Holley-proform Carb Issue.

Hi Again Group.im Hoping Someone Can Point Me In The Right Direction To Fix This Problem.i Have Been Trying To Get The Bugs Out Of The 383 Sbc Engine I Built And Put In My Nova.here Are The Engine Parts List So You Know Where To Start.i Started With A Freshly Bored And Honed 350 4bilt Main Block.i Put In A Scat 3.75 Stroke Cast Crank.scat 5.7 Rods,arp Bolts,kb Hyper Silvolite Flattops,speedpro Rings Which I End Gapped To Match The Clearances Black Wanted On These Pistons Because Of Ring Placement.clevite 77 Bearings Throughout.aluminum Heads,2.02,1.60 Valves,double Springs To Match The Cam,a Lunati Voodoo Hyd Cam,527in,544ex And I Think A 110 Lobe Seperation.duration Is 244,254 @.050.lunati Hyd Lifters,comp Cams Push Rods And 1.5 Aluminum Roller Rockers And Stud Girdles.melling Oil Pump,edelbrock Rpm Airgap Manifold And A Holley 750 Vac Secondary And A Carter Mechanical Fuel Pump.the Engine Ran Real Good But Seemed Like It Had Way More To Offer.i Installed A Proform Main Body.now The Trouble.it Idles Good,drives Good Under Light To Medium Pedal.but When I Get On It,about 3500 Rpm It Acts Like It Was Shut Off Until The Engine Drops To Around 1500 Rpm Then It Perks Up And Runs Fine Until You Get On It Again.before The Carb Work It Would Pull Till About 5500 Before It Would Start Breaking Up.any Help Would Be Greatly Appreciated,thanks In Advance.

How much fuel pump pressure do you have? What is the ignition system? Is the accelerator pump on the carb giving a full shot of fuel?

Fuel Pressure Is 7-8 Psi,the Ignition Is An Accel Hei And When I Operate The Carb By Hand Its Shooting A Good Stream Of Gas.

Put the carb back like it was----

If you want to run the pro body make sure you have the correct application

What Is Incorrect?????

Probably the one you have---you didn't solve anything by changing the main body, but evidently created a major problem

You have a vacume sec base plate and are not evidently getting any fuel to the seconaries---float level, needle and seat,filter? power valve passages????

The facts that you have presented say this started when you put on the carb body---so take it off and see if the probalem goes away

I Follow You Now.i Guess Ill Keep Digging For An Answer.thanks

Does that mean you'll change the base back?????

do you have jet extensions? Have you checked your float levels? could be you're uncovering the secondary jets? (no gas on hard acceleration) or perhaps even dumping raw fuel out of the primary bowl vent (primary float too high)... black smoke when it stumbles? Will it pull hard for less than a second before it falls off, then pick up again?

-Chris

Chris It Sounds Like You Have Had This Trouble At One Time.i Just Took The Box Stock Holley,bought The Proform Main Body And Very Carefully,step By Step Followed The Instruction Sheet And Built It.no Jet Extentions,the Float Levels Were Left As They Came From Holley.its Not Dumping Gas Out Of Either Vent Tube And There Is No Black,or Any Smoke When It Stumbles.but It Does Pull Hard Like You Said,for Less Than A Second,falls Then Picks Up.is It Needing Extentions?floats Adjusted,power Valve?

Dog

It sounds like your not geting enough fuel----but----if it ran ok with the other body--change it back--if the problem goes away get rid of the proform body as it is either defective or the wrong application---something you did is wrong--put it back to check it out

Jerry

If the body you got is a higher flow rating---you will need to give it more fuel--bigger jets, power valve, pump/squirters

Are all the gaskets on correctly? Power valves ???

ever since i put that POS proform on my car i have had nothing but trouble. and i mean years of trouble. i am saving up for a demon as we speak

Jerry I Have Done A Pile Of Digging For Answers And Keep Getting One Common Factor,this Main Body Is ,well,less Than An Engine Builders Friend.i Think Its Time To Put The Holley Back Together,the Proform Body Back In The Box And Take A Ride To Summit.since The Whole Point Of This Swap Was To Increase Airflow By Reducing Turbulence And Maybe A Little Better Fuel Flow With The New Metering,with The Engine Build I Have,what Carb Would You Run? A Demon? Edelbrock? Quick Fuel? What Cfm And Should I Run A Vac Secondary Or Double Pumper? Thanks

i was reading about quick fuels they use proform main bodys it said on jegs. i would say a 750 demon or holley would suite you well.

Quote:

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Originally Posted by gassersrule_196

ever since i put that POS proform on my car i have had nothing but trouble. and i mean years of trouble. i am saving up for a demon as we speak

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I don't know if you want a Demon. I have seen a lot of complaints about their QC including metal trash in the carbs out of the box. I also have heard that they have a weird stumble, not easily cured, coming onto the the primary circuit from the idle circuit.

I own an earlier model Speed Demon and have not used it yet but I will be looking inside it before I do. Let ya know if its chippy! :LOL:

I wish now I had bought a Holley 4150HP carb for $200 more. :rolleyes:

Kitz

I run a box stock Holley 850 4150 so I can't comment on the ins and outs of Proform, etc.

The experience I had was after finally getting the right torque converter, the car launched much harder than before and would behave as you describe... pull hard for a second then practically die then come alive like a bat out of hell. I found that my secondary float was set way too low... after raising it up to the sight hole that problem went away but later I added secondary jet extensions and a notched float for some added assurance....

It sounds like your problem is a momentary disruption of adequate fuel supply whether from uncovering the jets or fuel pump can't keep up or several other possibilities... if it stumbles right went you mash the gas pedal, you should have a look at the accelerator pumps as mentioned...

-Chris

Hey Smokedog, I have a 383 with specs like yours. I am running a simple Holley 4150 750 cfm double pumper that produced 500+ hp right out of the box. Clear float level plugs help with adjustments. Cleaning the needle valves is a simple task. Good luck.

The flow numbers on the new holley Hp series are way off. I have a 4781 850 holley that is old as the hills , I was looking at the new hp series carbs and the hp 1000 has the same dimentions as my old 850 why the huge increase in flow numbers. I think Holley is playing the numbers game the old bigger is better thing. A 900 hp is just a suped up 800 . No wonder the Demons are out flowing the Holley per rated size .

I have a Proform main body sitting around, FREE to anyone. But don't ever report back ot me.

Are you sure you have the right gaskets for the carb body,I have seen Holley carbs starve for fuel because someone installed the wrong gasket or installed the gasket upside down . This sounds simpe but it happens quite often. I have never used a Pro-form carb but I know of guys that are going real fast with a Pro-form carb body.

Hey, no idea anymore. I tried it some 5 years ago, fooled around with the jetting to try and make it work, but it was way out of wack. I could not tune it.