my holley dribbles

[Werner R.]

oh no! i installed the holley 1850-2 [4160 vacuum secondary 600 cfm] the i just rebuilt. the car surged badly and would not idle. i noticed fuel dribbling from the main discharge nozzles even with the throttle plates closed. they were in the correct position at close, with just a very small bit of the transfer slots showing. i know that the float level is correct [definately below the sight plug], and my electric pump delivers a steady 6psi.
when i took it apart for inspection, i noticed that someone had filed the primary and secondary plates. there is a lot of light around them when the plates are in the maximally closed position. i suspect that there is enough air flow to send a signal to the main metering system which causes fuel to flow from the main discharge nozzles, even at "idle". the gaskets are correct. before i buy new plates, does anyone have any other explanations for this??
any help would be appreciated.

[John Thomas]

Re: my holley dribbles

what engine? What year? The transfer slot should not be uncovered on either the primary or secondary. Any clearance around the butterflies at idle is too much.

[G B.]

Good idea

If you know the throttle plates have been modified, I think it would be a good idea to replace them first. The other possibility is a warped main body gasket surface. The primary and secondary side faces of the main body can be re-surfaced, but how much more money and time are you willing to put into an 1850?

Actually, I can tell from your profile that you will want to do this repair yourself. I'm not even going to suggest that you send the main body out for machining. You can buy a wide, double-bastard flat file at a hardware store for about $8. Don't try to use an old file; they aren't flat enough. Then, with just 3 or 4 hours of your time you can file the gasket surfaces on the main body flat. It will take this much time because most Holley main bodies are warped out at least .020".

I'll give you some stock throttle plates if you'll pay the postage. It will only take you a few more hours to get them out of the rusty baseplate that I'm going to send.

Naaah. I wouldn't do that to you. Let me know if you want the plates. My phone number is in my profile.

[Werner R.]

Re: my holley dribbles

john, it's a 427 in a 64. i am running a 750 cfm 3310-3. it runs pretty good, but i wanted to see how the response is changed by going to a 600 cfm unit. i got it at a swap meet, but did not notice the problem with the plates until i noticed the dribble [and took it apart completely]. i am going to try to put in a non bubba'ed set of plates because i think that the air flow at idle is activating the mains. can you think of any other reason [except a high float setting] that could do this? it is only the primaries that are leaking.

[Werner R.]

Re: Good idea

jerry, i loved the post. i did look at the warp of the main surface, and when i used several different pieces of square stock, and a carpenters "L", i didn't see much of a warp, but that was early in the morning and maybe my eyes were tired. i'll try again tonite, and use a feeler gauge. if it is a minor warp, i actually might try the file route you suggested [that sound you hear is my head beating against the wall!!!].
in any event, i will call about the plates you have. i am definately interested, and i need four of them because both the primaries and secondaries were filed.
if it isn't a warp, how about my theory that air flow around the very "loose" plates is activating the main system. does it make sense?? what else could it really be??
the holley books i have say that the correct setup is for a slight [.020] showing of the transfer slots at idle, and if you don't do this the sudden activation of the slots will cause a stumble or a bog. it makes sense to me, but several people have suggested that the slots should be completely hidden at idle. but i don't think the transfer slot is causing the pulling of fuel from the main discharge nozzle. do you?? i will call you asap aabout the plates.

[Clem Z.]

Re: bad idea

never file the metering bodies because you remove the little projections that do the sealing around the the opening in the gaskets. you can machine the main body but you must straighten the metering bodies in a jig using a press. new butterflys are available from holley.

[John Thomas]

Re: my holley dribbles

My 4160/3811 (original) does not have externally adjustable floats and I doubt your original did either. The float setting can cause the problem you are having and could be made worse by the butterflies. If properly set up, you should be able to "kill" the engine at idle by closing the idle mixture screws. If you can't, gas is leaking into the engine from somewhere. My guess is the transfer slots, either primary of secondary.

[G B.]

Transfer slot

I've found that almost a third of the primary transfer slot can be exposed at idle without ruining the air/fuel mix.

Now that you've admitted this is a swap meet Holley, I'm suspicious of everything else about it. I'd check the power valve in it and the jets to make sure some Car Craft subscriber didn't "improve" that Holley for his drag car. How about the idle air bleeds? Have they been enlarged? What secondary metering plate is in it? You might want to check the secondary diaphragm spring too. What color is it? A little more than 99% of the carburetors for sale at swap meets have been modified to death. I'll be stunned if the only damage done to yours was the throttle butterfly filing.

I don't think you're going to be able to see the warps and wows in a main body face unless you run the file over them to skim the high spots first. And for anyone who is hard of reading: I AM STILL TALKING ABOUT THE MAIN BODY, not a metering block.

[Werner R.]

Re: Transfer slot

jerry, i love it: "if anyone is still hard of reading"!! that was a stitch.
i replaced all of the stuff you mentioned with a renew kit. the secondary spring is silver [standard tension- a decent starting point]. i am going to run a file over the main body face [clem-i will not damage the bead no matter what. i will not attack the main metering block. even i'm not that dumb, but i can see how someone could easilly do it removing the old gasket]. the thing is i did not pay that much attention to the throttle plates until i noticed the dribble.
jerry, i will call you about the plates. i tried earlier today, but i think my cell phone was in a dead spot. i will try again. i think it is great that you guys take the time to respond. it's fun to read some of these posts and i like learning stuff, too.

[Clem Z.]

metering body

what i was pointing out is that it does no good to flatten the main body if the metering body is warped. about 50% of the holleys i do have warped metering bodies and it got worse when they went to the 5/16" hex head bowl screws that you can use a ratchet/socket to tighten them up. the new HP models have renforcement ribs in the main and metering bodies to prevent warpage.

[Werner R.]

Re: metering body

clem, here's what i found when i looked carefully at the main face: the venturi flares were not well done. they protruded quite a bit above the surface of the main face. i didn't mesure them, but .020 at least.
first question: if the metering block gasket does not seal well, will that allow fuel to dribble out of the main discharge nozzles at idle??
the warp of the main face was about .006 max. i used my files to get rid of this warp, but also to make the venturi press fit flare flush [whew] with the face. it looks good now.
then, i again checked the warp of the metering block. it really doesn't look like it is more than about .006, which doesn't look like that big of a deal. this car is a driver, not a racer.
second question: would a .006 metering block warp cause fuel to dribble out of the main discharge nozzles at idle?? i might add that the brass tube that was in the passage that leads from the metering block to the main discharge nozzles was protruding above the surface of the metering block. i gently tapped this so it is flush with the block surface.
finally, i think i said on a recent post that i cannot reverse rotate my engine, even without spark plugs, when tryinig to find TDC. i might have said i need a "torque wrench" to turn it [even in the correct clockwise direction]. actually, i use a breaker bar, although i can do it with the 1/2 inch socket wrench, but it is tough.
third question: what in the world could make it so hard to rotate my engine counterclockwise [no matter what, i loosen the crank nut after turning the engine more than a few degrees counterclockwise]?? it seems to run well. good torque etc....
as always, any thoughts would be appreciated.

[Clem Z.]

Re: metering body

it sounds like you have done every thing i would do and .005/.006 warpage should not cause nozzle drip.warped body faces will cause a rich idle problem. the part i do not understand if the butterflies are open enought to cause dripping from the discharge nozzle how you can get the idle RPM down.make sure the bowl vent is not restricted and because of the lowness of corvette air cleaners the bowl vent tube should be cut on a 45 degree angle to allow the proper venting of the fuel bowl pressure. the bowl vent tube should be 1/2" below the air cleaner top. you said you were looking for better throttle responce with this smaller carb but if your larger carb has a vacuum secondary i can only see going to a smaller carb will limit you top end HP not help your throttle responce.

[Werner R.]

Re: metering body

clem, two comments:
first, i could not get the rpm below 3,000 while the mains were dripping, no matter what i did. the engine raced, probably because of the extra fuel dripping into the carb.
second, i hope that the smaller throat of the 1850 carb will cause increased air flow [on an equal rpm basis] and therefore lower pressure at the booster venturis at the same rpm. i think this will improve the low rpm signal in my system. higher vacuum should follow from the faster air flow. does this make as much sense to you as it does to me??
finally, any idea why i cannot rotate my engine counterclockwise without loosening th acranki bolt??

[Mike McKown]

crank bolt

Werner:

If your engine is loose enough to turn backwards by the crank bolt, it is probably worn out. I assume you are talking about the big one that screws into the center of the crank.

Rotating the bolt in the direction to loosen it when you turn the engine backwards overcomes the torque appled to tighten it. I wouldn't turn the engine either way if it were mine with this method. Good way to strip threads. Seen it done!

When the engine is cranked by the starter and it fires and runs, it kicks the starter drive out of engagement from the flywheel. If you use the starter to "bump" the engine, the starter drive will many times stay engaged to the flywheel. If you use a bar to rotate the engine forward, it will kick the drive away from the flywheel. If you use a bar to rotate it backwards, it will pull the starter drive into deeper ingagement with the flywheel teeth. So you get the drag of the starter plus if the starter is not aligned just right or the starter is worn you get additional drag. All of which you don't get going forward.

Question for you: Is your dribbly Holley one of those that richens the idle mixture when you turn the needles clockwise?

[Clem Z.]

Re: metering body

the signal to the boosters will be stonger with the small carb. when we build race engines were the track rules require a small carb,even a 2 barrel we close off the butterflies completely and drill holes in the butterflies to get air for the idle circut. some times we drill as large as 1/4" dia in each butterfly to get the engine to idle and prevent fuel being pulled from the boosters. opening the secondary side butterflies a small amount sometimes will help with the primary booster drip on a 4 barrel. small carbs will even cause fuel to be pulled from the accelerator squirter at full throttle because of the strong signal.my suggestion would be to get a 1850 carb that you know that works correctly and try that unless you have time to kill.