Engine misfire ... Now solved

[petrolhead]

I have a 1330cc engine with RE13 cam (Similar to 286), 37/29 Swiftune head, Calver modded distributor running Acuspark electronic ignition, new Lucas gold coil and twin HS4 SU carbs. Its running about 32deg total advance . Engine running about 200psi on compression test on all 4 cylinders

The engine now has about 2000 miles on it however it’s always miss fired at about 5500 rpm.
I took the car to Bogg bros who set it up and it stall miss fires so David changed the plugs from NGK BP7ES to NGK B7ES. This did improve things however it misfired at just under 6000 rpm. Engine was putting out about 70bhp at the wheels.

We ran out of time and I have just put up with it but its starting to annoy me. It seems to happen no matter what the throttle position is and I am unable to drive through it. Likewise pulling the choke out, in case it was running lean, makes no difference

Interesting No4 insulation in pink in colour whereas No1 is grey/white.

My thoughts are could the coil not be man enough and the spark is getting blown out?
Any other thought or suggestions

[1071 S]

I would be thinking about a set of new plug leads - BTDT.

Cheers, Ian

[Spider]

I have to say I haven't found those Lucas Coils brilliant, so maybe start there.

If you've a Points dissy, maybe slip that in and set it for 30 - 32 deg total advance, just to see if your current dissy is acting up.

The 200 PSI you are getting on a Compression Test does raise one's eyebrows, I'd say that your Dynamic CR is quite High, unless you're using some exotic (ie non-pump) fuel. Running a Cam with those sort of timing numbers would normally give a much lower PSI Number on a Compression Test due to the later closing of the Inlet Valve. Ideally, your Dynamic CR should never exceed about 8.7:1.

[petrolhead]

The leads are new Copper Core ones

I am going to replace the Acuspark with points and also try another coil

RE 200PSI, I have done many Mini engines that often have about 200PSI and never had a problem associated with that. I spoke to Calver today and did not raise an eye when I told him

[Smiffy]

Are you using the rotor arm out of the accuspark kit or the magnetic ring and standard rotor arm ? Check the fitment of the rotor arm in both cases, with the ring some i've seen need modifying so they go down far enough. Due to molding edges/flashes on stop corner pieces.

[petrolhead]

Are you using the rotor arm out of the accuspark kit or the magnetic ring and standard rotor arm ? Check the fitment of the rotor arm in both cases, with the ring some i've seen need modifying so they go down far enough. Due to molding edges/flashes on stop corner pieces.

Will check, thanks

[pad4]

Interesting - similar spec engine to my black mk3 S which at 28 degrees advance was to much for it on the rolling road - would your 32 degrees be way to much ?

pad

[petrolhead]

Interesting - similar spec engine to my black mk3 S which at 28 degrees advance was to much for it on the rolling road - would your 32 degrees be way to much ?

pad

Did the same at 29 deg

[petrolhead]

Sorted, it was the acuspark unit