westofsouth Posted June 22, 2017 Report Share Posted June 22, 2017 A subject I know very little about. With the rocker cover off noticed that the inlet valve remained cracked open for about the first 40% of the compression stroke. Is this normal for a TR5 cam? Is there a straightforward way to check cam timing? Thanks Quote Link to post Share on other sites
Rob Salisbury Posted June 22, 2017 Report Share Posted June 22, 2017 Hi, If you assume it's a standard TR5 cam (ie CP cam) then the valve timing is 35/65/65/35. This means that the inlet valve of any of the 6 cylinders should begin to open at 35 crankshaft degrees before top dead centre of it's compression stroke. So you need a degree wheel connected to the front of the crank and this needs to read zero at top dead centre with cylinder no.1 on compression stroke, wind the crank back past 35 degrees before TDC and see if your valve in No.1 cylinder (second valve in from the front of the engine) has fully closed (check valve clearance with a feeler gauge), then bring the crank back towards 35 degrees and you should gradually see the the valve clearance close up (this is the clearance ramp), at 35 degrees the valve should begin to open, if it really is a TR5 CP cam, and if the cam has been timed correctly. Cheers Rob Quote Link to post Share on other sites
John L Posted June 22, 2017 Report Share Posted June 22, 2017 Rob I think you need to reread your article, I think the inlet should be closed on the compression stroke, not opening. Quote Link to post Share on other sites
rhine Posted June 22, 2017 Report Share Posted June 22, 2017 Helpful article on how to time a camshaft - http://www.newman-cams.com/camshaft-fitting/ Richard Quote Link to post Share on other sites
HSM Posted June 23, 2017 Report Share Posted June 23, 2017 From the workshop repair manual to check cam timing set no 1 cyl. on t.d.c. adjust no 11 & no 12 rocker clearances to .120in. This may vary according to the lift of the camshaft used. NOTE- this clearance may vary according to the lift of the camshaft used. The clearance should be sufficient to enable feeler gauges of reasonable thickness to be inserted when the valves are on the rock. Oscillate the camshaft a few degrees so that numbers eleven & twelve valves are on the rock whilst checking both valve clearances with two feeler gauges of the same value. when the clearances are the same the camshaft & crankshaft are in there correct relationship. If when checking the clearances are not the same the timing is not to spec. Harvey S.Maitland Quote Link to post Share on other sites
Rob Salisbury Posted June 23, 2017 Report Share Posted June 23, 2017 Rob I think you need to reread your article, I think the inlet should be closed on the compression stroke, not opening. Yikes!!!, that's not going to work!!, brain fade!!, ..... Suck, Squeeze,Bang,Blow!! is how it should go .... from TDC on the compression stroke (both valves fully closed) I should have said wind the crank back 1 full cycle plus more then 35 degrees, then you are at the beginning of the inlet stroke and the inlet valve should begin to open. Age creeps up on you, I used to know all this stuff without even thinking about it!! Cheers Rob Quote Link to post Share on other sites
john.r.davies Posted June 23, 2017 Report Share Posted June 23, 2017 (edited) westofsouth, Sad to say, most are fixated on the minutiae of degrees, and as you will have read above, even the well read get confused. May I refer you to my article in TRaction last year? "Equal Lift on Overlap" (ELoO) Consult your library shelf for the May/June, 2016 issue, or use the new online archive from the Home page of this site. Click on "Members Area". Log in - you might have to register first. In the box marked "Search" type "Equal lift", then click on the first hit on the list. OR, ELoO at its simplest. Set your engine to Top Dead Centre, with No.1 cylinder on the firing stroke - both valves closed, rotor arm pointing at No.1. Then look at No.6. The valves will both be slightly open. Rock the crank slightly to and fro (easiest with all the plugs out) You will see that the Inlet valve is opening and the exhaust is closing. This is normal. If you measure their height at TDC - you can do this with a vernier gauge - and they are the same height, then your cam shaft is correctly timed. No degree wheels, no feeler gauges, no worries! Good luck! John Edited June 23, 2017 by john.r.davies Quote Link to post Share on other sites
Graham Posted June 23, 2017 Report Share Posted June 23, 2017 Yikes!!!, that's not going to work!!, brain fade!!, ..... Suck, Squeeze,Bang,Blow!! is how it should go .... from TDC on the compression stroke (both valves fully closed) I should have said wind the crank back 1 full cycle plus more then 35 degrees, then you are at the beginning of the inlet stroke and the inlet valve should begin to open. Age creeps up on you, I used to know all this stuff without even thinking about it!! Cheers Rob Rob I know the feeling, but has anybody noticed an unusual feature of engines in that they gain weight as the years go by……..I can quiet clearly remember rebuilding my 6 engine 30 years ago and whilst the engine wasn't light by any means I could still move it about on the bench as I carried out the rebuild. Move on 30 years I pull the identical engine out of the car with the hoist drop it on the bench and I can't shift the bu@@ger ? clearly something is going on with the metallurgy of the engine and its gaining weight Quote Link to post Share on other sites
Rob Salisbury Posted June 23, 2017 Report Share Posted June 23, 2017 Blame gravity, the earth sucks!! Like-wise I can remember picking up a bare 6 pot block and putting it in TR's boot, the spare wheel feels heavy now!! Quote Link to post Share on other sites
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