1.8TC exhaust system options

[martinclan56]

The 1.8 based Roadster I am restoring currently has what I believe to be an exhaust manifold from an MGB, which I understand was slightly longer than that from a 1.8TC, which has led to the previous owner contructing an exhaust that runs under the chassis rail. The exhaust is shot anyway and I would like to replace it with something like that was originally intended exiting above the chassis via the bonnet side. Preferably with the exhaust system itself in stainless.

Would the forum like to suggest what are the options? I guess that 1.8TC exahust manifolds are now virtually unobtainable which means whatever I do it will have to be based arround whatever is available for the MGB. Pictures would be good :-)

Cheers, Robin

[jon_cox]

Re: 1.8TC exhaust system options

If it were me, I would build a new system from stainless, including the manifold. The cast iron manifolds are not free flowing, are prone to cracking and most importantly can't be wrapped in heat tape. There has always been a long standing debate (and quite recently too) on overheating issues. Exhaust wrap will significantly help with under bonnet heat and stop fuel evaporation in twin carb models with slim (or no) spacer blocks fitted between carbs and inlet manifold. I note you have early bonnet sides with no louvres fitted so this is even more important in your case.
Just my opinion so hope it helps to guide you.

[HairyDave]

Re: 1.8TC exhaust system options

I wonder if the LCB exhaust could be modified to fit? In SS without the right welding equipment a bit problematic. The SS LCB is not cheap to begin with. Possibly a trawl through exhaust makers.

[stevejgreen]

Re: 1.8TC exhaust system options

An MGB exhaust might be a starting point but the MGB has a much greater ground clearance and more room than a roadster, unless you want to compromise ground clearance running the exhaust under the car from front to back, rather than under the running board side exit, which always worked for me.
There are multiple variables of inlet manifold from the Marina TC (combined inlet/exhaust) setup to infinite choices depending on your chosen carburettor.
If you are hunting for more power, Zetec is possibly the best option.

[Ye Ol Ripper]

Re: 1.8TC exhaust system options

Jon- it is interesting that you have said that the cast Iron manifolds are not free flowing as various technical articles on the MGB state that the manifold with twin down pipe's works very well and is unlikely to be improved on.

Steve Green, what's your opinion on the 1.8TC manifold with twin downpipes?

Maniflow Developed the LCB manifold and RC40 rear box for the mini, he also makes an MGB version in two diameters.

It would be worth taking your car there if your near Salisbury ,Hampshire , as when I was dyno testing his exhausts worked well and gave useful gains . A manifold and system on our bench dyno for a vauxhall 2.0 16V gave 10 BHP over the standard system on a standard 150 BHP engine. However if you modify your B series with cylinder head Work and a Camshaft the gains should be a bit more than 10 BHP.

Maniflow can supply a good flowing exhaust box or make you a bespoke system in their workshops with the car on their ramp. Try giving them a call , I used to deal with David Dorrington for other cars I had in the past .
https://www.maniflow.co.uk/


Another chap to contact is Mervyn at Fast Road Conversions, Ashford in Kent.
his exhausts are also of top quality and also worked very well on the Dyno.

http://www.fastroadconversions.co.uk/kit-cars/

[lil_red_roadster]

Re: 1.8TC exhaust system options

Would the forum like to suggest what are the options? I guess that 1.8TC exahust manifolds are now virtually unobtainable which means whatever I do it will have to be based arround whatever is available for the MGB. Pictures would be good :-)

Cheers, Robin

It's possible to butcher an MGB downpipe to exit under the chassis rail (I did this back in the day and IIRC the chrome-bumper downpipe is the shortest version), but getting the 2-1 section bent to exit via the bonnet side would probably require trailering the car to the likes of Maniflow, Custom Chrome or other professionals. Another option is an MGA manifold, which is a 3-1 system, meaning only 1 pipe needs contorting. I have this arrangement, although it still (with flexi-pipe, temporarily, long-term!) exits under the chassis...one day I might get around to asking Custom Chrome to finish the job properly...but for now it works fine.

MGA_Manifold_small.JPG

[Ye Ol Ripper]

Re: 1.8TC exhaust system options

The 3 branches on the manifold that goes into 1 from a MGA , appear longer than the 3 into 2 manifold I have fitted on my Roadster.
Mine still has the original fabrication exhaust that the car was built with in the late 80's, it heads out under the chassis rail, the car clears all speed humps that I have been over so far without touching . It does an almost 90 deg turn heading to the nearside and s bend before the silencer.

I plan to lose the first 90 deg bend by rotating the downpipe on the manifold downpipe Doughnut sealing rings by the 90 degrees, it will then route under the chassis rail. I will make the exhaust using 2" Stainless tubing.

1& 7/8" will work just as well but I think 2" tubing is more readily available.

[lil_red_roadster]

Re: 1.8TC exhaust system options

TC downpipe on eBay here item #253117890637

[stevejgreen]

Re: 1.8TC exhaust system options

TC downpipe on eBay here item #253117890637

Wow, that’s expensive, and you don’t get the manifold either!

[Ye Ol Ripper]

Re: 1.8TC exhaust system options

As the 1.8TC exhaust has to be cut would the following fit from moss ?
https://www.ebay.co.uk/itm/MGB-Exhau...sAAOSw24hcq6Qn

[martinclan56]

Re: 1.8TC exhaust system options

As the 1.8TC exhaust has to be cut would the following fit from moss ?
https://www.ebay.co.uk/itm/MGB-Exhau...sAAOSw24hcq6Qn

I suspect it has something like that at the moment - albeit 90% rust. The problem is that it exits below the chassis rail. I really want to avoid that.
What would be interesting to see is what the Marlin supplied exhaust looked like. There was one specifically for the TC I believe looking at the build instructions.

I checked my car again today and it definitely has an MGB exhaust manifold. I am trying to verify that this was longer than the Marina TC one thus making the problem of getting the exhaust to exit above the chassis rail even worse.

Cheers, Robin

[lil_red_roadster]

Re: 1.8TC exhaust system options

The TC manifold, 12H3550, is different to the MGB insofar as it has plinths cast into it upon which the inlet manfiold is bolted. There are 2 manifolds listed for the MGB, 12H709 for HS carbs and 12H3911 for HIF - the only difference being the flange depths.

I'm not aware of any differences in length between TC & MGB manifolds, though would expect downpipes to vary due to differing ride heights etc. (CB, RB & Marina all being different).

The top-bottom height of the TC manifold, measured from the top of the centre head flange to the face of the downpipe flange, is 270mm.

TC Manifold 02 Small.jpg

TC Manifold 01 Small.JPG

[stevejgreen]

Re: 1.8TC exhaust system options

The TC manifold, 12H3550, is different to the MGB insofar as it has plinths cast into it upon which the inlet manfiold is bolted. There are 2 manifolds listed for the MGB, 12H709 for HS carbs and 12H3911 for HIF - the only difference being the flange depths.

I'm not aware of any differences in length between TC & MGB manifolds, though would expect downpipes to vary due to differing ride heights etc. (CB, RB & Marina all being different).

The top-bottom height of the TC manifold, measured from the top of the centre head flange to the face of the downpipe flange, is 270mm.

[ATTACH=CONFIG]11815[/ATTACH]

[ATTACH=CONFIG]11816[/ATTACH]

I would concur with Jez.
I have had several B series manifolds alongside eachother none of them significantly different apart from the TC version having mounting bosses for the inlet manifold.
So far as down pipes go, the MGB ones vary but I have never measured them because I could not positively identify their actual origin, if I could, I might well have documented it.
Suffice to say that the down pipe of a TC roadster that I have specific experience of, I believe Marlin original, turned quite sharply to exit above the chassis rail, the whole assembly not being close to free gas flow, being restricted by physical space to try anything else.

[martinclan56]

Re: 1.8TC exhaust system options

Thanks all for the info, particularly the pictures. The MGB and TC manifolds do appear to be similar in length - certainly not significantly different. In which case I will have to re-think the exhaust system as it would require a considerable bend to get it to exit above the chassis rail. May look better but not good for gas flow as Steve said.
If anyone has an original Marlin system still in place (they were stainless) it would be good to see a picture though!

Cheers, Robin

[Ye Ol Ripper]

Re: 1.8TC exhaust system options

My Roadster has the 2 bolts from the inlet manifold going into the exhaust manifold , ie I have the 1.8TC manifold fitted .

As previously mentioned my exhaust runs under the chassis rai and which from what I have read yesterday, seems to be a better method for gas flow.

Furthermore, interestingly the side mounted silencer only uses the Marlin chassis welded exhaust hanger for the attachment of a flexible strap as the silencer used sits further back than normal towards the rear wheel.

Possibly because of the location of the silencer,this may possibly make the bends more gradual, which maybe a point to consider when making your exhaust.

I do think there is scope to improve on what's been created by the original builder of my Roadster, but importantly it has passed over some very high speed bumps without touching them so far.