4K With 266 Duration Kelford Cam Tuning

[Kirill]

Hey guys I been playing with the motor a bit. Its a 4K, slight port job, harder springs. I just put new rings on it and gave it a hone.

 

I put a cam in it, The specs are; Kelford CE695. Duration 266 (inlet and exhaust). Timing at 015 Inlet opens 28 closes 56, exaust opens 56 closes 28. Inlet Fully open 105 ATDC, Lobe centres 105. I set the cam by standard markings.

 

I'm running aisan carb (stock). I don't have tach but it feels like the car pulls strong just after1500-2000 rpm. Clean and smooth. However below that it runs really crap. I played with timing setting and idle adjuster screw and cleaned the carb jets etc etc.

 

My question is, is it a tuning issue that could be dialled out with weber 32 36 for example or is it just the cam being lumpy.

[TRD ke70]

check for vacumn leaks, i've had way bigger cams idle nicely.

you may find that the idle jet may need to be opened up a little as well.

[Kirill]

no probs

 

heres the vid of it idling

[GJM85]

It may have a lumpy rough idle down low because of the cam. The cam is probabley good for between 3500 & 7500rpm.

Carby and exaust would make a huge difference in performance. You'll likely never get a smooth idle below 1000rpm.

[Kirill]

So you recon if i fit weber that might help?

[Kirill]

heres a clip of what I'm talking about

[Kirill]

it just looks like its dumping juice... i didn't change jets

[altezzaclub]

The idle circuit actually runs the motor up to 1500-200rpm before it hands over to the main jet completely, so it could be the idle is blocked a bit or too small. Strip the carb and hose out all the drillings with a syringe full of petrol.

 

An air leak would do it too. That stock carb should run it at low revs much better than it can at high revs.

 

I'm using a 270deg cam with twin carbs and extractors, and it idles lumpy like yours, but pulls clean as soon as I touch the throttle.

[Kirill]

I need to sort this out, cheers altezza

[bruce]

Installing a 32/36 Weber would be beneficial, since the idle circuit can be finely adjusted with the idle screw and a selection of idle jets. Good performance upgrade.

 

 

Are you running vacuum advance on the distributor or is it blocked off?

What ignition timing did you set it at? You might need to increase the timing to get a more smoother idle, cause of the lower dynamic compression ratio and air speed at idle with the larger camshaft.

[Kirill]

I can get it to idle ok. Its when you step on the gas it hesitates runs rough then once revs get to about 1500 rpm it piks up no problems. Its that transtition from idle jet to primary

[altezzaclub]

Can you see the accelerator pump working down the carb throat?? Take off the air cleaner & without starting the car just flick the throttle wide open, and you should see a jet of fuel squirt down there.

 

If that is blocked it gives an instant flatspot whenever you boot it.

[Kirill]

Its working... could it be that the acceperator pump jet is too small now to feed the motor?

[Kirill]

Ok me and my mate got it to runs heaps better by taking off the top of the air cleaner (was choking the motor alot!), played around with timing.

[CREEDY]

my ke35 has a very angry kelford cam in it, i've had to advance the timing a lot just to get it to start