Triple Weber Rebuild
- Thread starter Tom P
- Start date
MyFemurHurts
Well-Known Member
I'm jealous of your triples. They look fantastic.
Triple Weber porn!
That is the cleanest install I think I've ever seen.
So you ditched the soft mounts-good move.
Definitely post your jetting specs for posterity.
My only suggestion would be to consider removing the oil breather filter and run it down to a catch can, that filter will get all gummed up quickly, I had one before.
#4 and #6 intake runner - are those threaded holes for linkage or do they go through for vacuum and you have them capped?
That is the cleanest install I think I've ever seen.
So you ditched the soft mounts-good move.
Definitely post your jetting specs for posterity.
My only suggestion would be to consider removing the oil breather filter and run it down to a catch can, that filter will get all gummed up quickly, I had one before.
#4 and #6 intake runner - are those threaded holes for linkage or do they go through for vacuum and you have them capped?
Last edited:
interesting approach to the fuel lines ... overall, extremely well done
AHHH - your picture took me back 38 years! '77 was when I installed a set of triple DCOE 40's on my '73 3.0 CS (setup was from Korman works in NC). Couldn't find neat thin air filters like you have in that era, only the dome shaped ones. Had to push the dome in a bit on the rear one, due to the brake booster. When I got them tuned (a process I actually enjoyed), it was SO much better than the original twin carb setup. I also think they make the engine bay look a lot better than the FI systems (which I have on the current '74).
Very clean install, and I'm sure you will wonder why you didn't do it even sooner!
Very clean install, and I'm sure you will wonder why you didn't do it even sooner!
Last edited:
Ubeautiful
The only thing I'd do differently is eliminate one of the the threaded rods on carb 2/3 and connect the carbs with weber's "side by side" coupled
Throttle levers for 50% easier synchronizing.
Nice install.
jamesw
Well-Known Member
That is a beautiful setup - kudos to you.
I just got back to driving mine yesterday now that the "nuclear" part of the summer is over here and really enjoyed that triple weber song.
James
I just got back to driving mine yesterday now that the "nuclear" part of the summer is over here and really enjoyed that triple weber song.
James
Tom P
Well-Known Member
Thanks to you all for such a positive response! I've really enjoyed this part of the project. Next on my list is a 123ignition distributor. SteveHose feedback is quite impressive regarding it. That plus AFR sensors / O2 gauge will take me to the next level of tuning although I feel like I could just stop here and I'd be happy. My guess is there's another 10% to find so let the hunt begin!
Here are my current jetting specs:
Triple DCOE 40-18's on M30-B35
Intakes = Port Matched
Main Venturi = 34
Aux Venturi = 4.5
Main Jet = 135
Emulsion Tube = F11
Air Correctors = 190
Idle Jets = 50-F9
Acc. Pump Jet = 40
Pump Ex. Valve = 55
Idle jets are backed off their seats 1-1/4 turns and throttle lever is just off it's base by 1/4 turn or so - idling nicely at 900rpms. Using an IR temp gauge, header pipes are all running within 10% each other.
Few more action shots attached for your viewing pleasure!
Here are my current jetting specs:
Triple DCOE 40-18's on M30-B35
Intakes = Port Matched
Main Venturi = 34
Aux Venturi = 4.5
Main Jet = 135
Emulsion Tube = F11
Air Correctors = 190
Idle Jets = 50-F9
Acc. Pump Jet = 40
Pump Ex. Valve = 55
Idle jets are backed off their seats 1-1/4 turns and throttle lever is just off it's base by 1/4 turn or so - idling nicely at 900rpms. Using an IR temp gauge, header pipes are all running within 10% each other.
Few more action shots attached for your viewing pleasure!
Attachments
TodB
Well-Known Member
If you think you're happy now, You'll love this.
+1 on the 1-2-3
Tom,
Is it any quieter than when I last saw it?
Beautiful work.
Stan
Tom,
Is it any quieter than when I last saw it?
Beautiful work.
Stan
Tom P
Well-Known Member
@Stevehose: Yes, definitely need to ditch that vent. Already getting gummed up! Would like to see if I can pull some vacuum on that line through a catch can but I don't want to push that dirty air back through my intake. Anyone doing this sort of vac? Seems like that would create some add'l efficiency.
Those holes on #4/#6 intake runners are threaded but they're not through holes. Just tapped for linkage risers. I decided to pull vacuum on underside of #3/#4 - we figured those are opposite the firing order to balance the pulse. Capped now but will use them with 123ign and an anti-pulse valve (per your suggestion!).
@bfeng: A coupler would be great! These rod ends were actually touching each other so I shaved the round edges square. They're working great now but I agree - a coupler would be best!
@Stan: Yes, it's quieter now! Sounds great!
Those holes on #4/#6 intake runners are threaded but they're not through holes. Just tapped for linkage risers. I decided to pull vacuum on underside of #3/#4 - we figured those are opposite the firing order to balance the pulse. Capped now but will use them with 123ign and an anti-pulse valve (per your suggestion!).
@bfeng: A coupler would be great! These rod ends were actually touching each other so I shaved the round edges square. They're working great now but I agree - a coupler would be best!
@Stan: Yes, it's quieter now! Sounds great!
Attachments
MyFemurHurts
Well-Known Member
I still gotta get a ride in your Coupe. I'd love to hear those carbs singing at redline.
Tom P
Well-Known Member
Brendan, you got it. How about this deal, I'll even let you drive it but only if I can drive your friend's McLaren!
FYI, for anyone with triple DCOE's....
I've been following Keith Franck's engineering work over on his Sidedraft_Central Yahoo Group. In his words he has just obtained "Weber nirvana" this past week with a new emulsion tube design and new bow wave aux venturi designs. Seems his testing of Weber physics & flow dynamics has gone way beyond Weber's original work. More than half the time I can't even follow his thoughts - very deep! Looking forward to trying out his design to try to get my carbs to sing an even higher note!
FYI, for anyone with triple DCOE's....
I've been following Keith Franck's engineering work over on his Sidedraft_Central Yahoo Group. In his words he has just obtained "Weber nirvana" this past week with a new emulsion tube design and new bow wave aux venturi designs. Seems his testing of Weber physics & flow dynamics has gone way beyond Weber's original work. More than half the time I can't even follow his thoughts - very deep! Looking forward to trying out his design to try to get my carbs to sing an even higher note!
jmackro
Well-Known Member
I think I understand. You are seeking a source of vacuum to provide a signal to the 123 distributor - not to replace the vent on the cam cover.
But why use a vacuum signal at all? Why not just get a 123 with a two dimensional map (rpm vs advance)? Not clear what adding a vacuum signal adds, particularly since the vacuum signal from Webers is likely to be noisy.
MyFemurHurts
Well-Known Member
I'd say deal, but they're not my keys to hand out. We are all trying to make it to Canepa Cars and Coffee next month in Scott's Valley, as its their last event of the season. Might be worth attending to see if you can sweet talk Dave out of his keys.
Tom P
Well-Known Member
@JMackro: I opted to tap into my manifold for this vacuum while i had everything apart instead of realizing I needed it later when it was all back together. The 123ign distributor offers vacuum advance as an option on the programmable unit I spec'd out for my application (6-R-V-B). I understood that its used to increase the advance at idle to smooth out idling and used to increase the advance when cruising at low RPM's to offer improved fuel economy. I don't think it's necessary but it gives an additional layer of tuning flexibility. We'll see - that's a winter project.
As for the evac system idea, my RPM's increase at idle if I draw vacuum from my valve cover breather. I might be off base here but increased RPM for the same amount of fuel being delivered seems to indicate a performance gain / more efficiency at least at idle and when cruising. I don't think this was done back in the good ol' days but I believe these M30 motors were designed to have negative crankcase pressure. Would love your thoughts and ideas here...
As for the evac system idea, my RPM's increase at idle if I draw vacuum from my valve cover breather. I might be off base here but increased RPM for the same amount of fuel being delivered seems to indicate a performance gain / more efficiency at least at idle and when cruising. I don't think this was done back in the good ol' days but I believe these M30 motors were designed to have negative crankcase pressure. Would love your thoughts and ideas here...
I don't have any vac attached to oil breather, I'll trade off whatever efficiency is gained for not clogging up the intake of a carb.
I forgot we did the math on the vacuum ports, that will feed the 123 nicely. Here is my latest curve that seems to work well, one of these days I will finalize on a dyno. Here is my current curve, a little quicker all in, and has idle advance and shift retard:
I forgot we did the math on the vacuum ports, that will feed the 123 nicely. Here is my latest curve that seems to work well, one of these days I will finalize on a dyno. Here is my current curve, a little quicker all in, and has idle advance and shift retard:
Are there versions of 1-2-3 that can take a TPS input?
DCOE TPS's and not expensive and they will give you a clean electrical signals at is related to manifold vacuum.
DCOE TPS's and not expensive and they will give you a clean electrical signals at is related to manifold vacuum.