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Mikuni Carbs from an R1  Rating:  Rating
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 Posted: 12-07-2010 03:30 am
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superk83
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Hello all, I'm new to the community and the 907 as well... I've picked up a motor and trans from a 75 and intend to use it in a Lotus 7 replica. Since most of my extra cash is going into the rebuild, I've decided to update(save cash/time in the long run)a few components. I intend to use the R1 carbs and Megajolt along with the Ford EDIS ignition system. Do any of you have experience with bike carbs and distributorless igntion on this motor?

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 Posted: 12-07-2010 03:14 pm
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JodyKerr
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Sounds like a neat project!

The guy who's done the most on distributorless is Steve Duschene. I am not certain he's online in this forum. I'll point him here.

He just finished setting up a megajolt conversion on his 907 using some ford bits and other miscellany. He and I are presently (mostly him though) are working at adding FI to the Stromberg based manifold to go with the fancy ignition.

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 Posted: 12-07-2010 05:08 pm
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superk83
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Great!! Thank you! I'll be picking up the small bits along the way, the major bits around tax time...

Any advice or instruction would be awesome! I think I've seen some of the photobucket pages of the progress with efi... Looks good!

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 Posted: 12-07-2010 05:11 pm
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Jensen Healey
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I fail to see how this is a good HP/buck value. 

The 907 suffers from short stroke, low compression and mild cams as well as carburetion. It's easy to bolt on the parts for about 180 HP. Flow work will take you to 220 HP. Up there crank fired ignition is more important. Block flex also becomes an issue.

A late 912HC engine with it's stronger 2.2L block, cams and better flowing heads may be cheaper than building a 907.

How will you get the Mukinis jetted? That's got to be costly. You can get jetted Dellortos with manifold for 220 British pounds from Mike at Lotus Bits.

Kurt

 

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 Posted: 12-08-2010 12:57 am
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StevenD57
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Jensen Healey wrote: I fail to see how this is a good HP/buck value. 

The 907 suffers from short stroke, low compression and mild cams as well as carburetion. It's easy to bolt on the parts for about 180 HP. Flow work will take you to 220 HP. Up there crank fired ignition is more important. Block flex also becomes an issue.

A late 912HC engine with it's stronger 2.2L block, cams and better flowing heads may be cheaper than building a 907.

How will you get the Mukinis jetted? That's got to be costly. You can get jetted Dellortos with manifold for 220 British pounds from Mike at Lotus Bits.

Kurt

 

How can you say this is not a good bang for the buck when you have NO IDEA how much the crank-fired distributor-less ignition actually costs or what benefits you will see?

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 Posted: 12-08-2010 01:20 am
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superk83
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I don't understand how you can not see the hp/dollar value... Traditional Carbs, ie; webers, dells cost a few hundred dollars with the manifold before tuning. My R1 carbs cost $35... and another $35 with the proper jets... R1 carbs have been used on many 4 cylinder automotive applications and the jetting for specific displacements and airflow capabilities is fairly well documented.

For less than the cost of a new Lucas distributor, I'm getting Megajolt and the Ford EDIS system. The distributor alone costs nearly $300... Electronic ignition on top of that, another hundred or so...

I've already budgeted nearly a grand(USD) for the required gaket, ring and bearing kits.

Regarding Mike's Lotus Bits, I get paid in US dollars, which turns your 220 quid into $360, a bit much for the budget for a single component...

This is all going into an 1100 pound car, so I'm not looking for mega-hp... 150-160 would be great...

Hopefully, this doesn't sound rude...lol! On the other hand, if you're offering to trade a sorted 912 for a 907 and a zf 5 speed trans, I'm open...lol!

I don't want my first post to be taken the wrong way, I'm not trying to buck the establishment or piss people off, just wanting to learn as much as I can as I go along. I appreciate all of the knowledge available here and the unique perspectives each of you hold. Thank you all for your contribution...

By the way, what are the 912's going for these days? My ears and mind are open...

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 Posted: 12-08-2010 01:26 am
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superk83
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Reading back on that, maybe I should go into more detail of what I'm starting with...

I have a 907 minus the dizzy, intake mani, carbs, exhaust manifold and starter. I do have a water pump from an esprit, not sure what year...

And that is why I'm sourcing the cheaper bits...

I've not picked up the trans yet, so I'm not positive what's included there. Paid $250 for the lot... I'm not upset at all...lol!

Last edited on 12-08-2010 01:26 am by superk83

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 Posted: 12-08-2010 01:33 am
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JodyKerr
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I wouldn't worry too much. You're just not going the traditional Jensen Healey route. With J-Hs we deal with much more weight, and are all secretly longing for the much later lotus 910 engines. :) I have to say that the 907 in a locost is an uncommon selection. But, as you get more into the car, if you want you can eventually get a LOT moer power down the road.

I think the project sounds like a lot of fun. I've had the locost books sitting on my shelf for a long time now. The idea is to eventually do one, but I've got 5 cars in the works right now. :)

I've read about the mikuni's being used a lot with little 4 bangers. Could/should be an interesting combination. I've been fighting with my bl**dy strombergs for a while now and am really leaning to FI instead, mainly because I dislike the carbs *that* much.  My other JH, however, is likely going to have the Dellortos.

I've had a number of my peers not quite understand the locost concept in the past. It's mainly about grabbing what's available and sticking it together. :)

 

Jody

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 Posted: 12-08-2010 01:42 am
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superk83
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StephenD57, are you the EDIS EFI guy? I'd love to chat you up about your install...

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 Posted: 12-08-2010 01:47 am
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superk83
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Jody,

Awesome to have someone understand...lol! Locosts are great little contraptions and extremely competitive in the local autocross...

I have a link for you, regarding a gent converting from injection to the R1 carbs. It's incredibly simple. Is it ok to post links to other forums here?

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 Posted: 12-08-2010 02:10 am
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JodyKerr
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I don't see any reason not to post it. :)

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 Posted: 12-08-2010 02:15 am
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superk83
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http://forums.vwvortex.com/showthread.php?4647341-Switching-to-Bike-Carbs.-Heres-a-write-up!


Posted!!!!

And in regards to more power, I've got a rebuilt td04 for my SAAB sitting on the shelf that'd be happy to provide motivation through the Mikuni's... 8.5 compression ratio should be about perfect for that!!!

Last edited on 12-08-2010 02:33 am by superk83

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 Posted: 12-08-2010 02:18 am
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StevenD57
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superk83 wrote: StephenD57, are you the EDIS EFI guy? I'd love to chat you up about your install...Yes, I am working on that. I have the crank-fired EDIS ignition working now on the car. I am the person who has been accused before of doing projects that "do not give adequate bang for the buck"  or "only needed for all out race motors" or "not really worth the hassle"

I guess many people prefer to use springs and spinning weights technology that was invented in the 1920's or 1030's to control their ignition timing.

Last edited on 12-08-2010 02:41 am by StevenD57

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 Posted: 12-08-2010 02:25 am
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StevenD57
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superk83 wrote: http://forums.vwvortex.com/showthread.php?4647341-Switching-to-Bike-Carbs.-Heres-a-write-up!


Posted!!!!
Ah! That guy had CIS fuel injection. Ancient crappy fuel injection that is mechanical instead of fully electronic. The Megasquirt I am doing is MUCH more modern electronic fuel injection.

The CIS injection was also used on the early US only Turbo Esprit cars from 1985 - 1988 (mix of angular sharp edged G-cars and later rounded contour Stevens cars). I have heard of people upgrading those cars from CIS to fully electronic fuel injection using either the Megasquirt or the GM/Delco stuff used on the later Turbo Esprits. The word I have heard on that conversion was "totally transformed the car" so I am looking forward to my Jensen-Healey with EFI verses the original ZS carbs.

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 Posted: 12-08-2010 02:43 am
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superk83
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EFI may come in the future, and if/when I go that route, I'll probably run with the GM bits... I've heard the US models had more power than the UK versions...


What sensors did you need to get the EDIS up and running? I know the EDIS module and coil pack, the "wheel" and sensor and a TPS sensor(which, fortunately, came with the carbs)... Any thing I'm missing? Aside from Megajolt, obviously...

Again, I'd like to thank everyone for their interest! Comments appreciated!!!

Kurt, I'd like to hear more from you to understand your perspective, if you wouldn't mind...

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 Posted: 12-08-2010 02:50 am
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Jensen Healey
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Hi StevenD,

As I stated, "I fail to see." So tell me, what are the benefits of running bike carbs? More torque? More HP?

If I told you what I paid for my euro JH Derllortos and manifold setup would it make a difference? ($100 American)

I have read replacing distributors with crank fired ignition can give you 2 or 3 HP. Is this wrong? I'm sure lots of stuff is stated as fact that's not.

Have fun with your project and let us know how it turns out!

Kurt

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 Posted: 12-08-2010 03:08 am
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Jensen Healey
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Hi SuperK,

I'm not opposed to any modifications or fun in the garage!

One of the cool things about the exotic Lotus 907 is that Lotus spent the next 20 years perfecting the motor. We get the benefit of that development in the form of bolt on go-fast parts.

Sorry if the tone of my post was negative, I was just surprised that bike carbs and electronic ignition would be inexpensive.

Kurt

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 Posted: 12-08-2010 03:10 am
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StevenD57
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Jensen Healey wrote: Hi StevenD,

As I stated, "I fail to see." So tell me, what are the benefits of running bike carbs? More torque? More HP?

If I told you what I paid for my euro JH Derllortos and manifold setup would it make a difference? ($100 American)
I have more than one Jensen-Healey. One has the european DHLA45 Dellortos and the other has the ZS american carb setup. I have never driven a car with a bike carb setup.

All I can tell you so far is that the crank-fired EDIS ignition is noticeably smoother running on the highway and starts a LOT better than the original distributor setup. As a computer systems engineer with a mechanical engineering degree I am very comfortable with putting things under computer control. I also know that every Jensen-Healey I have owned has had an oil leak from the distributor. By going to the crank-fired ignition, I also get rid of an annoying oil leak. Too bad I cannot do the same for the poor cam cover sealing design.

Last edited on 12-08-2010 03:10 am by StevenD57

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 Posted: 12-08-2010 03:20 am
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StevenD57
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superk83 wrote: EFI may come in the future, and if/when I go that route, I'll probably run with the GM bits... I've heard the US models had more power than the UK versions...


What sensors did you need to get the EDIS up and running? I know the EDIS module and coil pack, the "wheel" and sensor and a TPS sensor(which, fortunately, came with the carbs)... Any thing I'm missing? Aside from Megajolt, obviously...

Again, I'd like to thank everyone for their interest! Comments appreciated!!!

Kurt, I'd like to hear more from you to understand your perspective, if you wouldn't mind...
I have not installed a TPS sensor yet. I will be adding one with the EFI but the EDIS works quite nicely using manifold vacuum for it's primary load calculations.

Since I am doing the EFI as a follow-on project, I went with the Megasquirt controller since it is also useful for fuel control which the Megajolt does not do. One other advantage is I installed a coolant temp sensor which will be necessary for the EFI but the Megasquirt ECU also has a timing control trim function based on engine temperature. I don't believe this is possible with the Megajolt.

As I stated in another forum thread here, I have a 14 page PDF article I wrote on the EDIS based crank fired ignition conversion with illustrations and diagrams that I can E-mail out to you if you are interested. I have sent this out to a number of other folks on various Jensen and Lotus mailing lists and it seems to have good reviews and feedback so far.

Last edited on 12-08-2010 03:20 am by StevenD57

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 Posted: 12-08-2010 03:26 am
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superk83
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Most of the reason for using the parts I'm using is cost and availability... For what I'd pay for Webers or Dells and manifold, at least in this area(N.KY) I could almost build the rest of the car... I didn't get carbs with the engine, so I chose a cheap, proven alternative... I've had trouble with distributors in the past, and as the engine didn't come with one, I figured I'd go ahead and spend a few bucks and go stand alone electronic... HP gains? Probably... But the fact that condensation won't affect it and a tune up will require pretty much only spark plugs sounded good to me...

Most of the guys who switch over to bike carbs do see some gains in hp in the top end where efi setups usually drop a little. But that's not really because of the carbs. Typically, it's because they're mounted mere inches from the head instead of the "ram horn" style intake used by most oems. Shortening the runner length after the TB lessens the restriction on the airflow, getting air in faster.

Again, the biggest reason for most to switch to bike carbs is cost. $35 for 4 carburetors? Maybe $25 in aluminum bits to fab a manifold and a few bucks for jets and I've got less invested in the entire induction system than most have in a single carb... Oh, wait... Filters...lol!

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