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Help - rough running after new camshaft


tjolliffe
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Hi all,

Rite, i've just replaced the camshaft in my 3.9 (along with new timing chain and gears and a new dizzy). Having issues trying to get it to run rite.... Its running really lumpy (may not be firing on all cylinders).

Also the timing seems to be very odd, I had to re-time it all after i put it all back together. I did it by the book - set crank to TDC (as shown on the pulley) then set the dizzy up to fire on No.1 accoring to the manual but it only seems to work if all the leads are changed so it is 180 degress out ie. all the leads swapped to the opposite side of the dizzy. - hope thats understandable.

Anyone got any ideas what might be wrong? would really like to try and get it sorted, proving to be nightmare at the moment.

Thanks

Tom

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Hi Tom

just put one of these back together myself so been through the dame dilemas.

Remove your dizzy and mark on the side where No1 ign lead is.

when you put the timing chain back on did you align both dots at 6o'clock on the cam and 12 on the crank while at TDC?

to make sure it's a TDC when on compression stroke,remove the pass side rocker cover and turn it over until it opens the valves on No1 then go past TDC and back to TDC again.You should be at TDC on compression then.

replace your dizzy and align rotor arm roughly with No1.it's a bit of a fiddle to get them to align and it's just a case of in and out,turning the rotor anticlockwise until it engages with the cam gear.

then start it up.you may have to move the dizzy anticlockwise a bit at a time until it catches,but it should go.just check you've got the right firing order.

hope this helps

Ralph

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Hi Tom

just put one of these back together myself so been through the dame dilemas.

Remove your dizzy and mark on the side where No1 ign lead is.

when you put the timing chain back on did you align both dots at 6o'clock on the cam and 12 on the crank while at TDC?

to make sure it's a TDC when on compression stroke,remove the pass side rocker cover and turn it over until it opens the valves on No1 then go past TDC and back to TDC again.You should be at TDC on compression then.

replace your dizzy and align rotor arm roughly with No1.it's a bit of a fiddle to get them to align and it's just a case of in and out,turning the rotor anticlockwise until it engages with the cam gear.

then start it up.you may have to move the dizzy anticlockwise a bit at a time until it catches,but it should go.just check you've got the right firing order.

hope this helps

Ralph

Hi Ralph,

Thanks for the advice. I will try what you suggest tomorrow. As for the timing chain, I have to admit i didnt line up the dots or anything, simply marked the orientation of the cam (accoring to its key) on the casing, slid it out and then slid the new one in and put the new chain and gears on. Would that not work?

It's looking like I may have to have the front off again to see if I have got it right.... :unsure:

Cheers

Tom

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Are you sure you timmed it on number one, the leading cylinder on a V8.

Timed which bit? The chain or dizzy? Fairly sure i did on the dizzy, number one cylinder being front of left (passenger side) bank? Really odd it'll only run if I set it all 180 degs out tho :S

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Hi Ralph,

Thanks for the advice. I will try what you suggest tomorrow. As for the timing chain, I have to admit i didnt line up the dots or anything, simply marked the orientation of the cam (accoring to its key) on the casing, slid it out and then slid the new one in and put the new chain and gears on. Would that not work?

It's looking like I may have to have the front off again to see if I have got it right.... :unsure:

Cheers

Tom

erm, i don't quite understand what you're trying to say. but on the cam timing gear there will be a mark which looks like "O" that needs to be down i.e. at 6 o'clock.

then when you put the crank timing gear on, there is another mark "O" which needs to be at the top. so in effect the two "O"'s are looking at eachother.

your engine will be at tdc at this point. well 99.9% it will ;)

with regards to your timing being 180 out, remember the cam turns 2 times for the cranks every one. so take your dizzy out, turn the crank 360 degrees ant then put the dizzy back in.

HTH

Gordon

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Attached is a picture showing how the marks should line up.

I've had to draw them on, as mine have triangles and circles LOL, but still the same idea as a standard setup.

post-9903-127492878285_thumb.jpg

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OK - update guys. Had the front of it off today to check the timing on the timing chain, it was spot on :( so put it all back together.

Have had some joy in getting it to run better though, thanks to ralph for the phone conversation earlier :rolleyes: !

I've adjusted the timing on the dizzy as best I can. Also replaced a collapsed 'breather' pipe that connects to the plenum housing - that made it run and idle better. Also re-duct taped my dodgey air intake pipe which again made it run better. Does anyone know where I mite be able to get a new pipe btw? Perhaps a silicone one, i'm feeling rich :lol:

Its now idling much better, still a little lumpy but i'm going to change the plugs and leads and hopefully that will go some way to sorting it. It drives nice and smooth now so i'm happy to live with it as is.

Thanks for the help.

Cheers

Tom

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