Before you start, about six or seven things can mess up and muddy the Small I6 144-170-200-250 tuning waters.
A. A cam change from the stock 240 or 256 degree cams to other more aggressive cam,
B. porting the head and
C. exhaust headers varies the carb tune.
D. The ignition settings,
E. vacum porting and
F. any adaptors for mounting the carbs changes what the Weber likes at idle a heck of a lot.
G. They GENERALY like a lot of initial ignition timing with an aggressive ramp up by about 2800 rpm, and then not too much total advance. 32 to 36, depending on cold cranking compression.
Did you know that there are about 30 different Holley Weber list versions from 1969 to date, and about 13 different factory Weber versions of the 32/36 and 38, all told?. The carbs are made in Spain, Italy, then USA (under licence) for some versions, and there are illegal Chinese knock-offs as well. Forest Gump and Chocklates reference applies.
The base jetting needed for 200 cube sixes varies mostly due to the subtle changes in the mirror image 52xx/62xx/65xx Holley Weber, then Weber Weber D series 32/38 and the Weber D series 38 in
nine ways
Bad, cheap aftermarket parts not in spec don't help. If the needle and seat is faulty, the normal Pierce Carb tune process will have you looking in a black room for a black cat taht isn't even there.
They key parts are:-
1.floats
2. Needle and seat shut off size and quality (2.5 works best),
3. well tubes/emulsion tube variances ( huge variations, but what is there stock is often okay)
4. the kind of idle circuits influence Idle Air Corrector restriction size
5. the type of secondary operation they used( some secondary squirters are blind, some drilled, and they can vary a lot).
6. The amount of fuel pressure they like varied between the float type used. Normmaly 3 psi or more causes calibration issues, so a well functioning Mr Gasket or Holley or Malpasi fuel pressure regulator is needed, but Ford used a bleed back restrictor without a fuel pressue restriction in European 1972 to 1987 Weber 32/36 and 38 carbs.
7. The Positive Crank case Ventilation and the degree of baffeling sets them off for off idle sensitivity. Using certain ports is suggested, but creates tuning issues in practice. Ford Europe, Austalia and America used a baffled system on its engines, so often a 50 dollar valve is needed to eliminate problems that factory systems did away with.
eg
mark_hagen's "Engine will not idle - Weber Carb Tunning problem"
viewtopic.php?f=1&t=73925&p=568220#p568220
mark_hagen":2p0lfzb3 said:
Long time since my original post...found two things. 1) brass tee fitting on intake manifold for brake booster and vacuum canister had a hairline crack on the underside. 2) PCV valve letting too much air to pass through at idle. The store bout PCV valves have spring tensions set for a stock motor. After researching how to select a PCV valve for a modified engine, I purchased and installed a Wagner Adjustable PCV valve (Not cheap). This valve has two circuits; an idle circuit and an off-idle circuit. Once installed, turning the idle adjustment screw made the engine idle smooth out. No more idle circuit problems.
Positive crankcase ventilation (PCV) is a great idea for any street engine if for no other reason than any fuel that vaporizes will be instantly drawn into the engine and burned and will not remain in the engine. This adjustable, billet aluminum PCV valve from M/E Wagner allows the user to adjust the amount of blow-by the engine will pull into the intake tract. But even if you don’t use this particular valve, a PCV valve is essential for any street engine. It also keeps the outside of the engine cleaner, too.
8. The Economiser (power jet) assembly in some carbs has a casting flashing fault that needs checking and correcting.
9. Lastly, the potential for dirt in the air bleeds and fuel system can give them funny tuning issues.
Get those things square away, Webers just need some individual trimming up or down form the box stock jetting.
Its a great carb, and rember, a Holley 2-bbl guy told you that.
You cant go wrong with the Weber, just gotta get some basic matters sorted.
Stovebolt, Pierce and other suppliers know all this stuff, and they'd rather have you use there stuff than deal with those 9 matters from people in the field.
Updated.
I've delt with the Weber and Motorcraft 1-bbl engine idle issues with in line Ford Sixes since membership here in October 2001, 15 years, plus my own Weber experience (an extra 21 years with Ford Pinto 2 liter engines, and 1-bbl Motorcraft Belfast Autolite 1250 series carbs on Ford in line fours and some sixes, and that's 36 years. As a 10 year old, during school and summer break, I used to go "help" (read= frustrate!) the workshop techs at the Municpal Power Supply Company the Old Man worked at....he was kinda glad to get me out of his hair. Ford addressed ALL these problems in 1972 with the beed back revision for Weber 2-bbls, and further with 1980 European Union Emmisssion Control and 1980-1982 Swedish Emmision control engines...there isn't much I've not seen or experienced. They did Liquid Propane Gas conversions, so they had to idle and start of gasoline, so the stock systems had to be understood, with operation down to 12 degrees Farenheit. Then the furhter complication of really cheap propane gas on switchover, so these technciains had to really know there stuff. And it was all small Ford fours and sixes, with a few Windsor and Cleveland V8's from staff personal vehicles. We had Alan Ireland, a brillant Dunedin Ford trained service tech, who came on board in 1980, and he was awesome, and still does the same stuff as a 65 year old in my old home town. Ford serivice technicians are a special, if often corrosive breed, and, lemme tell ya, if Ford TSB says something obsure, its put into to practice, and understood.
All idle problems are not problems with the carb, but the whole engine combination. Weber 2-bbl Fords fours and sixes from 1969 to 1987 always idle well if you follow the rules. Not including emission controll, there are those 9 items above, plus another 7 general matters to check, and then you'll get a great idle in comparison to anyhing. About the only thing it lacks is a really good choke pulldown for quick, reliable warm up, but again, there is an electric choke 7 volt lie off the alternator and choke pulloff circuit that was used on the US 52XX/62XX/65XX and Swedish emissions versions from 1980 to 1987...its was all done by Ford of Europe as well as Ford USA.
Lastly, a Holley 2-bbl 2300 series 7448 "350 cfm 2-bbl" or 4412 "500 cfm 2-bbl" will be even better with respect to emissions and idle than a Weber 2-bbl, but it has its own set of issues. So too the 1-bbl Autolite 1100/1101/ Holley 1940/1946 and Carter RGB and YF/YFA's..They have there own 20 item wrap sheets. Nothing is perfect, but I've weighed in on every post almost for 13 of those 15 years here, and its all been answered by Ford systems used on US SOHC 2 and 2.3 Fords, and other Ford I4, I6 and V6 engines the world over.
Its kinda unacceptable to me that anyone should have to deal with not getting the help they ask for. So this is provided to help out.
it's pertty easy to tell by looking inside the distributor or If you can post a picture showing your distributor we can ID what distributor you have. But chances are if its from a 1960 to 1967 (1966 in Calif.) engine it will be the old LOD type without centrivical advance. Good luck 