Mk1 plenum / bonnet clearance
Mk1 plenum / bonnet clearance
Author
Discussion

sportster1250

Original Poster:

19 posts

115 months

Wednesday 28th February 2018
quotequote all
Hello Guys,
Is there any dimensional differences between the 350 flapper plenum and the later LR 390 hot wire plenum?
Reason for asking is that my original has been swapped out in favour of a 390 so the throttle pot is compatable with the MBE injection fitted....
I don't have the car in front of me, but the guys at the paint shop say its in hard contact with the bonnet and fear the bonnet will fatigue crack if its left latched down.
The original plenum has made a deep impression in the sound proofing.... does removing the sound proofing in this area give a noticeable increase in clearance?
Can the top of the plenum be relieved.
Lastly is the throttle bore size the same on the 350i flapper and later 390?
As ever appreciate your input.
Regards David

batman400

1,486 posts

220 months

Wednesday 28th February 2018
quotequote all
Hello,

The plenum is pretty much the same, I've got a Hotwire one fitted to my flapper equipped 400se, they are pretty much the same with the exception of the cold start injector, TPS mount and the later ones have '3.9' cast into the top. The throttle plates are the same diameter too but either can be bored out to 72mm.

gmw9666

2,739 posts

216 months

Wednesday 28th February 2018
quotequote all
Not sure on dimensions but this size may help? http://www.mez.co.uk/ms12-new.html

I guess it depends which you have now, some of the LR ones do look taller?

sportster1250

Original Poster:

19 posts

115 months

Wednesday 28th February 2018
quotequote all
Thanks Batman,
Good to hear they are the same physical size, I guess the plenum / bonnet fit is likely to be much the same as when I last saw the car.
Removing the sound proofing over the plenum, and if necessary milling a few mm's off the plenum top surface will I hope, sort the issue.
Any one else who had similar issues, be good to hear your solutions.
Regards David

adam quantrill

11,609 posts

258 months

Wednesday 28th February 2018
quotequote all
You may get a few more mm by loosening the engine mount bolts (the ones that face fore/aft that bolt onto the chassis) let it sag down then do them back up.

If you have PAS make sure the pulleys then clear the steering rack.

jon haines

956 posts

262 months

Thursday 1st March 2018
quotequote all
They are the same physical size. Make sure it has not got a gasket under it as they normally only have sealant.

sportster1250

Original Poster:

19 posts

115 months

Thursday 1st March 2018
quotequote all
Thanks Guys,
I will check it out when I see the beast, I am hoping to fit some ATC Carbon Trumpets, so I can give it a good fettle then. Cheers David.