Tappets ajustment
Discussion
Getting the tappets set right is straight forward if you are used to working with shims. You need a micrometer and you can get shims from e.g. TVR Power. I dress slightly thick ones down using an oilstone to get them right.
BUT....
You have to set the cam timing when you replace the cams. That means you will need a means of fixing TDC on cylinders 1 and 8 (one on each bank), and a means to confirm equal lift on the inlet and exhaust valves of each cylinder at TDC...and there are no timing marks. This is where the 'specialist' comes in. A few thou of uneven lift at TDC means your cam timing's out and your power's down and you may get problems with running. Do a search on the forum there's some good threads.
Good luck
BUT....
You have to set the cam timing when you replace the cams. That means you will need a means of fixing TDC on cylinders 1 and 8 (one on each bank), and a means to confirm equal lift on the inlet and exhaust valves of each cylinder at TDC...and there are no timing marks. This is where the 'specialist' comes in. A few thou of uneven lift at TDC means your cam timing's out and your power's down and you may get problems with running. Do a search on the forum there's some good threads.
Good luck
Found this, not sure if it is all there, but it may help a little, i will delete it if someone in the know says it's no good.
Procedure as extracted from the cerbera workshop manual
If adjustment is required proceed as follows turn the front pulley until, the front 2 cam followers are on the overlap (inlet just opening, exhaust just closing) remove the uppermost cam sprocket bolts. Turn the front pulley clockwise until the back 2 cam followers are level, and then carefully turn the crank clockwise slightly more until the inlet cam follower is exactly 1.5mm lower than the exhaust
DO NOT TURN ENGINE BACKWARDS DURING THIS OPERATION
Now scribe the camshaft and camshaft sprocket with a line exactly level the top of the cylinder head, a carbide tipped scribe may be required.
Now remove the remaining cam sprocket bolts and fit the cam sprocket retaining tool ( a bar with a spigot on it to keep the sprocket in place which bolts to the cylinder head)
Now turn the crankshaft anti-clockwise until the camshaft has moved 1 & ½ teeth if working on the odd cylinder bank, or clockwise if working on the even cylinder bank.
This puts the engine in a safe position so no valves are bent when removing the camshaft. Slacken the timing chain tensioner but do not remove it then slide the cam sprocket off the cam and onto the spigot of the retaining tool.
The cam caps bolts cam then be slackened evenly and then removed the cam can then be removed, remove any of the tappets which required adjustment and remove the ‘top-hat’ shim underneath. Measure the shim with a micrometer and replace with one of the appropriate thickness to provide the correct clearance ( 0.010” on the exhaust and 0.008” on the inlet)
The camshaft can now be replaced and use plenty of engine oil to lubricate all parts during reassembly, while the crankshaft is in the ‘safe’ position the cam can be rotated safely to check all clearances, repeat adjustments if required.
When complete torque all cam caps to 17ft/lb and turn the cam until the scribe marks match on the head and pulley at this point the cam bolts can be de-greased with solvent, apply loctite thread locking compound to their threads and refit, torquing to 20 ft/lb, retighten cam tensioner and secure with lockwire.
Turn the crankshaft 1 revolution and refit the other 2 camshaft pulley bolts loctiting as before
Procedure as extracted from the cerbera workshop manual
If adjustment is required proceed as follows turn the front pulley until, the front 2 cam followers are on the overlap (inlet just opening, exhaust just closing) remove the uppermost cam sprocket bolts. Turn the front pulley clockwise until the back 2 cam followers are level, and then carefully turn the crank clockwise slightly more until the inlet cam follower is exactly 1.5mm lower than the exhaust
DO NOT TURN ENGINE BACKWARDS DURING THIS OPERATION
Now scribe the camshaft and camshaft sprocket with a line exactly level the top of the cylinder head, a carbide tipped scribe may be required.
Now remove the remaining cam sprocket bolts and fit the cam sprocket retaining tool ( a bar with a spigot on it to keep the sprocket in place which bolts to the cylinder head)
Now turn the crankshaft anti-clockwise until the camshaft has moved 1 & ½ teeth if working on the odd cylinder bank, or clockwise if working on the even cylinder bank.
This puts the engine in a safe position so no valves are bent when removing the camshaft. Slacken the timing chain tensioner but do not remove it then slide the cam sprocket off the cam and onto the spigot of the retaining tool.
The cam caps bolts cam then be slackened evenly and then removed the cam can then be removed, remove any of the tappets which required adjustment and remove the ‘top-hat’ shim underneath. Measure the shim with a micrometer and replace with one of the appropriate thickness to provide the correct clearance ( 0.010” on the exhaust and 0.008” on the inlet)
The camshaft can now be replaced and use plenty of engine oil to lubricate all parts during reassembly, while the crankshaft is in the ‘safe’ position the cam can be rotated safely to check all clearances, repeat adjustments if required.
When complete torque all cam caps to 17ft/lb and turn the cam until the scribe marks match on the head and pulley at this point the cam bolts can be de-greased with solvent, apply loctite thread locking compound to their threads and refit, torquing to 20 ft/lb, retighten cam tensioner and secure with lockwire.
Turn the crankshaft 1 revolution and refit the other 2 camshaft pulley bolts loctiting as before
The setting info is correct, but you still need a method of determining TDC, I modified a spark plug so it had a bolt tapped into the engine end so the piston runs into it you then turn the engine in both directions and adjust a degree wheel blutacked to the front pulley so it reads the same either side, then bisect the figures to give TDC.
You don't have to make up a sprocket tool either I used a couple of ty-wraps to lock the pulley to the cam chain before I removed the last two bolts.
Matt
You don't have to make up a sprocket tool either I used a couple of ty-wraps to lock the pulley to the cam chain before I removed the last two bolts.
Matt
Gassing Station | Cerbera | Top of Page | What's New | My Stuff