Anyone have actual experience with weber DCOEs on a slant?

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robertob

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I'm hoping to find someone - anyone - who has successfully run sidedraft webers on a slant. I'm working on setting up a used set of DCOE 40s I bought (really they are probably too small for a 225) and the jetting is totally wacky.
 
Didn't Doug "Doc" Dutra run a setup like that for a while? Ping him on slantsix.org
 
Never on a slant, but 40mm DCOE's will be adequate for a fairly robust slant. Figure out EXACTLY what you have now. There should be plenty of Weber savvy resources on the interwebs that can help point you in the right direction.

If only you were running SU's...
 
C130 Chief said:
Never on a slant, but 40mm DCOE's will be adequate for a fairly robust slant. Figure out EXACTLY what you have now. There should be plenty of Weber savvy resources on the interwebs that can help point you in the right direction.

If only you were running SU's...
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what cfm is a 40mm?
 
Dart270 on slantsix.org ran that setup on his 66 valiant . He told me that the carbs had sat around too long between running them again and didn't perform the way they should have . His new plan is to use the dcoes as throttlebodies on converted to mpi manifold . I will say that the setup looked awesome!

My only experience was swapping out the twin SUs on my 68 spitfire to a single 45 DCOE . You would not believe the increase in power . All that said i have heard that webers don't like radical cam profiles because of the lack of vacuum .

My vote is " run em if ya got em "
 
Well, the choke size is the first big issue. The carbs came to me with 30mm chokes, which are about right for a very small engine, like a 170 or smaller.

According to the weber formulas, I should be running 36mm or 38mm chokes to make power up to 6,000 rpm. That means a 45 DCOE, since the largest choke available for a 40 DCOE is 36 (which flows no better than a 34mm choke).

Anyway, I got a set of 34mm chokes and I'll try them. According to the Weber formulas, they should run out of breath at 5,000 rpm.

The other issue is emulsion tubes - the carbs came with F11s, which are right for a very small engine. The Cobra guys are using F5s and F7s, and one book I have recommends F2.

Luckily I was able to rebuild the carbs without needing any new parts-- none of the gaskets tore and the needle valves were in good shape.

But I did have to get the 34mm chokes, larger main jets and bellmouths. They are very expensive to set up.

Next I have to sort the linkage - the setup that was on them was really mickey mouse.
 
40 DCOEs are somewhere around 350 cfm per barrel with 34mm chokes. But it's not directly comparable to a 2bbl or 4bbl downdraft because each cylinder only 'sees' one barrel.
 
Shot of them on the motor. Baseline setup:

34mm chokes
50F8 idle jets
175 air jets
F11 emulsion tubes
135 main jets
40 pump jets
50 pump inlet/bypass jet

Short stacks are so they fit under the air cleaners (short, because tall ones won't fit between the carbs and master cylinder).

I still need to sort the linkage, I might try to make it work with a modified rod throttle linkage, unless I find a cable throttle somewhere.

I also have to make a vacuum manifold to join them all together for PCV and vac. advance - they don't have an advance port but I think I can make it work with non-ported advance like a Chevy.
 

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I had a triple SU manifold for a while, but I went with Weber carbs because they are easier to get tuning parts for. I had a Mini with an SU and tuning it to be spot on was a real pain. Also when they get some wear they go out of tune easily. Webers/Mikunis are "set it and forget it".
webers do not wear out - they have ball bearings on the throttle shafts, and every tuning part is easily available.
 
I sent my SUs (plus a couple of extras just in case) to Island Automation up in Canada. We discussed the usage (225 slant) and engine specs and based on that he rebuilt and matched internally all 3 with new parts (and polished the domes for a little extra bling!). He said it should run quite well right out of the box with little or no extra tuning. I'm optimistic everything will run well.
 
robertob said:
I had a triple SU manifold for a while, but I went with Weber carbs because they are easier to get tuning parts for. I had a Mini with an SU and tuning it to be spot on was a real pain. Also when they get some wear they go out of tune easily. Webers/Mikunis are "set it and forget it".
webers do not wear out - they have ball bearings on the throttle shafts, and every tuning part is easily available.
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did you replace and top off the oil properly? i had SU's on my 72 Z and i pulled that car out from under a tree, only thing i did was air up a tire and somehow it started. then got it home and did a tune up, adjusted the carbs and never had to touch them even before i sold it a yr later.

now if you had 4 screws i understand lol
 
Hitachi HS6 SUs (on Z cars) are much improved over the British ones. I had troubles with throttle shaft wear on mine, and the needle wore flat as well.

That said, I am sure they will be fine.
 
robertob said:
I meant the regular "round top" Japanese SUs, they were all made by Hitachi. NOT the square ones like in that picture. The round top, Hitachi-made, SU carbs are better than the british ones made by Skinners' Union (SU).

Anyway, my car had a regular british made SU.
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oh maybe i was thinking of the zenith carbs, ive been out of the z stuff for long enough i forget the little things...
 
I have a pair of Asian SU type carbs.....Asian is owned by Toyota....I haven't a clue what they are off.....They have a triangle shaped flange for attachment to the intake.
 
cjh said:
I have a pair of Asian SU type carbs.....Asian is owned by Toyota....I haven't a clue what they are off.....They have a triangle shaped flange for attachment to the intake.
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Those are from an old Toyota Corona with pushrod 3R or 4R engine (1968-72ish). I had one of those cars but in the U.S. we got the standard 2bbl downdraft carb.
 
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