1970 GT6 MK2

[Speedysix]

Slow progress last night, but slow is better than none! I gave up with the cam in the end. Just took difficult to do the Eloo method with only one dti, I have seen John's other method with the level but I didn't have that sort of kit either, couldn't find the will in the cold either to make somthing up and risk getting it half right. So ordered another dti from amazon, that way I can accurately measure the overlap point and have some confidence about it! 

All I did manage was to clean the sump face, take one last look at the bowels of what I hope will be a 100k engine, and not a 5k engine

Sealed Er up with a good quality gaskit and a thick smear of blue hylomar. Dti should arrive Sunday so it would be nice to get the cam timed in and all the front of the engine back together.

That's all untill tomorrow

Jacob

[flatter4]

Hey Jacob, all looking good, and hopefully you're enjoying the engine build.

I definitely don't want to add any confusion - but I would advise setting the cam siming with the crank a few degrees (3 or 4) advanced when fitting with a new chain.  This means that after the initial stretch the timing will be spot on.

Take your time, have a large pad of paper to take notes, and remember whether you're measurung cam or crank lift / timing.
Once you've set it you can relatively easily check timing on inlet / exhaust against a carefully positioned crank timing wheel

[flatter4]

... and remember you can only get it 'so' close (I can't remember the maths at this time of night, but effectively 1/2 a cam wheel tooth)  as you don't have a vernier wheel - it will be fine

[Speedysix]

22 hours ago, flatter4 said:

Hey Jacob, all looking good, and hopefully you're enjoying the engine build.

I definitely don't want to add any confusion - but I would advise setting the cam siming with the crank a few degrees (3 or 4) advanced when fitting with a new chain.  This means that after the initial stretch the timing will be spot on.

Take your time, have a large pad of paper to take notes, and remember whether you're measurung cam or crank lift / timing.
Once you've set it you can relatively easily check timing on inlet / exhaust against a carefully positioned crank timing wheel

Thank you, I enjoyed it the first time, second and third not so much

Thanks for the info, I shall be deploying this shortly, everything is all setup ready to go. Not the job I want to rush

Jacob

[Speedysix]

So after waiting all day for Mr amazon to deliver the parcel, delivery at 1400, delayed to 1500, delayed to 1545... eventually it turned up. I'd put it down to the weather but Sadly our inch and a half of sno disappeared over night, so sad the gt6 wasn't mobile otherwise I'd have been out having some fun I think

Anyway, very fiddly to setup:

engine set to no1 @TDC. Then after spending 10 minutes trying to position the dti stands, pushrods and followers inserted for no6.

I then set the them when there was zero lift on both inlet and exhaust, ensuring to push down on the follower before zeroing both DTI's. 

I then begin rotating the cam slowly until the exhaust begins to lift, counting the number of passes on the gauge. Full lift is about 6.3mm, so 6.3 full revolutions on the gauge. I then continue to rotate the cam and watch the numbers decrease, as this is happening the inlet on no6 begins to lift, counting down until exhaust has 2 revolutions to go, the inlet has just completed one revolution, they end up meeting at exactly 1.51mm, the overlap point when both valves achieve the same lift.

I will them fit the sprocket and chain.

For some reason I just have the number 105atdc in my head, so for future I want to check if this is right. So after I install the chain I'm going to move my degree wheel to 105atdc on the crank. As the cam should be bang on in the right spot I'm going to rotate until no1 inlet is at full lift and no1 is at tdc, and my degree wheel should be on 105atdc. This is just so that in future I have the magic number, of which is pretty confident is 105atdc.

Feel free to chime in here if this is all rubbish

Jacob

[Speedysix]

Edit to that last bit, as I can't edit my own posts? I meant to say leave the pointer at zero then rotate no1 to tdc and no1 inlet at full lift and it should be at 105 atdc.

[Speedysix]

Chain nearly fitted, just fettling around with the numbers. I had both valves at the overlap point, then when I put the gear and chain on with bolts, both DTI's change by Equal amounts opposed. So the exhaust dropped by 0.075mm and the inlet increased by 0.09mm, I'm sure we can ignore the 0.015 diffrence as the gauges not being bang on zero, so equal change. I assume this is OK?

[flatter4]

The TR5 cam spec is 6.25 mm cam lift - so you're measuring correctly, and the cam is probably what you asked for.

Kent Cams give some useful data, here is their 'blueprinted' TR5 cam detail - which confirms your 105deg. value.
....again I'd suggest making some allowance for chain stretch

https://www.kentcams.com/part/307689?manufacturer=33&model=180&engine=119

 

[flatter4]

....and you can always check on the other cylinders.  But that way madness lies:  as you will certainly find some differences due to crank grind errors (so TDC's are not exactly 120 deg apart) and maybe cam phasing errors.
I found up to 2 deg difference across the cylinders - but I like measuring

 

[flatter4]

... and I suspect your movement when installing the chain is just the system winding up / unwinding against the springs.
Turn the engine through 720 deg and check again.

[Speedysix]

Thanks flatter4, It's very tedious, and hard on the thumbs, pretty sure they both have permanent teeth indentations! Yes I think I'm trying to been to accurate, and forgetting it's a triumph engine, not a space shuttle component!

I started from scratch today, set no 1 to tdc, reset my dtis to zero on no6, rotated can until equal lift. This time I degreed the cam atdc (clockwise from the front) by about 2-3 degrees. Now after trying the 4 diffent holes, the only place it's happy sets the dti's 0.07mm appart. I want to get this right, but at the same time I'm loosing the will to live the amount of times I'm doing this

[Speedysix]

Think I've got the b*****d.  

I'd say thats slap on, and the chan is fitted. The crank is advanced by about 3 degrees and all seems to line up spot on.

I think I'm happy.....

Jacob

[egret]

I basically lost my mind with cam timing using the standard 4 hole sprocket.  I appear to have blanked that from my mind, but I think I used the ELOO method, but used feeler gauges as I had the head on and didn't have access to two dial gauges.  It went on in the end at a level that I deemed acceptable, if not perfect, and the engine runs really nicely (when the fuel and spark are playing ball)...

[Speedysix]

30 minutes ago, egret said:

I basically lost my mind with cam timing using the standard 4 hole sprocket.  I appear to have blanked that from my mind, but I think I used the ELOO method, but used feeler gauges as I had the head on and didn't have access to two dial gauges.  It went on in the end at a level that I deemed acceptable, if not perfect, and the engine runs really nicely (when the fuel and spark are playing ball)...

I dread to think how insane it would make me with the head on I'm sure no engine from the factory ever came this accurately times anyway and they ran fine... sometimes. Im sure its acceptable.

[Speedysix]

I have just checked my work, and the number, set no 1 to tdc and set my cam wheel to zero, then rotated watching the dti on no1 inlet to peak lift. Cam wheel is at about 106 107 degrees. Makes up for the advance I added. I'm sure this is perfectly adequate and within tolerance. Now I know for next time it's at 105 atdc

[flatter4]

I think you mean CRANK wheel is at about 106 / 107
...not trying to be an arse, just making sure

...and doing with a head on is fine, I use a "dead stop" - down the spark plug hole, which  is actually a very accurate way of determining TDC (wind engine up to stop CW then ACW - TDC is then the mid point betweeen the 2 stop points.

[Speedysix]

7 minutes ago, flatter4 said:

I think you mean CRANK wheel is at about 106 / 107
...not trying to be an arse, just making sure

...and doing with a head on is fine, I use a "dead stop" - down the spark plug hole, which  is actually a very accurate way of determining TDC (wind engine up to stop CW then ACW - TDC is then the mid point betweeen the 2 stop points.

Haha yes I do, don't worry, I haven't been bolting the timing disc to the cam always best to be sure

Sounds simple enough, I just wouldn't have the patience

[Speedysix]

all fitted, thank you to all for you help, couldn't do it without you guys

Next task will be distributor drive gear and end float, does anyone know why both haynes and factory specify either putting no1 to tdc on compression, (both valves closed, or moving the pulley to 13°btdc, they are diffrent positions?

[JohnD]

Well done, Jacob, on trying with ELoO, and achieving it with two DTIs!

Onwards and upwards!

John 

PS As said above, you can only get so near to a perfectly accurate cam timing, as the teeth each occupy just under 4 degrees.    You can't get it closer than that, without a Vernier pinion.     This is true of the Triumph Six, which is a pity as the Four has two sets of bolt holes, each pair slightly offset from the other, so that using the other set, and/or turning the gear wheel over you can get to less than one degree of error! J.

[Speedysix]

1 hour ago, JohnD said:

Well done, Jacob, on trying with ELoO, and achieving it with two DTIs!

Onwards and upwards!

John 

PS As said above, you can only get so near to a perfectly accurate cam timing, as the teeth each occupy just under 4 degrees.    You can't get it closer than that, without a Vernier pinion.     This is true of the Triumph Six, which is a pity as the Four has two sets of bolt holes, each pair slightly offset from the other, so that using the other set, and/or turning the gear wheel over you can get to less than one degree of error! J.

Thanks John, go there in the end! 

Yes it's a bit of a pain, the vernier wheels would have been nice but not needed, I'd rather spend the time to get it right than throw more cash into this bottomless pit

[Speedysix]

I think that will do! Im going to put the engine in! Dizzy gear ill do with the head on, far easier. Head has yet to go to the machine shop so wont be done for 3 weeks yet, so theres no real reason why the engine cant go in now. I'll give the bell housing a clean out and then get cracking. It's always nicer to build it up completely but space is very tight and I've been tripping over my engine stand for long enough!

I can then bolt er up, fit the spin on housing and a few other little bits. Need to order a prv plunger which is why it's not fitted.

[JohnD]

Jacob,

If I may?  Before you install the engine, without its head, cover the bores.    A sheet of cardboard with masking tape around the edges is quite sufficient to stop dirt, metal parts or spills getting onto the block face or into the bores while you lift it in or do other work.

If you have a bare chassis, no problem doing it late, but I recommend joining the engine and gearbox before if the body is in place.    In which case a "Load Leveller" to tilt the whole  assembly.

John

[Speedysix]

1 minute ago, JohnD said:

Jacob,

If I may?  Before you install the engine, without its head, cover the bores.    A sheet of cardboard with masking tape around the edges is quite sufficient to stop dirt, metal parts or spills getting onto the block face or into the bores while you lift it in or do other work.

If you have a bare chassis, no problem doing it late, but I recommend joining the engine and gearbox before if the body is in place.    In which case a "Load Leveller" to tilt the whole  assembly.

John

Thanks John, but I'm a step ahead!

No foreign objects are getting into this engine! 

Sadly I don't have the luxury of a load leveler, it's been on the to buy list for many years now, next time I'll get one. 

Once the gt6 is done I have my mini and recently purchased mk3 spitfire project to keep me occupied, so a load leveler will definitely come in handy.

She's out and on the floor as we speak, I'm trying to do it without opening the garage door and letting all the heat out

I aim it'll be in in the next hour or so, everything on the car is all built, the bonnet is in the house so should be a breeze!

[JohnD]

Great minds, Jacob!

[Nick Jones]

Good work. The OCD is strong in this one 

You know the front valve is an exhaust valve right ……. (I have that t-shirt )