My Emira has a screw loose (boost bypass valve)

[Orchardbike]

Mine (pictured earlier) actually seems to have a screw in it. However, it’s almost like it’s snapped off. There’s no head and it’s flush with the bracket. I don’t know whether they came like that for a while or whether it has actually been broken off.

 

[RPM]

UPDATE: Waiting on the part from Lotus, so I bought a marine grade SS screw and nut. They were 8-32 or 10-32 thread. It is there just to prevent the butterfly valve from sticking. The tolerances are very tight, and the spring is pretty strong. Without the stop screw the butterfly flap can slap shut and catch the edge of the opening - jamming it in place. Depending on your assembly tolerances and how smoothly machined the lip on your supercharger is it may or may not be a problem. Although, constant slamming even without jamming could cause excessive wear and not allow the valve to properly seal, leading to lost boost/power. If it does get jammed shut, you are running on constant boost which is not good long term for your engine and SC.

I recommend for anyone missing the screw to contact your dealer ASAP to get it fixed. If you are mechanically inclined, you can get a screw and nut from your local hardware store and install them. You can feel the valve shut when you flip the lever arm manually. I set the screw a 1/4 to a 1/2 turn past that, just to keep it from sticking. If the dealer gives me any info on the proper calibration of this I will share here.

 

[me73]

They were 8-32 or 10-32 thread.

Interesting that they used imperial threads. It's got to be one of the only non-metric on the car.

 

[geoffbland]

I've just been on the phone with Lotus Silverstone - they looked at mine where the check value stop bolt was missing.
They have replaced the bolt and confirmed that this bolt definitely should be present. So if yours is missing - ask the dealer to have it replaced.

It's also worth noting the bolt is not mentioned in the parts manual for the Emira so you need to order this separately.

 

[RPM]

Interesting that they used imperial threads. It's got to be one of the only non-metric on the car.

Edelbrock is based out of Mississippi, USA.

 

[RPM]

Mine (pictured earlier) actually seems to have a screw in it. However, it’s almost like it’s snapped off. There’s no head and it’s flush with the bracket. I don’t know whether they came like that for a while or whether it has actually been broken off.

It is possibly a set screw which has a hex head inside the top, and not a separate screw head. Check to see if the top is smooth or if it has a hex insert cut into it.

 

[scc.131.fe]

Edelbrock is based out of Mississippi, USA.

Great point. And Eaton is out of Michigan. Not sure who's part it originally was, but probably 'Merican.

 

[Orchardbike]

It is possibly a set screw which has a hex head inside the top, and not a separate screw head. Check to see if the top is smooth or if it has a hex insert cut into it.

Thanks. I’ll have another look, but it didn’t look like it had a hex head.

 

[RPM]

Great point. And Eaton is out of Michigan. Not sure who's part it originally was, but probably 'Merican.

Eaton, not Edelbrock. got my "E"-based performance manufacturers mixed up.

 

[RPM]

Not a Lotus, but similar set-up and may be helpful:

How to Adjust A Supercharger Bypass Valve

 

[scc.131.fe]

Eaton, not Edelbrock. got my "E"-based performance manufacturers mixed up.

Could be either, it's an Eaton compressor in an Edelbrock housing.

 

[Orchardbike]

So I’ve crawled onto the engine bay to take a picture, but still can’t tell. It doesn’t look like it has a hex or anything else. It kind of looks like it’s broken off, but not really!

 

[me73]

Edelbrock is based out of Mississippi, USA.

That's fine, but that doesn't keep them from using metric hardware. Most of the parts I've put in production used metric hardware. In my case the choice often depends on what the other hardware is going to use.