 Acc. Pump volume question, Dellortos |
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| type11969 |
 Mar 30 2007, 07:21 AM
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#1
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Senior Member  Group: Members Posts: 1,231 Joined: 2-December 03 From: Collingswood, NJ Member No.: 1,410 Region Association: North East States  |
I'm trying to get my Dell 40s set up properly and I'm currently adjusting the pump volume. In the dell tech manual it states that .4-.5ccs should be released for every two throttle pulls for a 1600cc engine. I can only get ~.2ccs for two throttle pulls at max pump stroke. Would changing the pump jet actually change the volume? I don't see how it would. I'm running a 45 for a pump jet, certainly open to suggestions! Also, suggestions regarding how much more pump volume I should be pushing for an 1800cc, pretty mild with 8.2:1 CR and a web 86 over the .4-.5ccs for a 1600?
Thanks, Chris |
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Replies(1 - 8)
| gopack |
Mar 30 2007, 07:37 AM
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#2
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CHEESEHEAD in CA, MARK Group: Members Posts: 744 Joined: 7-August 04 From: Folsom, CA Member No.: 2,472 Region Association: Northern California |
Slight HIACK
Isn't a Dell 40 too big for a 1800? i remember reading that a Dell 36 is equivelant toa Weber 40, so reason suggests that a Dell 40 is more like a Weber 44? the reason I ask is that I have a 2 liter of unknown internals that has Dell 36s, but the venturi seems to be around 40 mm wide. END HIJACK BTW, sorry I don't have any clue on the answer to your question. I just got excited seeing a Dell question so I chimed in! |
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| type11969 |
Mar 30 2007, 07:47 AM
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#3
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Senior Member Group: Members Posts: 1,231 Joined: 2-December 03 From: Collingswood, NJ Member No.: 1,410 Region Association: North East States |
I've been under the impression that I will be fine, I think it comes down to venturi selection. I'm running 32mm vents, if I was running the largest that a Dell 40 could fit, then yes, it probably would be too much.
-Chris |
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| terrymason |
Aug 2 2007, 12:43 PM
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#4
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Member Group: Members Posts: 346 Joined: 23-November 05 From: Virginia Beach Member No.: 5,174 |
Hey Chris, did you ever get this figured out? Also, how exactly did you measure this? I tried holding my kitchen measuring cup under the carb, but that was pretty much a joke..
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| Joe Ricard |
Aug 2 2007, 03:21 PM
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#5
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
Pump volume is extremely important to smooth take off when you mash the gas.
Pretty simple, if it stumbles you need more gas. Pump jet increase would be my guess if everything else is working properly. I so love my Webers as I can just tighten the nut on the linkage to increase volume. I can see what's going on with my wide band A/F meter. Mash the gas stumble gage shows lean= more adjustment. Mash gas pin head to head rest gage says 12:1 life is good. |
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| terrymason |
Aug 2 2007, 03:42 PM
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#6
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Member Group: Members Posts: 346 Joined: 23-November 05 From: Virginia Beach Member No.: 5,174 |
QUOTE(Joe Ricard @ Aug 2 2007, 01:21 PM)  Pump volume is extremely important to smooth take off when you mash the gas. Pretty simple, if it stumbles you need more gas. Pump jet increase would be my guess if everything else is working properly. I so love my Webers as I can just tighten the nut on the linkage to increase volume. I can see what's going on with my wide band A/F meter. Mash the gas stumble gage shows lean= more adjustment. Mash gas pin head to head rest gage says 12:1 life is good. I've got about the same setup, I just want to make sure that both carbs are pumping the same volume with each squirt. |
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| Joe Ricard |
Aug 2 2007, 04:06 PM
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#7
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CUMONIWANNARACEU Group: Members Posts: 6,811 Joined: 5-January 03 From: Gautier, MS Member No.: 92 |
I hate instructions but what if.
the meaning of the measurement process is 4cc total or 2 cc each barrel. Start with equal adjustment and test. if they are even cool. if they are off tweek as required. The real test is the mash the gas test. |
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| BMartin914 |
Aug 2 2007, 07:43 PM
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#8
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||| Group: Members Posts: 1,408 Joined: 30-May 04 From: Oregon Member No.: 2,128 Region Association: Pacific Northwest |
.4cc to .5cc sounds about right (.4cc to .45cc is the volume for a Solex 40).
That volume is per "barrel", two strokes of the pump. We use a very small graduated cylinder that fits down into the "barrel" and under the nozzle. Small incremental changes can make a huge difference in performance too. |
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| type11969 |
Aug 7 2007, 12:09 PM
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#9
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Senior Member Group: Members Posts: 1,231 Joined: 2-December 03 From: Collingswood, NJ Member No.: 1,410 Region Association: North East States |
I used a baby medicine dispenser for a graduated cylinder, readily available at any drug store. I found that with an increase in pump jet size (I was at 45s, now I am at 55s) and with replacement of the pump spring I was able to get close to the .4-.5cc pump volume as spec'ed in the dell book. The hesitation I was having when mashing the gas is almost completely gone . . .
-Chris |
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