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Webers or ?  Rating:  Rating
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 Posted: 08-18-2014 02:59 pm
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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.

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 Posted: 08-19-2014 02:00 pm
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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.

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 Posted: 08-19-2014 03:27 pm
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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

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 Posted: 08-19-2014 04:09 pm
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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

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 Posted: 08-19-2014 04:16 pm
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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.

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 Posted: 08-19-2014 04:56 pm
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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/

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 Posted: 08-19-2014 04:59 pm
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tallyhoe
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Thanks again. USA. Minnesota. I am suspicious of a compression problem from exhaust notes, however.

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 Posted: 08-19-2014 08:24 pm
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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.

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 Posted: 08-19-2014 08:42 pm
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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.

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 Posted: 08-20-2014 07:59 am
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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

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 Posted: 08-20-2014 12:48 pm
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tallyhoe
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I am sure a carb rebuild is in my future so it may be a good purchase.
Thanks

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 Posted: 08-21-2014 04:28 pm
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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
#19670
#11002

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 Posted: 08-22-2014 12:02 am
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tallyhoe
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Something to think about. HS2?

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 Posted: 08-22-2014 12:36 am
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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

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 Posted: 08-22-2014 12:42 am
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tallyhoe
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Plymouth. Neighbor.

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 Posted: 08-22-2014 03:52 am
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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

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 Posted: 08-22-2014 04:36 am
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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

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 Posted: 08-22-2014 01:03 pm
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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.

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 Posted: 08-25-2014 01:55 pm
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Mitch Ware
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tallyhoe wrote: Something to think about. HS2?

HS6

Mitch Ware
#19670
#11002

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 Posted: 09-01-2014 06:43 pm
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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.

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