EarthwurmJurm Posted February 19, 2008 Share Posted February 19, 2008 so I put a timing light on my fiat twin cam, and I assumed it would be timed off the marks that are on there, 10 btdc, 5 btdc, and tdc.. but the only way I can get it to run properly is at about 30 btdc? is this right? I'm a bit confused :\ Quote Link to comment Share on other sites More sharing options...
sholdowa Posted February 19, 2008 Share Posted February 19, 2008 Cheap timing lights can have a significant rise time, so the flash is a fair bit after the spark. This will make it look like it's well advanced. Quote Link to comment Share on other sites More sharing options...
Unclejake Posted February 19, 2008 Share Posted February 19, 2008 30 degrees at what revs? Quote Link to comment Share on other sites More sharing options...
EarthwurmJurm Posted February 19, 2008 Author Share Posted February 19, 2008 at idle Quote Link to comment Share on other sites More sharing options...
Unclejake Posted February 19, 2008 Share Posted February 19, 2008 Doesn't sound right - but I can't offer any constructive suggestions sorry. Quote Link to comment Share on other sites More sharing options...
EarthwurmJurm Posted February 19, 2008 Author Share Posted February 19, 2008 swt cheers anyway Quote Link to comment Share on other sites More sharing options...
cute wee gem Posted February 19, 2008 Share Posted February 19, 2008 Whats the compression like man? if its low you usually have to run more advance. my old 4k had some mega overlap on the cam and needed 30deg at idle as it brought the comp way down Quote Link to comment Share on other sites More sharing options...
drftnmaz Posted February 20, 2008 Share Posted February 20, 2008 did you dissconect and block the vac advance? that would take it up quite a bit if it was seeing manifold vac... Quote Link to comment Share on other sites More sharing options...
EarthwurmJurm Posted February 20, 2008 Author Share Posted February 20, 2008 it doesnt have a vac advance on the dizzy, it's quite oldschool and has bob weights and springs on top Quote Link to comment Share on other sites More sharing options...
EFI_LC Posted February 20, 2008 Share Posted February 20, 2008 what does it do when you rev it? At idle does it stay static or bounce around a bit? Has the engine been modded? Quote Link to comment Share on other sites More sharing options...
drftnmaz Posted February 20, 2008 Share Posted February 20, 2008 these motors are quite common for skipping a tooth, i've got a 2l one at home and its one of the weirdest motors to do a timing belt on, you get the pully and set it at 38 degrees or some wak sh!t and then put belt on. You wouldnt be able to figure it out without the book me thinks, i've never tryed running one with it a tooth out but it MAY produce results like you are getting? im no expert tho Quote Link to comment Share on other sites More sharing options...
Abarth Posted February 22, 2008 Share Posted February 22, 2008 Hey I have done this before on my FWD twin cam. If you are a tooth out the engine will as flat as a pancake though the revs. If you go any more than that the valves collide. For a standard twin cam there are markers that line up with engine markers. Up top the two cam wheels have notches on the back of them. These should line up with the notches on the cam boxes. Down below there is a pulley with a marker at around 32 degrees? Cant remember exactly. On the gear box end there is a hole in the housing where you can see the fly wheel. On the fly wheel there is markers, I think the first notch is TDC. And should line up with the marking on the gearbox casing. Put the car in gear and push the whole car to move the flywheel in position. Should check the Haynes manual though, Quote Link to comment Share on other sites More sharing options...
Testament Posted February 22, 2008 Share Posted February 22, 2008 30deg. is wrong, it should definitely be 10deg. The cam timing is easy, there is a dot on each camwheel, these need to line up with the points on the camboxes/and or steel cam timing pointer bolted to the thermostat housing. Also you MUST have the aux. shaft wheel in the right position, the dot at approximately one thirty from memory. otherwise the fuel pump cam on the end of the shaft will hit no. 2 connecting rod. Also remember they are timed up with no. 4 firing What I usually do for finding TDC is take out a spark plug (cyl 1 or 4) and put a long screwdriver or piece of wire down and then slowly turn the crank watching it go up until it starts going down then go back to the mid point of the dwell at TDC. Quote Link to comment Share on other sites More sharing options...
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