I recently bought one of these engines which I intend one day installing in my motor. One problem I've seen mentioned in various threads is how do you lower the plenum chamber to avoid making a hole in the bonnet? I haven't found the answer in any forums and wonder if anyone on this site has done it and is able to help me please? The Jolly Green Giant managed it with a 2.0 efi pinto but the twincam is a bigger challenge. Help!!!!!

I had a similar challenge with my E Type, I cut the inlet flange from an xj6 efi manifold and welded a Nissan plenum on.

You could do similar, I searched ebay ads for something which looked suitable.


nearly there 3

Hi,
I have the 2.0i twin cam installed in my Haynes Roadster, and I had the same problem as you.

First, I did the same thing as another builder did : shortening the tubes (elbows) and rebounding the plenum with "Chemical Metal". It sounded a very good solution at first, especially for me who can't weld aluminium.

Before:
2014-07-01 _13-59-31 by Voucht71, sur Flickr

After:
2014-07-17 _18-52-33 by Voucht71, sur Flickr

On the car:
2014-08-08 _12-27-18 by Voucht71, sur Flickr
2015-08-07 _15-02-42 by Voucht71, sur Flickr

Posts about that on my build blog: (you can select the language at the top of the right menu)
Post1
Post2
Post3
Post4
Post5

Or complete album on my flickr

But after a while, I could see the chemical metal starting to crack, so I no longer trusted this assembly
2015-08-07 _15-02-56 by Voucht71, sur Flickr
2015-08-07 _15-02-50 by Voucht71, sur Flickr

So I went for a welded solution. Redoing it completely from ally plates and elbows is almost impossible because the water thermostat housing is (stupidly) part of the manifold. So I used the original manifold, cut the plenum, and adapted a round tube as a new plenum. And I had the whole assembly welded by a pro.

Final result (and how it is now):

2015-08-07 _14-58-21 by Voucht71, sur Flickr
2015-08-07 _14-58-06 by Voucht71, sur Flickr
2015-08-07 _14-57-58 by Voucht71, sur Flickr
2015-08-08 _11-26-46 by Voucht71, sur Flickr
2015-08-08 _11-27-10 by Voucht71, sur Flickr

Post about the new plenum on my build blog(you can select the language at the top of the right menu)

Or complete album on my flickr

I'm pretty happy with the result (and the engine works perfectly), even though the throttle housing is a bit out, and I has to cut the lips on my nose cone and bonnet. I should have planned for a slight angle on the plenum tube to keep the end (throttle housing) more inside the car.

Hope that will help

Thank you both very much for your replies which are both very helpful. It seems that you have both created new plenum chambers and adapted them to the existing manifold. This seems to be the avenue I shall need to go down. Thanks again!:)

[Edited on 23/5/17 by geoffxt]