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bugedd
05-28-2011, 11:23 PM
I'm not too happy with the performance of my Weber DGV and its flat spot, so I am kicking around the idea of a Weber 45DCOE setup. I talked to a local Datsun guy and he said the DGV is known for off idle flat spots, which I have, and they are not easy to get rid of. Does anyone have any input on the 45DCOE?

Gerard
05-29-2011, 01:36 AM
I'm not too happy with the performance of my Weber DGV and its flat spot, so I am kicking around the idea of a Weber 45DCOE setup. I talked to a local Datsun guy and he said the DGV is known for off idle flat spots, which I have, and they are not easy to get rid of. Does anyone have any input on the 45DCOE?

The 45 is too much carb for a stock 1275 unless you really choke it down and it is much, much harder to jet properly than the DGV. You can get rid of the flat spot on the DGV with the proper jets and will take much less experimentation then a DCOE. I succeeded with the '72 I had by going down one size on the jets. The DCOE has ~6 jets and emulsion tubes (x2) that you'll have to fool with, plus you need to get the choke size right. A 40 would be better, but you'll still have the same number of jets to try and experiment. Why not go back to the SU's?

bugedd
05-29-2011, 10:13 AM
I thought about it, I have some SU's in a box. They need to be rebuilt/restored, so that will cost a pretty penny. And I don't know if they are right for the motor. And I don't know how adjustable they are to modified motors. Such as they may be fine for the stock 1275, but what if I build a hot motor? Then can I jet them and make them work? Or will I be throwing money away?

jlaird
05-29-2011, 10:29 AM
It all depends on the model of SUs you have. The H2s will work just fine on a 1275 no matter what you do with it.

Keep in mind they need to be tuned for the engine as well.

bugedd
05-29-2011, 11:10 AM
How can I tell which SU's I have?

jlaird
05-29-2011, 01:34 PM
measure the intake. 1 1/8 H1 948

1 1/4 H2 1275

Guest
05-29-2011, 01:54 PM
I love my single 40 on the 1500. I have a 40 Delorto that needs work and an A series intake you can have for $200.

Sarastro
05-29-2011, 04:22 PM
Remember, if you need to tweak the SUs for a modified engine, you can get needles with all kinds of different profiles.

bugedd
05-29-2011, 05:06 PM
I didn't know that. I guess I am not familiar enough with SU's. If I can tune them to whatever I need, then great. Then it will be worth rebuilding them.

jlaird
05-29-2011, 08:08 PM
Did i not see in the Moss catalog a needle finder chart??

Or ask Hap for his advise for your application, Needles are cheep and he will have a good idea where to start.

twas_brillig
05-29-2011, 11:50 PM
We've been running a DCOE 40 on our 948cc BE for several decades and have been happy enough - there's some Weber threads with jetting info on this forum.
We're looking into converting a 1973 BMW 2002 with dual side draft PHH Mikunis to megasquirt electronic fuel injection, retaining the Mikunis as the throttle bodies. If anyone feels rich out there,it's probably roughly $ 1500 to for the EFIconversion, irrespective of the car ....
And I ran across a Volvo thread last week (sorry - didn't record it) that extolled replacing SUs with side draft single barrle Mikunis after doing some dynamometer comparisons.
Doug