david johnson Posted November 24, 2012 Report Share Posted November 24, 2012 The later TR4A inlet manifold has 35 mm ports at the head junction. The TR3A unit 38 mm ports. Should you widen the ports on the manifold, or presuming it was made for the same head leave alone. Thanks David Quote Link to post Share on other sites
vivdownunder Posted November 25, 2012 Report Share Posted November 25, 2012 It's only a 1.5mm step around the circumference. I've seem them chamfered to suit but it's not essential in a road car. More of a problem with the TR4A inlet manifold is the front H6 carby with original aircleaner being too close to the inner guard. Viv. Quote Link to post Share on other sites
BrianC Posted November 25, 2012 Report Share Posted November 25, 2012 When I had a head modified by SAH many years ago, the conventional wisdom seemed to be to have the inlet manifolds/ports matched. However, after the demise of that head, I had a NOS standard head modified and asked for the matching again but was told it's now considered better to have a little disturbance of the gas flow, so I should save my money. Quote Link to post Share on other sites
Rodbr Posted November 25, 2012 Report Share Posted November 25, 2012 FWIW I spoke recently to Andrew Turner of Turner carbs and he advised that the step was in fact benificial to good fuel air mix on an otherwise standard engine. The slight turbulance in fact helped and good exhust flow was a better option. Went with this on my otherwise standard engine but for the tubular manifold and seems to work. My early 2 had in fact a step from the ST from day one. rgds Rod Quote Link to post Share on other sites
Andrew Smith Posted November 25, 2012 Report Share Posted November 25, 2012 Hi David, TuRK has got the later TR4A manifold (307455) and HS6s bolted straight on and goes like stink without any mods to the ports - fit and forget! Just remember to blank off the breather thread! Cheers Andrew Quote Link to post Share on other sites
Guest ntc Posted November 25, 2012 Report Share Posted November 25, 2012 Andrew What dizzy do you have fitted there? Quote Link to post Share on other sites
Andrew Smith Posted November 25, 2012 Report Share Posted November 25, 2012 Neil, It's a 25D4 (Moss LU40795R) for 86mm and has been fitted since 2003 - TuRK's original was shot to bits. See: http://www.moss-europe.co.uk/Shop/ViewProducts.aspx?PlateIndexID=17543&SortOrder=7 Cheers Andrew Quote Link to post Share on other sites
peterm Posted November 25, 2012 Report Share Posted November 25, 2012 Hi Andrew, Those air filters look like they might be just what I'm after. What make are they and where can I get them? I presume they fit HS6s and also, what's the clearance with the inner wing? Cheers, Peter Quote Link to post Share on other sites
Alec Pringle Posted November 25, 2012 Report Share Posted November 25, 2012 On a standard engine there isn't much difference either way between opening up the manifold or leaving it 'as is'. If the engine is well tweaked and the cr raised it's a another story, and there is significant top end benefit from port matching. So I found playing with TR manifolds on a rolling road long ago. Cheers, Alec Quote Link to post Share on other sites
Andrew Smith Posted November 26, 2012 Report Share Posted November 26, 2012 Hi Andrew, Those air filters look like they might be just what I'm after. What make are they and where can I get them? I presume they fit HS6s and also, what's the clearance with the inner wing? Cheers, Peter Hi Peter, These are the little chaps: http://www.moss-euro...409&SortOrder=5 - and the wing clearance is about 1" at the closest point Cheers Andrew Quote Link to post Share on other sites
david johnson Posted November 27, 2012 Author Report Share Posted November 27, 2012 Thanks all for the advice Regards David Quote Link to post Share on other sites
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