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TR7V8mike

14CUX EFI trumpets dislodged

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Hi,

 

I have a 4.6L Range Rover P38 engine in the TR7 with a 14CUX EFI on top. I recently noticed a very marked decline in performance which had me baffled because pretty much all of the components are new or restored. I was installing a modification to get cold air intake and poked my finger in the air intake and found that the butterfly would only open by about 15 degrees before it stopped with a clunk. I pulled the plenum off and all of the trumpets were laying on their sides with one down the intake, jambing the butterfly. I had no idea this could happen.

 

I can't find anything on the web, so would someone kindly advise the best way to keep the trumpets upright and doing their job properly?

 

Cheers

 

Michael

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Yeah the trumpets are removable, if you use the car for competition sometimes there's less room in the engine compartment and it's common for the height of the plenum to be altered by shortening the plenum casting itself. That means less space available around the end of the trumpets between them and the plenum and so to claim back the volume of air available the trumpets are removed and shortened or replaced with shorter units.

The trumpets in the plenum are likely all the same length and so should just push (with a slight screwing motion) back into the plenum base, if they are various lengths (they may have been altered otherwise why are they loose ?) replace the trumpets in the best positions to allow the air max volume above them. If the trumpets are slightly loose or rattly in the plenum give each Trumpet a couple of dabs of Loctite Red bearing fit before you screw them back in, allow 24 hours before using the car for the Loctite to go off.

 

From memory the 14CUX EFI is the "Eagle" unit with the "Hotwire" air inlet self sensing and self learning programme which will adjust the engines fuel requirements accordingly no matter what you do. Unless my memory is at fault I have my spare unit in the garage having sold the race car.

 

Mick Richards

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Yeah the trumpets are removable, if you use the car for competition sometimes there's less room in the engine compartment and it's common for the height of the plenum to be altered by shortening the plenum casting itself. That means less space available around the end of the trumpets between them and the plenum and so to claim back the volume of air available the trumpets are removed and shortened or replaced with shorter units.

The trumpets in the plenum are likely all the same length and so should just push (with a slight screwing motion) back into the plenum base, if they are various lengths (they may have been altered otherwise why are they loose ?) replace the trumpets in the best positions to allow the air max volume above them. If the trumpets are slightly loose or rattly in the plenum give each Trumpet a couple of dabs of Loctite Red bearing fit before you screw them back in, allow 24 hours before using the car for the Loctite to go off.

 

From memory the 14CUX EFI is the "Eagle" unit with the "Hotwire" air inlet self sensing and self learning programme which will adjust the engines fuel requirements accordingly no matter what you do. Unless my memory is at fault I have my spare unit in the garage having sold the race car.

 

Mick Richards

Hi Mick,

 

You're right. When I installed the EFI I had to have the bottom of the plenum machined down 10mm and the plenum base about 8mm to make it all fit, even with a double-hump bonnet. I took 10mm off the bottom of all of the trumpets to keep the distance between the top of the trumpets and the plenum the same as when manufactured. Thanks for the Red Locktite tip. I'll slap some on.

 

Does anyone know if the flared carbon fibre trumpets actually make any difference?

 

Cheers

 

Mike

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Hi Mick,

 

You're right. When I installed the EFI I had to have the bottom of the plenum machined down 10mm and the plenum base about 8mm to make it all fit, even with a double-hump bonnet. I took 10mm off the bottom of all of the trumpets to keep the distance between the top of the trumpets and the plenum the same as when manufactured. Thanks for the Red Locktite tip. I'll slap some on.

 

Does anyone know if the flared carbon fibre trumpets actually make any difference?

 

Cheers

 

Mike

 

Mike:

 

They make a huge difference. Install them and you will notice your wallet is much lighter!

 

Vance

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I used the inlet trumpets from the Weber 40DCOE carbs by

machining the plenum to accept them.

I fixed them with the Weber washers and bolts.

Together with the other improvements like double throttle plate

quite a big improvement.

 

Keep in mind the original base was designed for the 3.5 litre

engine and it is pretty small.

 

Anyway the job is not done with the larger trumpets, also the rest must fit

including the valves. mine increased from 39mm to nice 46mm.

 

Trial fit in the base with a cut top cover

post-13092-0-24633600-1519688496_thumb.jpg

 

Weber trumpet and the base to be machined to accept

post-13092-0-73679300-1519688592_thumb.jpg

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