Inline dual fours
 

I bought an older replica with inline dual four Holley 1850 carbs, built and adjusted for Reno> 5,000ft elevation, back in 99. I've been messing with them ever since. When I moved the car to western Washington < 500 ft elevation) it was diagnosed as a lean missfire. Then after several major reconfigureations it ended up being right at the maximum for HC PPM at cruise at the emmission testing station but allmost 11 times the maximum for idle. I had two new primary metering blocks made with changeable restricters for the idle circuits. I have all the small brass set screws, micro drills, drilling fixture and such, but haven't touched anything other than the idle mixture screws. I intended on having a friend with modern test equipment and knowledge help diagnose and refine things last summer but overtime, conflicting schedules, and weather killed that. Last summer the few times I had the car out, it depended on the choke to mintain an idle untill it was fully warmeded up. Now that its cold and I can't help and beleive that the idle is way lean now. I intend to wait untill its warmer ( like late spring ) to start redoing anything. I'm very aware of it's potential and even have the programable rev limiter set to 6,000 rpm to protect myself here on the street. Cam and intake are intended for high rpm but I do not beleive the S&H air cleaners would let it get there.
Feel free to jump in anytime.

At a certain point, carbs that have been heavily modified for special service (marine, high altitude, exacting emissions regs, an unusual engine) are not worth trying to rebuild for other service. You might actually save a great deal of time and money by starting with some stock carbs. 500 ft altitude is within normal service range and should only require minor adaptation to reach perfect jetting etc.

EDIT: A good carb shop might give you decent exchange/core value for your carbs against another good, used, stock pair.

I believe that any motor with a high lift cam and long duration will never pass a smog test. Motor is way too lumpy at idle to be clean. I had my 418W sniffed by the smog police when I lived in California (a requirement for record purposes only) and was told that at 2500 rpm the motor was clean enough to pass as a 1965 Ford. At idle I was told that I was a gross polluter. The best you can do, in my opinion, is to set the carbs so the motor runs at its best at idle, transition to the high speed circuits, and full throttle. If you are required to clean up the motor to pass a smog test you could have trouble. Has your car been on a chassis dyno with a sniffer up the exhaust? Your plugs will always tell you what's going on inside your motor. Clean up the plugs by proper jetting and you're good to go.

All good advice.
High rpm cams will not pass emissions with carbs, period.

Sequential EFI or milder cam with less overlap.

I'd be throwing the 1850s in the bin, fit a pair of 600 Edelbrocks.

Huh?!:eek: Mike, run from this man!

My car is now outside this states emmission testing age. My car was built and dated as an 84, it is now twentyfive years old . What I was aiming at was the obvious drooling of gasoline at idle. Man! the garage stunk from gasoline at startup and after returning. 11 times the hydro carbon limit is a waist of gasoline. Cruise is great, just what I'd think you would want It's the idle that needs attention. The emmission standards were just a target. I never thought I would ever reach actuall emmission standards. I intend on getting into it this coming summer. I think it would make the engine more "crisp" If my idle was a little leaner. I curently don't consider this engine "crisp" off idle. I've had engines that were a lot more "crisp" from idle.

See posts 25-28 of this thread, I think its relevant to the situation you are describing:

http://www.clubcobra.com/forums/967140-post.html

Your right, This is what I'm addressing . I have a pair of new primarry metering blocks prepaired for me that have the set screw style replacable idle restricter-jets. I think we started around .019" on the idle. Not much use getting started on adjusting in this weather summer is so different teperaturte and moisture. All this information is being taken in ,thank you.
Also looking for something different in an inline dual four aircleaner.Twin S&H s I think are restrictive.

Would you keep us posted?

Jim

This is from K@N and meets the max air intake demand of the carbs.

http://www.clubcobra.com/photopost/d...ngine_shot.jpg

Years ago i had a friend that ran a rather radical 289 in a Cobra MKii street/racer and was required to pass an annual sniffer test of those early days of the seventies. He would regularly remove the well modified 715 CFM Holley with a simple small two barrel and leaned it out like awful. Removed the puny accel pump linkage and of course it didn't run very nicely at anything much over idle plus. But, it did pass inspection, barely.

i would suppose it might also be done today. He finally left NJ and did it for a few years in FL before the testing was dropped. The car saw less than several hundred street miles per year, so it didn't seem like much of a hazard at the time.

He liked to drive it to a few events each year and enter it in the street class, as a sleeper. Murdered the "vettes. Frequently won BTD over modified cars.

Wouldn't do it myself, though. Not very sporting.

And won't fit under anything resembling a stock Cobra hood. I have the same AC with a standard K&N in it (about one inch of filter) and it barely fits after some work on the baseplate.

My S&Hs are about 1 3/4" tall with a taper. I trimmed the perforated steel rings on each filter so that one side is about 1/4" lower than the opisite side creating a taper oposite from the spot welds. When mounted the spot welds are between the carbs and the front and rear top edges are lower. The front 1/3rd of the front aircleaner is under the hood in scoop area. The rear aircleaner just touches the back of the scoop. Before I trimed they actually left marks in the underside of the hood. I'm still looking for something to change like another hood scoop that would let me put a better aircleaner on the engine or a Spectre cold air system that would fit under this hood. I've been thinking about a cowl induction scoop like I have seen on a Kirkham. Not correct but probably really functional. I liked the looks. I'm not trying to pass this off as an original car. I remember the phrase " historically warranted modifications"

Not quite sure why you'd say that, Lovehamr--I bought an already running Cobra replica with a Holley carb, and despite having been fiddling with these beasts for decades I just couldn't bring it to its knees.

I bought an Edelbrock, just for grins, and the thing pulls hard from idle to redline........much better than any Holley I've ever had.

Having said that, though, I feel a case of GAS (gear acquisition syndrome) for a 600 CFM double pumper, center hung floats Holley.....would love to see if I could get one of those to run like the current Edelbrock. Gotta love the looks of a good Holley!!!

Cheers from Dugly :cool:

I might send a pair of O-1850s to the parts bin, since they are the cheapest carbs that Holley makes. But I sure would not replace them with Edelbrock/Carters. A well prepared Holley is infinitely more tunable and has far more driveability and power potential. No question about it.

That's a big call.

Holley's 1850 is the cheapest for that reason, entry level 1 four barrel.

Hardly a comparison really for those who have played with AFBs.
You can perform virtually ANY mod to an AFB without taking the carb off the car and not lose a drop of fuel.

Personally I don't look at anything Holley unless it resembles a QFT.

Another summer has come and gone. I didn't get around to having it snifed to set a base line for the idle. My friend with the sniffer or I , or the weather were not available. I wanterd to use warm weather as a starting point before I started opening the new idle fuel restrictsions. Now it's getting cooler and I know the idle is going to be even leaner

Why do you have to set the baseline in summer? By that rationale that's the only time you can drive it. Why wouldn't you just tune it to "today" and adjust as/if needed as the temps change?

Michal C here is something I found when rebuilding my 2 x4 1850's on a 427 FE SO with a CC 282S cam. I understand the 1850's are meant to be stand alone carbs. There is an idle circut in the secondaies to use fuel from the secondaries so the fuel stays fresh in the bowls. When I took mine apart, I found the thin secondary metering plate (I forgot the number) had the air bleeds in the channel at the top with a diameter of .026 " and a number 35 lower sized jet hole in the bottom of the channel. Anyway, someone had put a .020" piece of wire in the channel extending from the bottom of the channel pushing up along the entire length of the channel into the .026 upper air bleed to block off/ restrict that part of the idle circut. All four of my mix screws are out about 1 turn out for best idle at about 850 rpm's.

As a note, they still rich and a little blubery , but very drivable. I have not checked or changed from the 66 mains and 6.5 PV's from the builder, I need to get an A/F meter and test with a vacuum guage, but it does not ping at cruise, 80-120 mph with 3:54's and toploader (Tremec is on the winter list), and spend time in the 3, 000 to 5,000 range on the Bahn with the pipes still dark/rich colored . This winter I will either I will go with a set of Barry R's QFT 2x4's or Webers because I know there is better and cleaner mixing.

Now it has been two years ago a member of this club offered to prepare a pair of primary metering blocks with removable idle jets made from brass set screws with verry small holes (as I remember about .019"). I installed the same main jets as before. He later sent me a drilling fixture that he had made for me to drill additional screws that I could use as replacements to acheivethe desired results. I bought more screws from Mcmaster Carr. I went on line (ebay and bought a selection of micro bits in a set, in the range I'd be using).

On my last trip to the state emmission testing station, before I did any of this. My cruise seemed fine , almost down to the state standard. It was the idle that was way off. Almost 11 times the state standard for unburnt Hydro Carbons . My garage just reaked at startup of raw gas.. The new primary metering blocks improved my garage thing. I haven't done anything further yet. The carbs allready have the Quick Fuel metering plates in the secondaries. I absolutely have to use the choke to get it lit and keep using the choke in decreasing amounts untill the engine is completely is warmed up. It seems to be just on the edge at take off. I have to give a little throttle or the engine will try to stall and has. I have lost a little more of my low RPM umph. Noticable in the parking garage. But my garage isn't as fowl at atart up.. In cold weather starting gets worse. But I don't drive much in ther cold weather. I wanted to get the exhaust sniffed before I do anything more. I have a friend with a motis that would sniffed it in his driveway. The thing has been either the weather was bad or he or I were doing something. He works M-F untill 3PM and I work M-T untill 5PM. Frday my wife and I usually go to the movie , that leaves Sat and or Sun. Now the weather has changed for the worse.