I am going to install the Jenvey Heritage Throttle Bodies on my car and need a manifold and linkages. If someone has a complete setup I'll take that and am also willing to buy a new set and part out if someone else needs some carbs.
WTB: Weber Triple Carbs
- Thread starter bwalvoord
- Start date
daddywad
Well-Known Member
From what I understand the Jenvey linkage differs from the Weber one.
The Jenvey setup looks cool, please keep us posted on install and running!
readie
Well-Known Member
hi all, I am thinking of putting the triple carbs in mine also any pointers would be helpful...
You need to do several things in preparation for triple Webers:
-- install a thermostat housing that will allow room for the first carb (Korman in North Carolina sells one);
-- install a tii brake booster in place of the stock brake booster to allow room for the center carb; and
-- remove the mechanical fuel pump, block off the opening and install an electric fuel pump.
I did all of these things, and tested them with the downdraft DGAVs before I attempted the triple Weber install. You can get by without changing the brake booster, but that would entail different air filtration for the center carb. I did not want to do this.
You can see the tstat housing, tii brake booster and fuel pump block off in this picture. My new fuel pump is mounted just forward of the rear subframe.
If you go down this path, these babies will be for sale soon (but I will be keeping the manifold):
-- install a thermostat housing that will allow room for the first carb (Korman in North Carolina sells one);
-- install a tii brake booster in place of the stock brake booster to allow room for the center carb; and
-- remove the mechanical fuel pump, block off the opening and install an electric fuel pump.
I did all of these things, and tested them with the downdraft DGAVs before I attempted the triple Weber install. You can get by without changing the brake booster, but that would entail different air filtration for the center carb. I did not want to do this.
You can see the tstat housing, tii brake booster and fuel pump block off in this picture. My new fuel pump is mounted just forward of the rear subframe.
If you go down this path, these babies will be for sale soon (but I will be keeping the manifold):
We just installed triple Webers as well. Pre-restoration, so the engine compartment is not nearly as pretty as Chris's. Love your fuel line routing, by the way. But we got away with a standard BMW t-stat housing (part number 11 53 1 710 959). Currently have an electric fuel pump in the trunk, but would like to relocate it. And I am looking for a tii brake booster (should anyone have one available...). Can't fit the middle trumpets currently, which the carb does not like... This was just a test fit/run before pulling the engine for chassis work.
These are DCOE 45's I am still determining if this is too much carb for this engine. These have less than an hour of running time on the engine, and may be for sale soon as well (depending the decision above). Sorry if I'm hi-jacking this thread.
These are DCOE 45's I am still determining if this is too much carb for this engine. These have less than an hour of running time on the engine, and may be for sale soon as well (depending the decision above). Sorry if I'm hi-jacking this thread.
I think the 45s may be too much for an M30b30. Don't know about the M30b35?
Probably not as much of a concern in MKE, but I decided to mount my fuel pump to the rear subframe as low as possible while still using the subframe to protect it in order to minimize the possibility of vapor lock on hot days.
Probably not as much of a concern in MKE, but I decided to mount my fuel pump to the rear subframe as low as possible while still using the subframe to protect it in order to minimize the possibility of vapor lock on hot days.
I know a couple people that had 45's on Bavaria's and more than happy with them
Mark is right; my earlier post was misleading. If you already have a set of 45s, you don't necessarily need to change to 40s. Both will accommodate chokes in the appropriate range for our engines (30-34 mm). The "40s are better" is only helpful if you are determining which carbs to buy. There is no need to seek out 45s over the 40s; the larger throats in the 45s would only come into play if our engines could pull in a whole lot more air than they are designed to do.
long ago I had a 2002 with 45, higher compression, semi race cam
The only problem was it got 15 mpg
The only problem was it got 15 mpg
I am still peeling the layers of this onion (learning what a PO has done), but we know it has higher compression piano top pistons (presumed to be 9:1), a larger cam (do not yet know the duration), and a Stahl header. So theoretically it should breathe better. The venturis are currently 36mm.Stevehose said:
Perhaps a less "knee jerk" solution would be to replace the 36mm venturis with another size. I had found the charts/math to properly size all if this at one time. Can't find it currently, but I think that would provide insight. I'd consulted that reference originally when I purchased the 45's, but I was led to believe the engine was a 3.5 liter replant at the time. That was just the outer skin of the onion... :eek:
jmackro
Well-Known Member
One resource that discusses sizing Weber carburetors is at: http://www.s262612653.websitehome.co.uk/DVAndrews/webers.htm
A key chart in David Andrews' write-up looks like this (I believe this chart assumes a 4-cyl engine, so the displacement axis would need to be scaled by 1.5 to apply to a 6-cyl):
Someone told me that the equation behind that table is: Choke Diameter (mm) = (Individual Cylinder Displacement (cc) X max rpm / 2500) ^ 1/2
Plugging some numbers into that equation: Say you have a "3L" BMW engine that actually displaces 2,986 cc. That's 497.7 cc per cylinder. Say your maximum intended rpm is 5,500. The square root of [497.7 x 5,500 / 2,500] = 33.09. Since Weber chokes typically come in even sizes, you would want to use a 32 or 34 mm choke.
What I believe this accomplishes to ensure that the airspeed through the venturi is not too low at idle to allow the fuel to atomize, nor so high at peak rpm that the flow becomes turbulent.
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YES! That is the equation I once knew. And in doing the same calcs for a 3.5 liter the resulting venture size is 35.8 (36). When you multiply that by 1.25 you get a barrel diameter of 45. That is what led to my current purchase. I will still need to decide if I will live with the 45's and maybe replace the chokes with 34's. Or sell these "one-hour old" 45's and replace with 40's for this engine. Either way, I am committed to the triple carb solution. 
jmackro
Well-Known Member
What leads you to believe that 36 mm chokes are too large? Or that 40 DCOE's would be better than 45's?
At this point, nothing more than the results of that equation. It's the fear of not knowing that gets me. I will soon remove the engine from the car, spend a long time re-fabbing the chassis, and then eventually drop the engine back in. I'll have long forgotten this discussion and will have executed a number of other modifications to the overall mechanical systems surrounding the engine. But I'll hope that it runs well - as good as it can. But if it is overcarbed because of my original calcs for a 3.5 liter set-up, I'll be sorry that I didn't dial back on this now - while these 45's might find another good home. Then again, everything might purr just fine and this is all just nervous energy. It runs now, but it's on an open header, a sketchy radiator, and 2 of the 6 trumpets do not fit because the brake booster is in the way. Which is to say, I haven't felt it is worth investing the time to tune these carbs and dial everything in (which would include needing to get that brake booster out of the way). Chicken or egg?
Like I said, I know 2 or 3 people that had 45's and no problem, I will send you a pm