1500 carb conversion to Weber DGV

[tosoutherncars]

Hi all,

I suppose an introduction is in order. I'm Duncan, and I have a 78 Midget 1500, in Vermillion, that I bought in California last summer. I drove it back to Ottawa, Ontario (don't ask!) and it's been sleeping all winter. I've got a laundry list of things I'd like to do before summer hits. Key among them are:

- DGV carb and Lumenition spark
- front-end suspension rebuild w. poly bushings

The car's coming out of storage next week, and the parts have started arriving from my eBay spree. Here's the used Weber DGV and Cannon manifold.

(You'll have to forgive the pictures, taken with my phone)

Thankfully, I had the good sense to send off for a DGV rebuild kit and a new filter, so I suppose it's time for a rebuild!

Although it's marked as a DGAV (water choke) someone must have upgraded at some point, because it now has an electric choke. Thank goodness!! After the gawdawful Zenith Stromberg, I've had my fill of water chokes.

The Cannon is a nice, simple bit of kit. I was toying with the idea of having it powdercoated, but I think I may just clean it up and use it. "Milo" isn't a show car.

The DGV is a progressive carb, with a 32mm barrel for idle and primary, and a 36mm secondary that opens under heavy throttle.

This must be a fairly early version, it has the brass floats rather than the later, plastic version. Everything shows a lot of residue inside, along with dried O-rings and gaskets.

I'd say the linkage was probably not correctly set up on the previous car; it looks like it's been running on the primary only. no deposits whatsoever on the secondary, which is stiff to open.

I do have an exploded diagram, but I've laid out each component during disassembly, just to take a photograph so I know how it should be going back together.

I've disassembled the choke too. I don't have a kit for it, but I might as well clean it up as best I can, while I'm in there.

I'm using a brass-bristle brush and carb cleaner... slow work, but satisfying. Here's the product so far.

The castings themselves look a little better, but they've gone back into a tub of carb cleaner overnight, just to see if some more of the staining will come off.

I'll be assembling tomorrow... Will post more, if people find this sort of thing to be of use?

Best,
Duncan, Otttawa
'78 Midget 1500 "Milo"

 

[DrEntropy]

Always interested to see photos of task and progress!

And welcome to the forum, Duncan! /bcforum/images/%%GRAEMLIN_URL%%/savewave.gif

 

[tosoutherncars]

Thanks Doc!

So, I now have a shiny new(ish) carb, and a couple of questions for the forum.

Q1 - There are two diaphragm return springs: one for the accelerator pump, and one for the choke.

Would I be right in assuming that the shorter, stronger one is for the accel pump diaphragm?

Q2 - Here are the parts I have 'left over'.

A = circlip for the throttle plate linkage. Done.

B = 'plate' (i.e. plastic tube) for choke shaft. Will order new one, this one is wrecked.

C = fuel strainer. Must pull brass inspection plug and replace.

D = alum. washer from... fuel intake, I think. I used thread sealant, don't know whether I'll bother replacing it.

E = OK, I have NO IDEA where these came from. Three small brass flat washers. They're not the ones above & below the accel. pump jet. The primary main and secondary main jets don't have washers. (These are slightly too large for that space, anyway.) I'm totally stumped. Ideas?

F = mounting nuts

G = leftovers from the rebuild kit. The only rubber O-rings I used were for the primary and secondary idle jets. I realize the kit may have extras due to it covering all DGV, DGAV and DGEV, but I seem to remember pulling out at least three rubber O-rings. What am I missing?

H & I = One gasket, two aluminium washers and a cotter pin. The first three would fit the fuel intake, see letter D. I'm guessing that's the intended use. The cotter pin? No idea. There was a v. small clevis pin included, which was used to secure the fast idle control rod.

Here's a pic of the almost-finished product...

-Duncan

 

[tosoutherncars]

Here's the exploded diagram, if that helps.

Exploded diagram, 32/36 DGAV and DGEV

 

[DrEntropy]

Look at #34& #67 to apply "G" O-rings around screw heads for externally accessible jets(?).

The brass washers "E" were likely under the screws which hold the top part of the thing to the body: #3.

I'd need to have the beast sitting in front of me to really be certain. I'm a DCOE type. Last down-draught Weber of that ilk I touched was two years ago, at least.

Sorry to be of so little help. /bcforum/images/%%GRAEMLIN_URL%%/frown.gif

 

[regularman]

Looks like you have done well. The electric choke version does well. Is it adjustable? Some would not allow it. Be sure and have a good hot wire from inginition to that.

 

[terriphill]

We converted our 77 midget over to a DGV and found that the downdraft manifold did not fit flush because the exhaust manifold interfered with its ability to go down. We had to grind off two spots on the exhaust manifold to allow the intake to clear and snug up so there were no air leaks. (We spent a week trying to figure out whether it was timing or our inability to set the carb correctly..duh!)

Here's a pic....

 

[tosoutherncars]

Doc, I would agree with you that #67 seems like a likely candidate for a missing O-ring... but were does it go? In the diagram, it's just floating in space, the one piece that's not part of a sub-assembly!

Kim, yes the e-choke is adjustable, the same way the water ones are. it has a metal coil in the round plastic 'can', and the whole assy can be rotated (to advance or retard the action of the choke) once the three retaining screws have been loosened.

Terriphill, I had heard about the manifold issue, but I'm glad someone explained it completely! I'll be sure to look for it. Someone on another board had suggested that a quarter of the 1500-powered cars driving around out there probably had manifold leaks. Any thoughts as to whether doubling up the head-to-intake gasket would help?

-Duncan

 

[piman]

Hello Duncan,

it is too late as you have already got the kit, but I fail to see any advantage and many disadvantages of converting from a progressive choke to a fixed choke carburettor, especially as complicated as a Weber. I can understand a DCOE or two for out right performance but nothing beats a progressive choke set up for a road car. I personally prefer S.U.'s to Strombergs but either are simple to maintain and overhaul and they are reliable.

Alec

 

[DrEntropy]

Can't recall.

A true W.A.G.... Does the idle screw hole in the carb body have a recess around it for that O-ring? I seem to remember something like that. The spring on the screw holds tension against it?

again, it's been a while since I've been thru a Weber like this... tho I thought I caught a whiff of old fuel while studyin' that diagram /bcforum/images/%%GRAEMLIN_URL%%/wink.gif

 

[terriphill]

I'm not sure doubling the head gasket would help cause it's the same gasket for both the exhaust and the intake. We just got out the old grinder and ground off the higher spots on each side. (If you look, it appears that something used to mount there and the edges of the mounting holes are what interferes with the intake seating.) We took em off and the intake set flush...no leaks. Now, could it be the reason no one ever noticed this is cause my exhaust is not original? Who knows...these cars are often piece meal when we get em and this was just a glitch I discovered. Thought it might help if you looked for it on the front end instead of like me, taking it apart three times before figuring our why I had leaks (My husband kept telling me it was cause I didn't have the manifold bolted down tightly enough...you know those long bolts in a place no normal human hand could ever fit?)

 

[DrEntropy]

NO "DOUBLE GASKETS!" That'd INSURE it doesn't seat/seal. Just check fit as Terri suggests and if there's interference, gnaw some off the offending "ears" with a file, grinder, mink... whatever.

 

[tosoutherncars]

Hi Alec,

In general design terms, I might agree with you. Variable venturi carbs are a more elegant solution. The change specifically from Z-S 150CD to Weber DGEV has a lot of upside and no downside. The 150CD was put on the later Midgets to get them 'in compliance' with US emissions law. They are poorly designed, make little power, aren't very fuel-efficient, and the choke design is Machiavellian. They may be simple to overhaul, but the only thing they do 'reliably' is run rich and use dashpot fluid.

The DGEV simply;
- makes more power,
- returns better mileage
- stays in tune longer
- doesn't have a dashpot that requires filling every week

As an added bonus, you have the choice of water, electric or manual chokes, and spares that are are much more readily available AND cheaper to boot. Plus they sound good and lairy when the second throttle opens!

That's my thinking in doing the switch, anyway.

Best,
Duncan

Hello Duncan,

it is too late as you have already got the kit, but I fail to see any advantage and many disadvantages of converting from a progressive choke to a fixed choke carburettor, especially as complicated as a Weber. I can understand a DCOE or two for out right performance but nothing beats a progressive choke set up for a road car. I personally prefer S.U.'s to Strombergs but either are simple to maintain and overhaul and they are reliable.

Alec

 

[DrEntropy]

the only thing they do 'reliably' is run rich and use dashpot fluid.

heh. I'm a DCOE freak. If this had come up as a "What Carb Should I Fit?" thread, I'd say DCOE first, a big ol' HS6 SU next as that'd nearly bolt up and go with existing manifold.
...but a DGEV is as good as any when the "baseline" is a ZedEss. It (the Weber) has a PUMP! /bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif

Duncan, did you look at that idle screw hole yet?

 

[tosoutherncars]

/bcforum/images/%%GRAEMLIN_URL%%/devilgrin.gif[/img]

Duncan, did you look at that idle screw hole yet?

No, I'm stuck at the office 3-11 today, so the ol' screw hole will have to wait until I get home. I'll get stuck in ASAP, and take pictures!

-Duncan