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tallyhoe
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I am a new owner of a JH so please be patient. I am looking for direction on the what is the best process to check out the condition of the units. Apparently an old owner did some performance work of dubious quality. I am after just a good driver. I am an old BMC mech and know SU and Zenith carbs well. No experience on Webers. Any idea n where to start? The engine kinda runs at idle and nothing else.
Thanks anyone who helps.

Paul Koehler
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Beg,borrow, buy or steal Des Hammond's book on Dellorto's & Weber carbs; read it  3 or 4 times or enough times until it starts to sink in and then have at it with your Webers. Alternately, find a set of ZS carbs( E-bay or most people who have made the switch to Dells/Webers have at least one set laying around), install on your new find, and enjoy the car while you learn the mysteries of Webers.

tallyhoe
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I was afraid of that. Anybody ever change them to SUs? Yah, right. It off to Ebay for me. thanks

Jensen Healey
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The carbs may be gummed up due to sitting. A rebuild kit, float adjustment, and a good cleaning should get them back to normal.

I would first check the compression, timing, cam alignment, and clean the points if they're still in there.

90% of carburetor issues are ignition.

Welcome to the board! Kurt

tallyhoe
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Thanks. It is gummy. No Points a Pirahana electronic is installed but I will pull it apart farther in a day or so to see what is really there. Where is the best place for a carb kit.

Jensen Healey
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Weber carb kits are readily available. Your location should determine your supplier.
http://www.piercemanifolds.com/default.asp
http://www.webercarbsdirect.com/

tallyhoe
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Thanks again. USA. Minnesota. I am suspicious of a compression problem from exhaust notes, however.

Jensen Healey
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I have several heads with burnt exhaust valves. I suspect the engines didn't have proper maintenance since adjusting valves on the 907 is so difficult and time consuming.

The stock pistons are 8.5:1 and the cams have a lot of overlap, so don't expect compression readings over 130psi.

A leak down test should help identify the issue, unless your engine has multiple problems.

When I got my car the leak down showed air leaking past the rings blowing out the breather tube. Also air leaking through the exhaust valves into the exhaust system. I did a total rebuild.

tallyhoe
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Thanks. I am planning a compression test and oil fog if needed to start zeroing on issue. Later part (19 years) of it's life before me was woman owned as a toy, so I suspect maintenance was an afterthought. It shall be interesting.

subwoofer
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Mods: This thread should be moved to the appropriate forum?

Paul Koehler wrote:
Beg,borrow, buy or steal Des Hammond's book on Dellorto's & Weber carbs; read it  3 or 4 times or enough times until it starts to sink in and then have at it with your Webers.

That book is highly overrated. I have it, and in terms of actually explaining how carb circuitry works it contains next to nothing. But good for rebuild instructions, I'll give it that.

--
Joachim

tallyhoe
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I am sure a carb rebuild is in my future so it may be a good purchase.
Thanks

Mitch Ware
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I converted my car to SU's. Almost a strait bolt on swap. the float bowl on the front carb hits the alternator though. So I had to put a longer belt on and swing the alternator to a lower position. Also, I had to very carefully grind away part of the float bowl to clear.

Other than that an easy swap.

Mitch Ware
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tallyhoe
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Something to think about. HS2?

Esprit2
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tallyhoe wrote:
Thanks again. USA. Minnesota.Where in Minnesota. I'm in Wayzata... west suburb of Minneapolis.

Last edited on 08-22-2014 03:03 am by Esprit2

tallyhoe
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Plymouth. Neighbor.

Esprit2
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First, do you know when the timing belt was last replaced? If not, replace it now before putting the car into general service. The belt is supposed to be replaced every 24k miles or 24 months (whichever comes first), and time is just as important as mileage.

If you'd like to get together sometime, I'll take a look at it. No promises, just another opinion. We can make certain the cam and ignition timing are right, then dig into the carbs a bit.

Which Webers? Including the dash number after the throat size... like DCOE40-151.

The problem with Webers is that neither J-H nor Lotus ever used them on their stock versions of the 907... both used Dellorto DHLAs instead. So with Webers, you don't have that history of factory settings to use as a starting point, and you're pretty much starting from scratch.

What jetting is in the carbs now? Matt Cooper at Eurocarb Ltd in the UK knows both Weber and Dellorto carbs, and he also knows the Lotus 907/ 911/ 912 engines very well. Perhaps he could comment on the current jetting. I'm a Dellorto guy, and could offer some more specific input on DHLA/ 907 set-up, but Weber jetting would be more of an exploration.

In the chart below, the first two columns are generic jetting set-ups by the standard Weber jetting formulas. The third column is what Charlie S. used in the otherwise stock 907 in his Lotus Eclat. Pete B's Yelodog is 2.2 liters, 11.1:1 compression, big cam, ported, 0.180 oversize valves... etc, etc... so probably not a good match for yours.

.......................................................... Charlie ..... Pete's
Weber Jetting: .. Power ..... Economy ... Seabrook .. YELODOG
Carb Size ....... 45DCOE9 .. 45DCOE9 .. 45DCOE9 .. 45DCOE9
Choke (mm) ...... 36 ............ 36 ............ 35 ............ 36
Main Jet ........... 135 .......... 135 ........... 120 ........... 135
Air Corrector .... 160 .......... 175 ........... 180 ........... 180
Emulsion Tube .. F16 ............ F9 ............. F2 ............ F3
Idle Jet .............. 55 ............ 50 ............ 50 ............ 50 (50F9)
Idle Air Bleed ..... F9 ............ F9 ............. F9 ............ F9
Pump Jet ........... 40 ............ 40 ............. 50 ............ 45

Charlie’s comments:
"If gas mileage is really important, the 45F8 idle jet can be used. Idle jets on Webers control the mixture from idle all the way up to and beyond 4000 RPM. With this jet, you get some slight lean surge and a definite hesitation when opening the throttle at 3000-3500 RPM. The 45F8 saved me about 2 MPG on long trips over the 50F9. If you want better off-idle response, use 55F8 idle jets. Again, you will lose another mile or two per gallon."

IMHO, Charlie’s set-up is rather conservative and biased more for economy that performance.

Pete posts here. Perhaps he will chime in.

Regardless, knowing what jetting is in your carbs now would be a good place to start. Open them up.

Dyno-Tech (Tim Moore, or it could be his son by now) off I-94 in the Hwy 280/ Cretin-Vandallia area knows Webers and could tune your engine on a chassis dyno.

DynoTech Automotive (Tim Moore)
(612) 379-4205
2090 Gilbert Ave, St. Paul, MN 55104
Dynomometer tune-ups - Power or Emissions
https://www.facebook.com/pages/Dynotech-Auto/138837712830146

Last edited on 08-22-2014 04:39 am by Esprit2

Esprit2
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tallyhoe wrote:
I am a new owner of a JH so please be patient. I am looking for direction on the what is the best process to check out the condition of the units. (Snip)...How long have you had the J-H, and did any service history come with the car? Not to beat on it too hard, but do you know when the timing belt was last changed? If you don't know, or if it has been more than 24 months, then make replacing the timing belt job #11. The 907 is not a clearance engine. That means that if the belt breaks or jumps timing, the pistons will wipe out the valves. You don't have to be paranoid about it, but do be smart.

What year is the car? What's the engine number? It's stamped on the top of the block's rear flange, above the starter. Peer down between the firewall and the rear carb.

Do you have the Workshop and Parts manuals? If you don't, get them.

Weber DCOE carbs look like Dellorto DHLAs, and the factory used Dellortos. Are you sure they're Webers?

Last edited on 08-22-2014 04:37 am by Esprit2

tallyhoe
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I have no info on the car. Last titled in 09. 48K. I assume nothing is right, or good, or replaced on time. It runs, barely at idle. Compression 120, 75,70, 120. Dies upon pushing the accelerator. New fuel pump was installed to make it kinda run. Bottom end sounds real solid. No funny noises at idle but I can't re it up. I suspect cam timing a problem also. A new belt and carb kit is ordered.

Thanks again everybody.

Mitch Ware
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tallyhoe wrote: Something to think about. HS2?

HS6

Mitch Ware
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tallyhoe
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I finally got all my numbers everybody.
Body 13911
Engine B 7308349
Webers 40 DCUOE 2 #66

Cam timing and ignition are good. Fuel pumps and filter are in full flow and floats and needle jets look good and don't leak. Still just kinda idles and dies on acceleration. I will pull distributor next. This car has an oil cooler installed which makes removing the filter an act of God needed to accomplish. Is there a shorter one that works?
I also mis-typed in that it has 68K on it.

Esprit2
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tallyhoe wrote:
(Snip)... This car has an oil cooler installed which makes removing the filter an act of God needed to accomplish. Is there a shorter one that works? Lotus .................... C907E6000F

The following compare directly with Lotus "C" filter
Baldwin ................. B163
Coopers ................ Z27A
K&N ...................... HP-2004 (K&N 2004)(It's a tight fit)
Lucas .................... F5534 (Tingles supplied for all 9XX)
Mann..................... W712/38 (? Found in an Esprit SE)
Mobil-1 .................. M1-204 Full Size (M1-102 is the small size)
NAPA Gold.............. 1307 Regular Lotus B-prefix size
Purolator Pure-One.. PL20081
Wix........................ 51307 Regular Lotus OEM can size
Volvo OEM filter ...... 1950-present gas engines, except 850

All Lotus applications have an oil cooler with a sandwich plate adapter between the filter and the auxiliary housing. There's not a lot of extra room, but there shouldn't be a problem installing/ removing one of filters listed above, with the exception of the K&N.

The K&N HP-2004 has a 1 inch nut on the end to aid in removal. But that makes the filter longer and a difficult fit in Lotus 907 applications.

Smaller alternatives:
Wix 51307 = NAPA Gold 1307 - Full Lotus OEM size can
Wix 51342 = NAPA Gold 1342 - Small size
Wix 51348 = NAPA Gold 1348 - Small length & small diameter
Wix 51374 = NAPA Gold 1374 - Small size
(Wix makes NAPA Gold filters, private label)

Wix quality is good, but smaller filters have smaller capacities. If you go with a small filter, change it frequently... at least at every oil change.

Last edited on 09-02-2014 05:22 am by Esprit2

tallyhoe
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Thanks.
Jay

Esprit2
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The Weber Factory Settings for a 40DCOE-2, plus a couple other 40DCOE set-ups. All that really doesn't mean anything for your 907.

Model ........... DCOE-2 ... DCOE-32 ... DCOE-18 ... DCOE-151
Throat .......... 40 ............ 40 ............ 40 ............. 40
Choke .......... 33 ............ 32 ............ 30 ............. 30
Aux. Venturi... 4.5 ........... 4.5 ........... 4.5 ............ 4.5
Main Jet ........ 115 .......... 130 ........... 115 ........... 115
Emulsion Tube F16 .......... F9 ............. F11 ............ F11
Air Corrector.. 150 .......... 200 ........... 200 ........... 200
Pump Jet ....... 35 ........... 35 ............. 40 ............. 40
Idle jet .......... 50F9 ........ 50F8 ......... 45F9 .......... 45F9
Pump Bleed ... 55 ............ 60 ............ 50 ............. 50
Needle Valve.. 200 .......... 150 .......... 175 ............ 175
Float Height ... 8.5 ........... 8.5 ........... 8.5 (brass)
Float Droop ... 15 ............ 15 ............ 15 (brass)
Float Height ......................................................... 12(plastic)
App: ............. Maserati .... Alfa .......... Lotus ......... Modern
..................... 3500 GT .... 1750 ........ Elan & ........ Weber
........................................................ Cortina ....... Box Stock
........................................................ 1558 cc
........................................................ Twin Cam

Weber nomenclature is not linear or logical.
The scale of Idle Jet Air Bleeds is:
Weaker ........................................... Richer
F3, F1, F7, F5, F4, F2, F13, F11, F8, F9, F12, F6

Sizes in common use are:
F2, F11, F8, F9, F6

Here's the generic, by-the-book standard jetting for a 1973 cc 4-cylinder, sucking on two 40DCOEs, and creating peak power at 6200 rpm... sounds about like a 907. Also included for comparison is the stock Dellorto jetting used by Jensen-Healey.

..................... Generic, by the book ...... Jensen-Healey OEM Jetting
.................... Power ......... Flexibility .... Emissions ... Non-Emissions
.................... WEBER ....... WEBER ........ Dellorto ..... Dellorto
Model ........... DCOE ......... DCOE ......... DHLA ......... DHLA
Throat .......... 40 ............ 40 ................ 40E ............ 40
Choke .......... 36 ............ 34 ................ 35 ............. 35
Main Jet ........ 145 .......... 140 .............. 130 ............ 130
Air Corrector.. 180 ......... 180 ............... 160 ............ 160
Emulsion Tube F9/F16/F2 ... F9/F16/F2 ... 7772-5 ........ 7772-5
Pump Jet ....... 40 .............. 40 ............. 45 .............. 45
Idle jet .......... 50F9 .......... 50F9 .......... 52-55 .......... 50
Idle Air Corrector ................................ 7850-5 ........ 7850-1
.......................................................... (leanest) ..... (mid-range)

Esprit2
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Jay,

Nice to meet you and your Jensen-Healey face-to-face this morning

A 20W-50 oil is recommended. The 907's lubrication system is designed for relatively low pressure, a high flow rate, and high viscosity oil. Thin oils result in low indicated oil pressure once the engine is up to temp. The normal hot pressures are:
5 psi minimum at 900 rpm idle (scares me, 30 psi hot idle is more normal).
40 psi at 3500 rpm
50 psi at 6500 rpm

Your engine was idling hot at 30 psi with 10W40 oil... that's pretty good, and bodes well for the condition of the bearings.

The oil I mentioned is Mobil 1 20W50 V-Twin Motorcycle oil (Harleys). It's the old Mobil 1 Lotus used to recommend, but it contains way more ZDDP anti-wear additive than is allowed in cat converter friendly engines these days. So it was simply rebranded as a motorcycle oil. Or, Mobil 1 0W50 Racing Oil helps with cold weather starts, contains a full compliment of street additives, and a lot of ZDDP.

*~*~*
Don't use the timing belt tension specified in the J-H manual, as it's lower than is desireable. Lotus built variations of the same engine for 20 years after Jensen closed it's doors, and learned a lot more about keeping it running well. You'd be wise to use the higher belt tension that came from further experience.

Lotus recommends the Borroughs gauge, but it's a little expensive for some people's taste. The small tension gauge I showed to you is the Krikit KR1, made by HMC International, and marketed by Gates Rubber. Any Gates dealer (belts & hoses) can order one for you if they don't already stock it. The NAPA warehouse in Golden Valley stocks them. Call your nearby NAPA store in the morning, and the gauge will be in the store with the afternoon parts run. Or just go to the warehouse... you're close. I have a NAPA receipt from my last purchase and the line-entry reads:
Qty . Part No . Line . Descrip . Price .. Net ..... Total ... Code
1 ..... KR-1 .... NBH . Gauge ... __ ... $10.89 . $10.89 . T6N

The Krikit is made in several sizes, you want the smallest, the KR1 (KR-1)... mine is model 91107. The KR1 is made in several versions with different units of measure, but each also contains a pounds scale. You can use any of the KR1 versions, just be certain to read the pounds scale, as follows:

44 Too loose. Don't drive it. Avoid going below Krikit 50.
50 Normal minimum, time to re-tension the belt.
52 Used belt – target for re-tensioning a used belt.
55 New belts – set a little tight the first time to allow for stretch.
58 Too tight

*~*~*
With the carb jets cleaned up, the engine ran quite well. There's some smoke (quite a bit at first), but the rings are probably corroded after sitting for so many years. Cross your fingers, they may bed in again with some running. Actually, the smoke abated quite a bit in the brief time we ran the engine.

I intended to bring my magnifying visor, but forgot it. My old eyes couldn't read the markings on the emulsion tube, but here are the jet sizes I found in your Weber 40DCOE-2 carbs:
.................... Stock ....... Your J-H
Model ........... DCOE-2 .... DCOE-2
Throat .......... 40 ............ 40
Choke .......... 33 ............ ?
Emulsion Tube F16 .......... ?
Main Jet ........ 115 .......... 130
Air Corrector.. 150 .......... 200
Idle jet .......... 50F9 ........ 50F9
Float Height ... 8.5 ........... 8.5
Float Droop ... 15 ............ 15

Pretty much stock DCOE-2, except the main jets and air correctors are larger. Each new iteration of the DCOE got a new dash number. Yours are -2, and current production 40 DCOEs are -151, so lots of water has gone under the bridge since yours were made.

The idle jet nomenclature, 50F9, refers to a two-piece assembly. The idle jet is 50, the idle air corrector is F9, and they are purchased separately if you need to do some tuning. The engine ran quite well once the jets were cleaned out, so the 50F9 might be about right.

Since your carbs are DCOE-2, it's a pretty safe bet that the emulsion tubes are F16 as stock, but I'd still like to find the marks. Old eyes... I'll make a point to bring my magnifier visor next time.

*~*~*
The carbs need soft mounts ! The best are the die-cast Lotus parts I showed to you, unfortunately, they're also the most expensive. JAE has them in stock at $25 each, and two are required per carb, four total. Lotus made them for both 40 & 45mm throat carbs, so be sure to specify that you have 40mm DCOEs. I just talked with Jay, so it's fresh in his mind if you don't wait too long.
JAE, Jay Makwana, (805) 967-5767, Goleta, CA
Jay@JAEparts.com
http://www.jaeparts.com

If you don't want to spend that much on soft mounts, then JAE, Delta Motorsports (Jensen Specialist) and a lot of other places sell versions with a plastic spacer plate at a 'much' lower price. That soft mount will have a straight bore without the funnel taper (Kamm anti-reversion lip). They work, but lack the reversion flow control.
Delta Motorsports, Michael Dilimpio, (602) 265-8026, Phoenix
delta-ms@earthlink.net

Finally, most Weber/ Dellorto/ Jensen/ Lotus suppliers (including Delta) also sell a thin, stamped steel plate with an integrally molded O-ring. It also works, I currently have it in my Europa, but I don't like it as well as the O-ring/ spacer plate/ O-ring type above, either plastic or die-cast. The Lotus die-cast soft mounts I showed to you are going into the Europa soon.

Any of the above will work better than the solid mount and air leaks you have now.

All soft mounts also require some manner of spring between the Nyloc mounting nut/washer and the carb flange. The original is a steel coil spring called a Thackeray washer. An alternative is a molded rubber grommet (polymer spring) that seats in a stamped steel cup washer. Either provides compliance to the joint as long as you don't screw it all down tight. Properly tightened, there will be a 0.030" gap between the manifold flange and spacer plate, and between the spacer plate and carb flange. With no gaps, the O-rings will be crushed. I can help you install the soft mounts, if you wish.

Last edited on 09-11-2014 02:18 am by Esprit2



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