holley carbs need to be freshed up once in a while.. they are not that hard to do... after you have removed the original gaskets.. sometimes a major job getting them off..

how is your fuel quality... could it have gone bad while changing motors..

did you tighten and then torque the intake down in an X pattern so the manifold is properly centered. not leaking vacuum from the bottom of the gaskets against the cylinder head intake surface..


i posted this a while back when i did an 1850-3 rebuilt.. that is also a 4160 style carb.. Holley R1850-3 - Album on Imgur go thru the images .. each one opens to a larger image... making it easy to read.. or print...

 

Yes fuel is old. Will be addressing this before more time spent tuning/troubleshooting. Wouldn't old fuel cause a lean condition?
Haven't looked for a vacuum leak due to the extreme rich plug reading. Vacuum leak would cause a lean condition, correct?
Just asking more questions. Thanks for the reply.

 

Yeah a vacuum leak would cause a very lean condition but its usually more noticeable at idle then driving but it can vary. If you got bad fuel it can cause an engine to run very horrible and not burn very well as I have had bad gas before and I had to add quite a bit of good fuel and some fuel additive to it in order to get it to run right and the carb was just fine. Depending on how often you use your boat and how much it sets depends on when a carb needs rebuilt.

I don't drive my truck during the winter months and it sits with just a start up and warm up once a month during them times and after two years I was expecting to find a bunch of build up in my carb but was surprised it was almost clean and just had to use a little carb spray and clean out the metering blocks and some new fuel bowl and metering block gaskets and it was good to go.

 

I have 15" of vacuum at idle. If I try to turn down the idle below 900 rpm it will begin to "hunt" or surge approx 200-300 rpm. It seems very rich, I done see any fuel dripping or spilling over in carb. Is it possible the secondary stop screw needs to be opened a bit? If i ever so slightly, cant see it move, put pressure on the lever the idle smoothes out. I thought or at least according to holley that adjusting the secondaries was for large cams only. Thoughts please.

 

It will idle correctly if the idle air screws are at 1/2 turn out from all in. If power valve was leaking woudn't I be able to see fuel leaking? Or float level too high would I be able to see excess fuel? Throttle plates are dry.

 

So I tried adjusting secondary stop screw. I adjusted until the plates were even with the bottom of the transfer slots. Now the idle mix screws have an influence but idle is 1100. lol. So I assume I need to back off secondary screw? I am about to pull my hair out here. errgghh.

 

there is NO perfect adjustment on the bench.. there is ONLY ball park..

you may have to open the secondaries..

you may have to INTRODUCE more vacuum leak... IE... bigger PCV valve... needle metering valve.. Tee'd into the PCV hose... between the PCV and the carb fitting... so you can adjust the bypass air into the manifold.. let me explain this.... carb base... hose.. TEE.. hose... pcv...
from the TEE the needle valve... a filter of some kind.. either fresh air or from the crankcase breather.. if you are just testing.. leave the end of the needle valve unfiltered. just open to the air..

this won't effect PCV operation.. as you will only have it only slightly.. this is like drilling holes in the throttle plates... but less damaging.. and fully adjustable.

other people have done this to make Tunnel rams work on the street..

easily removed if it does not work.. only cost lay out is the tee fitting... and the fine adjustment needle valve.. plus some hose.


open secondary more.. to allow primary to close.. fractions of a turn...

like balancing on a ball... you don't know which direction to roll... you just keep rolling this way and that.. till you either fall off on your tush.. or get it right..

i wish there was an easy way to do this other than DECADES of experience with carbs.

i start too much stuff.. there was a guy in early 70s chevy truck today.. man he was gassing me with his exhaust... it was loading up at idle.. i almost made the mistake of telling him to come over so i could adjust his carb to make it run great.. then i realized... i don't need any more headaches..

i wish i was in good enough health to get a small shop someplace and just do carbs and fuel issues. someplace with a old school dyno just to load the engine ... but perhaps several mules.. of various displacments to get the idle transition circuilts tuned close to what the carb owners engine is.. its really hard to adjust a carb for a 454 on a 302.. or visa versa..

keep adjusting.. open those secondaries... install a larger flowing PCV... put a TEE and install a SECOND PCV... thats cheaper than a needle valve... use a small hose clamp to compress the middle of the vacuum hose fun.. to the second one to change the flow. actually those are emission hose.. 11/32, 15/32, 19/32.. and that is actually in the back room of many parts stores and they don't know it.

Armor Mark/PCV hose good year pcv hose..
AZ Part Number: 50290 goodyear Part Number: 65185 Size: 11/32 in.
AZ Part Number: 50291 goodyear Part Number: 65186 Size: 15/32 in.
AZ Part Number: 50292 goodyear Part Number: 65187 Size: 19/32 in.

 

Ya I think I went to far open with secondary screw being now I cant get it down below 1100. I will pull carb off tomorrow, back secondary off some more as well as set primary throttle plate so that amount of transfer slot showing is square. Does this make sense? Or sound like Im headed in the right dirrection?

 

What are your engine specs such as compression and cam size etc. It sounds like to me you have a mild performance cam with only 15 inches of vacuum which is still not bad but I in my opinion don't think you should need a needle valve in order to get this carb to run good but is an option if it will help and exactly what holley 4160 is this? Is it the model 1850 manual choke version or the 80457 electric choke version by chance or a 750 3310 manual choke version or 80508.

I have that carb and I can give you almost a book on it since that and a few other holley and quick fuel brands and such with several different combos over the years from stock to mild to higher end performance I have done a lot with tuning holley carbs. There could be several things with your idle but 10 degrees of initial timing will not work with a cam producing 15 inches of vacuum at idle.

To give you an example I have mild hydraulic roller cam producing 17 inches of vacuum at idle and it will never run on that low amount of timing and I have another engine with only 12 inches of vacuum at idle and it takes quite a bit of timing around 18 degrees in order to idle correctly and be able to adjust my carb.

When it comes to performance stuff even mild sometimes and using a carb that is not calibrated this is some of the things you run into without advance tuning but you really need to know your holley and how each circuit works with each other and know how they function and how changes will effect things. I wish I could say in some simple things but first things first maybe give that engine some more timing say around 14 degrees and also if you have vacuum advance on your distributor run it on full manifold which it will give you more extra timing at idle allowing you to close your butterfly's more and not have to open them so much in order to idle.

If is not an adjustable one then get one from summit or jegs or maybe your local auto store might carry them so you can adjust it to what your engine needs. Usually about 12 to 14 is the best for performance stuff. I would take the carb off and reset your secondary to all the way closed then look at your screw sticking out of the base plate then once it starts to just touch the brass linkage open them up about a half a turn. Then on the primary back the idle screw completely off and then turn it till it just makes contact then turn it while looking at your transfer slot and turn it as many turns as you can till where you see that your transfer slot is no longer a square shape but like a rectangle and that is how many turns would be too much and that would cause fuel to be pulled out of the transfer slot instead of the fuel discharge port and make for a very rich idle. You want to stay in the range to where your transfer slot is square. If you have feeler guage then about .020 is a starting point.

On the rear also never set it to show the transfer slot as it sits up .020 higher then the front on all vacuum secondary carbs and will always lead to a high idle that won't go down. If you could post your engine specs it sure would help if you know them. Also testing a power valve if its good or not is kind of easy but its not so simple as having a rich idle as you need to have everything tuned and set before you can try a simple test if its good or not. Once you got everything that needs done all you have to do is turn one idle mixture screw all the way in and if it kills the engine then most likely its good and fine and no need to replace it. If one is blown it will allow excess fuel at idle and thus your idle mixture screws won't work but if you don't have the carb adjusted right along with enough timing and you have the primary's open too much then it also will render the idle mixture screws to not adjust and work and give the false reading of thinking of a bad power valve and it gives a rich idle since its sucking fuel from the transfer slot.

 

Engine specs
Chevy 350 .030 over
9.3-1 comp
Cam specs
http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=99&sb=2
Carb is a Holley 4160 list# 80551
Motor is in an aluminum jet fishing boat.

I adjusted secondary plate to be even with bottom of transfer slots, after doing this the idle mix screws can be adjusted for peak vacuum. However it now idles too high, 1100 rpms. So I'm guessing my next step is to back off the secondary plate adjustment. Also set my primary to .020 on transfer slot?
As far as timing. It's a boat so I have no vacuum advance. How far can I advance before I have starting issues? Dizzy is set for 24* all in at 3k.
Thanks for the help.

 

Well since your engine is inside a boat and that is a marine holley that kind of gives me a slight challenge as I don't know the specs of that carb but I would assume it should be close to my holley 600 out of the box. Depending on how much load is on your motor etc you should have at least between 32 to 36 degrees of total timing in by 3000 rpm to 3500 rpm at the most with out having any issues of pinging with 92 octane.

You might get by with 89 as my hydraulic roller lunati voodoo cam is very similar in specs to your cam but with more lift and I had to recalibrate my holley in order to get the correct idle and even enough timing was not enough. But that is a whole different time for that as its really advance tuning changing the idle fuel curve.

If you got a timing light reset it to about 14 degrees initial and with 20 degrees advance you would have around 34 total. That cam will never idle right along with that carb as is at only 10 degrees of timing. You might need to run it up to 16 degrees initial which is where I have mine set and I have 32 degrees total timing minus vacuum advance by 3500 rpm. Since you don't have vacuum advance disregard my comments about that. I would start from scratch and reset the secondary to half a turn open and the primary to .020 or a square transfer slot showing and mark down how many turns on the primary idle screw is too much so you can keep it square without having to keep taking it off and also put the idle mixture screws at 1.5 turns out. Before adjusting your carb readjust your timing with more initial.

That would be a good starting point. Trust me with out the proper timing you can adjust your carb all day and it will never work right. I mad that mistake before of not enough and returned a brand new carb thinking it was bad but I did not give my engine what it needed lol. Was years ago but you learn as you go. Sounds like a nice build

 

Ok I will adjust timing. How well will it start with that much initial timing? One good thing is there is virtually no load on engine until 1800-2000 rpm. It's is a DUI hei distributor. I think regular hei timing parts will fit.

 

Power valve? That was always my first go-to item when the idle got strange on any Holley. It was before the check valve mod/manuf. change though

 

I don't know what kind of starter your using but I don't use the big bulky size like gm used as stock starters way back when as I had nothing but bad luck with them as they don't work well with performance builds with more then 9 to 1 compression so I use a aftermarket gear reduction mini starter and I also use a toggle switch so I can turn the engine over a few seconds then I flip my switch to give power to my distributor then it fires right up so like that is helps not to put strain on the starter and such.

At only 16 degrees it might or might not want to kick back it just depends on the starter itself and how much it can take. I just reset my timing the other day as somehow my distributor moved just a hair and I had way to much timing at idle which was almost 40 degrees but my starter never gave any issues since I have my interrupter switch. Give it a try and see how it does. If its a more heavy duty modern starter it might be enough. Also you have a DUI distributor and you can't get any better then that.

 

Ok will play with it a bit tonight. I do know I timed by ear/ where it idled best at and that was at 10*. Any more or less it wasn't as smooth. But I will play with it again just to double check. The starter is a stockish starter. Again it's a boat. So the marine rating, for insurance reasons, causes prices to rise quickly on the electrical parts.
As far as timing goes at idle. Is there a rule or just set it where I get best idle quality?

 

Yes I was wrong, this thing likes 14-16* timing. However my starter does not!!!! So I have it set to 12*. Total timing is 36*. Idle is pretty good now after adjusting throttle plates. Here is what I did, please correct me if I did something incorrect.
First I set primary throttle plate to .020 of exposed transfer slot. I then set secondary to get close to ideal rpm at idle. I used a vacuum gauge and adjusted idle mix screws to highest vacuum.

Here is video with idle. I am new to anything but stock, so how does it sound?
https://youtu.be/Q_amvczyD9w

 

that actually sounds really good... does not sound like you are going to foul spark plugs at extended idle..

i usually set conventional carb idle mixture screws (non 4150/4160) with a vacuum gauge.. getting them right to the highest vacuum.. then turning them in slightly so the vacuum dropped overall 1/2" so if highest idle vacuum was 16" tiny amount of turn in equally of both to make it 15.5" this is lean best idle.

so you are really really close if not perfect.

its really hard to do this with a holley.. as the idle mixture screws are course thread.. so.. don't mess any farther...

enjoy your carb..

i spent yesterday deep into a 4150 myself.

 

That motor sounds pretty good and I would say your doing and learning good as that is how I set my idle is I set the front and adjust the rear and go back and forth a 1/8 of a turn each screw on the primary idle and secondary screw without going past my transfer slot range and get my desired idle setting and as far as setting the mixture screws for highest vacuum that works ok on stockish motors or with small rv type cams but with any thing performance it always leads to lean of a setting and have to add a extra amount of idle mixture which lowers the vacuum signal some but performance cams need a richer mixture and higher idle in order to run right cause of several things. Glad you got it going good. If it runs good at 12 degrees initial and everything else is good then I would leave it as it is.

 

on the STARTER not having enough POWER issue..

please print and perform this voltage drop test..

you may want to rig up a 14 or 16 gauge wire with a ring terminal from the starter top post to the digital volt meter lead for doing starter voltage drop testing. usually less than 1.0 volts but you might get slightly more..

please perform test 2 while cranking..

you don't have a voltmeter....

use your jumper cables... hook Both of them to the engine block. or somewhere good to ground both of them to on the engine .. then both on the negative post... if you have an issue with the negative being too small or improperly hooked up ... and it happens... your engine will crank easily now..

you can also perform the six steps of the voltage drop test with just a test light... only test 1 should result in the test light bulb turning on... if it comes on in tests 2 thru 6.. you have an issue..

since most hot rods don't have an underhood power distribution box or underhood fuse block.. look for power distribution studs.. either on the firewall. or fender mounted starter relays..

its only a test... i use it almost daily.. sometimes i perform it 5 or 6 times.. usually twice on each car.. one when i open the hood.. the last just before i close the hood to verify... try it on a different car or several different cars first so you know what the meter display looks like..


starter ground path..

negative post, negative cable terminal, negative cable, ring terminal at the block, the starter mounting face on the block... the starter nose that is bolted to the block.... if you have paint or a loose connection you may not have enough electrons to crank the engine.


positive path to the starter.

positive post.. positive cable terminal, positive cable, ring terminal at the starter solenoid..

there are a lot more places for the starter to not get enough electrons on the negative side. painted components... poorly selected mounting locations.. loose fasteners. thru multiple layers. .

 

i should also mention that yesterday... i found an idle issue with the 4150 i was working on.

i found the baseplate to main body gasket was too long and holding the baseplate slightly away from the main body.. it was dribbling fuel out the drivers side and up where it looking like it was leaking out of the metering block to main body gasket.. see attached pics... i used a pair of scissors to trim it down on both sides..

i also gave it an extra half turn on the secondary idle speed screw.. i am going to pull it back off monday and drill the IFRs farther.. and give the secondary idle screw 1/2 more. it had 0.027 IFRs.. i drilled it to 0.033" i think i am going to go to 0.37 as i have that size drill and this is on a 429SCJ motor rebop carb. it still has a flat spot just off idle.. this thing does 100 plus mile freeway runs several times a week..