Montecarlo Weber Carb Installation on Scorpion

[Timo04]

Greetings,

I guess this is a newbie type of question. While I was at the Concorso Italian last month in Monterey, Ca I was told that the OEM Webber carb that came on the Montecarlo will not work on the Scorpion without modification becaue the Monte Weber did not come with the auto "water" choke and only came with a manual choke. Therefore a choke cable should be installed in the car. Is this correct?

While on this subject are there any fittment modifications (besides different jetting ect...) that need to be performed on the US spec Scorpion when installing a Monte Webber? I guess the Monte Weber is a 34 DARTA? Is this the correct Weber that will fit on the US spec Scorpion. I'm just after a little more power without drilling any holes or changing the OEM intake look.
Does anyone know what model # twin choke Weber carb that will be a bolt on mod for the Scorpion? Thanks in advance!

Ciao,

Tim

[Will]

Hi Tim;

Scorpion uses DATRA and the Monte DGV?(IIRC- I can't seem to remember if the stock Scorpion unit is DGAV or DATRA- mind blank!) so you could use DGAV= the "A" as in "aqua"= water activated choke.
You can use an electric choke (DGEV) "E" for "electric"

Or you can rework the bracket for the throttle cable and use DFEV(electric) or DFAV (water)

Confused? OK your basic choke options are manual (cable) , water (A), or electric (E). DFV is like a DGV except the primary is on the other side and the throttle shaft turns the other way. But the DFV will work better where you aren't pulling a lot of vac. Or so they say, can't say I've ever seen a single carb scorpion do a heck of a lot in the power department no matter how much it's dinked with.

[cthargiss]

Tim,
The monte s1 used a 34 DATRA 200, as did the euro 2L Beta. Both are a straight bolt in, as both used the water choke. On the Beta carb you will hve to move the ball on the throttle arm 1/4 in closer to the throttle shaft in order to get full opening when used on the Scorp. The Monte carb needs no modification.

Will,
The upgrade to a 34 from a 28/32 offers 5-7hp. On an un-modified engine this is signifigant. As to horsepower available with a single carb, my IT Beta puts 135hp on the ground with a single 36DATRA, 152 hp at the crank. I built a 2l for a customer that put out 178hp with a single Holley 500cfm 2bbl. Please don't try to tell me or others that you can't get signifigant horsepower from a single carb.

[SubGothius]

According to Brian Long's Lancia Beta book, the Monte first came with a 34DATR2/200, later a 34DATR4/250; he only lists a "twin-choke Weber" for the Scorpion, same as for all other US Betas. so that must be the 32DATRA fitted to other 1800 Betas in the US. You can prolly get pretty much any other DAT or DATR to work, tho' you may need to swap out different venturis or jets (both easier in practice than in principle) and adjust your static ignition advance, and there may be some strange vacuum ports to relocate your hoses to or simply plug off if superfluous. DMTR will also work and is an established favorite of X1/9, 128 and Beta racers due to its simplicity, tunability and (former) availability, tho' you will have to rig up a non-stock choke cable and close off the auto-choke coolant loop.

In Beta-engined applications, I have heard the DFV/DGV family (indeed, most dual-barrel Webers in general aside from the D-T family I discuss below) pose an issue with fuel delivery in hard corners and long sweepers? Like most Webers, they only appear to have a single-chambered float bowl along one side of the barrels, so when the fuel sloshes away from the fuel uptake port in the bowl, the engine starves. The DGV and DFV are essentially mirror-images of each other, so one version does it on lefts and the other does it on rights, and the severity of the starvation depends on fuel demand vs. lateral-Gs.

This appears to be the exact issue that led to development of the DMTR design and its derivatives (DAT, DATR, DATRA, DHTA, etc.). The D (as usual) denotes Dual ("due") barrels; the T apparently indicates a Transverse engine application. This design splits the float bowl into a "saddlebag" configuration, with smaller bowls straddling either side of the barrels and connected by a shallow channel across the front, and a two-lobed float attached to a forked tang.

Ironically, I have read that this design (in some or all versions?) can also suffer from fuel starvation, albeit less severe than in other designs and only in combined conditions of both high lateral-Gs and high fuel demand simultaneously -- i.e., when high fuel demand (pedal to the metal ;D ) draws the float level way down whilst extreme cornering sloshes all the fuel into one bowl and away from the fuel pickups along the bowl walls.

I have also read that this can be mitigated with a short length of 1/8" copper tubing inserted into the fuel pickup ports on the bowl walls and pointed down into the bowl bottom to act as a fuel siphon "good to the last drop"; however, simply fitting a larger needle valve is much easier, reversible and foolproof, and this may be sufficient to supply enough fuel to keep the bowls from draining too low (altho' your fuel economy may suffer due to less-precise fuel metering of the larger needle opening).

[Will]

Craig;
I don't know where we disagree on the math, but 81HP + 7HP (giving you the high end of the spectrum and you are talking about plus sizing the carb) is only 88HP. Your race motor and the one with a 500CFM Holley notwithstanding, one cannot expect a big gain in performance from a single Weber of stock type. Yeah, I am obviously not talking about single-carb forced induction, single carb tuned race motors, single carb +2L +cams+porting+valves highly modified engines, but rather the notion that one will swap to a bigger carb and solve the fact that a Scorp is seriously underpowered. Considering the car being compared to is a monte, the Scorp will still be underpowered vs. the Monte even with the monte carb. You know this as well as anybody, so I don't know why you you'd say something like"don't tell me or others that you can't get significant horsepower from a single carb", because we both know the best you can hope for is about what you'd get out of a header. Enough that you just might be able to tell the difference if you paid really close attention. This is assuming that the carb IS the modification, not that you are turboing the thing to 3 bar ,etc., 'cause that's an irrelevant comparison. 5HP yeah, maybe you can get something a little more respectable with a DCOE and a custom manifold that doesn't have a right-angle corner in it, but I don't think that's what's being discussed here. The post was Monte carb on a Scorpion, which is a valid pursuit if you have the carb, but not anything to go searching for when you can get an entire Beta FI rig for the same $200 or so of a used Weber + rebuild kit. Yeah, I kniow this doesn't fly for your vintage race classes and such, but again, that's not the topic. and to qualify my statement I wrote that I couldn't say I've seen......and I haven't driven your car. But I did make an earnest effort with mine and reads perfectly just over stoich across the whole band, and none of the other single cartb scorpions I've driven were any better, ditto for the FIATs except John's, and he's got 9.8 slugs and a 2L to boot. Kind of apples-to-oranges.

[Will]

Should probably add they work pretty well with NO choke- haven't had a working chocke on mine since it was plumbed for nitrous, that's I guess about six years- of course the car is not driven in the dead of winter, but I did have it out several times below the freezing mark and it started quite happily with an extra pump on the gas. Personally I'd be inclined to mount the carb first and worry about the choke (if necessary) later. The water and electric chokes may be interchangeable, I don't know. Cable choke to me sounds like something i'd not want to "add".

[cthargiss]

"can't say I've ever seen a single carb scorpion do a heck of a lot in the power department no matter how much it's dinked with."
Here we disagree. I have built signifigant single carb engines, and it is a LOT easier to install and tune than duals or EFI.

"I'm just after a little more power without drilling any holes or changing the OEM intake look"
A 6%-8% in crease IMHO is signifigant, and makes a big difference in driving. A very easy and simple upgrade.
Craig

[Will]

I was referring to how much the CARB is dinked with (i.e.tuned), we al know you gan build a 150HP motor and then put a single carb on it and still get 140HP out of it- especially a 2L.That's not the point.See topic.

With all respect Craig I think you have been building and running hi-po motoers long enough that you may not remember how painfully slow a stock scorpion is. If you are going to Mike's next weekend, drive his yellow car around. That's what a stock scorpion is like.

[cthargiss]

Will,
one of my Scorps IS stock, full smog equipment and all. My daily driver is very similar to what Tim wants to do. De-smogged stock 1.8, 36 DATRA, and ansa exhaust. The difference quite remarkable. We don't need to go into what the 1.8 EFI turbo is like.
Craig

[Timo04]

Hi Will, Sub and Craig,

Thank you gentlemen for all for the helpful information on Weber carb model options for the Scorpion. Since I have no plans to track my Scorpion I'm not really after too much more power out of this little car. We not only have to pass the smog test every other year here in California but we also have California's finest to contend with as they seem to be out in force patrolling the local highways and expressways with radar (even at night!)* :o. If I can even start to keep up with an Alfa Spider or an older Mazda Miata in my Scorpion, espcially with my fat *ss in the car, I'll be tickeled pink!

Thanks again,

Tim

*BTW: Not to hi-jack my own post. I can say that in my 30 mile, one way freeway commute to work each day that the traffic seems to have been slowed down signifcantly over the past 6 months along Hwy 280 by the ever looming presence of the CHP. Maybe it's just me and new found max speed of 65mph? It is not un-common to see two or even three motorist pulled over per a day in my 60 miles of freeway commuting. *If* this law enforcement effort really does save lives then I'm all for it. However *if* the goal is to just add to the state's coffers then I'm of course against it.

[Will]

Craig comes from the world of racing where you skin youre knuckles for months to get 3HP and it's significant, to me anything short of a 2L in a Scorpion is just too darn slow. To be honest though, I didn't realize you were in CA, I mistook you for the guy in the UK that has a monte and scorp and is putting the scorp back together- all I was thinking to myself is that "If that guy is used to Montes and he thinks putting a Monte carb on a Scorp is going to solve his lack of HP problem, he's gonna be REAL disappointed!".

Sure you will be able to pass those Alfas and Miatas with no problems at all- let them zoom past you and then wave and honk as you pass them pulled over by the CHP! :)

You can parlay all the money you save on speeding tickets into funding the purchase of a laser jammer for when you actually get a fast car. It's true you CAN get a speeding ticket in a stock scorpion, but only if you have at least a fifteen minute commute that includes a long straight followed by a steep downhill! ;)

[Timo04]

Will,

That is one thing I like about driving my stock Scorpion here in CA is that it actually forces me to slow down because it aint got much more to go at the top end. I have received two tickets in the past year driving other cars. If I work hard enough I can get another ticket in the Scorpion on the downhills to work, this will make it three for three! ;D

As a side note: When I was a kid in late high school and early college years I drove a Lancia Appia Vignale convertible around. This car was already over 25 years old at this time so it did not need to pass smog. At any rate this was a 3rd series Appia and it had a two barrel Weber and supposed warmed up engine with a slightly hotter cam from the factory. From pure memory I believe this 3rd series Appia engine put out about 62 hp at the fly wheel. This was a lot of hp for an Appia from the factory! If my memory serves me correctly the 1.8L stock Scorpion *seems* to have *about the same* freeway cruising speed as this 1.1L Appia (The stock Scorpion is faster than the Appia to be sure)! The problem with the Appia on the freeway is that I kept mentally reaching for a 5th over drive gear when there was none. A very well built little car though, it had tons of leg room and nice big trunk, fun top down cruising in the summer too, nice for day outtings in the country. Take care and have a good one.

Tim