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65 Lotus Seven S2


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Stripping the carburetor for 3&4, no major hangups yet other than the seized and broken screw in the bottom plate. Have drilled that successfully but even with heat and broil it isn't budging, yet. Hoping it will loosen with the hot ultrasonic cleaning as my next largest drill is likely to begin taking some threads (I wasn't perfectly centered).

 

At any rate, a couple of pictures - had definitely sat a while, and frankly not sure how it was running as well as it was with the intake blockage. I'll definitely be adding an online filter between pump and carb.

 

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The 3/4 carburetor cleaned up nicely, but the no luck with the bottom plate screw remains, even with further drilling. Didn't have a 5mm .8 helicoil and couldn't find one locally, so waiting for Amazon and boxed the bits up for now.

 

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The 1/2 carburetor disassembled more easily and completely, will clean it tomorrow.

 

1-2carbs.jpg

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  • 2 weeks later...

Helicoiled the bottom screw on the back carb, got everything laid out for reassembly.

 

Got a great surprise from an Australian Lotus fanatic who has been helping me try to find the original owner (along with several here). We learned the original owner had passed, but that his wife at the time is still alive and today Mike emailed me scans of a couple pictures she sent him. Great fun to see some history (these are circa 1966), and to learn the car left Cheshunt green with a red nose (their records had indicated red, which I'd assumed had been aluminum and red).

 

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Carburetors cleaned up and back together, with only 1 additional surprise. I somehow missed on disassembly that 1 of the air correctors in the main jet assembly was different than the others (should be 180s, one was a 160 - so obviously someone has been in the back carb). I've ordered a set of 180s, they are fairly inexpensive and may as well make sure none of the others were altered. The originals are in the carburetors for now, a simple swap when the new ones arrive.

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The throttle linkage cleaned up nicely, but the main rod and brass bushings for the manifold were both highly worn, so I cut some new bushings and a piece of ss rod to replace them, just need to drill the rod for cotter pins.

 

Also took advantage of the weather to pull out the little yellow car to drive the next few days - feels quite refined after driving the Seven!

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He is the oldest son, still a toddler at the time.

 

As I somewhat expected, drilling 1/32" holes through stainless is above my capability and facility, so after a failed attempt and a few bits I decided to groove the bar slightly and use e-rings. I think that will work fine and maybe look cleaner, but I also made a rod from mild steel that I drilled and polished as a backup.

 

Did a dry fit and part check, perhaps get everything back together next weekend.]

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  • 2 weeks later...

Whew, re-installing the carbs/intake manifolds and exhaust manifolds on the pre-crossflow is a booger! I used hex key bolts rather that studs, but the angles make getting it all in place tough and getting the bolts tightened nearly impossible. I need to find some angled allen keys, or some other trick! But, they're on - will work on the linkage tomorrow, then possibly start it up.

 

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Edited by SENC
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Whew, re-installing the carbs/intake manifolds and exhaust manifolds on the pre-crossflow is a booger! I used hex key bolts rather that studs, but the angles make getting it all in place tough and getting the bolts tightened nearly impossible. I need to find some angled allen keys, or some other trick! But, they're on - will work on the linkage tomorrow, then possibly start it up.

 

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very nice! Are both ceramic coated?

 

I use 3 different tools to tighten those bolts: one shortened hex-key wrench with a ball end, one shortened hex-key wrench with the shalf bent at a slight angle, and one of these. I use a socket and extension on the hex keys just to be able to apply more torque.

 

It also helps to have dowel pins on the intake manifolds, but it's a bit late for that. You'll want to check them occasionally as they do tend to loosen.

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Thanks Dingo. I've purchased a set of stubby ball-end L-wrenchs for next time No, not ceramic coated, just a coat of high-temp paint.

 

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Reinstalled and running. Have some additional tuning to do but got it in the right ballpark for a short drive - enough to tell me I need to do some more tuning on the Elan, this Seven is exhilarating when in the gas!

 

I realized I was blowing oil from the breather. The dipstick has registered a bit over the full line since I got it so may just have been overfilled. I took advantage of today's warm-up to change the oil and filter and we'll see how it does next tuning session. I'm not familiar with these pre-crossflows or this breather apparatus - does anyone have any advice?

 

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Assuming that the engine is in basically sound condition and therefore the rings are not allowing excessive blow-by, then what you are experiencing is the oil being mechanically thrown out. The breather is directly above the eccentric lobe on the cam that drives the fuel pump.

 

I've never seen a breather like that. Most kent's use a breather block and route the pcv hose out of the breather into either a catch tank, the intake, or back into the rocker cover. The latter removes 50% of your breathers though.

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I've been told elsewhere that the breather I have is an early one and should have an elbow on top of it that terms in a pipe (originally to the environment below the car, or preferable to a catch tank then environment). Here is a picture of the elbow:

 

breather elbow.jpg

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I love watching your progress.

 

You might want to consider getting an extra thick intake/exhaust gasket. I too have a '62 pre X-flow with the same manifolds. I have found that with the stock gasket the manifold mounting screws tend to back out over time. The thick gaskets (approximately 3/16 inch thick) I'm using now have eliminated that issue. I get them from Ivey Engines. I also use a small O.D. washer under the screw heads from ARP. You can just see the top edge of the gasket in this picture.

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I'm very much interested to see how you handle the crankcase breather system. I've just fabricated a system for my car and installed it this past Saturday. So far it seems to be working properly with no measurable oil consumption after about 140 miles. But the jury is still out.......

 

Please continue to keep us updated.

Edited by escondidoron
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Thanks Ron, I used a cometic gasket and know I'll need to tighten after the first few heating/cooling cycles, but hope it will be ok afterward. Will keep your thicker gasket recommendation in mind if not.

 

I am curious about the black tubes protruding between the air trumpets.

 

I'm also interested in the history of the carbs themselves - I recently bought a pair of Weber DCOE2s as backups that have 2B/2C numbering like yours.

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I used a cometic gasket and know I'll need to tighten after the first few heating/cooling cycles, but hope it will be ok afterward.

 

 

I have used the Cometic gaskets and find them to be the best in my experience. In my case I found it necessary to keep a set of appropriate tools in my travel case as re-torquing those bolts was a fairly regular service item until I switched to the thicker gasket.

 

 

I am curious about the black tubes protruding between the air trumpets.

 

 

The black tubes are my homemade crankcase vent ports. I did not want to have a catch can that requires servicing and I did not want to simply vent to the atmosphere. I have attempted to design a system similar to that found on modern cars as opposed to the ancient 'road draught tube' that was originally fitted by Ford and Lotus pre 1963. However some compromises have had to be made since due to the multi-inlet-runner carburetor system it was not reasonable to tap into the intake manifold on each cylinder between the carb and the head as there is no common plenum. As a result I have vented to the air cleaners. Here are some pics of the setup and the individual pieces:

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For the front carb. Note that the one for the rear carb is similar except that the tube along the bottom is a continuous pass thru so as to be able to provide a path to the front carb.:

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And the Tee fitting to tie the various ports together:

 

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It's a fairly simple approach to crankcase ventilation plumbing. I have connected the port on the distributor side of the block to the right angle port on the bottom of the Tee fitting with a 5/16" I.D. hose. The back of the valve cover is fitted with a 3/8" MNPT x AN10 adapter with a 90Deg AN10 push elbow attached. that elbow is connected to the Tee fitting with 5/8" hose. the other end of the Tee fitting is connected to the plenum / port plates on the faces of the carbs. The black tubes that you noticed go into the foam air filters allowing any pumping vapor to be drawn into the carb inlets. I added a port on the back of the air filter socks by cutting / punching a hole with a sharp (knife edge) 1/2" hollow punch. The tubes are 5/8" O.D. The mis-match, along with the barb on the tubes, provides air / debris seal. The filter socks just stretch around the trumpets for mounting. They also fit nicely within the confines of the little S2 air scoop on the left side of the bonnet.

 

Here is a view with the filter socks installed:

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After about 150 miles of fairly spirited driving to date the insides of the filter socks are still dry and there is no measurable oil level change in the sump. I am running a semi-dry sump setup. I did make one change to the vent system after I took these pics: I disconnected the 5/16" line that exits below the oil fill cap from the Tee fitting and connected it to a clear plastic fuel filter with a paper element. The other end of the filter is open to the atmosphere. It allows air to pass into the valve cover (or exit as the case may be). So far that appears to be what is happening as there is no discoloration of the paper element. Also, I can detect a slight vacuum on the open filter end if I put my finger over it with the engine running. I have capped off the unused branch on the Tee fitting.

 

I made the parts on my friend's 3-D printer out of ABS. After printing I brushed them with a coat of Acetone to promote external layer bonding. I.e. the Acetone melts the outside of the layup together. So far the parts are are holding up to the environment. I'm concerned about both heat and fluid contact long term. We'll see. The ABS should be OK with the mineral oil that I use for engine lubrication. Serious fuel contact would however be an issue. As a precaution I applied a light coating of Hylomar Blue to the inside of the clamping flanges of the velocity stacks when I put everything together as Webers have been known to drip occasionally around the outside edges of the inlet trumpets. I also put a 1/8" wire diameter x 2" O-Ring over the trumpet flanges, on the outside of the clamp ring flange, to act as a washer for the retaining tabs. I thought this necessary as the flat base of the vent plenums would otherwise restrict the tabs from directly contacting the clamp ring outer faces to secure the trumpets.

 

 

I'm also interested in the history of the carbs themselves - I recently bought a pair of Weber DCOE2s as backups that have 2B/2C numbering like yours.

 

 

The Webers on my car came with it at the time of my purchase. Its a Cosworth 109E and according to the Register these are the proper original carbs and manifolds for the engine.

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Wow, that is beautiful design and work!

 

My car originally came with an oil cooler (partially visible in a 1966 photo). The oil radiator that used to sit in the nose and all of the plumbing is long gone, but I have a few pictures from around 2008 that show a rather large "catch can" that was part of the recirculating system.

 

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