View single post by Esprit2
 Posted: 11-12-2016 08:45 pm
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Joined: 05-01-2005
Location: Minneapolis, Minnesota USA
Posts: 500
Bfitz241 wrote:
I haven't weighed the floats...however I do have a scale that can do that, nor have I checked float level...sounds easy enough to do.

I have no idea what was done to the engine outside of it has LOTUS pulleys on the cams and auxiliary drive. My understanding is that is not how Jensens came.
You don't have to weigh the floats, the weight should be engraved on the top side. It's easier to read when the floats are out of the carb.
Bfitz241 wrote:
I will say this about the engine, it starts easily, idles well and will idle down to 850 rpm. Maybe that can help your analysis.Don't set the idle too low, even if the engine runs smoothly at low rpm. A little faster idle makes the engine easier to get off the line, and takes a little pressure off the Idle Air Corrector being dead-nuts perfect. It's nice to have a little lattitude. Lotus specifies 900-1000 rpm, and I prefer 1000-1100 rpm.
Bfitz241 wrote:
One thing I would like clarified, you refer to redline...I take that to mean 7,000, am I correct? To be more clear I think you are referring to the same level of rpm for both the Lotus and JH engines
Now, admittedly I haven't driven this thing yet...mostly because it was not capable of being driven. But its mechanical issues are being corrected so that will happen.
I hadn't planned on revving it higher than 6,000.
A related question, what rpm was the horsepower rated?
The stock redline with the chilled cast iron tappets is 7000 rpm. Install a set of steel tappets before revving higher.

The next limiter is the stock connecting rods, at about 7400-7500 rpm. Clean them up, shot-peen and polish them (and do a really good job of balancing the engine) and they're good for 8000 rpm. The Sunbeam-Lotus rally cars raced the 2.2 liter 911, and made 240 Hp at 9,400 rpm with 'prepared' stock rods. With stock cams, there's little point to exceeding 7000 rpm.

The rpm for peak torque and horsepower varied a bit with compression ratio, carbs and (emissions) tuning. In general terms, peak horsepower is at about 6900 rpm, and peak torque at around 5900 rpm.

The engine likes to rev, and limiting your driving to 6000 rpm will leave a lot of fun un-tapped. It trundles around at normal speeds quite well, but it doesn't really 'perform' unless you're willing to bury your right foot and work the gear lever aggressively.

Tim Engel

Last edited on 01-08-2017 11:14 pm by Esprit2