1966 2a 2.25 petrol no 4 cylinder not firing.

Lyndasbottom · Apr 11, 2025

Replaced a diesel with a cracked block with a 2.25 petrol. Have got it running but it has now decided that number 4 cylinder doesn't want to fire. Swapped plug and lead with another cylinder but the fault stays with number 4. Has a new coil, leads, plugs and distributor. Timing is as it should be, it's getting a spark and compression is fine as well so pretty much run out of ideas? Distributor is a cheap Chinese copy, could that be it? The original distributor has a cracked body.

kermit_rr · Apr 11, 2025

you need fuel, air, compression and a spark for a cylinder to fire. you've checked for a spark, is it a good strong spark? you've checked compression, what have you got on each cylinder? What have you set the timing to?

have you checked the valves are opening and have you checked the gaps on #4 valves?

Lyndasbottom · Apr 11, 2025

kermit_rr said:
you need fuel, air, compression and a spark for a cylinder to fire. you've checked for a spark, is it a good strong spark? you've checked compression, what have you got on each cylinder? What have you set the timing to?

have you checked the valves are opening and have you checked the gaps on #4 valves?

Spark is bright white. 120 psi or so on each cylinder. Timing set at 3° btdc. Can see the valves opening and closing with the rocker cover off and set to 10 thou. Plug is wet so damn thing should fire but isn't.

kermit_rr · Apr 11, 2025

Ok so if you've got a spark on #4 and you've got fuel, air and compression then yes it should fire. Do you have timing gun? Clip it onto #4 and see if you still have a spark under compression.
If not then either cap/lead/plug are failing under pressure. If you've swapped the plug and lead to another cylinder and that works then it must be the cap. Anything else any you wouldn't have a spark anywhere

Lyndasbottom · Apr 11, 2025

Thanks, I'll give that a go tomorrow.

1966 2a 2.25 petrol no 4 cylinder not firing.

Lyndasbottom

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kermit_rr

Very

Lyndasbottom

Active Member

kermit_rr

Very

Lyndasbottom

Active Member

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