I currently have a cross ram on my car with 600cfm eddys. I have read about staggering the jetting on the crabs and was wondering if anyone has done this? I have the cross ram on a 440 with comp cam hyd roller, 440 stealth heads, stock bottom end, 3400 stall, MSD, TTI, 3" exhaust and 3.55 gears in a 65 belvedere II. I have the chart for the max wedge with 3705s, and was wondering if it is the same sizes that will fit the newer eddys. or is there a conversion chart? Just installed the heads and cam, and want to try and tune the carbs a little better.
cross ram carburetor jetting
- Thread starter MD Mopar
- Start date
lewtot184
Well-Known Member
use the jetting for the 3447 carbs. 3705's are larger; same size as 750's.
Are you referring to the Chrysler staggered jetting for the super stock cars? Are you setting your car up for drag racing? If so, I concur with Lew.
Goldencommando
Well-Known Member
Can anyone post the chart?
Meep-Meep
дворянин
The only reason to stagger jet is to deal with fuel distribution issues. And the only way to find fuel distribution issues is with a thermocouple or and O2 sensor in each EX port. Since many components on your engine aren't stock I would start with the OEM Eddy 600 CFM jetting and go from there. If you get a stumble when getting into the secondaries then up the secondary jets 4% and try again.
The car is just for street use. I do not have 02 sensor ports installed in exhaust. So you recommend going with stock settings and adjust from there? Why was the jetting staggered on the cross rams? I normally tune the carbs using a vacuum gauge and balance the 2 carbs as close as possible.
lewtot184
Well-Known Member
factory recommended jetting for the 3447's was; .098" primary with a .068"x.050" metering rod and .082" secondary jets. this is for both carbs.
Meep-Meep
дворянин
Stagger jetting is to deal with fuel distribution issues under WOT. Figuring this out requires a dyno and EGT or O2 monitoring at each exhaust port. Tuning the carb as you described is basically for setting idle mixture and that's it.
OK, Thanks for all the information. I also read that each carb was jetted different. Do you know why this was done? I will try your suggestions and see what happens. If this doesnt workout I will try and find a dyno and mopar expert near me in Maryland who can help with tuning a cross ram..
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I also read that even each carb was jetted differently; choke vs throttle side.
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I also read that even each carb was jetted differently; choke vs throttle side.
lewtot184
Well-Known Member
the 3705 carbs had a staggered secondary jetting, but the engines with 3705's were a little different than the engines using 3447's. there was more to the factory carbs than jetting calibration. there was a specific throttle blade angle for those carbs. i think what your trying to do is irrelevant. you don't have any of the factory pieces, everything is aftermarket, so how can anyone say that factory jetting is even correct? staggered jetting is primarly used to make up for intake manifold problems. how do you know you have a problem without the proper equipment to find a problem? the only way i know to do this is with some kind of EGT probe at each exhaust port. lastly, if you have 1405 carbs you probably have an idle jet problem and it will need to be checked.
383man
Well-Known Member
You know I have an old Mopar eng/tune book from the 70's and they had the recomended staggered jetting for racing with the crossram. Course they had no 02 sensors systems back then as I guess they did most of the tuning back then by reading the plugs as they were aware of uneven fuel distrabution back then. Ron
Ron: Thanks, I might take you up on that. I need to find out more on placement of 02 sensors, and who can weld them on my exhaust. Then find someone who can tune the car with the right equipment. I will try and tune the old way and see how that works out.
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