Tuning Weber 36DCD's
02-12-03, 11:49 PM
#1
Tuning Weber 36DCD's
Well, I have been playing around with the RE intake trying to tune the carbs and have come to the conclusion that I am in over my head. The UNISYN tool that I have does not work with the dual barrel config of the carbs, I can't find a book with any info on what screws are what (though I have had some success with guessing. BAD James), and there doesn't seem to be any sites on the web with a how-to. Can anyone give me any advice on what to do here? Link me to a page with a how-to? Anything? I am running out of hairs and I really wanna drive my car. I have been driving the 79, but it just isn't the same as the 80. SLOW. I need my baby back on the road.
TIA,
James
TIA,
James
02-14-03, 02:18 AM
#6
EliteHardcoreCannuckSquad
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I can't answer your question, but my advice would be:
Don't limit yourself to just asking RX-7 people. Figure out who would know best about tuning dual weber carbs like this - maybe VW or Porsche guys? I don't know.
Find a manual for weber DCD carbs - I'm sure there's one. There's entire books written for DCOE's and Dellorto's, there must be a manual/book that talks about how to tune DCD's. There is FOR SURE at least a diagram available that would tell you which jets are which, etc. And I'm sure instructions on how to tune them.
Just broaden your search criteria and I'm sure you'll be OK. Oh, and definitely ask on www.mazspeed.com if you haven't already.
Don't limit yourself to just asking RX-7 people. Figure out who would know best about tuning dual weber carbs like this - maybe VW or Porsche guys? I don't know.
Find a manual for weber DCD carbs - I'm sure there's one. There's entire books written for DCOE's and Dellorto's, there must be a manual/book that talks about how to tune DCD's. There is FOR SURE at least a diagram available that would tell you which jets are which, etc. And I'm sure instructions on how to tune them.
Just broaden your search criteria and I'm sure you'll be OK. Oh, and definitely ask on www.mazspeed.com if you haven't already.
. They are for many different carbs. Also, he had a good idea. Call some VW shops and stuff. talk to other people that used the DCDs on their cars rather than just RX-7 people.Trending Topics
02-14-03, 09:16 PM
#9
I really just need a confimation of what each of the 4 screws are that allow for adjustment. I believe that the bottom center is mixture and that the lower left is idle speed, but I have no clue if I am right or what the other adjustments are. So far, I have not been able to obtain a sustained idle, though I can keep it alive with feathering of the throttle as long as I want. Also, I need to get them synced, as the front one is definitely out of adjustment compared to the rear (front header pipe is glowing while the rear is not). The unisyn tool that I have will not work with the unique dual barrel configuration of the DCD. What do I do to sync it? Thanks in advance for your help.
02-14-03, 10:16 PM
#10
Bottom scew is primary circuit adjustment, left screw is idle speed, top screw gets you to the idle jet, and the 10mm nut gets you to the primary jet (there's another nut on the other side that does the secondary).
Here's a starting point for your adjustment (you'll still need to fine tune) Engine off - Turn the primary circuit adjuster all the way in (not tight, not even snug, you'll strip it if you put force into it) and back it out two full turns. Same with the idle speed screw, all the way in, then back it out four full turns. Make sure the idle jet screw and 10mm nut aren't loose. If you do that, it should idle.
To sync them you'll need to loosen the linkage and play with it a little. You can check the sync by having someone hold the throttle open (engine off) while you look down the carbs - are both secondaries equally open?
Here's a starting point for your adjustment (you'll still need to fine tune) Engine off - Turn the primary circuit adjuster all the way in (not tight, not even snug, you'll strip it if you put force into it) and back it out two full turns. Same with the idle speed screw, all the way in, then back it out four full turns. Make sure the idle jet screw and 10mm nut aren't loose. If you do that, it should idle.
To sync them you'll need to loosen the linkage and play with it a little. You can check the sync by having someone hold the throttle open (engine off) while you look down the carbs - are both secondaries equally open?
02-16-03, 07:35 PM
#12
Well, I finally got an idle, albeit at 3K rpms I think I have an issue with the front carb as it is putting through quite a bit more gas than the rear one, but it could have to do with how out of sync they are. when the secondary for the front is fully open, the rear is only about 1/3 of the way there. I'm still trying to figure out how to adjust that. I'm still in over my head, but I have enough info to be dangerous.
Any hints or tips on adjusting the secondary linkage? Just loosen the nuts and have at it?
Any hints or tips on adjusting the secondary linkage? Just loosen the nuts and have at it?
Last edited by JDuncan; 02-16-03 at 07:38 PM.
02-16-03, 08:23 PM
#14
I gave you those setting so that it would idle high as you were prolly way too low to start with. Bring your idle down by adjusting the idle speed screws.
To adjust the sync you just want to loosen the nuts on the arms that are attached to the bar that rotate in the heim joints bolted to the manifold (make sense?). You don't want to be messing with the primary/secondary operation, just the big levers attached to the manifold, let the carb internals handle themselves. Once you loosen things make sure the OMP rod attachement is still properly aligned. To actually perform the sync, hold open both carbs fully and individually (you may need some extra hands) then line up the levers with eachother on the rod and tighten things down. It will take a few trys before you get it just right so be patient. To test have the car off and have someone mash the gas for you. then make sure both carbs can't open anymore. If they can, adjust the linkage/cable as necessary.
When you're done with that, you can start playing with the primary circuit adjustment.
To adjust the sync you just want to loosen the nuts on the arms that are attached to the bar that rotate in the heim joints bolted to the manifold (make sense?). You don't want to be messing with the primary/secondary operation, just the big levers attached to the manifold, let the carb internals handle themselves. Once you loosen things make sure the OMP rod attachement is still properly aligned. To actually perform the sync, hold open both carbs fully and individually (you may need some extra hands) then line up the levers with eachother on the rod and tighten things down. It will take a few trys before you get it just right so be patient. To test have the car off and have someone mash the gas for you. then make sure both carbs can't open anymore. If they can, adjust the linkage/cable as necessary.
When you're done with that, you can start playing with the primary circuit adjustment.
Last edited by nimrodTT; 02-16-03 at 08:27 PM.
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