Fitting cylinder head and timing cams
Discussion
I'm about to embark on trying to fit one of the cylinder heads today, and then change the cams. At the moment the engine is half in bits, with the cylinder head for bank A off the engine, and the timing chain removed ready to fit a new one.
I've been reading in the engine workshop manual that you get the valves for piston 1 and 8 on overlap, and then pistons 1 and 2 exactly between TDC to fit the cylinder head.
Is there an "easy" way of doing this, or do I have to go and find a dial gauge and timing disc, and work out exactly where 'half way between TDC on 1 and 2' is? Is it possible to do it using a top dead stop and then making some marks on the crank gear, or something along those lines?
Also, apparently there is a slightly different method to setting up the cams to what is detailed in the workshop manual. I've been told that you set the inlet and exhaust lift to be exactly the same on overlap, instead of being slightly stepped. Is this correct?
Cheers
I've been reading in the engine workshop manual that you get the valves for piston 1 and 8 on overlap, and then pistons 1 and 2 exactly between TDC to fit the cylinder head.
Is there an "easy" way of doing this, or do I have to go and find a dial gauge and timing disc, and work out exactly where 'half way between TDC on 1 and 2' is? Is it possible to do it using a top dead stop and then making some marks on the crank gear, or something along those lines?
Also, apparently there is a slightly different method to setting up the cams to what is detailed in the workshop manual. I've been told that you set the inlet and exhaust lift to be exactly the same on overlap, instead of being slightly stepped. Is this correct?
Cheers
jammy_basturd said:
I'm about to embark on trying to fit one of the cylinder heads today, and then change the cams. At the moment the engine is half in bits, with the cylinder head for bank A off the engine, and the timing chain removed ready to fit a new one.
I've been reading in the engine workshop manual that you get the valves for piston 1 and 8 on overlap, and then pistons 1 and 2 exactly between TDC to fit the cylinder head.
Is there an "easy" way of doing this, or do I have to go and find a dial gauge and timing disc, and work out exactly where 'half way between TDC on 1 and 2' is? Is it possible to do it using a top dead stop and then making some marks on the crank gear, or something along those lines?
Also, apparently there is a slightly different method to setting up the cams to what is detailed in the workshop manual. I've been told that you set the inlet and exhaust lift to be exactly the same on overlap, instead of being slightly stepped. Is this correct?
Cheers
The AJP is a 75 degree flat plane V8, therefore, once you have found the right position for bank A then you just need to move the 75 degrees in the correct direction to find the same position on the other bank. Cylinders 1&2, 3&4, 5&6 and 7&8 run off the same crank journals, therefore, looking from the timing chain side of the engine and turning the crank clockwise, the piston on the left hand bank (as you look at it) will reach TDC 75 degrees before the one on the right. Using this method with a timing wheel disk secured to the flywheel or the front pulley you should be able to fit the heads safely and time the cams properly, though I would definitely use a dial gauge to make sure that the one TDC that you can measure is absolutely accurate.I've been reading in the engine workshop manual that you get the valves for piston 1 and 8 on overlap, and then pistons 1 and 2 exactly between TDC to fit the cylinder head.
Is there an "easy" way of doing this, or do I have to go and find a dial gauge and timing disc, and work out exactly where 'half way between TDC on 1 and 2' is? Is it possible to do it using a top dead stop and then making some marks on the crank gear, or something along those lines?
Also, apparently there is a slightly different method to setting up the cams to what is detailed in the workshop manual. I've been told that you set the inlet and exhaust lift to be exactly the same on overlap, instead of being slightly stepped. Is this correct?
Cheers
Regarding the timing, all of the people I spoke to during my rebuild (including Joo and Dom at Power) advised setting the cams up with even overlap as that would help it run best and produce most power. It's also easier to set up in this way and therefore more likely to be accurate.
The cam timing can be a bit of a fiddle to set up, but it's definitely worth getting right as it will have a big impact on how well the engine runs. Also, make sure that you set it up with the correct cam chain tension. If you want to have a chat about it give me a call, I've PM'd you my number - Clive F helped me out when I was doing mine and offered valuable assistance and reassurance!
Right, I'm half way through the cam timing and just want to check a couple of things.
I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
jammy_basturd said:
Right, I'm half way through the cam timing and just want to check a couple of things.
I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
Anyone? I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
Hi Jammy 
Hopefully I can help a bit with this one.
1. Use the full timing chain cover to locate the gears and tension the chain. You'll be taking it on and off a few times and soon get used to removing / refitting it whilst holding the chain tight with a spare hand! If you have got the timing close enough, you be making minor adjustments by slackening the bolts on the end of the cam and moving it within the slotted part of the gear.
2. In short yes - you need to remember that in effect you are timing two 4 cylinder engines. Therefore, initially you just get it close-ish by setting up equal overlap when the engine is between the two TDCs but then you have to adjust the cams so that the relevant cam has the correct timing when each bank is at TDC. IE - firstly, when 2 is at TDC, you set the cam timing for valves 7&8 before moving the crank round so that 1 is at TDC and you can set up the cam timing for valves 1&2. It's important to repeat this several times to check that the timing is right once the engine has been turned over a few times and the chain has found it's natural tension.
Regarding the fact that the book recommends the inlet valve being 1.5 mm lower than the exhaust valve; it would appear to be commonly accepted amongst those who know (Joo, TVR Power, APS) that it is better to set the cam timing up as equal overlap as the engine runs better and makes more power. It's also easier to set up this way... To check when I had got the overlap equal I used a metal set square held against the side of the cam which was broad enough to cover both cam followers. If you can position a light behind this it's very easy to see how much light shines through the gap between the cam follower and the set square an adjust the cam accordingly.
If you've got the same manual as me, that TVR "mechanic" isn't adjusting the cam, he's hitting it with a big mallet to try and get it to move
- you are right with your assertion that you are setting up TDC 2 with valves 7&8 and TDC 1 with valves 1&2. Rather than hit the cam with a hammer, I found it rather easier to use a long steel bar with two M5(?) bolts though which where spaced to coincide with bolts which hold the cam gears on - that way, when you loosen the cam gear you just have to use the lever to tweak the cam position whist the gear remains still. If you need to make any bigger adjustments, I found it easiest to pull the timing chain cover off and move hop the chain over by a tooth.
I am convinced that cam timing is critical to making good power - so make sure you get it right! Good luck!
Hopefully I can help a bit with this one.
1. Use the full timing chain cover to locate the gears and tension the chain. You'll be taking it on and off a few times and soon get used to removing / refitting it whilst holding the chain tight with a spare hand! If you have got the timing close enough, you be making minor adjustments by slackening the bolts on the end of the cam and moving it within the slotted part of the gear.
2. In short yes - you need to remember that in effect you are timing two 4 cylinder engines. Therefore, initially you just get it close-ish by setting up equal overlap when the engine is between the two TDCs but then you have to adjust the cams so that the relevant cam has the correct timing when each bank is at TDC. IE - firstly, when 2 is at TDC, you set the cam timing for valves 7&8 before moving the crank round so that 1 is at TDC and you can set up the cam timing for valves 1&2. It's important to repeat this several times to check that the timing is right once the engine has been turned over a few times and the chain has found it's natural tension.
Regarding the fact that the book recommends the inlet valve being 1.5 mm lower than the exhaust valve; it would appear to be commonly accepted amongst those who know (Joo, TVR Power, APS) that it is better to set the cam timing up as equal overlap as the engine runs better and makes more power. It's also easier to set up this way... To check when I had got the overlap equal I used a metal set square held against the side of the cam which was broad enough to cover both cam followers. If you can position a light behind this it's very easy to see how much light shines through the gap between the cam follower and the set square an adjust the cam accordingly.
If you've got the same manual as me, that TVR "mechanic" isn't adjusting the cam, he's hitting it with a big mallet to try and get it to move
- you are right with your assertion that you are setting up TDC 2 with valves 7&8 and TDC 1 with valves 1&2. Rather than hit the cam with a hammer, I found it rather easier to use a long steel bar with two M5(?) bolts though which where spaced to coincide with bolts which hold the cam gears on - that way, when you loosen the cam gear you just have to use the lever to tweak the cam position whist the gear remains still. If you need to make any bigger adjustments, I found it easiest to pull the timing chain cover off and move hop the chain over by a tooth.I am convinced that cam timing is critical to making good power - so make sure you get it right! Good luck!
jammy_basturd said:
jammy_basturd said:
Right, I'm half way through the cam timing and just want to check a couple of things.
I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
Anyone? I'm currently in the position where the pistons are half way between TDC on 1 and TDC on 2.
The cams are positioned so that odd is on overlap on valves 1 and 2, even cam is on overlap on valves 7 and 8.
Reading through the manual it says I now have to fit a dummy timing cover. It then says to move the crank anticlockwise past piston 2 TDC, and then clockwise so that piston 2 is at TDC (to make sure all the chain backlash is on the tensioner side).
Firstly, I assume I can get around needing a dummy timing chain by fitting the timing cover, and then using a cam sprocket removal tool (or lockwire) to remove the cam sprockets?
Secondly, is the timing really done with piston 2 at TDC, I always thought it was done halfway between piston 1 TDC and piston 2 TDC?
Lastly, it says adjust the camshaft so that the inlet bucket is 1.5mm lower than exhaust bucket. In the build manual it shows the mechanic adjusting valves 3 and 4 on the even cam. Is it not meant to be valves 7 and 8 on the even cam and valves 1 and 2 on the odd cam?
Thanks for that James, massive help! 
If I'm going to be taking the timing cover off and putting it on several times, it does raise one last question. Currently I have my timing disc bolted up against the AC pulley, with a home-made pointer, so I can work out where TDC 1 and 2 is (having measure TDC 1 with a dial gauge). Now, because it's quite late and I'm lacking sleep, I can't figure out a way for me to keep track of TDC in between removing the timing disc and fitting the timing cover. Is it going to be much easier to remove the gearbox and just use the marks on the flywheel?
If I'm going to be taking the timing cover off and putting it on several times, it does raise one last question. Currently I have my timing disc bolted up against the AC pulley, with a home-made pointer, so I can work out where TDC 1 and 2 is (having measure TDC 1 with a dial gauge). Now, because it's quite late and I'm lacking sleep, I can't figure out a way for me to keep track of TDC in between removing the timing disc and fitting the timing cover. Is it going to be much easier to remove the gearbox and just use the marks on the flywheel?
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