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I personally don't like Webers, so I'd never go that way. The EFI will give you more power and better fuel economy than a carb will. I have recently been working on a 1972 V12 E Type and I can say that getting 4 carbs in sync is no fun at all, 6 would be far more difficult.
The car in the photo has a throttle for each cylinder, so that means that intake tract is very short. That in itself will produce very little low end torque and a lower volumetric efficiency, so in real world driving off a race track it would be slower than a standard car ( assuming no other changes). The V12 is already an engine that produces power and torque quite high up the rev band, I wouldn't want to shift it any higher.
That was just an example. from a quick websearch of pretty V12 motors
I was thinking more cross ram with port injection EFI throttle bodies and not all the fkn hoses and extraneous plumbing cluttering up the current engine. Or two or three central mounted EFI T-bodies with port injection You could even use short intake runners and six T-body EFI, but no, i wouldn't use carbs.
There is way too much garbage on top of that motor, I am sure most has to do with emissions.
It's not a pretty engine, but it is impressive. I actually like that everything is on top and accessible. Once you get to the cam covers, there is hardly anything underneath that needs access. About the only thing is O2 sensors. Having the distributor, AC compressor and hoses, fuel rails and injectors and cruise control actuator in the center of the V generates much of the visual clutter.
Relatively little has to do with emissions. A modern programmable ignition system would get rid of most of the vacuum hoses, that was a mechanical way to give the engine the advance it needs, Take a look at a 1995-97 XJ12 sedan with the distributorless ignition, it's a bit cleaner. Although the coilpacks, plug wires, fuel rails and injectors are still in the V.
Modern cars just cover it all up with plastic covers, but if you take them off, the engines look as bad or worse. The 6.0 V12s had a plastic cover over the center of the engine, which helped looks significantly.
That was just an example. from a quick websearch of pretty V12 motors
I was thinking more cross ram with port injection EFI throttle bodies and not all the fkn hoses and extraneous plumbing cluttering up the current engine. Or two or three central mounted EFI T-bodies with port injection You could even use short intake runners and six T-body EFI, but no, i wouldn't use carbs.
There is way too much garbage on top of that motor, I am sure most has to do with emissions.
Doug
Doug I completely agree with you regarding the mess on top of our V12’s. No. The reason it’s such a mess is because of cost accounts who simply wanted to save a few cents per car on fuel lines etc.
It can be fixed and the way you suggest is the best solution. When Rob Beere was racing his XKE ( V12 ) he used 6 Webers in a home made manifold the used 45 DCOEs 3 per side that went up and over the valve covers and still fit under the Bonnet. It was a very powerful engine. As he often beat much newer cars.
A rather simple project to replicate if you have any welding skills.
For my Group 44 tribute car I’m using a set of six IDA Webers. Because the shorter IDF’s don’t really add that much power over the stock Carburators, due to the proximity of the carbs to the bonnnet. And how short the runners are.
To solve the clearance problem, I’m making a fiberglass hood and going to drill 12 holes for the rams to pop through. Ideally the tops of the rams will barely clear the hood.
I’m also going to lower the engine in the chassis. The rubber mounts give me an inch although the front cross member might limit that a bit. Since it’s a race car solid mounts won’t bother me. In fact I always solidly mount the engine in every race car
If you are going with individual throttle bodies instead of carbs. You absolutely will need to change the ECU. Megasquirt MS3 Pro will work but wow is it going to be complex to wire. Patience is needed. Or you can find a local Mega squirt, GUY to wire it for you. The factory has a list of references to help or you can use the forum. ( but first read and understand the 370 page manual). You are dealing with geeks. I’ve seen beautiful jobs done on both the wiring and fuel lines, that’s where tidy wiring will really make a difference.
Also you can’t use your distributor. The best one will be an early 1975-1980 British spec distributor Yes I believe you can change the internals of yours although I haven’t tried it myself.
Instead I’m eliminating the distributor completely. Like the later 6.0’s did. The MS 3 Pro will handle both the individual spark and the fueling for each cylinder. You can do it as the factory did which was to use 6 dual lead coils. Stock the Jaguar system used wasted spark like a Harley does. No you don’t have to use the Rare Jaguar coils Ford also made dual lead coils for their V6.
What I intend to do is use coil on plug because that will be a whole lot neater looking. You can just plop something like the GM LS coil on plug or go aftermarket which is neater and more compact plus reportedly generates a stronger spark. Needed because of that stupid HE head .
The great thing is that if you wire it correctly the Mega squirt is self learning. That is it wire fire right up and figure most things out for you. To get it to run as smoothly as the factory has it, will require patience and understanding.
One final point. The potential for some real power gain is just 1 sensor installed in the fuel line and some key strokes away.
E85 is a magic elixir! On the V12 HE you can gain up to 15% more power and a cleaner engine.
How? The Stock Jaguar is batch fired. That is the injectors squirt several cylinders needs at a time with fuel and let the valves sort it out.
The problem with that system is cool fuel hangs around baking on the hot walls of the valve pocket and the back side of the intake valve. Eventually building up enough to restrict some flow into the cylinder. With the Mega squirt each cylinder gets its own squirt when the time is right. Plus 85% alcohol won’t leave the deposits like gasoline does.
With the sensor you don’t have to worry. You can pour any gasoline in and the sensor adjusts volume and timing to optimize whatever you have.
A full tank of premium? OK a fuel tank of E85 ? OK mix and match however you want it adjusts itself based on what is coming through the fuel line.
You can buy an expensive kit with the sensor in it or much much much cheaper take the kit off any car that has the flex fuel option on it. Pickup trucks are easy, lots of ground clearance. To crawl under.
I put port sequential fuel injection on my '61 Corvette with its very large displacement small block, so i know what is involved. And it uses a 15 YO Accel ECU, but it does control spark advance vs MAP (vacuum) vs RPM. I know the modern ECUs are a LOT better, but the car is already tuned, so no point in changing unless it croaks.
MSD makes a controllable ign module you can mount in about any distributor. One could probably use the factory intakes and switch to sequential with a prog dizzy and get same or better performance and get rid of most of the crap. I don't use cruise control, anyway, on anything, even if it has it.
Doug: Yes that engine looks fab compared to mine, mine has alum corrosion on everything, the lines are all dirty, rubber tubes brittle, etc, etc.
Getting twin SUs to work together on my Datsun Roadster was a Real challenge sometimes.
I can't even imagine getting more to play nice together!
(';')
honestly? Dual carbs are maybe 5-6 minutes to synchronize perfectly. Add another few minutes for each extra carb. Then tighten the linkage up and don’t mess with it.
It’s called a unisyn I guess I got mine sometime in the 1960’s. Before that I used a rubber hose and listened. But the Unisyn is far more accurate and faster.
You do realize that tuning the carbs is the last step in a tune up? If you are having trouble doing it that’s a prime indication you’re doing it wrong.
Mobeck makes a decent system, perfect for the plug and play crowd.
But if like me you search for more power, you need the ability to change things yourself. One setup for pump gas, another set up for racing gas and a third set up for E85. Plug in your lap top and a few key strokes you can have those or something else.
Then again I’m the kind of guy who brings a calibrated air density meter to the race track and change jets or needles as the conditions change.
Now days with EFI that’s always automatically adjusted. Once you’ve changed things for the cam, pistons, ignition you’re using. Then Bobs your uncle.
I personally don't like Webers, so I'd never go that way. The EFI will give you more power and better fuel economy than a carb will. I have recently been working on a 1972 V12 E Type and I can say that getting 4 carbs in sync is no fun at all, 6 would be far more difficult.
The car in the photo has a throttle for each cylinder, so that means that intake tract is very short. That in itself will produce very little low end torque and a lower volumetric efficiency, so in real world driving off a race track it would be slower than a standard car ( assuming no other changes). The V12 is already an engine that produces power and torque quite high up the rev band, I wouldn't want to shift it any higher.
Group 44 in winning its XJS championships used 7500 as a normal shift point with an occasional blast up to 8000 Rpm. On a pretty stock motor with only a careful balance job difference. In fact I’ve raced whole seasons with Junkyard engines @7000 rpm. All that’s required is some way to control oil surge. I started out using dry sump but recently switch to just baffles and one way trap doors.
Due to its short stroke compared to most other cars high revs like that is less stressful than a V8 at 6000 rpm. It’s about piston speed, remember the piston has to go up stop and then down stop.
Each stroke. The acceleration rate of speed is measure in FPM. Normal production limits are below 2500FPM.With the V12 at 1650 FPM @6500 RPM. Even extreme professional racing limits tend to remain below 4000FPM @ 9500 rpm. ( formula 1 has even shorter strokes )
Also compared to optimizing the EFI like the factory did with both their XJ12 C race cars and TWR did with their XJS in later efforts with Jaguar’s assistance. Webers were very cheap and straight forward.
I’d remind you that in those days the ECU didn’t have any way to change operation to meet racing needs ( and street cars still don’t ) short of soldering up a whole different mother board.
If you read about the factories efforts you will understand the complexity involved.
I personally don't like Webers, so I'd never go that way. The EFI will give you more power and better fuel economy than a carb will. I have recently been working on a 1972 V12 E Type and I can say that getting 4 carbs in sync is no fun at all, 6 would be far more difficult.
The car in the photo has a throttle for each cylinder, so that means that intake tract is very short. That in itself will produce very little low end torque and a lower volumetric efficiency, so in real world driving off a race track it would be slower than a standard car ( assuming no other changes). The V12 is already an engine that produces power and torque quite high up the rev band, I wouldn't want to shift it any higher.
I’m sorry you’re having trouble with such simple ( lawn mower simple) carburators. I hope you are using something like a Unisyn? That’s the best $15 I ever spent but that was its price back in the 1960’s.
That and knowing the procedures makes tuning a V12’s set of Webers a barely 20 minute task.
honestly? Dual carbs are maybe 5-6 minutes to synchronize perfectly. Add another few minutes for each extra carb. Then tighten the linkage up and don’t mess with it.
It’s called a unisyn I guess I got mine sometime in the 1960’s. Before that I used a rubber hose and listened. But the Unisyn is far more accurate and faster.
You do realize that tuning the carbs is the last step in a tune up? If you are having trouble doing it that’s a prime indication you’re doing it wrong.
I'm sorry if I come across as a bit dense, maybe I am, but like a lot of other things in life, balancing dual (or more) carbs is probably Lawn Mower Simple IFF you know how! At the time I was new to anything Non-USA, had no one to show me what I was doing wrong, knew Nothing of specialized tools, so I had to fumble my way through best I could.
By the time the 18RG came along with dual Mikunies, it was a walk in the park and I never had to touch them after installation. I sold the car with those on. but don't look back fondly on my experience with dual side drafts!
(';')
You can have multiple setups with the Mobeck kit. He only gives you his best one for the street, but there’s no reason you can’t plug your laptop in and make another. It’s a MaxxECU with all the work worked out for us amateurs. If you’re already a Megasquirt guy with experience there’s no point in the Mobeck kit, but for everyone else it’s surely the way to go. It’s the way I’ll be going shortly!
I have some, not a lot, of experience balancing multi-carb set ups. Sometimes successfully, sometimes not.
I think what happens, as often is not, is that other problems can flummox the adjustment process.
No matter if single or multi carb, if you're making carb adjustments and not getting the response that you should be getting then there's probably something elsewhere that needs to be fixed. Ignition, timing, vacuum leak, low compression, etc.
You are right, For most people the Mobeck is the way to go. Especially if smooth operation is a priority.
Only weird racers like me used to creating race parts from odd leftovers and used stuff to keep a budget smaller than the average monthly gas bill do it.
I don’t need to worry about smoothness or even power. Especially below 4000 RPM
I use a lot of older high mileage parts because racing needs added clearance to improve oil flow. ( more important then high oil pressure) high mileage rings offer less drag then new rings and the added end gap is a god send in elevated temperatures. OK so I use a little extra oil in the race. Oil level is checked before each track session and changed after every race weekend.
I can use high octane racing gas and pay $8-12 a gallon or make more horsepower using E85 @ about $2.50 a gallon.
Race tires are an expensive item unless you race with used take offs. A whole set of qualifier’s lightly used race tires. May be a few tenths of a second slower but nothing that experience, and skill can’t overcome. In addition as they cycle through heat sessions. Tires get harder and harder providing more duration ( at a cost to lap speed) thus I can get a full season or more out of them.
The biggest money saver is in DIY. Instead of a great mass of money. Paying others for the work. All that is saved.
The great thing about racing is you get a real solid answer to your skill as both a driver and a mechanic.
01-12-2024, 09:58 PM
