Missfire after New Head?

[Bobby Doc]

My Head Cracked three weeks ago so I have fitted a new one with my old but good condition parts machined onto it.

The old head worked fine even when it was cracked and chucked out the water, but with the new head on it missfires at about 2000 rmp it is alright at tickover and it seem to drive well, but it missfires when it is free revved.

I have fitted all new filters with redex in the fuel and the fuel filter and the fuel pump timing is correct and I don't think there is air getting in through the injection pipes.

Dose anyone have any idea's or dose the Head just need to carbon up a bit?

[BUSHWHACKER]

My Head Cracked three weeks ago so I have fitted a new one with my old but good condition parts machined onto it.

The old head worked fine even when it was cracked and chucked out the water, but with the new head on it missfires at about 2000 rmp it is alright at tickover and it seem to drive well, but it missfires when it is free revved.

I have fitted all new filters with redex in the fuel and the fuel filter and the fuel pump timing is correct and I don't think there is air getting in through the injection pipes.

Dose anyone have any idea's or dose the Head just need to carbon up a bit?

Did you double check the timing marks are all lined up?
The camshaft timing mark is at '6 o'clock' not at 12 0'clock like most other vehicles. Check that the marks on the fuel pump pulley are spot on too. The trick is to fit the timing belt one tooth before the mark so when the tensioner is released, the marks line up.

[Bobby Doc]

Without stripping it down again, I do think the Timing marks are correct, I did double check by turning the engine over twice by hand and again running it for a second before I put everything back together again. It dose drive alrigh with no noticable missfires, and even though I am trying to keep the speed down to 50 ish MPH for 500 miles to bed everything in, I found myself at 70 MPH on the motorway with no problems.

If the timing was out I would have thought it would be missfiring somewhere between 900 and 3700 RPM when driving but it only seem to do it free revving?

[BUSHWHACKER]

Without stripping it down again, I do think the Timing marks are correct, I did double check by turning the engine over twice by hand and again running it for a second before I put everything back together again. It dose drive alrigh with no noticable missfires, and even though I am trying to keep the speed down to 50 ish MPH for 500 miles to bed everything in, I found myself at 70 MPH on the motorway with no problems.

If the timing was out I would have thought it would be missfiring somewhere between 900 and 3700 RPM when driving but it only seem to do it free revving?

Could be a vacuum hose off or in the wrong place.

[surfenstein]

could be the injectors themselves.

[scooby69]

help

was there a cure for this as mine missfires at 2000rpm as well but fine at all other rpms