Inlet manifold

[Paul West]

Hi all,

I'm undertaking a GT6 mk3 rebuild and I have what looks like an early inlet manifold purchased with Strombergs with the yellow plastic covers.

These carbs have no internal parts.

A newer pair of carbs (with 6j needles) came with the car but can they fit the manifold? I have tried but seems the throttle linkage strikes the manifold body. Is there a solution as inlet mans are rarely available.

Many thanks

Paul

[Adrian Saunders]

Hi Paul, could you post some pics: both carb sets; manifold with carb on, errant linkages etc. 

[Pete Lewis]

6J is std needle for mK1  vit /gt6 2LTR.

i expect these have what i term the thames barrier type choke , where a ramp lifts the air piston,  so are early CD150

mk3 would have had CDS  150  with starting valve choke on front carb or later CDSE  150 with cap over the old adjuster under the float and have temperature compensators  on the sides and needle adjustment down the dasjh pot 

mk1 manifold is very different to a mk2 engine manifold  this is probably why they wont fit without much modifying the levers 

with associated   rod throttle  to  cable throttle evolution..

the air pistons are interchageable   even the bottom adjuster can fit the dash pot adjuster with a bit of fiddling and mix and match.

but early had fixed needle  cdse had biased needle   you can mix biased needle pistons into fixed  jet carbs 

Peet

 

[Paul West]

Thanks Adrian and Pete.

I have taken photos of the parts so will post asap to shed light on and solve this prob.

Paul

 

 

[Paul West]

Adrian and Pete,

Below are the photos.

The manifold is Stanpart 311749 and the spare carbs are tagged 3166.

The car is a Nov 73 reg on VIN plate KE 235700 so hope this helps but it may be that the spare carbs can be adjusted to fit, but if not your suggestions will be gratefully received.

Many thanks

Paul

[Pete Lewis]

Yes top pics are cdse correct for a mk3 cable throttle  the lower are older cd150 rod throttle the 

You need to change the throttle spindle levers over to make the cd 150 use the cable throttle .

Just what is missing from the cdse units   as they would be better to rebuild 

Pete

 

[Paul West]

Pete,

the butterflies are the only internal parts remaining on the cdse units.

This is my first rebuild and I'd like to up the engine from 96bhp (I own a 150bhp TR5) as I fear it may be underpowered by fitting a 150bhp cam and changing the carbs. I don't want anything too radical, just less strangled than the production figures.

Any recommendations will be gratefully accepted as I would like a reliable reasonably powerful tourer driven by the frustrating unreliability of my 31 year owned TR5.

Rgds

Paul

[NonMember]

Personally I like the early 150CDs - much easier to adjust and have never given me a problem. The factory did fit them with cable throttle on late Mk1 Vitesses, so the bits you need ought to exist. However, if you're planning to run a wild cam, and are willing to accept the unreliability that could induce, then you probably want to look for a TR250-like manifold and fit 175CDs. (I've heard that the actual TR250 manifold doesn't fit a UK head but I don't know the details)

[Nick Jones]

Another vote for the early Strombergs here.

As regards squeezing more power from the engine, the factory Mk 2 Vitesse and GT6 cam (also used on the earlier 132 bhp PI saloons) is an excellent all rounder and not the limiting factor on this engine. A bit of head work, a better exhaust manifold and then bigger carbs should make for a nice torquey engine that will also rev well and still have a good idle and traffic manners.

The TR5 cam does not play nicely with CD carbs at low rpm and really needs ITB injection or Webers. Some say the Newman PH 1 (mild) & 2 (sportier) can add power without sacrificing too much at the bottom end.

As regards the TR250/ Federal TR6 manifolds, it depends. Some, but not all, have different port spacing from the usual Euro spec, so care is needed.

Nick

[Paul West]

Thankyou for your replies.

I will swap over the relevant parts of the CDSE's to ensure the CD's fit (possible?) as they have the vote of confidence.

A TR5 cam was recommended earlier but sounds a bit wild so is the Newman PH2 the same as the Mk 2 Vitesse, Mk 2 GT6 and 132bhp PI cam? If so, I'll go with that.

I've found a good gearbox/ overdrive and a 3.27 diff  as I plan European touring and favour the longer final drive, partly influenced by my pal's non o/d Mk 1 Vitesse (at 70mph almost unbearably loud) and my TR5 (A lazy 2700rpm at 70mph).

Any other pointers or things to avoid will be gratefully received.

Many thanks

Paul

I've source a good gearbox/overdrive unit from a Mk 3 GT6 and a 3.27 d

[dave.vitesse]

The later 150CDSE carb generally runs too weak. Fitting the 150CD or 150CDs will improve the overall performance of the late 2 Litre engine. The Mk2 Vitesse/GT6 cam is the best Triumph cam when using carbs. Part number 308778, one large groove as well as the smaller retaining groove.

The 150BHP TR5/TR6 cam has too much overlap for carbs, this results in a large amount of the fuel going down the exhaust pipe! It's intended to have a shot of fuel delivered by an ejection system. With carbs as long as the engine has suck the carb will deliver fuel hence the problem with the overlap with this cam.

If you have a late GT6 Engine, KE10001 onward, it has the TR6 125BHP cam. KE1 to KE10000 had the Mk2 cam.

In the distant past I have fitted the Mk2 cam, 150CDs and a Mk2 dizzy to a domed piston engine, late Mk3, and this woke the engine up.

Dave

[Paul West]

Thanks everyone.

I'll go with the 308778 cam, CD150's and a better exhaust manifold.

The engine and head will need rebuilding which is beyond my capabilities so is there a rebuilder members favour? I've been recommended to Bromsgrove Engineering but wonder what you think?

Paul

 

 

[Nick Jones]

Worth noting that Chris Witor sells a variant of the 308778 cam with extra lift on the inlet lobes. This seems to get good results. There are a few out there that have the extra lift on the exhaust lobes (by mistake we assume) but now CW is aware there won't be any more of the latter!

Nick

[Paul West]

A thought. As I'm having trouble with the carbs not being compatible with the manifold I have, to which models were CD150's fitted and would that manifold fit the GT6 Mk3? It would seem easier than cobbling together a mix of 150's and 150se's which may or may not be successful.

Paul

[Pete Lewis]

Without checking I would say  the CD150 were on mk1 so very different manifold porting

As the base CD150  castings is pretty similar to a CDSE I can only think its the idle and other levers on the throttle spindles that

restrict the fit of them to the mk2 engine manifold  these have to be swaped to make them cable pulled design of the mk2 engine set up

( this being mk2 engines not mk3 gt6  or Gt6+   which has a mk2 engine )

 

[Nick Jones]

Mk 1 manifold is completely different at the head end, no chance of it fitting the Mk 2 head.

I have run CD 150s on a Mk 2 Vitesse. They came from a fairly late Mk 1 2L and were originally used in conjunction with an early Mk2 2000 saloon manifold. Later on I swapped them to a Vitesse Mk2 manifold. I don't recall any particular issues getting things to work but it was a long time ago now (late 80s) and I certainly had the benefit of having the complete Mk 1 and complete 2000 saloon setup to hand at the time. Also the benefit of the cars lying around in scrapyards if more parts needed.......

I don't remember why I didn't use the 2000 saloon carbs.

Nick