hotrod swinger
Well-Known Member
Thanks for checking in. There are two screws and they are balanced.
Off idle hesitation - solved
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I've never given a crap whether the air screws were the same number of turns out. I adjust by a vacuum gauge, so I put them wherever I get the best vacuum signal and let her rip.
Yep, You never what balance of flow/signal each barrel is getting, especially a Slanty intake or factory dual-plane....
hotrod swinger
Well-Known Member
Interesting, I might try that for giggles.
Plus, who's to say both air screws are machined exactly the same? If the points start at different places, or the points are different lengths, or the bores they screw into aren't quite the same. There could be some tolerance stacking there.
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Dave999
Well-Known Member
also which areas of the plenum are favoured by which runners
screws set to achieve consistent mixture at the inlet valve of all may not be set exactly the same up at the carb.
screws set to achieve consistent mixture at the inlet valve of all may not be set exactly the same up at the carb.
That's kinda what I meant, balanced by way of highest attainable reading on each adjustment screw, based on what a vacuum gauge would be telling me, not necessarily the same # of turns out..
hotrod swinger
Well-Known Member
Is that truly what you meant because I looked at your post and it doesn't read that way. Are we jumping on the bandwagon here?
Conventional wisdom (and the FSM) says that the screws should be set at the same number of turns.
No they need to be set for the best running, per engine demand // usually they pretty close side for side, but not always. If the engine is happy with where those adjustment screws are positioned that's the important thing
I don't remember any manual saying they have to be equal in number of turns out, when everything is set for the best running.
Set the same as a starting point upon a rebuild or just plopping a certain carb on a particular engine? Yeah. But if one side is 1/2 a turn different from the other and that's what the engine wants? Who cares
If you're just doing a tuneup and going over the adjustments when you get to the carb you're probably not gonna bottom them out and start over .. just gonna tweak it from where it sits.
So, often you won't actually know how many one mixture screw is from all the way in vs the other one
I don't remember any manual saying they have to be equal in number of turns out, when everything is set for the best running.
Set the same as a starting point upon a rebuild or just plopping a certain carb on a particular engine? Yeah. But if one side is 1/2 a turn different from the other and that's what the engine wants? Who cares
If you're just doing a tuneup and going over the adjustments when you get to the carb you're probably not gonna bottom them out and start over .. just gonna tweak it from where it sits.
So, often you won't actually know how many one mixture screw is from all the way in vs the other one
Swinger 340
Well-Known Member
Another good reason to spray carbs, every now and then with carb cleaner and not W-D 40 or other sprays. Any oil product will attract dirt and gum up and bind the linkage. My 340 was starting to not have any balls (there is that word again) in power and it was the accelerator pump. (plugged openings and plunger seen better days). I cleaned the carb and installed a new plunger and was good to go.
BillGrissom
Well-Known Member
Besides having a 2 bbl Stromberg WWC carburetor, other things are much different than a 1966 slant. I doubt due to Canada. Yours has an EGR intake manifold, which I don't think was until the mid-1970's. Even California cars with the Clean Air Package in 1966 had only a few additions like PCV w/ breather tube to air filter. 1966 slants also had a rotating throttle rod, rather than a cable. Your throttle cable bracket looks perhaps custom-made.
My 1965 Chrysler Newport w/ 383 had a factory 2 bbl Stromberg (Bendix) WWC carburetor (replaced). If someone retrofit that on a 1970's Super-Six 2bbl intake manifold, your engine would be way over-carb'ed and idle poorly, giving poor mileage and smelly exhaust. You could check the carb PN against a C-body and see if yours is too big. Super-six engines used a Carter BBD carburetor, which was also common on small-block V-8 engines (different PN). You can buy new Chinese knock-offs for ~$100 (ebay), but insure with the Mopar throttle connections since many manufacturers used a BBD.
My 1965 Chrysler Newport w/ 383 had a factory 2 bbl Stromberg (Bendix) WWC carburetor (replaced). If someone retrofit that on a 1970's Super-Six 2bbl intake manifold, your engine would be way over-carb'ed and idle poorly, giving poor mileage and smelly exhaust. You could check the carb PN against a C-body and see if yours is too big. Super-six engines used a Carter BBD carburetor, which was also common on small-block V-8 engines (different PN). You can buy new Chinese knock-offs for ~$100 (ebay), but insure with the Mopar throttle connections since many manufacturers used a BBD.
Swinger 340
Well-Known Member
Most of the time when I have a carb issues, it is not the settings, but a cleaning one. When I dismantle a carb, I document the screw settings and location (left or right) and start from there when assembling. The plunger and plunger arm slots should also be documented. This should put you on the right path on your set up.
There were 318s the a came with a Stromberg carb, that was a smaller Stromberg than would be in a 383. Just like there were 2 different versions of a BBD in those years, the 383 one was much bigger. The carb shown on this engine doesn't look like the 383 version
So Bill, I don't think that's "it".
So Bill, I don't think that's "it".
BillGrissom
Well-Known Member
Why I said to check the PN. But, even a carb for a 318 would be oversized for a 225 slant. I understand the BBD on slants had a lower CFM rating than for a 318.
A 4 bbl carb can be even more over-sized on a slant, unless you can find one of the rare and expensive 370 cfm 4 bbl. An aftermarket TBI EFI might allow a better fit since some use regular MPFI injectors, allowing swapping in smaller ones, though haven't seen anyone try that on a slant.
hotrod swinger
Well-Known Member
The intake is a later two barrel intake with EGR, but the EGR is not connected and the plate is flipped as a block off.
I don’t have any of the super six linkages so I made my own custom bracket and used a Bouchillion Performance cable.
hotrod swinger
Well-Known Member
I sourced all of those parts myself and did all of the brackets custom.
I don’t think the carb is too big, and I’m not having any of those problems. This thing hauls ***!
Yeah I have a couple of lokar cables here, have to figure out how to make a bracket or 2, for my converted super 6... If I don't decide instead to just put my 833OD in there instead.
Then there's the 2bbl to 4bbl swap I have on a 318 in another car I have. ( That's why I have more than 1 lokar cable on hand.... )
Then there's the 2bbl to 4bbl swap I have on a 318 in another car I have. ( That's why I have more than 1 lokar cable on hand.... )
BillGrissom
Well-Known Member
Thanks for splaining your setup. Is that WWC carburetor correct PN for a slant? volaredon above said that some Super-Six came with a WWC instead of a BBD. There were also WWC and BBD models for much larger Mopar engines (and other makes).
hotrod swinger
Well-Known Member
I’m not sure whether or not the 170 slant 6 ever came with a Stromberg WW3, but I’m attaching photos of all numbers on the carb for someone smarter than me to comment.
This engine is built recently. Cam, head shaved, block shaved, etc.
All I know is this two barrel carb seems to be perfect for this engine now that I have the bugs worked out. @slantsixdan recommended it.
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No I never said that any /6 came with a Stromberg carb
Though they did put 2 bbl carbs on for some marine, industrial and export /6s could be had with a 2bbl carb before the "super six" came out on US cars in 77... I don't know what carb was used on those early non US version.
I have a 318 spec BBD on a /6 that runs like a million bux... All I had to do was to put a different link on the choke shaft, I found a place on eBay that had the /6 choke link.
Conventional Wisdom? Is that like asking Joe down the street and Bob at the bar?
Lets think about this. There are a number of reasons the other guys already laid out for having individual idle mixture valves (aka screws). At least for me, the technical rationale outweighs the popular thoughts on any technical matter.
Now as far as the FSM, you've got my attention. I too would like to know where you saw this. Seriously. I'm betting what you saw was a starting point after an overhaul. Take another look and let us know.
Well, well, well.
This would have been helpful to know before I started digging in the FSM.
Once the compression and cam has been changed the factory settings no longer apply. Depending on how the changes effect the compression and valve overlap the factory specs might be a clue as to a new baseline to tune from.
What I'm saying is that tuning a hot rod is really that. It's a process.
Links if you are interested in learning more
Basic Concepts:
Timing is related to engine speed and fuel mixture.
Fuel to Air needs are mostly related to load.
Changes to manifold vacuum will impact the low speed fuel circuit, espcially at idle. Illustration here. So factory settings may have to be altered.
Increased overlap will allow more exhaust to stay or even get pushed back into the combustion chamber at idle. This calls for more lead time between the spark and and when the piston is going down.
Increased compression will created higher fuel density in the chamber and also more heat. Therefore will require less spark lead time.
Practical Performance Tuning:
Tune for Best Performance
Dale Davies
Well-Known Member
Canadian was pretty much US Federal.
But sometimes just like California vs US federal, where US federal was a year or more behind implementing certain requirements, Canada was often a year or 2 further behind in some of their requirements vs the the same model built for use in the US. I remember several models (like F-M-J especially) where we were choked up with having to run 3 converters, and Canada cars still had none or maybe 1.
Or US cars having lean burn BS and Canada still having the standard 4 pin electronic ignition box on the same given year and model
Or US cars having lean burn BS and Canada still having the standard 4 pin electronic ignition box on the same given year and model
Absolutely! Say we're running a dual plane intake manifold. Do you think each side of that intake will have exactly the same vacuum signal? Hardly. Even on something like a slant 6 with a two or four barrel, while theoretically, each side "should" have the same vacuum signal, it most certainly "may not". That was a great point, Dave!
Dale Davies
Well-Known Member
That is a starting point, then final adjust for vacuum and smoothest idle.
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