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Exhaust manifold.


Paul Amey

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I have a tubular manifold on the Spitfire because it's had an engine transplant (1500 instead of 1300) and I didn't have the correct cast manifold, which has a reputation for downpipe gasket problems anyway. The tubular was an economical option for a reliable solution.

When I had a TR7 it was already fitted with a tubular manifold, although that wasn't in great condition and I had to replace it with another one. However, that car had a Sprint engine, for which the correct cast manifold is rarer than rocking horse manure.

Those are the only two of the dozen Triumphs I've owned that I've changed the manifold on. Unless the cast one is broken, it works well enough on a moderately standard car.

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1 hour ago, Paul Amey said:

Thanks Rob, I think there might be an issue with how flat the cast manifold is. When I removed it I noted that it had two gaskets on it!?

Paul.

It is possible to get them flat. You need a good straight edge (back of a wood/panel saw is a good choice) a file and patience. Also a good quality gasket, Payen would be my choice. 

The tubular manifolds will aid power on a well set up engine. How much? Not a lot.... but it all helps.

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tubular pipes are noisier than a cast unit you get all the detoations pinging down the tubes so its noisier under the bonnet 

depends on the maker but 6 3 1 collector can be a pig to seal most are a slip loose joint to allow the primery to expand 

on a vitesse there can be clearance /lack off between steering column and the tubes which might need a rack shuffle 

having had one on the vit6 ( same head as mk1)  i would not  bother with one now ,  

can be nice or a headache that cost ££££ss

did it make any power increase   well over 4k it would come on  with a amazing exhaust song   so  makes you think its better 

Pete

 

 

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17 hours ago, Paul Amey said:

I think there might be an issue with how flat the cast manifold is. When I removed it I noted that it had two gaskets on it!?

If this is a Mk1 Vitesse engine then I also tried two gaskets on mine at one point. It's not because the manifold's not flat, in my case, but rather a combination of modern gaskets being a tad thin and the clamping method being highly sensitive to any difference in the flange thickness of the inlet and exhaust manifolds. I think I ended up filing the inlet down a fraction to make them match, and I've not had any trouble since.

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Phoenix ones are a terrible fit,had one on my 2.5 Vitesse for a while and ended up selling it on e bay,i was lucky enough to find an original Mike Randal,

(Mike the pipe) 6-3-1 for sale so snapped it up,lovely hand made thing with sand bent tubes and proper joints.

My 1500 Herald has a 4 into 1 with a 3 inch collector and Vitesse system,manifold bought off e bay years ago,does it make a difference?..no idea.

Car is great to drive and quite torquey,it made 93bhp when rollered.

Steve

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  • 1 month later...

I had a look at a racing Vitesse at Mallory today. It had what looked like two three branch manifold's into two pipes . It seemed to fit ok. Don't know if the rack had been moved. But surely moving the rack to allow clearance for the steering column will cause other issues?

 

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2 minutes ago, Paul Amey said:

I had a look at a racing Vitesse at Mallory today. It had what looked like two three branch manifold's into two pipes . It seemed to fit ok. Don't know if the rack had been moved. But surely moving the rack to allow clearance for the steering column will cause other issues?

 

Was it this one, I wasn't there but my mate sent the pic to me

WhatsApp Image 2021-10-17 at 12.29.53.jpeg

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On 17/10/2021 at 19:50, Paul Amey said:

I had a look at a racing Vitesse at Mallory today. It had what looked like two three branch manifold's into two pipes . It seemed to fit ok. Don't know if the rack had been moved. But surely moving the rack to allow clearance for the steering column will cause other issues?

 

I moved the steering rack, about 3/4", when I first put a zetec in my spitfire. It was fine in a straight line, but horrendous feel when turning. Took 3 days to get the rack moved back to the correct position.... but worth it. I won't make that mistake again.

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49 minutes ago, Paul Amey said:

How did you get the clearance if you moved the rack back again?

Had to move the engine. ie remake mounts, cut bulkhead, cut/reweld gearbox mounting bracket, shorten the exhaust. Luckily the prop had enough free splines to JUST fit. Tunnel needed the stick hole moving, and I had to move the handbrake too. Rad hoses already had joiners, so that was easy. I reckon today that lot would take me 3 months, but I was nearly 15 years younger then.

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I've made a couple of 631 manifolds, all equal length primaries. One for the Vitesse and another for the gt6 with the addition of anti-reversion chambers. Both sand bent. Very little space to play with, but no clearance issues.  The first was made for the Vitesse engine moved back to the bulk head so wont fit with the engine in the standard position. Will work with SU's and PI.

The second manifold I made more recently, (Last photo) with anti-reversion chambers on each primary, fits the GT6 with the engine in the original position. Going to make another in the future, now I have a TIG, for neater welds. Lots of work and head scratching. Vitesse is a standard engine, sprint carbs on a 2.5 long manifold. Does go very well and picks up quickly.

Experimented with the scavenging effect of the 631 blowing compressed air down one primary and sucked in a ball of tissue into the other primary, spitting out of the merge collector at great speed, I feel sure a 631 makes a big difference to performance, but that's just a feeling,  needs to go on a rolling road.

ozAPL.jpeg

Bvreo.jpeg

20200129_121719.jpg

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