Hemi cross ram idle tuning

[2059]

Who here has experience setting idle mixture on 426 dual qual cross ram w/ ABF's. 1405 2059 carb numbers. Don't know if current is right. 1-1/4 out on passenger side carb and 2-1/4 out on drivers side. ???? Have an "oscillation" when idling. As if a lean/ rich condition.

 

[sleepar]

Ok here it is its not turns ok.. forget about that. Get 2vacuum gauges and hook one to each carb and synchronise the two carbs to run as one carb let the adjustment screws fall where they may... 8 carbs = 8 gauges like on a Lamborghini or a multi carb bike...

 

[2059]

Ok here it is its not turns ok.. forget about that. Get 2vacuum gauges and hook one to each carb and synchronise the two carbs to run as one carb let the adjustment screws fall where they may... 8 carbs = 8 gauges like on a Lamborghini or a multi carb bike...

I would assume get highest vacuum reading I can?

 

[sleepar]

Ok here it is its not turns ok.. forget about that. Get 2vacuum gauges and hook one to each carb and synchronise the two carbs to run as one carb let the adjustment screws fall where they may... 8 carbs = 8 gauges like on a Lamborghini or a multi carb bike...

A charge of $ 19.99 will be deducted from your for b bodys account when you renew you're membership.....

- - - Updated - - -

Yes but same on both same port manifold vacuum the bottom one

- - - Updated - - -

Read up on carb synchronizes ther should be tons then get the kit you need

- - - Updated - - -

May have to adjust distributor a touch and back and fourth till ti falls into the sweet spot

 

[snakeoil24]

Who here has experience setting idle mixture on 426 dual qual cross ram w/ ABF's. 1405 2059 carb numbers. Don't know if current is right. 1-1/4 out on passenger side carb and 2-1/4 out on drivers side. ???? Have an "oscillation" when idling. As if a lean/ rich condition.

With 2 carbs you need a Carb hat to set them using a bunch of vacuum gauges will not work. That requires individual runners. Put the carb hat on one carb and set as a primary if your street driving. If your racing then 90 percent equalize. TD machine sells the carb hat. Also remember that the Cross ram with AFB's never run well at idle. So get used to crap idle. If you want to get a better idle then you need to cut open the top and mill it down to reduce runner size.

 

[2059]

With 2 carbs you need a Carb hat to set them using a bunch of vacuum gauges will not work. That requires individual runners. Put the carb hat on one carb and set as a primary if your street driving. If your racing then 90 percent equalize. TD machine sells the carb hat. Also remember that the Cross ram with AFB's never run well at idle. So get used to crap idle. If you want to get a better idle then you need to cut open the top and mill it down to reduce runner size.

Thanks snake. I did get it "smoothed out" a bit getting about 16-14Hg on both. Still oscillates some but not bad. Also set the idle at about 1150. Initial timing at 26* with full at 34* @ 3K. no vacuum advance. Seems to start well hot and we'll see about running right as its time for a test drive.

 

[aldal]

Dvorak Machine sells a slick multiple carb synchronizer that might help you out.

 

[coloradodave]

You can make your own. Check my thread about 40 above here...

DIY Carburetor Synchronizer- CHEAP

 

[67 GTX]

Thanks snake. I did get it "smoothed out" a bit getting about 16-14Hg on both. Still oscillates some but not bad. Also set the idle at about 1150. Initial timing at 26* with full at 34* @ 3K. no vacuum advance. Seems to start well hot and we'll see about running right as its time for a test drive.

Just curious, what kind of vacuum does your motor pull at idle?

An idle at 1150 seems pretty high, but then again, I don't know what type of cam you are running.

 

[Meep-Meep]

You can't compare a cross ram to an individual runner setup like Porsche or Lamborghini because all the cylinders connect to a common plenum. In the case of the cross ram 4 cyls connect to one carb with a balance passage in between the plenums. What you need to do is start with a basic adjustment of each carb as follows: Set each idle speed screw about 1-1.5 turns from throttle blades lightly seated. Set each idle mixture screw about 2 turns out. Do this with the linkage disconnected. This should give you a reasonable idle speed, but if too low just increase each screw equally until you are happy. Once basic adjustment is established you can take a piece of heater hose or fuel line, and while the engine is running, listen to the amount of hiss from each primary venturi. The hose and a good ear can substitute for a flow meter. Work each idle screw until you hear the same amount of hiss from each side (or really each plenum). When you have equal air flow on each carb adjust the mixture one screw at a time going in 1/4 turn increments and pausing for several seconds after each turn. You want to find the lean drop of each screw as well as mixture strength of each cylinder. Pulling plug wires out of the cap while idling is a good way to determine mixture strength. Too lean or too rich will cause a cylinder or two to misfire. This will take time and can be frustrating and keep in mind things may change as the intake temp changes. When you have the carbs set connect the linkage and adjust each side until both throttle levers move exactly at the same time as pulled by the throttle cable. This is very important to adjust the linkage with the force excreted as in real time.

 

[2059]

You can't compare a cross ram to an individual runner setup like Porsche or Lamborghini because all the cylinders connect to a common plenum. In the case of the cross ram 4 cyls connect to one carb with a balance passage in between the plenums. What you need to do is start with a basic adjustment of each carb as follows: Set each idle speed screw about 1-1.5 turns from throttle blades lightly seated. Set each idle mixture screw about 2 turns out. Do this with the linkage disconnected. This should give you a reasonable idle speed, but if too low just increase each screw equally until you are happy. Once basic adjustment is established you can take a piece of heater hose or fuel line, and while the engine is running, listen to the amount of hiss from each primary venturi. The hose and a good ear can substitute for a flow meter. Work each idle screw until you hear the same amount of hiss from each side (or really each plenum). When you have equal air flow on each carb adjust the mixture one screw at a time going in 1/4 turn increments and pausing for several seconds after each turn. You want to find the lean drop of each screw as well as mixture strength of each cylinder. Pulling plug wires out of the cap while idling is a good way to determine mixture strength. Too lean or too rich will cause a cylinder or two to misfire. This will take time and can be frustrating and keep in mind things may change as the intake temp changes. When you have the carbs set connect the linkage and adjust each side until both throttle levers move exactly at the same time as pulled by the throttle cable. This is very important to adjust the linkage with the force excreted as in real time.

Thanks Meep and all. I'll tinker with it some more next weekend.

 

[2059]

Just ordered Dvorak's part. Not going to tinker with it forever. Time is money and in this case $60 is worth the hours for me. I'll post in use and results.

 

[coloradodave]

I'm sure you know, but I just want to say that the synchronizer tool ONLY allows you to set the idle SPEED of each carburetor the same. It doesn't help you with the idle MIXTURE settings. Have fun...

 

[Hemirunner]

If you have an oscillation at idle, start looking at the springs that are under the step up pistons. At that rpm you're probably just going out of the idle circuits control and going into the primary metering system. The metering rod is probably bobbing up and down into the primary jet causing it to go from lean to rich. Do you have a tuning kit for these carbs?

 

[2059]

I'm sure you know, but I just want to say that the synchronizer tool ONLY allows you to set the idle SPEED of each carburetor the same. It doesn't help you with the idle MIXTURE settings. Have fun...

Yes Sir, I do. I wan to make sure I eliminate each of the variables one at a time. gonna start here.

- - - Updated - - -

If you have an oscillation at idle, start looking at the springs that are under the step up pistons. At that rpm you're probably just going out of the idle circuits control and going into the primary metering system. The metering rod is probably bobbing up and down into the primary jet causing it to go from lean to rich. Do you have a tuning kit for these carbs?

I thought about that too Hemirunner. Gonna attack this one step at a time; disconnect the linkage, gauge the throttle return springs, check the butterfly shaft wear, check for sticking or gumming, sync and set the idle stop screws, check/adjust the Idle mixture. Until I can get this thing to idle solidly at around 900 rpm I won't know if I have other things going on internally. Quite likely, everything internally is OK. We'll see.

 

[Meep-Meep]

If you have a solid cam make sure the valves are perfectly set before you do anything else. Each cylinder must do exactly the same amount of work or behave the same before you can even think of fiddling with the carbs. Goes for ignition too so throw some new plugs in it. I'm sure you know that and I should have said it earlier just as an FYI.

 

[2059]

If you have a solid cam make sure the valves are perfectly set before you do anything else. Each cylinder must do exactly the same amount of work or behave the same before you can even think of fiddling with the carbs. Goes for ignition too so throw some new plugs in it. I'm sure you know that and I should have said it earlier just as an FYI.

good points meep!! hydraulic roller and new plugs are in the cabinet waiting for tune day!!

 

[Hemirunner]

Yes Sir, I do. I wan to make sure I eliminate each of the variables one at a time. gonna start here.

- - - Updated - - -



I thought about that too Hemirunner. Gonna attack this one step at a time; disconnect the linkage, gauge the throttle return springs, check the butterfly shaft wear, check for sticking or gumming, sync and set the idle stop screws, check/adjust the Idle mixture. Until I can get this thing to idle solidly at around 900 rpm I won't know if I have other things going on internally. Quite likely, everything internally is OK. We'll see.

http://www.edelbrock.com/automotive/misc/tech-center/carb-tech-videos.shtml

- - - Updated - - -

Go to the bottom of the page and download the manual. Read 5 times. Repeat as needed.

 

[2059]

got the carb hat last week. started looking at the linkage set up and don't like the way the Hemi cross ram return spring is set up with the AFB's. One spring pulls the linkage which pulls both throttle shaft arms back. I really like the Max wedge set up, where each carb has its own return spring attached it's own bracket and the butterfly shaft arm. I ordered a new setup from Ray Barton this morning. Should be here by Wednesday. With this set up I can completely take the linkage out of play when setting the air flow, idle points and the mixture.

https://sep.yimg.com/ay/chucker54/426-max-wedge-intake-carb-package-1.jpg

http://image.moparmusclemagazine.co...ge_engine_build+cross_ram_intake_manifold.jpg

 

[2059]

Well I took today off and yesterday my cross ram setup came from ray Barton. I only used the return springs and brackets. If anybody wants to buy the bell crank, linkage rods and cable bracket pm me. Anyway, checked for leaks, set the flow, reset the mixture screws and reset the timing. Idles right around 1050-1100.

Couple pictures and a vid link.

https://m.youtube.com/watch?v=IyBYkSflLSM