Inline dual four Holleys

[Michael C Henry]

I'm up for my last emmissions test go-around. First test HC (PPM) were supposed to be < 220HC(PPM). Idle was 2278 PPM. Cruise was close but still high at 279 PPM. So Idle is just slobering gasoline. Idle was set around 570 RPM. My garage smells of the stuff. Any suggestions?

Ford 427 FE sideoiler w/ Dove aluminum heads, 11.5-1 comp ratio ,dual 600 CFM Holley 1850 carbs, In Tacoma WA at about 2-300 ft above sea level.

[Jac Mac]

Purely out of interest, I have read back thru some of your older posts & how you deal with this 'emission' problem. Do you still use the Power Valve's or have you disabled that circuit. seems to me with that manifold that you might be able to get a lower idle HC count by doing so and reworking the carbs to suit. Manifold vacuum must be real low and erratic with being a large common plenum.

[Michael C Henry]

The cruise was tested at 2500 RPM in neutral. Powervalves are stiil being used.

[Jac Mac]

Hmmm, interesting method of checking cruise HC. If it was mine & I had to comply with your regs I would employ all of the following to improve the carb signal etc.
1. Anti Reversion cones in headers.
2. Anti Reversion plates under each carb.
3. Mod the carbs for Non PV operation.
4. Recurve dizzy advance and use a manifold vac advance source along with electric vac switch which is only activated by microswitch to trans shifter when in neutral/first/reverse.
5. Use electric solenoid to set running idle speed so that when you kill ignition it goes back to a minimal idle speed which will prevent run/on.
6. Fit vac pump to lower crankcase pressure ( Preferably dry sump setup, but anything will help )

[Michael C Henry]

I heard that the local ecology guy could give me a lifetime waiver if I could get my HC's under 900 PPM. This is my last time with mandatory state emmissions testing. 220 PPM or less is the standard. I got close to that at cruise without any catalitic converters (279 PPM). For a Ford 427 FE, that sounds reasonable? I realize I probably never even started to crack the second carbruetor. With out cats that reading of 279 PPM is probably just right jetting? Or should I mess with that part of the mix?
I tried to incorporate the electric solinoid dashpot. It didn't workout as I remember. I don't have as bad a problem as i once had with run on as I did years ago. I did replace the primary carb body with a carb that has a functional choke witha fast idle cam for starting and warmup.

Now during sudden stops the engine tries to die, I beleive that fuel is surging out the vents. I had incorporated vent whistles in the carbs before and had no problem with the engine trying to die. The carbs have since been redone and now do not have the vent whistles and the engine tryes to die in a sudden stop. I intend to refit these carbs with the vent whistles. Now the problem , I have to notch thetop of the side hung floats to clear the vent whistles. I did this before and now I can't remember what to coat the float with where I notch the float.

[cobred]

Maybe the float levels are too high? Maybe one or 2 of the needle and seats are seeping fuel.

[Michael C Henry]

The engine sets level ,the intake thusly has a forward slant. .I try to set the float level according to the position of that bowl. I do not seem to have problem with the exception of hard breaking to a stop. And idle emmissions. Trying to stop,watch the traffic a head swap gears and keep the stumbleing engin lit so I can cleanly leave when the light turns green. I could use another foot.

[Jac Mac]

When you look at a 4bbl Holley closely the sight plug for fuel level in the front (primary) bowl is slightly higher than the rear-- with the carbs mounted @ 180° from the norm plus the forward downslope of your intake manifold I would imagine that the fuel levels in your application need a rethink from what Holley recommend.

I seem to remember that the floats need to be sealed with a 2 pot epoxy type glue or paint, but in this world with changing brews of fuel etc that may no longer be correct.
The lack of whistles is likely to be your stall while braking problem.

Just so Im clear on this with your comment about cracking the second carb, are you running them staged ;IE one carb starts to open prior to the other or were you refering to the secondaries of each carb.
Also, Holleys idle on all four barrels of each carb, its just that only the primary barrels have adjustable mixtures on most models unless fitted at all 4 corners. You may be able to get a sweeter idle by closing the secondary butterflys idle setting slightly, or in some cases by opening them slightly if the cam is fairly radical.----screw in base of carbs ( on manifold side ) below secondary diaphragm link.

[427 S/O]

Jac, I would toss those sight plugs!, known for braking/leaking plus, they cloud up pretty fast.

[Michael C Henry]

I am basically using two Holley 1850 carbreuters with vacume secondaries, single fuel fuel inlets, side hung floats. The progressive throttle linkage is adjusted to be progressive but both carbs reach wide open at the same point, Fuel inlets are on the right, so I guess they are backwards. Working choke on front carb. Barry Grant diaphram adjustable fuellog with exscess fuel return, fuel delivery to carbrueters pressure set at 6 PSI. I used short cuved SS 1/2" tubes and AN fittings . Fuellog is between carb and right valvecover and parrallel with valvecover, all wrapped with DEI heatsleaving covering everything from carb float bowl to firewall. As I understand secondary buterflys are barely cracked open to keep everything fresh.

[mr0077]

Mike, I had the same stumbling problem when I put 1850's on my car, until I lowered the float levels on the rear carbs to account for the 9 degree forward rake on the manifold...like 2 1/4 turns lower (but do the math on the thread pitch and angle to determine the actual # of turns). No problem anymore, and dyno runs indicate A/F is right on. Another "trick" you might want to consider is putting a short piece of rubber hose on the vent pipe to raise the height, so the fuel slosh won't come out the top as easily.

[Michael C Henry]

Years ago I removed the choke towers completely because there were no mechanism in either one. Then I had some work done on the carbs and the cam on the primary throttle shaft for fast idle was removed and lost, so I lost even the fast idle capabilities for warm up. Starting ,in anything other than summer, became hard. So I had my internals Of primary carbrueter installed in another carbrueter body. Originally I had made my own arched vent tube for each carb resemling the Avenger carbs. Now that I have the front carb with a working choke and with the clearence inside a S&H aircleaners The hose on the vent tubes with a notch at the highest point isn't an option. So the vent whistles are the intended cure for the this stumbling part of mysetup.
I' trying to come up with a working plan to limit the number of times I have to take this apart. Is the HC reading of 279 PPM at cruise of 2500 RPM in neutral with no catalitic converters as lean as I should go on the jetting.
I don't expect to meet the standards but I'd like to get closer with atleast the idle emmissions. My garage getts bad when starting the car in side.

[SuperHart]

Holley carbs like to run level rather than pitched forward via the 4* power angle built into most intakes. Since most Cobra engines are installed relatively flat in order to keep the bell housing from scraping the ground there are two remedies for this situation: 1. have the carb mounting surfaces milled flat, 2. use a wedge. Many marine supply houses stock 4* wedges that will level a carb. I have heard that Shelby himself used these items in the early cars to level the Holley carbs. The wedges usually do not add much to the height of the air cleaners and do work very well. Either way, Holley carbs perform best when installed relatively level. Adjusting the float levels can help somewhat but it is always better to level the carbs for best performance. For example, Moroso part #65030 is a 5* wedge, expensive at $39.95 each from JEGS or Summit, but probably less expensive than pulling the intake and paying someone to mill it down.

[mr0077]

Mike, from the smell you mentioned, it sounds like the power valves may be fluttering open/shut at idle...what power valves are you using and what is your manifold vacuum reading? Also 570 RPM sounds a little slow for the idle, and it may be affecting the vacuum. Try an unported vac advance if the cam isn't too wild, and increase the idle RPM (at least for the test) to around 800 for a more stable manifold vacuum.
Were those readings done on a rolling dyno emission machine, or was the cruise RPM just a free, no-load RPM?

[Jac Mac]

Mike, its starting to look like addressing the angle the carbs are mounted at plus lowering the fuel level in the primary bowls will go a long way towards helping the HC count at idle. Personally I would not stage the carbs either as this creats an unequal fuel distribution in the manifold-- if you do have it staged I hope its biased to the forward carb as its primaries are closest to the center of the manifold. Dont make the mistake of trimming back the accelerator pump cam etc too much- this has no effect on readings taken at a steady/constant throttle opening.

[Michael C Henry]

I intend on taking the carbs off tomorrow. I'm through manditory emissions testing. My first test failed with 279 PPM HC and 2278 PPM idle. I had is repaired which was mostly turning up idle to about 980 RPM. That backed idle numbers down to1980 PPM . I went back to testing station and they dinked around with it running and temperatures got too high. I had to bail and take it out and cool it down. Back at testing station ,cruise was 185 but idle went to 2300. Now in the office what should have a examination of documents and a printer, turned to be a ("I'm the new manager and Millisa used to take care of these , You'll have to call the office of ecology and talk to a referee.")
1 800 and push this and the that now wait and leave your number. Tom Jones from department of ecology called while I was on the way to gasoline station tget more fuel (missed call). I called him back (he was in Vancouver). He pulled my info up on his computer and waived it then and there. He told me to go back to the testing station and ask for a reprint. The manager was ready when I arrived either Tom called or she had new infomation. Now I have a waiver in hand and on file3 to get the tabs.
My liesenced emissions repairer said to swap the jets down one or two numbers. I'm going to install the vent whistles. I'll check the powervalve numbers, readjust the floats . Then I'll see where I'am and see what we can do for the idle stuff. I'm still open foradvise on what can be done to lean down the idle .

[StanJ]

Michael,

As you've discovered, the Holley 1850 600cfm 4brl isn't factory-calibrated to work efficiently in dual carb applications. Specifically, the idle circuitry is far too rich (especially on the secondary side) and the circuit timing (primarily a function of air corrector sizing) is way off. Addressing these problems is straightforward enough; pick up a pair of adjustable metering plates (not metering blocks...I realize that you don't have the room for them) which are available from us or any of several other manufacturers, and have us or another competent carburetor technician of your choosing modify your primary metering blocks to accept screw-in idle circuit feed restrictions and your carburetor main bodies to accept adjustable air correctors. This will give you the tuning latitude necessary to bring your exhaust emissions into compliance, and at the same time allow for greatly improved throttle response, power, and fuel mileage.

Stan Justus
Stallion Racing Components

[Michael C Henry]

I have the Quick Fuel Technology secondary metering plates with regular replacable jets in both carbs. I'm notching the primary floats to accept vent whistle. It has been long enough that I have forgotten which epoxy to use to cover and seal the notched area in my Nitrophil floats. Primary carb had #65 primary jetts and #68 secondary jets. At 2500 RPM in neutral and progressive linkage, probably didn't even crack the secon carbrueter.
Any more reccamendation on leaning the idle out on this thing?

[StanJ]

Originally Posted by Michael C Henry

I have the Quick Fuel Technology secondary metering plates in both carbs. I'm notching the primary floats to accept vent whistle. It has been long enough that I have forgotten which epoxy to use to cover and seal the notched area in my Nitrophil floats. Primary carb had #65 primary jetts and #68 secondary jets. At 2500 RPM in neutral and progressive linkage, probably didn't even crack the secon carbrueter.
Any more reccamendation on leaning the idle out on this thing?

Michael, what size are the idle circuit feed restrictions in your Quick Fuel Technology metering plates? These are adjustable; as I recall QFT uses a #6-32 thread screw-in restriction there. I can’t recall QFT’s baseline idle feed orifice size in this part from memory, but your application should be quite happy with something around .032” dia.

As for the idle circuitry in the primary metering block, look at this picture:



The idle circuit feed restrictors in your metering blocks are likely located in the positions marked “1”, although depending on when your carburetors were manufactured they might possibly be underneath the outermost well caps on the top of the metering block. In any case, they should ideally be relocated the positions marked “2a” and “2b”. This positioning allows the idle circuit to respond more quickly to changes in throttle position and engine fuel demand, thereby allowing the use of a smaller orifice size. As I mentioned earlier, your primary metering blocks can easily be machined to accept screw-in restrictors in this position. I’d recommend starting out at .026” or .028” orifice size, which is considerably “cleaner” than the .032” orifice you have now.

[Michael C Henry]

I'l have to check and measure tomorrow but I did notice that in my primary carb (the one with a working choke) the backwards "L" on the right has a small piece of lead wedged in the channel at the top. That carb was not prepaired by Quich Fuel Technology but was put together locally for me and had my manual choke and adjusable secondary diaphram housing transfered from my other primary carb (with choke tower removed). Also the carb with the working choke, has a generic powervalve. I could not find and any numbers designating setting as in aftermarket powervalves. I have a selection of various powervalves.
I'd like to buy a couple of prepaired metering blocks like that. I could probably manage the drilling and tapping, but the brass 6 x 32 set screws with a pilot hole I don't have and I don't trust myself. I have a heck of a time when the chips are down the drill walks off center.