Seized Lotus engine,i HOPE not!!

[25v6turbo]

After several months messing around with my das 1974 Lotus Elite,he at last got it running today...The engine was removed 7 months ago,to replace the gearbox/manifold and other tricky bits to get to!!The carbs where rebuilt,but nothing internally was touched in the engine,cambelt left alone etcIt did have another dizzy fitted and we had to go back to points as the original electronic ignition box was shot,it sparks fine...Now my dad tried to start it up tday,and it fired up and ran O.K,he said a bit uneven but down to timing etc we think,but it was running,then my dad slackened the dizzy clamp bolt to try and set the timing up,then it just stopped dead!!! on idle at about 800-900RPM,tried to restart and nothing,like the engine had seized,he put a socket on the crank and couldn,t move it!!! nothing,he removed the cam cover and has commented on the cam looking a bit dry,but the engine ran fine 7 months ago and its been turned over often,so what has happened??Could it be the dizzy drive came out of the keyway causeing the engine to stop,but why is it locked,there is slight movement but not much,this is s/h info from my dad...if a cam seizing in the head doesn,t things go with a bang and the belt loose a few teeth??

[meggersdog]

A seized camshaft will indeed rip teeth off the drive belt but usually they squeak like crazy before seizing.Something loose in the rebuilt carbs won't cause it,just a tapping noise as it bounces off a piston.If the distributor is driven off the belt that's where I would look first.Maybe the keyway from the other dizzy is lodged in the shaft somewhere.If that shaft is driven off the belt then with it not turning none of the others will turn either.

[Station]

I remember adjusting timing (including removing the entire distributor mechanism, including the shaft), and then more than enough times, when I turned the engine over with the key, it would turn, but then STOP and then turn, like something was blocking it. Maybe the little cog has come off the end, it sounds like something might be in there. Have you tried taking the belt off and see if there's any (slight) movement in either cams or crank, narrow it down a bit.

[garethj]

These engines have pretty high compression, does taking the spark plugs out let you turn it over? Grandmother to suck eggs department, but you never know...Otherwise I'd start with taking the distributor out and see if there's anything missing off the drive gear, a woodruff key or something.

[M'coli]

I remember adjusting timing (including removing the entire distributor mechanism, including the shaft), and then more than enough times, when I turned the engine over with the key, it would turn, but then STOP and then turn, like something was blocking it. Maybe the little cog has come off the end, it sounds like something might be in there. Have you tried taking the belt off and see if there's any (slight) movement in either cams or crank, narrow it down a bit.

Is it a pre-engaged starter? Could be something caught in the ring gear.

[Station]

Oh yeah, starter motor! I've definitely had that before, and managed to take everything apart before realising the spade connector (to ignition) had moved and was no longer in connection.

[jonny69]

Could it have dropped a valve? Is it worth popping the cam cover off and having a look?

[Pete-M]

When it was running had the oil pressure light gone out? V8 Rovers often need the oil pump taking apart and packing with vaseline if they've been parked up for a long time, otherwise they tend to lunch themselves in the manner you describe.

[25v6turbo]

Latest update is that the exhaust can seized in the head and bought everything to a halt!!But it appears that no valve damage was done as the belt is fine and it slowed done slowly rather than a dead stop!!So the cam/carrier are ruined,but i HOPE we can save it with a replacement etc,fingers crossed,but the sump is coming of to see if theres any oil pump blockage,best be safe...