I have a 600 holley 1850 that I have been trying to cure rich (gassy) idle. This carb (600 1850) Has idle 055 diameter feed restrictions .

Also have a 6211 spread bore carb and noticed the idle feed restrictions are .027 diameter.
What is the possiblitly of installing the metering block from the 6211 spread bore with the smaller metering jets on the 1850?

If someone hasn't drilled the idle restrictions thats not the problem. The 6211 is completely different carb from the 1850 I really doubt anything lines up. First make sure your throttle blades aren't open too far or the power valve isn't blown before you start looking for any strange problems.

The operation of the idle circuit is dependent upon the air bleeds just as much as the fuel restrictor jet. I would bet that the air bleed on the 6211 is much smaller than it is on the 1850.

Common trick to reduce the fuel restrictor jet sizes on Holleys is to insert wire into the jet.

But as mentioned above, make sure you are not idling on the transition slots. And part of that is making sure your ignition is setup correctly. Bigger/longer cams require a lot more advance at idle.

on your 1850, if you screw the idle mix screws in all the way does it kill the engine?

Has it been rebuilt before? Do you know for sure or did you buy it used?

Can you remind us a little on you engine setup?

The operation of the idle circuit is dependent upon the air bleeds just as much as the fuel restrictor jet. I would bet that the air bleed on the 6211 is much smaller than it is on the 1850.

Common trick to reduce the fuel restrictor jet sizes on Holleys is to insert wire into the jet.

But as mentioned above, make sure you are not idling on the transition slots. And part of that is making sure your ignition is setup correctly. Bigger/longer cams require a lot more advance at idle.

Thanks guys for the replys. Mixture screws are responsive.I have gone through the ignition 20* mechanical adv. 18* intial adv. The primary plates are showing about .020 tranfer slot and the secondarys are just cracked slightly. (I went too far originally with the secondary screw, I couldn't get it to idle down lower than 900 rpm) I then backed off the secondary screw 1/4 turn. Idle then went back where I want it around 600 rpm. Rich idle returned. 8 inches of vac at idle. power valve is a 7.5. I was going to change it to 6.5 but was also looking into the idle transition size. I have read about the wire trick (but where can you get the v shape wire.
Oh, Motor 355 cam .298 lift 224* @ .050 tko 600

What is the possiblitly of installing the metering block from the 6211 spread bore with the smaller metering jets on the 1850?

None. The spreadbore Holley uses a reverse idle system that controls only air, not fuel. You can screw the mixture screws on a RI Holley all the way in or take them all the way out, and you won't kill the engine. Not only will the metering blocks "not line up", the system is totally different. It won't work at all...

Do you know the history of the carb? 850 double pumpers have IFR's in the .038-.040 range. Are you sure those are IFR or did you measure the power valve restrictions? Not doubting you carb knowledge but if they are in fact the IFR's they must have been drilled out at some point. What size are the idle air bleeds? The two work together to determine idle air/fuel. What is the whole list number (1850-?)?

1850 isn't a spreadbore and doesn't have reverse idle circuit. 6619 is the closest 600 RI carb.

So, here comes the big stupid question- if it's responsive to the idle screws and it seems rich to you why don't you turn the screws in a little? Like until you get a 50RPM lean drop?

I'm wondering if what you're smelling is raw mix being exhausted from a cylinder with a miss. Did you ever do a cylinder balance test, pulling one plug wires at a time?

http://www.innovatemotorsports.com/forums/forumdisplay.php?f=7

thanks for all ideas.
I want to go with the 600 square bore carb, just was curious about using the the metering block from the spread bore on the 600 because of the smaller idle restritions.(yes I am sure I measure the correct orfice and not the one under the power valve)
I will check the cylinder balance. Did not yet, (it seems to run good around 900-1000 rpm but still just a little rich) I would like to get it down to about 600 rpm but then it seems to run very rich. Thought I would get a 6.5 power valve but was just curious about the idle restritions.
Seems like every holley I have been around has a very rich idle. Maybe just me.......
I will play with it again tomorrow. Thanks for all the info and I will let you all know what I find.

I've used multi-strand automotive 12v wire successfully. Get it anywhere from Walmart to your local parts/hardware store. Cut off a 2" piece & remove the insulation. Pull a single strand out. You'll want a much shorter piece to install in the metering block. As far as the V shape, you could tie one strand into a knot if your fingers were small enough. :) I used a small pair of needle nose pliers. See if some of your buddies have scrap pieces of wire. I used a set of digital calipers to determine the diameter of one strand. Write it down. The diameter of the single strand should reduce the size of the restrictor by that amount. Wires come in diff sizes so round up several diff diameters to try. Good luck. Dave

Just another thought. Some metering blocks have the IFR up high in the block, under the soft plugs in the top of the block. Not readily available to measure or modify. I think these were later (newer) carbs. The real IFR's are a brass insert, not just a drilled passage in the metering block. If the IFR's you measured don't have the brass insert they aren't the real IFR's.

I've used multi-strand automotive 12v wire successfully. Get it anywhere from Walmart to your local parts/hardware store. Cut off a 2" piece & remove the insulation. Pull a single strand out. You'll want a much shorter piece to install in the metering block. As far as the V shape, you could tie one strand into a knot if your fingers were small enough. :) I used a small pair of needle nose pliers. See if some of your buddies have scrap pieces of wire. I used a set of digital calipers to determine the diameter of one strand. Write it down. The diameter of the single strand should reduce the size of the restrictor by that amount. Wires come in diff sizes so round up several diff diameters to try. Good luck. Dave

Thanks Dave,
I'm a little confused about the tieing the wire in a knot.
(how do you get the wire staked in the hole??)
Could you explain this some more?
The holes I'm looking at are the idle restrition holes and do have brass inserts.
I have large amounts of scrap auto wire so thats not a problem, just unclear as how to install it.
Thanks again.

Sorry about the confusion. Not a good time for me to be a smarta$$ with my remark about the knot. Cut the wire 5/16" to 3/8" long. (or whatever length works for your situation). Bend the one strand into a V. Stick one end of the wire into the hole that you want to restrict. When the carb is assembled the end of the wire that is NOT in the hole will be trapped against the metering block by the gasket. Once the carb is back together & the 4 bolt screws tightened (just snug enough not to leak -overtighten & they do strip), that piece of wire will be there until you take it apart & remove it. Dave

8 inches of vac at idle. power valve is a 7.5. I was going to change it to 6.5 but was also looking into the idle transition size.

I think you're trying to idle the car to slow you have a 224* in a 355 and trying to run 600rpm idle speed and only generating 8" of idle vacuum with a 7.5" PV. I would suggest raising the idle to 750 and lower the PV to at least 6.5".
Mike

Their is a couple of things here that do not make any sense. Have rechecked the running float level ?? make sure the power valve is not blown. Have you checked for vacuum leaks internally and externally, were is the timing set at. You should be using a vacuum gage when adjusting idle mixture screws. You want to adjust the mixture screw in or out, what ever it takes to get the highest manifold vacuum. This will allow the engine to idle smooth and clean (lean). If that is indeed you're cam specs. You're engine should have way more running manifold vacuum, unless like Tom stated a possible problem with a dead cylinder or a valve adjusted too tight. If the engine is in good mechanical condition, good ring seal, tight guides, etc. The engine should have over 15 " of manifold vacuum, if not more. A good vacuum gage will also tell you if you have a Serious internal problem like a bad valve. Once you ruled out any possible problems and have established the highest vacuum reading. Drop the car in gear and see where the vacuum drops too. Lets say if it is 10 to 12 ", the engine (carb) will need a 8.5 to a 10.5 power valve. If that dose not solve you're problem, then open up the idle air bleed .003, readjust the idle with the vacuum gage. I don't think changing to a square bore metering block will help either, if anything it will make the engine run worse. Why, look at a square bore carb and what do you see, two smaller front venturies. The calibration will be way leaner that the block from a 1850. A 1850 is a good all around general calibrated carb for small blocks.

Hope this give you some ideas and what too check,

Ron Miller 92Camaro:beers:

Sorry about the confusion. Cut the wire 5/16" to 3/8" long. (or whatever length works for your situation). Bend the one strand into a V. Stick one end of the wire into the hole that you want to restrict. When the carb is assembled the end of the wire that is NOT in the hole will be trapped against the metering block by the gasket. Once the carb is back together & the 4 bolt screws tightened (just snug enough not to leak -overtighten & they do strip), that piece of wire will be there until you take it apart & remove it. Dave


Excellent info agian!:hurray: that makes sence now.
I will try that, I have been very blessed by the info recieved from the guys on Team Chevelle. Dues are cheap and very much worth the money. Lots of info and help.
I'm going to run down and get a 6.5 or lower power valve and try the wire trick.
I will let you all know what my results are after I get these mods in place.
Thanks for the great help!

I've been using and building 1850s for over 20 years on all kinds of engines and have never yet needed to jack around with the IFRs. I've run literally hundreds of these carbs.

What about my question above? if it's too rich but responsive to idle mix screws why can't you lean it out a little?

I've been using and building 1850s for over 20 years on all kinds of engines and have never yet needed to jack around with the IFRs. I've run literally hundreds of these carbs.

What about my question above? if it's too rich but responsive to idle mix screws why can't you lean it out a little?

I will try that but, I'm about 1 turn from bottoming out on the idle jets. Just read about the IFRs and thought it was interesting. I think what I will do is try the 6.5 power valve 1st without any mods to IFRs and see what that gets me.

1850 isn't a spreadbore and doesn't have reverse idle circuit. 6619 is the closest 600 RI carb.


6211 is a spreadbore Holley with a RI circuit, and that's the carb he said wanted to use the metering block from on his 1850.

IF it isn't some other problem as suggested in this thread, I'd put a quick kit in the carb to make sure everything is up to snuff. It's always better to start at a baseline than to just start throwing parts at it to hope it works..That's just IMHO. I had a problem with a rich idle on a 4175 Holley, and it turned out to be a an internal fuel leak from the secondary metering plate "plate". Gas was seeping across the secondary throttle blades-just enough to cause rich running. I took it apart, hammered out the plate on a flat surface, put it back together, and it was fine.

I've had a couple of those. the metering plate were bent up on a lower corner, leaked fuel into the manifold via the secondary idle discharge ports. One of them was a 496 in a motor home, about drove me crazy trying figure why it was always so rich on hot restarts.

Ok, I have the 600 1850-3 carb with 6.5 power valve installed, .025 wire in idle restrictors. It's better and I can get about 750-800 rpm still a liitle gassy on the right bank.
When I hold my finger on the air bleeds ( the one on the left bank pulls the motor down, the one on the right bank seems to have no affect) That is the side that smells gassy now.
Also when I turn the ignition switch off the motor continues to run. Weird????:confused:

Try spraying carb cleaner into the air bleed this may have been your trouble all along. Try slowing the idle speed down a little and see if the run-on stops. Then try resetting your idle mixture and idle rpm to 700-750.

and take the idle screw out on that side, squirt carb cleaner in there too.

Try spraying carb cleaner into the air bleed this may have been your trouble all along. Try slowing the idle speed down a little and see if the run-on stops. Then try resetting your idle mixture and idle rpm to 700-750.

thanks guys. I will try that along with taking the idle mixture screw out tomorrow after church.
I wonder if I could squirt it down tonight and let it sit till tomorrow?

My mixture screws are responding now on both sides but still can't get the rich idle to go away. If I bring the idle down to around 700rpm it drops the vacume from 10. to 7.5-8.0 and really richens up the idle. I'm running a 6.5 power valve.
I'm tempted to purchase a new edlebrock carb if I knew that would solve my problem.
anyone try these edlebrock carbs on 355 engines

http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330097564872&ssPageName=ADME:B:EF:US:11 (http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=330097564872&ssPageName=ADME:B:EF:US:11)

Don't give up just yet there's still a few things left to try. You can run a power valve with an even lower rating try a 4.5". Try bumping the timing up a few degrees and see how it affects the idle quality,if it helps and doesn't cause problems cranking the engine try taking that same amount out of your mechanical advance and drive the car to see if you have any detonation problems. If your distributor has vacuum advance you need to hook it to manifold vacuum and see if you have enough idle vacuum to pull the vacuum advance in. If not you should try to find a vacuum advance unit that will pull completly in at your available idle vacuum. If that proves possible you will likely have to go back and limit the total vacuum advance so you don't get into detonation problems at cruise rpm.

Don't give up just yet there's still a few things left to try. You can run a power valve with an even lower rating try a 4.5". Try bumping the timing up a few degrees and see how it affects the idle quality,if it helps and doesn't cause problems cranking the engine try taking that same amount out of your mechanical advance and drive the car to see if you have any detonation problems. If your distributor has vacuum advance you need to hook it to manifold vacuum and see if you have enough idle vacuum to pull the vacuum advance in. If not you should try to find a vacuum advance unit that will pull completly in at your available idle vacuum. If that proves possible you will likely have to go back and limit the total vacuum advance so you don't get into detonation problems at cruise rpm.


I plugged the vac advance to manifold vac and the timming went from 18 to 40 degrees. Still gassy, but it does however shut down imeditatly when I turn the key off now.