murrayarnold Posted September 23, 2019 Report Share Posted September 23, 2019 Good day all. I have a wee dilemma. I have bought a set of triple strombergs including inlet manifold from the US for my tr6. Which is a british car. But i have only found out recently that there are different heads. Regarding the inlet ports. There are apparently 2 sizes. 48mm and 55mm. Where are these dimensions? I have to make sure i have the correct manifold and am not at home so need someone to take measurements. Any help much appreciated Quote Link to post Share on other sites
Dave McDonald Posted September 23, 2019 Report Share Posted September 23, 2019 Hi Murray or is it Arnold? Don't know about the 48 and 55 mm dimensions but generally the UK PI cars had a spacing of 22mm between each pair of inlet ports. The USA carburettor cars had a dimension of 17mm between the inlet ports. All the mounting bolts/studs on both types of head fit both types of manifolds. However, fitting the "wrong" manifold to the "wrong" head will result in a moon shaped crescent of misalignment, restricting the flow. Fitting USA carb manifold to UK PI head will place the crescent restriction near the middle of each pair of ports. Fitting UK PI manifolds to a USA carb head will locate the crescent restriction on the outside of each pair of ports. I fear that, if your car is an original British car with Lucas PI throttle bodies, then the USA manifold will result in this restriction. Ask me how I know! If you are intent on using these triple Stromberg carbs and manifold you may have to invest in a USA cylinder head. They are plentiful. Perhaps, if you are set on triple carbs, refurbishing those Webers might not be such an expensive option?! Dave McD Quote Link to post Share on other sites
dingle Posted September 23, 2019 Report Share Posted September 23, 2019 The early USA heads (narrow ports) are .640" between intake ports. The later USA heads (wide port) heads are .840" between intake ports and are the same as the PI head. I will let you do the inch to metric conversion. Berry Quote Link to post Share on other sites
murrayarnold Posted September 24, 2019 Author Report Share Posted September 24, 2019 were there a difference between American cars and British cars, or was this difference the same regardless? Quote Link to post Share on other sites
pheaney Posted September 24, 2019 Report Share Posted September 24, 2019 Some more info on the head spacing in a previous post CC75001 seems to be the change point. Quote Link to post Share on other sites
jr2 Posted September 29, 2019 Report Share Posted September 29, 2019 A quick way to determine head port spacing is by identifying the intake manifold type. TR6 to Engine number CC750000 Quote Link to post Share on other sites
jr2 Posted September 29, 2019 Report Share Posted September 29, 2019 (edited) Late / PI port spacing = Long branch intake manifold Edited September 29, 2019 by jr2 add "long branch" Quote Link to post Share on other sites
jr2 Posted September 29, 2019 Report Share Posted September 29, 2019 (edited) Thus US market production engines up to the end of model year 1971, Engine number CC750000, have narrow port cylinder heads - Intake port spacing 1-7/8″ center to center. This cylinder head was fitted with an shallow intake. US market 1972 onwards (LATE) engines had the same port spacing as the PI head - Intake port spacing 2-3/16″ center to center. This cylinder head was fitted with the long branch intake manifold. Thus if your car is an UK market car and retained it original PI engine, the port spacing for the used Stromberg setup = 2-3/16" I remember you mentioning that your car has Weber DCOE? I used to know of a man in Pula that used to tune them, but, he has since retired. I don't think that you will gain a whole lot with this set up except that it will be quieter and may drive around town easier. Edited September 29, 2019 by jr2 long branch Quote Link to post Share on other sites
murrayarnold Posted September 30, 2019 Author Report Share Posted September 30, 2019 thank you sir for that. I have a feeling my investment in the Strombergs now needs about 400 pounds spent on a new inlet manifold. Oh the joys of classic cars. This is exactly why i am going for triple Strombergs. My loud racing days are behind me. I want the car to be smooth and economic. I dont need the roar any more. I love just jumping in the car with my wife and driving the Croatian coast line. Which is a real undiscovered and unappreciated gem. The road hugs the coast and passes by so many lovely towns and sea side villages. Sitting in a cafe sipping a coffee, looking over the sea and the yachts with my classic car in the foreground. It dosent get any better. As you can see we do love to be beside the sea side :-) Quote Link to post Share on other sites
jr2 Posted October 1, 2019 Report Share Posted October 1, 2019 Agreed.. The Jadranska Magistrala is unappreciated.. These guys have figured it out.. Adriatic Odyssey Quote Link to post Share on other sites
jr2 Posted October 1, 2019 Report Share Posted October 1, 2019 As a side note.. the air box will also need to be replaced since the spacing of the carburetors are not the same. Quote Link to post Share on other sites
mgmike Posted February 1, 2023 Report Share Posted February 1, 2023 So I'm trying to determine if circle B cylinder head is wide port or narrow port.Do I measure the distance center to center on ports 1 and 2 or ports 2 and 3 Thanks Mike Quote Link to post Share on other sites
BlueTR3A-5EKT Posted February 2, 2023 Report Share Posted February 2, 2023 The inlet ports. They being 2 & 3. Quote Link to post Share on other sites
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