Exhaust Clearance

[barry p cook]

I have just trial fitted the exhaust manifold and the twin down pipe so I can design a bracket to support the exhaust as it passes the rear of the gearbox. My problem is that there is very little clearance between the down pipe and the chassis ( as seen in the attached photo). What clearance would you normally expect? The car was partially stripped down when I bought it so I don't know what it should be, but I definitely expected to be more that this.

 

Thanks,

Barry

[RogerH]

Hi Barry,

you could easily trim away the edge of the chassis flange with no trouble.

The engine rotates very close to that axis so there will be little movement to cause trouble.

 

Roger

[barry p cook]

Cheers Roger,

I like an easy solution. Do you reckon 4 to 5 mm would suffice?

 

Regards,

Barry

[RogerH]

Hi Barry,

as little as required.

 

Roger

[barry p cook]

Cheers Roger

[Guest ntc]

You should need none. Look at the engine mounts

[graeme]

I agree with Neil, find the fault rather than modifying the chassis.

 

Cheers

 

Graeme

[Geko]

+1 it should have a 5 mm clearance with the chassis, provided that the original bracket exhaust to gearbox is installed. I have a spare one if required

[peejay4A]

Is the exhaust manifold properly seated at the cylinder head? The reason I ask is that if the head has been skimmed the bottom of the exh manifold can foul on the block deck and this has the effect of pushing the exhaust outwards like yours.

[RogerH]

Hi Neil,

I would agree with you, find out if there is a cause. Looking at Barry's pipes he would need to raise the engine quite a lot.

 

When I bought my Revington pipes, a long while back with new mounts etc, I had the same problem and was told by them to trim the chassis.

It worked.

 

With a known tight spot I would have thought the pipes could have been profiled to give more room - a slight squeeze of both pipes.

 

Roger

[stuart]

Triumph used shims on the engine mounts for just this problem Item No 79 http://www.moss-europe.co.uk/shop-by-model/triumph/tr2-4a/engine/engines-components/external-engine-components.html

Also make sure you have the engine mountings correctly orientated if you have the 4a "fail safe" type as I have come across them fitted incorrectly.

Stuart.

[barry p cook]

Thanks Guys,

The exhaust manifold is flush with the cylinder head. The engine mounts are new land rover ones as recommended on the forum. I will look at using spacers on the mounts to see what the impact is.

Hi Stef,

Many thanks for your kind offer but the gearbox I am using is from a saloon and is fitted with a J type box.

 

Regards,

Barry

[mjdearing]

Hi Barry if you have oxy/acc gear get yer pipes cherry a few inches down from manifold pry off chassis and set what gap you need you will be suprized how easy you can tweek em. Martin

[tim hunt]

Barry, the Phoenix manifold on my 4A was always pretty close to the chassis. I had a head problem last year and when the exhaust manifold was off I had it Zircotek coated. I think this process might have distorted it slightly since when everything was reassembled it looked even closer to the chassis, sure enough when driving this caused vibration. Oh b****r! I whipped the manifold off

again and simply filed a nice 10mm scallop in the chassis flange. Job done. Nothing wrong with my engine mountings btw.

 

Tim

[barry p cook]

Thanks everyone, that gives me a number of options to sort it. There will be a delay before I give them a try as the chassis is now in storage and I've brought the body tub back for final preparation before it goes off for spraying. I was thinking of starting another thread on what are members least favourite jobs. My new least favourite job I've just discovered is seam sealing.

 

Thanks,

Barry

[RobinTR]

I'm coming into this thread a little late, but just to say that I had similar experience with exhaust down-pipe clearance, but I had been expecting it, as I had read in the advertising or brochure for a particular type of tubular manifold, that some grinding of the chassis flange would be needed. Unfortunately I cannot find the original reference, so cannot substantiate the claim.

 

What I would like to pass on is a good tip that I given by RogerH... that is to be aware that the flanges on the tubular manifolds are thinner than the original cast versions. The result of this difference is that the hold down clamps will not apply even force (and may actually bind on the stud before fully clamping the thinner exhaust manifold).

 

Roger suggested building up the clamp on one side; I did this using MIG after measuring the inlet and exhaust flanges to calculate the length of the new longer pip needed for the exhaust end of the clamp. I built up more than was needed then ground it back to the correct dimension and to make it all look more presentable.

 

I found that the flanges on my new manifold were slightly bowed, but they seemed to pull-up flat when the clamps were all torqued up. I am not sure if this was by design, to compensate for any potential bowing, but wait in hope for when I finish the installation and get in some miles on the road!

 

A thing that I noticed is that the two lower clamps (the longer ones) were quite tricky to get aligned so that they pressed on both the inlet and exhaust flanges (the historic dimple on the aluminium flange was very close to the edge). If doing this again I might consider making the longer pip slightly wider (for example: the full width of the clamp), as this might allow the clamping point to take place a little further from the edge of the softer flange.

 

I have a picture showing the modified clamp if you are interested, but unfortunately I have not been able to master the copy/paste feature of this forum.

[RogerH]

Hi Robin,

you can't copy/paste pics into a post.

 

Click on 'more reply options' bottom right

Click on 'choose file' bottom left

Double click on your pic from your file.

Click on 'attach this file'

Position cursor where you want the pic

Click on 'add file'

 

Roger

Edited August 18, 2016 by RogerH

[RobinTR]

Thanks Roger, I'll give it a go

 

 

[Lebro]

I did similar to above, only instead of welding, I drilled & tapped into the "pip" on one side, then fully screwed in a hex headed screw (M4 I think).

The thickness of the head was chosen to be the same as the difference in flange thickness. Result is the clamps sit parallel to the head.

 

Bob.