to get into a lean stumble or a low speed surge from being to lean. Hope this helps
Hey Randy..when converting to a 4 circuit idle can you drill and tap a metering block that doesn't have the mixture screws?
I've tried that but it's hard to drill the mixture screws straight , were they are perfectly aligned, I might try again , maybe try to make a jig to hold the block dead straight while drilling an tapping.
Great vids Randy. Could please do a video on the 4224 660 center squirter.
Thank you!
I dont have a center squirter right now , sorry. If I run across one I'll do a video.
Thanks Randy!
Man where have you been?
@@holleycarbshowtosadvice40y90 Haha usually I say that to you!! Been around. Still trying to nail the tune on my car. Neverending!!
Randy,
I have been trying to find info on converting a vacuum secondary Demon carb to a mechanical secondary. Everything I have read so far says that there are too many differences between the two carbs and you are better off just finding a mechanical secondary carb (unfortunately the 575 demon is no longer made, and hard to find used). My main question is, are the carb bodies different between vacuum and mechanical secondaries? I understand that the throttle plate assembly is different, and there is no secondary accelerator pump circuit.
I appreciate your videos, as they have helped me learn a lot. Thank you for uploading your knowledge to help others out.
There is really to many parts involved to change , main body, throttle plate , metering block and rear fuel bowl and some small parts, I would try and find a mechanical secondary holley. Good luck.
HI Randy
Can you do a step by step tunning of 600-650 vac sec holley electric choke model from bolt on to drive ?
Frank I can't I have back problems ,sorry.
Hi Randy been watching your videos. Great content a question on the 4 corner idle circut. The reason for this is so you can fattin up the idle air fuel ratio easier is that correct. Iam not really after fuel economy just tryin to dial this bad boy in. I installed a 2092 top end power kit from summit racing on a 351w engine. 1.6 rockers 1.75 long tube headers the carb is a 4160 600cfm. i installed a wideband o2 sensor in the exhaust. the exhaust is 3in from front to back with a y pipe installed. With a aod tranny and a 3.50 rear gear ratio for crussing capability. off idle problems were solved with a 50cc accelator pump with a 37 squirt nossel yellow cam. idle vacume is 10 power valve is 6.5 i got a preacy dial a jet installed on the primay side works amazing. Crussinr afr is 13-14 idle is 14-15 at 750 rpm engine under load is 12-13 afr reading i seem to have a lean bog around 1500- 1800 while the tranny is doin its thing. proably gonna jump to a 40 squirter nossel. The idle air mxture screws are turned out quite a few turns to richen things up. Primarys seem to be around the 70 mark secondaries are 74s. vaccume spring is a brown one. Thinkin the four corner process might help. Tell me what think
That is one of the reasons for a four corner idle circuit. You have an aod trans which usually is bad about shifting to early and slow to drop down a gear loading your engine heavily, all I can say is maybe try a larger carburetor with annular boosters and a lot of adjustability including , air bleeds , pvcr, idle fuel restrictors ect, hope this helps.
the next carbs going to tweak in are the old CARTER YH HORZIONTAL DRAFTS on my jetboat they used these on the old ford y blocks its a 1959 Beuhler Turbocraft jet boat the first jetboat ever made. putting in a 272 y block ford up from the old 256 ford dearborn interceptor
You know I don't remember the 256 but have worked on some 272, 292, 312 , but did not know much about them I was a kid, I worked for Ford for 30 years ,started at ford in 1973 only a few came in back then and I was in the learning stage ,but do remember the engine. Good luck to you.
@@holleycarbshowtosadvice40y90 Thanks Randy. you help me a bunch.
Want to know if you can tell me how to change a 1050 Dominator from a 3 circuit to a 2 circuit, if you don't mind? Thank you, in advance! BTW I have learned a lot for your videos, we appreciate you sharing your knowledge! Thank you!
I have not changed a Dominator , but I feel sure it can be done. I would have to see it.
👍
Thanks
Enjoying your videos. I went with a large duration cam and lost a lot of vacuum and it seems to affected my torque converter also(it’s a cheaper one) I have a 750 dbl pump Holley it seems like my idle set screws have no adjustment. Any advice would be great
Scott if your idle mixture screws are not changing the idle speed when you turn them in and this happened after changing to a high duration camshaft, watch my video , (Holley carburetor tunning: Idle circuit mods for high duration camshafts.) This should fix it. If you have any questions or problems afterwards leave me a comment. Hope this helps.
Where are you located? Just curious. Sound like you're from around my neck of the woods. You're a wealth of knowledge.
I'm in Jacksonville Florida.
Hi man awesome channel here just got into it again, awesome content.
May i ask the idle mixture screws do they increase/decrease AIR or Fuel on a std holley 4150 or and 1850 ??
Thank you
I think you mentioned it in one of your earlier videos a while back but cant remeber which one
The idle mixture screws control air and fuel together, up to the limits of the air and fuel restrictors size.
Thank you so much I really appreciate your comment. May i ask at what point do they main jets get used while driving?
Also do you have a patreon link ? I have a few more question and do not want to bother you for a lot of your time without compensation thankyou sir
I don't mind ,as to your question that will vary but usually anywhere from 1500 to 2000 is when they usually start ,a lot of factors including the load on the engine effects when the booster start to flow , size of engine verses small carb , float level and type of booster ect.hope this helps . PS are you after fuel mileage or performance? And you can ask me a question anytime. We are going to set up a patreon link soon but don't let that stop you from asking questions that would just help the channel grow, thanks for watching.
@@holleycarbshowtosadvice40y90 Hello thank you very much with your willingness to help i really appreciate it.
Unfortunately i am after feul economy as gas in my country is about $4.5 a gallon and at 15.5 mpg it adds up very quickly.
The set up on the vehecial is a 351c 2v, Frod c4 Tranny,Holley 1850 600cfm vacuum secondary,
16 inch of vacuum at idle when in gear and about 18 when in neutral.
I have set up the carb just like you have done in your carb videos with the transfer slot set correctly etc.
Who can i make it achive more Mpg in your opinion? And is my set up oky or would you change any thing.
Thankyou if you need any other info please let me know thankyou
Thank u Randy for showing these videos and thank u for mentioning doing the 4412 carb I really appreciate it!!!
You are very welcome, we are doing a holley 2 bbl video next, this is a marine carb but basically same as 4412 .
Hey Randy
I am interested to know how you taper the Venturi on a 750 when you use a 850 throttle plate
Also is there a modification on the main body idle circuit
Thanks
Stratos
Melbourne
Australia
I use a flapper wheel and you do have to modify the idle circuit , hope to do a video soon.