sperry14 Posted October 4, 2015 Report Share Posted October 4, 2015 Evening all - over the spring / summer I have noticed my 65 tr4a hasn't been as responsive as usual , i put it down to a slight exhaust blowing on the rh twin pipe box , power was there when I accelerated but noticeably was lacking power . However today ., got it out the garage warmed up nicely no problems drove to end of road, when I put my foot down absolutely nothing , went throught the gears nothing really low power, 3000rpm got it home doing about 30mph got it back in the garage ticking over fine ,revs pick up fine no problems , just massively down in power ..... Question iam still thinking exhaust , it definatley is still blowing but would it cause this ? Any other ideas ? Quote Link to post Share on other sites
RogerH Posted October 4, 2015 Report Share Posted October 4, 2015 I don;t think the exhaust would do that. Have you checked the oil level in the SU carb dash pots (please say you have SU's.) Roger Quote Link to post Share on other sites
sperry14 Posted October 4, 2015 Author Report Share Posted October 4, 2015 Not checked the dash pots , although did at the beginning of the year ... Zfs fitted ..... It ticks over and revs fine so iam struggling to think what my next options are ? Quote Link to post Share on other sites
Mark1965TR4aBRG Posted October 4, 2015 Report Share Posted October 4, 2015 (edited) My guess would be fuel supply under load... Edited October 4, 2015 by Mark1965TR4aBRG Quote Link to post Share on other sites
ianc Posted October 4, 2015 Report Share Posted October 4, 2015 Have a look at the filter bowl on the fuel pump - might contain a lot of muck which when flow increases, gets pushed against the filter mesh and thereby restricts flow. If that's the problem, see my article in Section K3 of the Technicalities CD. Ian Cornish Quote Link to post Share on other sites
TR 2100 Posted October 4, 2015 Report Share Posted October 4, 2015 Don't see that (lack of) fuel supply would cause your problem. Lack of fuel usually leads to a bit of coughing and spluttering. My guess would be weak spark. OK for revving the engine, but fails under load. We are all just guessing, but I would start with the electrics. AlanR Quote Link to post Share on other sites
ctc77965o Posted October 5, 2015 Report Share Posted October 5, 2015 Seized distributor or partial fuel blockage Quote Link to post Share on other sites
valvebounce Posted October 5, 2015 Report Share Posted October 5, 2015 I'd have a look at the condenser. Quote Link to post Share on other sites
ChrisR-4A Posted October 5, 2015 Report Share Posted October 5, 2015 Try removing the dashpot caps and start the engine and observe whether the two Pistons are rising and falling together. If ok then remove distributor cap and vacuum tube and suck on tube to check adv/ret is working. Baseplate should rotate, if not remove it and check bob weights are free to rotate and springs are not broken Chris Quote Link to post Share on other sites
sperry14 Posted October 5, 2015 Author Report Share Posted October 5, 2015 Great info guys thank you, I will take a look this weekend Quote Link to post Share on other sites
Peter Cobbold Posted October 5, 2015 Report Share Posted October 5, 2015 (edited) Badly retarded spark due to points gap closing up wont stop it revving stationary, but kills power under load. Cure is to regap points. Good idea to check static timing at same time. Peter Edited October 5, 2015 by Peter Cobbold Quote Link to post Share on other sites
sperry14 Posted October 17, 2015 Author Report Share Posted October 17, 2015 Ok so spent 2 days going through this, still not fixed , here's what I have done and noticed .... 1- cleaned fuel bowl , changed gauze filter - fuel bowl did have dirt in it 2- re set points and set static timing to 4 deg BTDC Result - tick over very smooth , took out for a spin under acceleration no improvement , 3- checked the carbs for jet centralisation ... Carb on cylinder 1/2 was perfect , carb on 3/4 needed adjusting 4- checked both air valves move up/ down together fine , Result - again tick over best I have known it start first crank no problem , though I was on to a winner , took it out again , really bad when accelerating , to the point came home just about got it into the garage up the drive. 5- lifted the Pistons a fraction when running to check mixture , appeared perfect , did not increase revs , or stall 6- got the colour tune out , appeared fine, possibly a bit rich , but didn't mess based on results from test above 7- checked the plugs , appear ok maybe cylinder 3 slightly oily / wet , not to bad . came in and re read the recommendations was starting to think clutch ? Or engine ? 8- took the vac advance off the carbs and sucked whilst lookin into the distributer with cap off , no vacuum at all !!??? , as though it was just an open ended tube , ?? Iam now hoping / guessing vac advance fail?? , would this cause the symptoms of under acceleration , no power ?, should there be at least resistance when I sucked the pipe ? Is it best just get a new distributer ? Maybe electronic ignition? Any other advice will be really useful . Quote Link to post Share on other sites
RobH Posted October 17, 2015 Report Share Posted October 17, 2015 Provided the vacuum pipe itself is air-tight then the diaphragm in the distributor has a hole. That will mean your carb adjustments are wrong of course, as they have been set up with too much air at idle and the timing will not be right either when running. The Distributor Doctor can probably help with a fix of your present distributor or you could get one of the cheap ones from e-bay as a stop-gap to prove the point. Its up to you and your wallet whether you go for an electronic distributor instead - you will get lots of conflicting advice on that point. Just consider whether you have been happy with the standard set-up until this fault.... Quote Link to post Share on other sites
Graham Harris Posted October 18, 2015 Report Share Posted October 18, 2015 Did you turn the rotor button to see if the mechanical advance and retard is free and working? Quote Link to post Share on other sites
Guest ntc Posted October 18, 2015 Report Share Posted October 18, 2015 A strobe light and rev it will tell you all. Quote Link to post Share on other sites
sperry14 Posted October 18, 2015 Author Report Share Posted October 18, 2015 Rotor arm turns and springs back so mechanical advance seems ok. I have found the vacuum pipe has perished and is not sealing at the distributer , I have put a short piece of pipe on and whilst sucking there is a vacuum and the arm pulls in, so appears new vac hose required before I can re test , fingers crossed it's the fault. Like I said in my original post the lack of grunt has been noticeable and steadily getting worse so maybe the leak has just kept getting worse over the last few months until total failure.... Quote Link to post Share on other sites
Rob Salisbury Posted October 18, 2015 Report Share Posted October 18, 2015 Have you checked that all your right foot action is being translated in to full throttle movement of both carbs? On a couple of occasions I have had the coupling link between the two carbs partially fail (they are funny little thin spring steel things) and appear to operate properly only to fail, when you give it some welly, and allow the second carb to snap shut with consequential sudden loss of power. Fixed this problem by fitting a pair of Webers!! Quote Link to post Share on other sites
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