Triumph 1200 6 port head to Single Weber Conversion Manifold

[Jon J 1250]

https://www.ebay.co.uk/itm/362221880363

Hi,

I'm not really into modifying cars but tempted to make my Herald 12/50 a bit more compatible with todays traffic when it comes back from extended hibernation, so giving it some thought.

See link above, has anyone got any experience with these, would it produce a meaningful power increase on a Herald 12/50 engine, especially if combined with a Rimmer Bros 4 Branch tubular manifold?

Regards

Jon

[poppyman]

I don't think it would be worthwhile Jon, not without a lot more work on the engine. You will have a bigger fuel bill for a start and not a lot of extra grunt. Just my opinion others might think different.

Tony.

[NonMember]

I think, as Tony says, you're going to need to be seriously "into modifying" to get anything worthwhile out of that. For more power in a Herald, if you really need it, it's probably cheaper and easier (and more reliable) to drop a 1500 in there.

[Pete Lewis]

agree if you want aheadache    go a head  but a  spitty   twin SU 125 would be far better suited and way better on ecconomy .

and if converting to spitfire spec add a cam change or you are just wasting money with no gain

the webber just eats fuel and wont add many horses as its all the other things that restrict getting mpre power 

the clue is fit what triumph specified on the uprated engine and it does what it says 

fit on a bolt on must have and you get the headache  plus sourcing linkages that are readily available 

cheaper and easier option is fit a 3.63 diff   we have 1200 with one down here and it has no trouble keeping up the pace 

Pete

[Colin Lindsay]

At the very least you'll need a hotter cam plus a better exhaust manifold; as the guys have said all you'll do is use more fuel and will struggle to get the mixture right.

I have a Weber setup for the 1200, had it for years but never yet fitted it:

I've also got an alloy blank for fitting the carb to the original manifold but reckon this would be for very little gain:

You can also get a Weber version of the Solex that's practically a straight fit, but again not much benefit over standard without other engine and head mods.

Twin SU on a Herald / Spitfire manifold with your 12/50 cam, plus a tubular manifold might give some boost, as much as you can get out of a 12/50 engine, but still miles better than my 39hp Herald engine...

 

 

[DanMi]

swop to the mk2/3 camshaft with twin 1.25 SUs and a tubular manifold, basically recreate a mk2 spit engine with 68hp as the factory did.

[Clive]

24 minutes ago, DanMi said:

swop to the mk2/3 camshaft with twin 1.25 SUs and a tubular manifold, basically recreate a mk2 spit engine with 68hp as the factory did.

Head? Are valves bigger and higher CR? Plus distributer curve. 

 

My take, a 1500 herald with overdrive is a great car.

[2500ku-man]

The 1500 engine swop is the best option with a lot less proble problems....   Bill.

 

[DanMi]

10 hours ago, clive said:

Head? Are valves bigger and higher CR? Plus distributer curve. 

 

My take, a 1500 herald with overdrive is a great car.

compression was 9 rather than 8.5 so maybe a small skim, the only other difference was the valve retainers are collets on the spit not the 8 shaped hole and yes the distributer curve is different. 1500 is a good choice but does need overdrive or a diff swop as it is a lower revving unit and the 4.11 is just too low geared. (had a 1500 in my mk2 spit for ages, but I personally prefer the revvy smaller unit in a sports car which of course the Herald isn't)

[Colin Lindsay]

10 hours ago, 2500ku-man said:

The 1500 engine swop is the best option with a lot less proble problems....   Bill.

 

Problem with that, is that it's an engine swap so not an upgrade for the original engine; depends of course what the OP wants but personally I like to explore what can be done with the original rather than fit a bigger engine. Most of the carb combinations I've used over the years were for conversation-pieces only at shows and never seemed to provide much of a difference to the actual power; in fact some actually made it worse, but then I never went as far as gas-flowing or uprating the cams etc. as I should have.

[Jon J 1250]

Thanks all, lots to take in.

I wanted ideally to keep the original engine as it is a lowish mileage car (50k) and has a lot of history with both me for past 26yrs and the previous owner for 30 years before that (only a 2 owner car).

I have looked in to the Spitfire mk2 exhaust manifold, which it appears Rimmers sell a stainless version of (looks same to me), I am I best going with this or an original Stanpart one?

Then I guess I will look out for a Mk2 Inlet manifold, are these rare as I haven't seen one for sale recently?

That way I should get 60+bhp with the 12/50 cam and will at least be using period factory upgrades.

I do have a recon and part assembled early Mk3 Spit engine in storage that I started assembling in the mid 90's but never finished, but still want to try perk up the original engine if I can.

[Clive]

 

1 hour ago, Jon J 1250 said:

Thanks all, lots to take in.

I wanted ideally to keep the original engine as it is a lowish mileage car (50k) and has a lot of history with both me for past 26yrs and the previous owner for 30 years before that (only a 2 owner car).

I have looked in to the Spitfire mk2 exhaust manifold, which it appears Rimmers sell a stainless version of (looks same to me), I am I best going with this or an original Stanpart one?

Then I guess I will look out for a Mk2 Inlet manifold, are these rare as I haven't seen one for sale recently?

That way I should get 60+bhp with the 12/50 cam and will at least be using period factory upgrades.

I do have a recon and part assembled early Mk3 Spit engine in storage that I started assembling in the mid 90's but never finished, but still want to try perk up the original engine if I can.

I would try to find an original, but rare thesedays. I got one 25 years ago, then about £20 but needed a bit of welding.

The real gains will be in compression and cam, plus a carb that is easier to tune. If teh budget is available, a single weber will work pretty well if the rest of the engine is sorted. My mk3 spit with a pair of Dellorto DHLA (same but better than weber) will get over 40mpg on the motorway. But needs a good advance curve for the distributer and properly setting up. It also has a "fast road 89" cam, but the torque at lower revs is very good. Of course, Colin has "history" with alternative carbs, and a single SU or Stromberg would also give good results.  The key is a fully thought out conversion. A carb plus exhaust won't do much.

 

[Pete Lewis]

if the dark art is dark

then sticking to Triumph based specs means it will do what it says 

Pete

 

[poppyman]

The twin choke down draft Weber that Colin has would be a worthwhile fit. They are a great carb it's like having a twin carb set up when you need it and a single when you don't. Even putting a 1500 in is reversable.

Tony. 

[DanMi]

the rimmers exhaust is a 2 piece it would seem, which will make it easier to fit than the standard, which is an absolute pig without a 4 post lift. You may also find that the exhaust fouls the crank pressure release tube as the mk2 did not have this. 

[Colin Lindsay]

Funnily enough the one I trial-fitted to the 1200 recently (a Triumphtune stainless version I've had for years) cleared the drain tube but fouled on the bellhousing and rear engine plate. It needs a bit of fettling (read bending) but I've gone back to the original setup in the meantime to get the engine running, after which I can experiment. As you can see Jon J it's the tubular setup for the 1200 plus a twin-SU manifold but for now it's on the back burner.