Lee Dutton Posted December 10, 2009 Report Share Posted December 10, 2009 I have found in my garage 2 new sets of spark plugs NGK BP6ES and Champion L87YC I thought that they were both suitable for my 4a but on closer inspection the threaded portion of the Champion is approx.10mm shorter than that of the NGK. Can anyone throw any light on this subject please? Also do the codes have any meaning? Best regards Lee Quote Link to post Share on other sites
RogerH Posted December 10, 2009 Report Share Posted December 10, 2009 Hi Lee, if you google the NGK and Champion web sites you can find all the info you need. Roger Quote Link to post Share on other sites
RogerH Posted December 10, 2009 Report Share Posted December 10, 2009 Hi Lee, thinking about it the BP6E is for a TR6. Roger Quote Link to post Share on other sites
Lee Dutton Posted December 10, 2009 Author Report Share Posted December 10, 2009 Yes Roger, the ones I have got are for a TR6 4a are BP6HS with a shorter reach,glad I checked! Quote Link to post Share on other sites
ianc Posted December 10, 2009 Report Share Posted December 10, 2009 I use BP7HS with 32 thou gap on my (modified) TR4 (4VC), which has a TR4A head and Newtronic (Piranha) electronic ignition with Sports coil. Never misses a beat, even in traffic jams in the heat of summer. Ian Cornish Quote Link to post Share on other sites
Nigel 628 Posted December 11, 2009 Report Share Posted December 11, 2009 Not that I'm a big fan of Japanese kit, but from experience I wouldn't use anything else other than NGK plugs, aspecially if the alternative is Champion! But NGK often come with the old-fashioned screw-on tips, so make sure you nip them up with pliers before fitting or they can come loose and cause misfiring. Ian: I realise if you don't use 4VC for historic rallies it doesn't matter, but do you have any info on the availability of electronic ignition on four-cylinder TR's prior to 1968? The general opinion is we have to stick with points but I well remember using Pirhana on my old Minis many years ago, I just can't remember when! Nigel Quote Link to post Share on other sites
lynchpin Posted December 11, 2009 Report Share Posted December 11, 2009 Hi all I notice that Ian mentions 4vc has a 4a head according to the register and going by engine No-s my 62 tr4 has a 4a engine, not unusual i admit due to age, i was wondering what the difference between the heads are. According to the specs the 4a is suspossed to have something like an extra 4bhp (big deal).. Cheers Phil.. Quote Link to post Share on other sites
TR 2100 Posted December 11, 2009 Report Share Posted December 11, 2009 i was wondering what the difference between the heads are. According to the specs the 4a is suspossed to have something like an extra 4bhp (big deal).. Squish area, I think. TR4A heads had one but TR4s didn't. Also, the 4A had a better designed inlet manifold which would contribute a little to the bhp. (all subject to correction by those better informed). AlanR Quote Link to post Share on other sites
Badfrog Posted December 11, 2009 Report Share Posted December 11, 2009 Also, the 4A had a better designed inlet manifold which would contribute a little to the bhp. AlanR I concur, the 4A manifold makes a big difference, although its requires some inside grinding. Read Kas Kastner on the matter. Badfrog Quote Link to post Share on other sites
ianc Posted December 11, 2009 Report Share Posted December 11, 2009 Nigel628: sorry, no idea. I used conventional ignition in the 1960s onwards and only went to Newtronic/Piranha when 4VC was rebuilt (back on the road in 1993). TR4Tony (Tony Sheach) should be able to advise - I suggest you PM him. 4VC has TR4A head and TR4A inlet manifold, both fitted by Gordon Birtwistle, who worked in the Triumph Comps Dept and bought the car from Triumph in 1964. Gordon modified the head and inlet manifold in the manner prescribed by American tuning wizard Kas Kastner, who was obtaining far more power from the TR 4-pot than anyone in the world at that time (so much so that Triumph in the UK wouldn't believe his figures until he demonstrated to them!). The use of the TR4A head and inlet manifold with these modifications, combined with the SAH 4-branch exhaust manifold and modified camshaft, work together to provide a lot of torque - which exceeds that of a standard TR4 from 2800 rpm onwards, is still increasing at 3500 when the standard car is starting to fall, hits its peak at 3900 and remains very close to that level to beyond 5000; at 4800 it is about 30% higher than the standard engine, which is diving fast! You can see the curves in TRAction 238 - 4VC is green, standard TR4 is red (you may need a magnifier!). Thanks to Pete Buckles, who imported the books in the early 1970s, I have Kastner's 3rd edition (1965) of his "Competition Preparation Manual TR4/4A" and the 5th Edition (1977). An up-to-date (and much larger) version is available from the Register Shop. Ian Cornish Quote Link to post Share on other sites
TR4Geoff Posted December 13, 2009 Report Share Posted December 13, 2009 Hi all I notice that Ian mentions 4vc has a 4a head according to the register and going by engine No-s my 62 tr4 has a 4a engine, not unusual i admit due to age, i was wondering what the difference between the heads are. According to the specs the 4a is suspossed to have something like an extra 4bhp (big deal).. Cheers Phil.. Hi Phil, I believe the so-called '4A' head was fitted to the later '4s' although I don't know when the change occurred. As Alan mentioned, it was the 'squish'area that made the difference and further efficiency was obtained from the improved '4A' inlet manifold . In addition the '4As' had a slightly different camshaft to the '4s'.I believe that unless you go to a specialist, you will now only be offered the '4A' specification cam. My '4' (1964)originally had engine No CT34397E and I have very good reason to believe that the recently replaced '4A' head was an original fitment. Geoff Quote Link to post Share on other sites
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