jbcollier

I have a ‘69 Lotus Seven S3. Sometime in the past, a PO removed the stock gearbox support and had two sections of square tubing added. This probably was part of a “improvement kit” sold by either Arch or DSK. I’m looking for a replacement mount. It is not the same as Caterham used. The photos below show the old mount next to a Caterham mount. The last photo shows the two back to back. Any idea where the mount I have might have come from?

For best symmetry, the rear one should be a tad longer...

Substantial my a**. Some? maybe. First, my main complaint with most online discussions: There are lots of anecdotal reports like: "I did this and it went slower." or "I did that and it went faster." Seat of the pants is not a good way to make decisions. Each change needs to be evaluated on an even playing field. Any changes first require recalibrating the jetting before testing. You removed/add something and it went better/worse. Big deal. Did you re-jet after the change? If not, all you are doing is evaluating different jetting! I did some digging and there is not a lot of good info online. By good info I mean changes backed up by careful testing before and after. I did find some charts and illustrations that explain the importance of the sides/edges of an air inlet: These show the importance of the edges of the air horn. Now look at this side profile of a screened air horn: Flow along the edge/lip is disrupted/destroyed by the screen. It's basically a cork. What you want is for the screen/filter to surround the air horn but not actually touch it. Here's an example:

Maybe they didn't know what they were doing? I run an 5/8"/0.625" clutch master and a 11/16"/0.70" brake master which gives a bit more "feel" than a 3/4"/0.75" brake master. YMMV

Figured it out. Hold the gear so you are looking through the mounting bore and, voila, 7T

This is my gear:

I've pulled down my Seven S3 gearbox (2000E) for a refresh it was getting a bit noisy. It was the input shaft bearing but I'm changing them all regardless. As part of the process, I'm counting teeth on my steel speedo drive gear on the mainshaft. I only get 6T unless I count sideways. So I went searching for the correct 7T gear and found this auction: https://www.ebay.com/itm/194390802014 My gear is identical. Am I going crazy or is the auction gear only 6T? If I'm not crazy, anyone have photos of what a 7T gear looks like? Any leads on a 7T?

Agree with MV8's assessment but would add: - pleated paper provides the greatest filter area, filters out the smallest particles, and has longest useable life. - screened throats filter absolutely nothing. - just foam can be a significant fire hazard. - oil-impregnated, pleated-cotton, gauze offers minimal surface area and minimal filtration. That all said, given a Seven's design limitations, the latter would seem to be the best compromise.

Here's an online calculator to simplify things: http://www.wirecloth.com/calculators/

Pretty simple calculation. Measure the wire width, spacing, and you can work out the percentage of area covered by the wire.

You will have to re-jet the carbs. These mesh screens block a minimum of 40% of the air flow wide open. This effect is biased: full at wide open down to negligible at idle.

It's the total length of the intake tract that matters. This is already quite restricted in Seven derivatives. The main thing the horns do in our case is smooth the flow into the carb, significantly reducing turbulence and thus increasing total flow. Long way of saying, yes, shorter stacks would probably be fine.

Well, in that case, there really isn't anything to fix or improve. Drive it and enjoy.

And what is it like where you live: lush and humid, dry and dusty, or?

I must admit that I would get another bonnet and cut that up to suit. Seven engine compartments run HOT. You want outside air for sure.

Most S3s came with a single downdraft crossflow.

Emphasis on the "-ish"! ;-)

The mesh screens are just that, screens. They significantly restrict airflow by a huge amount. And, all they filter out are rocks and pebbles. I have rebuilt a lot of engines (retired 35 year Euro mechanic) and never once have I had to do one due to rocks or pebbles getting in. Dust and dirt? That's a different story. So, first question: What is the climate like where you drive? Dry or humid? I live in a dry, dusty climate. I do not run without proper air filtration, period. You may live in a humid climate. Not much dust in the air in a moist climate. You could get away with no filtration and not limit your engines life too much. Second question: Exactly how much space do you have between the carb and bonnet? How much if you bin the air horns*? Could you build an air box with a side mounted air filter? I have done this in some tight spaces and it has worked out very well. Finally, I'm not a fan of foam air filters exposed to the carb mouths. One backfire and up goes your car in flames -- that I have seen, not pretty. Carb - air box - then remote foam filter, that's fine. *intake horns with screens give far less air flow than just the plain carb inlet with no horns -- maybe not as cool looking but tuning for cool at the expense of power is pretty dumb. Disclaimer: I write in plain-speak with no intention to insult.

Get it inspected. Get it inspected. Get it inspected. Put it on an alignment rack and see if anything is bent. These are used cars that people drive fast and often exceed their abilities. Things get banged, knocked about, and bent. A lick of paint can make a gawd awful pile of excrement look pretty good.

SW gauges were a common aftermarket fitment in North America. The AC gauges were/are not the most robust so having been replaced is not unusual.

After 35 years as a mechanic, I wrap my headers, pipes, silencer, and tail pipe, so I don't #$%@ burn myself. Works great!

These products offer minimal to no freeze protection. If the temps go down, you may toast rads, heater cores and possibly engine blocks. Just an FYI.

I use the “blue” coolant used in Volvos and BMWs. Works great.

I used Evans coolant in a fresh engine build for my Europa. Spent a lot of time chasing coolant leaks until I gave up and went back to “ordinary” long life coolant. Instantly, no more leaks. YMMV

The jets need to be centred properly or the needles will rub. Just google SU jet centring for the procedure.