3.5 V8 Rebuild

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discomark10 said:
Okie dokie, I want to try and sort my rough running between 2k n 3k rpm. Im pretty sure its not to do with the distributer as I checked timing at 2500 and its what it should be. It stll does it with the vac removed, so must be something else.
Could the fuel regulator cause it? And does it need to have a certain length vac pipe as I had to trim it as the end was split. Also is it correct to get the vac from the plate on the rear of the plenum that houses the idle valve? Seems a bit of an odd place to me!

Any input appreciated as ide love to sort it!
Click to expand...

Vac pipe doesn't change vacuum over length, we use long lengths for the MAP sensor on MS and its fine.

Rear of plenum is correct place :)

Is it rough under load or rough at standstill? Like when you hold it at 2-3k?

Mine used to pop bang and generally carry on if you hold the revs up at standstill, it does now to an extent but the mixture is better so not so much on MS but still similar, think it kinda burns fuel in the exhaust a LOT or something, tbh I'm not actually sure but it's always done it in any incarnation.
 
Mr Noisy said:
Vac pipe doesn't change vacuum over length, we use long lengths for the MAP sensor on MS and its fine.

Rear of plenum is correct place :)

Is it rough under load or rough at standstill? Like when you hold it at 2-3k?

Mine used to pop bang and generally carry on if you hold the revs up at standstill, it does now to an extent but the mixture is better so not so much on MS but still similar, think it kinda burns fuel in the exhaust a LOT or something, tbh I'm not actually sure but it's always done it in any incarnation.
Click to expand...

It runs fine with no load and with load up to 2k, and above 3k but between 2-3k it is very intermittent. I'm going to stick it on the oscilloscope tonight so ill try get a video as that will show more than me trying to describe it!


Mr Noisy said:
Are you using a speed sensor unit in the middle of the speedo cable?
Click to expand...

Ill take a look later
 
Ok, so I got some more info on the misfire.
This video is pretty self explanatory, you can see at the start of the vid I held the revs at around 2400 and you can hear it missing, but soon as it drops below 2kish its fine.
V8 2400 rpm - YouTube

This vid is of me driving, you can see the idle issue from around 30sec in I just cost and you can hear the idle is rather fast and at around 35sec when I stop it drops down to normal.
Also from around 45sec you can hear the missing once I reach around 2k rpm.
V8 driving and missing - YouTube


I also took some Oscilloscope readings from the output of the amplifier at the coil.
Seems to be pulsing regularly but not sure what the deal with the large spikes are?
3 pics at different scales.


 
Last edited:
pmsl :p

I got all mine done on the new heads apart from that one in the pic, I nearly came out the other side and its still pitted, I think it must in the casting :doh: :p
 
Going to start with my electronic spark controller (using coil packs and the dizy trigger wheel) in the next few weeks, got most of it planned and a shopping list of parts!
 
Bit of an update, Engine seems to be working brilliantly.. minus the fuel starvation issue due to the un-baffled tank, that has since been sorted.
Only thing I would say is its a lil smoky, I pulled the plugs out and plugs 1,2,3,5,7,8 had some oil on them. Its not noticeably drinking oil mind you.
Is this down to the seals or the guides?
I've found the seals but the usual question.. will the cheaper bearmach be good enough? or shall just stick with genuine?

Valve Stem Oil Seal V8 ERR1782 Island 4x4 - Specialists in Land Rover and Range Rover Parts and accessories for all models. UK and worldwide mail order.
Valve Stem Oil Seal - Neoprene type - Inlet & Exhaust - Genuine Land Rover at www.rimmerbros.co.uk
 
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