Just bought a '64 Nova with a 194 CuIn Inline 6 with 0.030 over pistons, 390 cfm Holly 4 barrel carb mounted on a Clifford Aluminum Intake, Crane Cam specs: cam timing .050 lift, intake opens 1.0 BTDC Closes 35.0 ABDC Max Lift 107 Duration 216, Exhaust opens 51.0 BBDC closes (3.0) BTCD Max Lift 117 Duration 228, Min RPM 2000 Max RPM 5000 Valve FLoat 6500 RPM. Headers with Flow Master Exhaust. Starts, Idles and runs great...but....at idle for a minute or 2 (normal wait at traffic lights) it starts to smoke (blackish color). It puffs smoke for the initial take off acceleration then goes away completely. Never smokes at high RPM or under a load...ONLY at idle. MPG city = 12MPG, MPG Hi-way 23 MPG @ 2400 RPM/60-65 MPH. had a few guys adjst carb with neg result. Have been told that this is a common set-up for a hot rod 6 and it is NOT over carb'd. I really like the sound and top end performane...win lots of beer cause everyone thinks it is a small block V8. Don't want to put a 2 Barrel on if I don't have to...sorry to be so long winded but wanted to give as much info as possible...HELP!
How much vacuum do you have?
Look at the power valve to see what vacuuum number is stamped on it.
Hank, I had the power valve changed by a top chevy rod tech here in Tracy, CA. I don't have the numbers for the vacuum or the new power valve but I will get them tomorrow. The tech that worked on it last checked the exact items you have mentioned. His initial thought was the power valve and changed it along with a lower tension spring. He said vacuum and fuel pressure were OK.
Maybe for the initial take off the accelerator squirter is too large. You can look at the number on the squirter & go smaller in size (smaller number),or put the accerator cam on a less aggresive cam profile or change that plastic cam all together if it has the more aggresive cam on there.The plastic cams go by colors, what color is your cam?
What model carb is it & what size is it? Double pumper?
When your mech adjusted the air mixture screws, did it change the idle or anything when they were adjusting it?
Hank, It is a Model 4160, P/N 05100-8007, 390CFM Holley with the "red cam". As I stated in my 1st post the "real problem" is after staying at idle for about 2 minutes the smoke is pretty bad and greyish/black in color . Again the smoke goes away after the initial acceleration and only returns when I idle for a period of time (1-2 minutes). If I drive around town for a day or 2 at 30-40 mph rpm 1400-1600 without opening 'er up...when I get on it she will leave a small greyish-black cloud behind me for a few seconds then it is clear. I am jet engine guy so please be patient with my carb terminology...if a "double pumper" has 2 fuel bowls (front & back) with a balance tube in-between...then that is what I have. The mech has lowered the jet to the smallest size (jet's don't affect idle do they?) reset timing to 8 degrees BTDC and idle to 850-900 rpm. She sounds great at idle just can't fix the smoke! Any more thoughts/ideas before I spend $90/hour would be appreciated.
A 4160 is a 600 holley not a 390. and this could very well be your problem.Thats why it is still loading up the plugs at idle.It is also a Vacum sedondary So yes it does have the transfer tube.The main Jets in that carb are at least a size 66 and you can't go much lower then a 60 with out having to go to a smaller carb.
6T4Duce,
You might want to go to
http://www.bob2000.com/carb.htm Lots of good info on Holley carbs.
Gordy
Well,
if it is a 600 vacuum Holly(can't remember numbers,plus I'm too lazy to look it up, but I'll take Larry's word on it.
I could never get a Holly 600 vacuum carb to run good.
It just seemed too big, which is was.
I could get a 600 DP to work better but that still,was too big a carb.
I am no Holly expert, but I have played around w/them long enough to say that a 600 is too big for a 250 mild build Chevy 6.
The main jets do not effect idle, there is an idle circuit(sp).
I think you should look for a smaller carb .
Maybe Larry has had a good carb combo to run for a single four barrel setup?
I just got spoiled after switching to side draft DCOE Webbers, I would never, I mean never ever go back to a four barrel.
I always had good luck w/the old Carter AFB's, Edlebrock makes them now.
I bought a tuners kit for the AFB carbs, you can change the springs, jets, metering rods etc..
Good luck!!
If you want to stick with the four barrel the 390cfm (vac secondary)Holley or the 500cfm Edelbrock are most likely your best choices as far as price goes.
Thanks to all for the responses. I should have looked before I leaped. I took for granted that the previous owner's notes were correct. I have found the original box and verified that it is a 390 CFM with Vacuum Secondary by cross-checking it with the invoice from the vendor, it is NOT a Model 4160. Went on a 60+ mile jaunt today and symptoms are as stated before...clean burn above 2000 rpm, imagine that, look at the cam specs in my original post. In stop & go traffic..accel from a dead stop = sooty puff then clean till idle for 1-2 minutes. Frustrating and the bikers in my rear mirror are holding their noses!!!!!
If it is a 390 you can still jet down. Many things can make a carb too rich but to me it sounds like your fuel level is set to high or it creeps up at idle,that would either be caused by a bad float valve or maybe the o-ring on the float valve is bad. You can check this by removing the the plugs on the sides of the bowls(opposite side of linkage) with a standard screwdriver. Next start engine, if you see fuel run out then shut it off imediatly, if not then let it idle a few minutes and watch to make sure the fuel stays below the holes and is not creeping up slowly. Good luck.
I ran a 600 On a Stock 250 with a offey and only Headers and I didn't see The problem he is Having with his. Yes it was a Little much But It never Puffed no matter how long it sat at a light(idleing) And you could stand behind it and not end up crying over the fumes.But you didn't really want to stand there for ever either LOL
So i would have to kinda agree with Diesel Check the floats On Both ends of the carb.
I have ran Holleys There better part of my life and could rebuild them with my eyes closed i guess you could say LOL. So my 2cent oppion is when only on the primarys of that 390 = (half) is about 170cfm Which is by no means to Big of a carb So there has to be some other issues You have not yet found. Hummmmm a small Brain fart here But are the secondarys trying to Open at Idle??? for what ever reason??? and leaking fuel??
Which may not show up above the butterflys.
But a float set to high will show up over the
butterflys.
Also I know some of the newer Holleys have what they call a Rev circuit.Im not sure if theyever did the 390 this way. But If it is Then the air fuel mixing screws are adjusted Just the opp.And that would make for a richer Idle mixture.
Gordy, thanx for the link to"
http://www.bob2000.com/carb.htm That was some excellent info, very informative and educational about Holley functionality. Some is still sinking in but I will be using the testing and troubleshooting tips given by Gerard. Of course ANY & ALL INFO provided by posters from this forum is most welcome. As I mentioned before paying $90 per hour shop rates for other people guessing can get quite costly.
What type of fuel pump do you have & what is the fuel pressure?
The fuel pump is OEM style mechanical type with an avg pressure of 5PSI, Vacuum at idle (850 RPM)is 18 PSI, the float levels have been checked and they do not "creep". It has the electric choke and kicks down to "full open" after reaching 150 degrees F, normal operating temp is a solid 180 degrees. Secondaries are not opening at idle. Power valve has been replaced and is a 4.5. All passages have been blown out with cleaner and compressed air. WHAT AM I MISSING?
You said this was a 194 ci engine? That may make the carb still to big. It sound like its just loading up at idle. Try installing a fuel regulator set to about 2 psi and see what happens. Is the engine using oil?
Yes it is a 194 ci bored 0.030 over and it is using some oil..smoke is grey/black not blue though. I will try to locate a fuel regulator and try to reduce the pressure down to 2 psi. One mech thinks it may be oil vs fuel due to so much fuel not being burned at idle that it is washing the rings. A plug check after cruising shows a slight brownish/light grey tint on the plugs. Again there is absolutely ZERO smoke at cruise and even when de-cellerating and re-cellerating. Love that terminology!
I know this is most likely not the problem but, is it the same 390 the circle track guys have to run to limit horse power? Would those carbs have large air bleeds to help with a rough idle. Maybe it is loading up at idle and when you get into the main circuit with a jet change it is better. My idea would be swap to a carb someone you know has that has worked on other engines. a 1850 600 holley is made for a STOCK engine and will have air bleeds that are small. It may not have as good a throttle response but may fix your idle. What is you list # for your carb? Were are your air screws at when adjusted for the best idle?
6t4
Nice setup!
I ran your engine combo thru my computer and it says you oughta make, assuming the cylinder head is stock:
Torque 179 at 4200
Power 175 at 6100 [wow]
That is a hefty increase over the stock 194 but what a screamer!
Here's a couple more ideas on that smoke:
1. I know it's warm these days (I live in East Bay too) but is the intake/carb staying warm enough - is that Clifford heated?
If not, Ford used to run a 1" 4v spacer that ran hot water thru it, early 60s Ford, swap meet item, it would keep the carb warm. Not likely that's it
2. That intake is an AWFULLY big plenum for a little 194, with no ribs or anything, more likely to make the fuel puddle.
3. Try a 4v-to-2v adapter and run a 2v Rochester or a 2v square-bore Ford Autolite 2100 (they're dime a dozen and run pretty trouble free..) to see if that makes the problem go away. It won't be enough carb to feed it (you DO need 350cfm or so 4v rating to feed all that horsepower!)
But, if running a little 2v solves the problem you know it's fixed then.
I forgot you have a Clifford intake on a 194 engine.
That intake volume is way too big, kills your torque ,gas milage,I would even say, kills your overall HP.
There is hardly any port velocity.
It would run a lot better w/a offy intake.
Two Cents
Yes the clifford is killing his low end street ablity. The Offey would be 100% better for any daily driver. It has Great low end to mid range power. I'm sure it would also give a much better signal to the carb with that Cam. and no dout would feel more kick from the cam when it hits that 2000rpm mark. As i went back to reRead things Nothing was said about the Head Is it stock or what? is the Boss still in it?
I am in agreement, the Clifford is huge for a 194ci daily driver with 5000rpm max(respectively)and while your carb may not be too big as far as cfm goes, most 390's are set up for ford v-8s that have small high velocity intakes, and near 100 more cubic inches. Maybe all that fuel is covering up a gnarly hesitation. Maybe someone enlarged the idle feed or altered something in your carb. It just seems like if you slammed open that carb, on that much intake,on a 194, it might take more than the red pump cam to get enough velocity for the the straight leg boosters (main circuit) to flow. I know thats alot of maybe's. Automatic trans??
Gentlemen;
The fuel mileage he's getting (12 city 23 hwy) is 'normal' that carb etc.
No matter what the manifold or CFM numbers are, there "out of the picture" at idle as the only air allowed past the closed throttle plate is determin by the adjustment (speed) screw. The only fuel allowed in is determin by the mixture screws.
The fact that it idles fine for a "few minutes" tells me the adjustment is okay and would indicate a internal fuel leak or a modification as mentioned.
As far as the intermediate (accelerator circuit) is concerned, that 'set up' is just overkill for that size engine. Remember; GM put a small 1 bbl carb there.
I would suggest a faster/leaner idle to help things out. The other is part of owning a Hot Rod.
Good luck.
Basically, I would try another carb to see if it does the same thing as the Holly, I doubt it will, sounds like the problem is the carb.
See if you can borrow one from somebody.
Again thanks to all for your ideas. This carb has been checked and re-checked and it is flawless. My next attempt is to heat the intake. This engine will not run/idle off the choke until a minimum of 150 degrees F. I have a Clifford catalog that lists a p/n 08-1900 exhaust heat kit and a p/n 08-1856 thermo/water heated kit. An ace mech I served with in Coast Guard Aviation recommends the exhaust kit due to it's instant heating capabilities vs the H20 (still have to wait for the cooker to heat it up). It is his and a few others thoughts that the lack of heat in that large cavity is not atomizing the fuel properly for low rpm/idle burn and raw fuel is going through and out the tailpipe. This manifold has 2 each plugged ports in the side of it? The Clifford catalog does not say what those ports are for? The next problem is the Clifford web site does NOT show those kits as available. Anyone got one preferrably the heated exhaust kit under the workbench that they will part with?
You now have another/different problem.
Check for a vacuum leak between the manifold & head etc.
You won't need manifold heat in California.
Like I said before, try another carb, to see if the problem is still there.
You can check & re-check carbs but there are passages that get plugged that you cannot check(bad castings) etc,,& will not clean up no matter how much you dunk it in carb cleaner .
The intake manifold gets plenty hot w/the exhaust manifold right underneath the intake manifold, esp, like John said in Ca, you really should not need carb heat, I never ran it.
It does sound like you have a vacuum leak as John stated.
Also,,, what color spring are you running in the vac ,secondaries? you stated a mechanic put a lighter weight spring in it? I would think,if it's a lighter spring, the secondaries will open too soon, causing it to possibly to bog?
I have an Offy intake if you want to buy it?
It will make a night & day difference in torque!!!
Hank,
I sent you an email with my phone number. Call me to discuss the Offy Intake. Also my intake has 6 plugged ports, 3 on the side and 3 underneath. Still can't find any info on what they are provisioned for...does anyone know?
John M. brought up a good point about the throttle plate being closed.Several years back I
had a 1970 Chevy pickup with a 250 that had a cam similar to yours and a stock intake that I had modified to accept a Rochester 2 bbl. It
had idle issues similar to what you describe. I found the throttle plate was open enough to uncover the slot for the transition circuit and
producing a rich condition at idle. On advice from a friend I drilled a small hole in both throttle plates(don't remember the size)backed the idle speed adjusting screw out and readjusted the idle mixture screws and it cured the problem. I know this is not an apples to apples comparison due to the different intake,carb and engine size,but would be easy to check while the carb is still on the engine.
Just a thought.
Gordy
The plug in the center on the side is manifold vacuum all the rest are for coolant.Most people use the two on the side for hose fittings to flow hot coolant through it, the two underneath are a little close to the exhaust,and the center underneath is best for draining. Heating can help when you have sloppy fuel delivery (puddling,large droplets,too much carb,to big manifold ect) but nicely atomized fuel in a colder manifold will give you more power (VE).Im also in CA and do not heat my manifold. I think if you try the offy you will like it. Good luck
Flip the carb over and look at the shape of the transition circuit that is exposed with the throtle plates closed, it should be close to a square. If you see that it is more of a long rectangle shape (longwise) then like Jhon and Gordy have mentioned, you have too much transition circuit exposed. If you have to drill holes in the plates start small!
By the way the hole should be drilled opposite
the transition slot.
Gordy
Gordy,
I am going to the "Good Guys" meet in Pleasanton tomorrow and on Sunday I will pull the carb and check your suggestions...thanx...hopefully we will tackle this soon.
from my experience my intake did need to be heated. it was a clifford and i had the same problems. one difference was mine was 292 ci. mine was the older design with no heat provisions. i had a tube welded to the bottom of the intake and ran my heater hose thru it. solved the problem. i only drove my car in the hot humid iowa summers too. p.s. a holley list 8007 is a 390 cfm carb.
OK Guys here is the latest scoop and I believe we can put an end to this post once and for all. I plumbed the 5/8 in. heater hose line from the inlet that is just below the thermostat housing into the fwd port on the Clifford intake plenum using 90 degree nipples and a pre-formed 90 degree hose up and over the thermostat housing. I then used the aft port on the intake plenum and plumbed it via a 90 degree restrictor nipple around the back side of the engine against the firewall back into the heater core using another 90 degree preformed hose. The install is very clean looking and WA-LA....no more smoke! Just returned from a combination city/highway 75 mile drive and the difference was unbelievable. Sat at numerous intersections and in parking lots for a couple of minutes and NO MORE SMOKE! Thanks again to everyone for the thoughts and recommendations....I am sure I will be back for more tricks and tips. I live in Tracy, CA near several of you that have responded to my post and look forward to meeting you guys and with other members in the NorCal Area.
Hello 6T4Duce I've been following your posts. Do you have a website where pics are posted of your car and engine?
Martin
Martin,
No website. But email me or send a private message via this board with your address and I will send them to you,