iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 Hi Guys yes its still a conundrum.......double , triple, N factorial checking end float at the moment Iain Quote Link to post Share on other sites
BlueTR3A-5EKT Posted January 9, 2017 Report Share Posted January 9, 2017 (edited) Be sure to get the gear end float (up and down movement) correct or this happens to the gear, plus it breaks a cam tooth You are looking for 0.003" - 0.007" running clearance (gap) between the gear and the distributor adaptor housing. Cheers Peter W Edited January 9, 2017 by BlueTR3A-5EKT Quote Link to post Share on other sites
iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 Hi Peter just off into the barn to check this out.....teeth on drive gear look nothing like the above....thankfully! Cheers Iain Quote Link to post Share on other sites
iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 (edited) Washer used as spacer = 0.0695" Pedestal gap = 0.0630" Clearance =0.0065" so in tolerance Teeth wear uniform and minimal on cam and gear. Lobe 2 which I can see with a scope ( through the dizzy drive hole) has witness marks on max lift....discolouring really, should I be worried? 3 has no such marks. Please so Nooooooooooooooo! Iain Corrected the maths ! Edited January 10, 2017 by iain Quote Link to post Share on other sites
Guest ntc Posted January 9, 2017 Report Share Posted January 9, 2017 When was the cam fitted? Quote Link to post Share on other sites
iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 (edited) Cam/ new followers fitted with engine rebuild 750 miles ago. Cam lube used. However the valve clearances have not changed at all. Iain Edited January 9, 2017 by iain Quote Link to post Share on other sites
Guest ntc Posted January 9, 2017 Report Share Posted January 9, 2017 Cam from where? Quote Link to post Share on other sites
LGFromage Posted January 9, 2017 Report Share Posted January 9, 2017 Iain, My guess is that the cam is at fault (ouch!) on the grounds that the gear is wrong. If so my recommendation is to claim your money back and fit a Kent high torque cam with Piper hardened followers. Nice performance on the road and satisfying at TR track days. Tim PS Of course that assumes this arrangement is different from your current set up. Quote Link to post Share on other sites
iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 (edited) Kent Cam Fast Road .Hardened followers. Edited January 9, 2017 by iain Quote Link to post Share on other sites
iain Posted January 9, 2017 Author Report Share Posted January 9, 2017 I've just pulled another gear from another lump.Its fits identically interms of gear mesh on the new cam.That is a bit sloppy. Tomorrow I will try my gear in the other lump......I can't see in there tonight! If that fits better it's a good guess it's the cam gear,if not? More pondering. Iain Quote Link to post Share on other sites
mjdearing Posted January 9, 2017 Report Share Posted January 9, 2017 Hi Iain im reading and acting on all the ideas thats thrown into the ring trying to cure my tapping, just fitted several different gears into dist hsg all have same lash also fitted new cam bearings into a spare block, fitted brand new cam and tried all the gears i have (5 in total i get the same lash with all of them, i removed tacho boss thingy altogether from dist hsg and rigged a pvc pipe up and funnel got engine upto temp and tapping away and launched 2 ltrs of oil straight down into gear area,nothing altered at all tapping stayed so im sure if it was gear lash this would have flooded the gears and silenced them for a short while,tomorrow im going to do this down the rocker cover filler to flood down to followers just for curiosity . Little ends seem more and more likley ? Martin Quote Link to post Share on other sites
Peter Cobbold Posted January 9, 2017 Report Share Posted January 9, 2017 I had a noise very similar to that and was convinced it was valve/tappet/cam related, started to strip the engine and found a manky inlet manifold gasket (small hole burnt through underneath) ... got one of the uprated ones from Revingbone and stuck it back together again, ... quiet as a mouse!!, ... well as quiet as a 4A can be on Webers!!. Cheers rob The one cylinder fed by that hole would be running a higher compression than the others. I think that could make it knock at hot idle ( though the presumably leaner mixture would complicate matters). A gasket leak would not show up on a compression test as thats done with butterflies fully open. Not sure how Iaian could test- listen with stetchoscope for a hiss? spray WD40 ? Peter Quote Link to post Share on other sites
iain Posted January 10, 2017 Author Report Share Posted January 10, 2017 Rob, this is the second report of this nature I have read this week.....will investigate and report back. Martin, I had forgotten in a barn was my brother-in-laws 4A in kit form ( since 1988!)......so borrowed his gear yesterday evening, its no better or worse than mine. I will check its fit to its cam today when I can see, too dark last night. I guess I will find the same as you that the lash seen in my video is Standard pardon the pun Iain Quote Link to post Share on other sites
GT6M Posted January 10, 2017 Report Share Posted January 10, 2017 (edited) NTC says in responce t, me respondo The drive trys to climb up and will not affect timing light. no buy into this, Even it it did ride up the gear, it would still be in constant compression,so t,say no only that, but a witness mark would be showing on gear top, where it meets the pedastal bottom the only marks are on the bottom, where it runs int block that means it going doon, no up,!! Iain, Did ye get one of them 5£ endoscopes of e bay !! I still thinkits cam related Did ye see if the push rods are rotating if they not, then a rut is getting put into cam follower M Edited January 10, 2017 by GT6M Quote Link to post Share on other sites
Rob Salisbury Posted January 10, 2017 Report Share Posted January 10, 2017 Rob, this is the second report of this nature I have read this week.....will investigate and report back. Martin, I had forgotten in a barn was my brother-in-laws 4A in kit form ( since 1988!)......so borrowed his gear yesterday evening, its no better or worse than mine. I will check its fit to its cam today when I can see, too dark last night. I guess I will find the same as you that the lash seen in my video is Standard pardon the pun Iain Hi Ian, it's the clattery/clacky nature of the noise I find similar, dead easy to check, just take the inlet manifold off with the carbs attached, in my case it was due to the very marginal fitment of the Cannon inlets supplied with my Webers, cured by building up the outer edges with some aluminum welding and then dressing the contact faces. Cheers Rob Quote Link to post Share on other sites
Guest ntc Posted January 10, 2017 Report Share Posted January 10, 2017 Hi Ian, it's the clattery/clacky nature of the noise I find similar, dead easy to check, just take the inlet manifold off with the carbs attached, in my case it was due to the very marginal fitment of the Cannon inlets supplied with my Webers, cured by building up the outer edges with some aluminum welding and then dressing the contact faces. Cheers Rob +1 I was going by the heading,indeed had a 6 in last year and he was conviced it was rockers,turned out to be a blown exhaust gasket on one pot. Quote Link to post Share on other sites
iain Posted January 10, 2017 Author Report Share Posted January 10, 2017 Guys I am just checking the inlet/exhaust gasket now.... Marcus, apologies yes the pushrod's are rotating unless under compression. With my endoscope, sump still on, I can see lobes 1,2,3 easily, the coloured area on lobe 2 is I believe the tuftriding that eventually brightens up. (According to the supplier). Will report later Quote Link to post Share on other sites
iain Posted January 10, 2017 Author Report Share Posted January 10, 2017 Exhaust ports all show a slight leak on lower edge.....ordered some of Neil R's extra thick gaskets. Apparently that is quite a normal amount of backlash in the cam/distributor gear meshing. Next area to explore, the cam followers I think, just in case they are too tight? I didn't check their dims on installation..... Iain Quote Link to post Share on other sites
Guest ntc Posted January 10, 2017 Report Share Posted January 10, 2017 It is a mix match and if you fitted the gaskets dry ? there you go. Quote Link to post Share on other sites
iain Posted January 15, 2017 Author Report Share Posted January 15, 2017 Latest... New manifold gaskets, didn't make any difference.......or if they did is was very marginal. Ian V thought coil binding, I can get a 0.004" feeler gauge into the springs on max lift, however checking yesterday I don't have the extra 3mm valve lift as specified by Neil R instructions for fitting new camshafts. He recommends that on Max lift you can then lever the valve further open to give a 3mm clearance. After multiple readings (x3), pushrod 3 has only 1.6mm of additional movement. (Range 1.6mm to 2.6mm for the other pushrods) Time for the head to come off and check valves, seats, inserts, guides followers and cam me thinks? Iain Quote Link to post Share on other sites
RogerH Posted January 15, 2017 Report Share Posted January 15, 2017 Hi Iain, you are getting me worried. My tapping is slightly different from yours in that it is a precise tap from the front upper part of the engine. The head is new (Moss) and came complete with everything installed. I have found that the new seal on the timing chain cover, with new hub, is leaking oil so when I remove that I shall investigate the cam etc - but when the warmer weather turns up - August. Roger Quote Link to post Share on other sites
iain Posted January 15, 2017 Author Report Share Posted January 15, 2017 Hi Roger dont fret it will be something really simple.......... I hope Head of later, its really beginning to bug me. Cheers Iain Quote Link to post Share on other sites
Peter Cobbold Posted January 15, 2017 Report Share Posted January 15, 2017 Whatever the tapping is it has to go away when the rpm are increased over tickover. That doesnt sound to me like a mechanical conflict. I'd check the spark timing on all four cylinders, not just #1. As the tapping is around #2 or #3 it may be that a bent disy shaft is over-advancing the spark on those, hence combustion is too early. A bent disy shaft will also give different points gap on each cylinder. Peter Quote Link to post Share on other sites
iain Posted January 15, 2017 Author Report Share Posted January 15, 2017 Well the suspense is over! I am now suffering from an extreme form of sense of humour failure.:-( Cam followers all rotate.....When cold. When removed however 1 through 5 all have witness marks that indicate sticking. One clearly does not rotate when hot...It's has a constant swipe area across it. One is about to loose a chunk out of it. Approx 1/6 of its surface to a side depth of 5-6mm. What a pile of rubbish...They do 350 miles with no issue then ..... Another question for the knowledgeable, should the cam lobes be central to the bore of the cam followers? Two are very clearly set 1/3 the way across the bore.... Iain I will post photos tomorrow. Quote Link to post Share on other sites
RogerH Posted January 15, 2017 Report Share Posted January 15, 2017 Hi Iain, are you saying 6 lobes are fairly central to the follower bores and two are off-set by apprx 1/3. Can you compare with an old cam? Roger Quote Link to post Share on other sites
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