SENC

.03", or .77 mm to be exact

Here is a picture of my old and replacement pumps, to the extent it may help you.

No. I don't have a thermostat in mine, nor are the swirl pots designed for them. The only use for the thermostat is to allow the engine to warm more rapidly by limiting flow through the radiator until it is warm enough to circulate. From all you've described and tested, it seems most likely you're just not getting sufficient circulation through the engine - whether due to restrictions or even blockages or due to an inefficient pump. Have you flushed the engine? Hose to the pump inlet and open the drain on the lower right side of the engine? Good flow? Clear or lots of crap? I replaced my pump when I rebuilt my engine. I'm 95% sure I saved the original - if you can't put your hands on one I'd be happy to send it to you to test if it makes any difference. I didn't replace it due to known issues, but just part of my rebuild.

Sharing a couple notes from an old Autopress manual for the Anglia, Corsair and Cortina... could the water pump have been rebuilt without the slinger or with the impeller too big a clearance? Trying to think of why else it may be working inefficiently or even direction water towards the pot rather than through the engine.

Timing, if wrong, can also be a big contributor to overheating - worth a double-check of that, too.

Unfortunately I fouled up the first video, from dead cold. At cold, water level in the swirl pot is about 1/2" above the bottom. Just jiggling with then engine at idle. When rpms hit 1500-2000 rpms, water begins to gush in from the upper, inlet pipe. This video shows the pot fairly full, but you can see the same effect.

Some have installed an electric water pump, others have reported using a smaller pulley to increase pump rpms. This is a topic that has been discussed a fair amount on lotuselan.net and seems common - if you haven't already you might dig around over there. Personally, I have a bigger problem in my Elan than in my Seven - my Elan does NOT like being stuck in traffic and heats quickly - but this is more about airflow as it cools quickly again when on the move. An electric fan and periodic blips to keep coolant flowing generally work to keep it from overheating unless ambient air temp is in/above the 90s. When it is really hot out I just need to get out of traffic. My Seven seems to have fewer issues - but if I'm at a light for any period of time on a hot day a few blips on the throttle yield a noticeable drop on the temp gauge. A few other thoughts/observations, in addition to what others have contributed... 1 - you say it is overheating, but what does that mean? Are you observing a particular temperature on a gauge, IR gun, temp strip, etc., or are you getting coolant overflow? 2 - there are, obviously, 2 main drivers of cooling efficiency - coolant flow and air flow. As it seems you're only stationary, what are you doing to ensure cool air is actually flowing through the radiator? Does increasing/decreasing that airflow have any material impact on the heat measurements you're getting? 3 - are there any signs of even miniscule oil contamination in the coolant, that might suggest leakage at the head gasket. Is coolant blowing out anywhere? If I can get a few minutes to run over to the shop this morning I'll try to grab you a video of my swirlpot when my Seven is idling and when I blips the throttle - that may give you a single point of comparison to what you're seeing - but my recollection is not of gushing flow.

I'm not following you on this statement. The pump outputs into the engine cooling cavities and then on up to the swirl pot. Are you giving it any revs, or is this all at idle speed? The pump is notorious for not moving much volume below 2k rpm - so if you're just idling I wouldn't expect to see much swirlpot activity. Otherwise, as MV8 and Croc have pointed out, it does seem like it would be something clogged in the engine cavities restricting flow or an inoperable/reduced efficiency pump. You don't have a heater box on your Seven, do you? That's another place to get clogged up.

Similar and generally interchangeable, but some significant differences. The biggest difference is the 105e is a 3 bearing block and the 120e (116e) is a 5 bearing, so preferable. The old Dave Bean catalogue has some great information on engine blocks, if you have one. Some of that may be online now. There are also some good online resources for Kent Ford engines - google that and Cortina and formula Ford as I recall. The following link is to a thread that includes an unpublished book by an enthusiast. A phenomenal resource. https://lotuselan.net/forums/viewtopic.php?f=39&t=52339

I was looking around the lotuselan.net site for something else and came across an alternator thread. Some reported the early 70s +2s came with the Lucas 17ACR alternators (type 36A), so maybe that is what you would have had. I can say that many retrofitted with Denso 45 to 55amp alternators.

I didn't have anything S3 specific in my files, but the S2 used the C40 generator. So did similar Elams and Cortinas, which then switched to the C40L for late 60s/early 70s runs. Given that, I'd bet on the Lucas C40L generator.

Agree. He was extremely helpful to me and did nice work.

I was off - about 1" difference.

I'll grab some measurements in the next couple of days, but going on recollection I'd guessnthe rope seal side is 1/2-3/4" smaller than the other end.

I forgot to get measurements, but feel free to point out what you want measured and I'll gladly get then for you.

I'll grab a picture side-by-side in a bit when I get to my shop.

It appears from the pictures that the MP version has ports on either side for attachment of the brake hose. Total speculation, but could "SP" signify a single port and "MP" multiple ports? Both being type 12s I'd suppose the guts are the same.

I've only paid attention to "type 12", "type 14", etc and not to the suffixes when considering calipers and rebuild parts on my Seven and Elan - so had to go look through old pictures to confirm what is on my 65 - 12SP. Mine were in good shape so I didn't have to rebuild my calipers, but I may have a set of pistons in my parts box. It will be tomorrow or Tuesday, but I'll check.

Yes, I'd have been sad, too - but you get to go lighter! Does the alloy version have the flat mounting point? I can't remember for sure, but I think I ended up finding my mount by searching Anglia and Consul Capri parts sites. It could have come from the 105e club.

Adding a couple of pictures and notes - may or may not be helpful to you depending on what you have (and what Lotus actually did 😀 and what the PO did). Following are pictures of the tailshaft extension from my 69 Elan and its wedgeshaped mounting point. This required the bottom mount in your first picture. As I understand it, Ford started making this version in around 1962 and Lotus used this version in Elans starting early in (beginning of?) the S2 range, so sometime in or after 1964. Following are pictures of the tailshaft extension from my 65 Seven, showing the flat mounting point. This tailshaft extension was manufactured in 1964, as I recall. This version required the top mount in your first picture (when used on Sevens). It was also used in S1 Elans, thoughbit required an additional fabricated part for mounting to the Elan chassis. As I understand it, Ford continued making this version until the Anglia was dc'd in 67.

The pictures look like the early and late gearbox mounting solutions. I would think yours, in 69, would be a late mount - but I may be wrong on the transition date. I'll see if I can find my notes on that for the Elan (can't imagine Lotus differentiated if they didn't have to). If I'm right about the transition being pre-69, perhaps the PO needed to replace the tailshaft extension and used an earlier one?

Chris, to be sure my previous response oversimplified. I used 2.5 inches simply based on the 40mm barrel size of 40DCOEs, and estimating the barrel of the air horns/trumpets to be approximately the same. I guess the real question of whether there will be "enough" air is to compare the open spaces of the filter with the restricted space of the choke/venture. ie., if you are running 30mm choke (roughly 1.2 sq inches), you'd need to make sure the screen had at least that much open space to allow in enough air or you've just moved the choke restriction way upstream. But enough air is only 1 piece of the puzzle, air flow and velocity another. The bell end on the trumpets serves the purpose of smoothing out the air flow, allowing greater velocity/flow. Another downside to the mesch/screen filters is that they oppose that design to some extent by attaching to and covering part of the bell end. Ideally, the bell end of the air horn would have at least one inch of "headspace", whether from the facing side of an airbox or from the back of the filter (of any type). The screen/mesh filters obviously have zero headspace, as they attach directly to the bell end (foam filter tube are generally designed with headspace and aren't snug to the bell end, by comparison). I think I've seen some testing results somewhere, will look through my files and see if I saved anything, but I think the knock on the mesh filters is that they both restrict volume of air flow (as does any filter, to some extent) and disrupt the airflow and the advantages of a well-designed trumpet. It's also worth noting that length matters with our Webers, as they don't have plenums and, as such, require trumpets of the right length to help reduce air/fuel mixture getting blown back out and to help get the air flow velocity optimized. Most of this understanding is from reading/study over the years - perhaps @jbcollier will come along and correct/clarify as it sounds like he has substantial experience in this area.

It's really just a surface area thing. If the open mouth of a ram/trumpet is about 2.5 square inches, how much is that reduced by the space the mesh wires take up? Obviously, bigger wires and/or more of them take up more space. I'd have to go back and measure/count mine - but just looking at them I'd not be surprised at all to find they restricted airflow 30-40%.

Thanks Yoram! Keep us posted in future years, too. I'm out of pocket this year, but that would be a great one for a meet up and subsequent drive.

I didn't want to post an idea I haven't tested, but one idea I've kicked around and just not played with, yet, is creating a aluminum-frame that fits snug within the scoop inlet (flush with or maybe extending slightly forward) that would hold filter foam (backed with mesh). Then fashion an alu surround for the rams that effectively turns the scoop into an airbox. I think with shorter rams it might work. I think you have a similar hood and scoop as I do, but I can't put my hands on a good picture of mine.