Lack of power

[sperry14]

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 ?

[RogerH]

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

[sperry14]

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 ?

[Mark1965TR4aBRG]

My guess would be fuel supply under load...

Edited October 4, 2015 by Mark1965TR4aBRG

[ianc]

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

[TR 2100]

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

[ctc77965o]

Seized distributor or partial fuel blockage

[valvebounce]

I'd have a look at the condenser.

[ChrisR-4A]

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

[sperry14]

Great info guys thank you, I will take a look this weekend

[Peter Cobbold]

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

[sperry14]

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 .

[RobH]

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....

[Graham Harris]

Did you turn the rotor button to see if the mechanical advance and retard is free and working?

[Guest ntc]

A strobe light and rev it will tell you all.

[sperry14]

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....

[Rob Salisbury]

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!!