1HD-FT (24v Turbo 80) valve adjustment

[IRLGW]

Chris it seems like a lot of effort for no real gain although it would be nice to sleep at night knowing all your gaps are right. Are you hoping for a an increase in power or economy? I assume that through wear you get shorter valve strokes and thus less throughput and I wonder if it has any noticeable effect on compression although I would also assume all the valves return to fully closed when they should.

Is it worth de-carbing the engine before you do this exercise to make sure the valves are seating properly before embarking on adjustment if we are talking about such small tolerances.

 

[Chris]

I'm not really hoping for anything really. Not in that sense. But it's done 250, 000 miles and never been touched. I've got the lid off so why not check the gaps. Seems pretty sensible. Now if I check them and they're marginal then I'll bolt the top back on and forget it. But at the second it seems like they're not right. It runs well enough and doesn't smoke or make a lot of noise, but if they're wrong then they're wrong aren't they. I don't want this to be any more complicated that it needs to be but getting started is proving harder than the very simple instructions in the FSM - line up marks, check clearances. Hmm yeah, right. Better economy would be nice, but I doubt that it will improve much given the size of the thing.

Not sure how the timing marks on the cam and pulley don't line up.

 

[IRLGW]

are you referring to the notches or white factory paint- possible the pulley has been removed and refitted in a different position at some point. Is the pulley fitted with a keyway or is it just an interference fit. You never know in another 250k it might al line up again! who knows...

 

[Chris]

White factory paint? Hmm, I doubt there's anything left that's factory about this 80 tbh. There's a notch on the pulley and a mark on the cam. I'd have thought they should line up to all give tdc for assembly. I don't think you can put the crank pulley on incorrectly. I'm going to go and stare at it for an hour before I start work.

 

[Chris]

WAIT. This just gets better. There's two matching marks on the cam backing plate. I have been looking at the obvious one at 12 O'clock. Whilst just getting my stuff out, I noticed a second mark hidden at 9 O'clock. It says TDC next to it.

FFS.

So I have the crank pulley at TDC compression and the cam matching on the TDC marks on the backing plate. With No 1 valve rockers loose and No 6 tight. Why doesn't the FSM just point that out to begin with?

Checking by hand they all feel very different with some clacking and some just moving. All the ones that are supposed to be free are, but so is valve 10 which shouldn't be.

 

[frank rabbets]

I put some white typex on my pulley timing mark. This way I could see it coming round to the mark on the cover in plenty of time. The timing marks are used differently for timing the camshaft so they don't line up in valve adjust procedure. (pistons have to be in different position). I clean the rockers off with degreaser then number them with marker pen, then cross through each one after its done. I open up the clearance wide first to get the feeler in otherwise even a too thin one won't get in due to canting over of the bucket.

Horrible job and takes 3-4 hours from start to finish. Terrible pain kneeling on the radiator.

 

[frank rabbets]

P.S. Some of the valves not to be checked on one cycle will have a small clearance, or none at all, depending on the cam follower position on the cam ramp.

 

[flint]

Terrible pain kneeling on the radiator.

Mundane and off topic, but knee pads are handy things. I've got some that fit in my work trousers and they're well worth having.

 

[Towpack]

You dont need the timing marks. I checked each cylinder in turn when the valves were fully closed by turning the crank and watching for the inlet valve reach fully closed position at the end of the inlet stroke then turn the crank half a turn more. Both IN and EX valves will now be fully closed approaching TDC on the comp stroke. Check each cyl in turn in firing order. This is how I did mine and in fact its how Ive always checked valve clearances on every engine Ive ever worked on. JMO

 

[frank rabbets]

That's very true TP and obviously brought forward to today by once owning a single cylinder motorbike I would have thought, like me. Trouble is you can do it all with 2 turns of the crank with the FWM method. Some base circles are not circular but have a profile so its vital to get the cam in exactly the right position. Rare though.

 

[Chris]

I'm not having a problem seeing the marks, it was finding the damn indicators on the engine that was the issue. I don't need to use tippex, I need a bore scope. Stupid places to put them. Not sure what you mean thought Frank. The TDC on the block and the TDC on the cam are now both perfectly aligned with their respective marks. I shall make a start tonight but not sure how I'm going to reach the ones near the bulkhead!

 

[frank rabbets]

I use a mirror on a stalk and can see the marks line up perfectly. A short run of typex highlights the groove in the pulley and gives one plenty of time to deliver it slowly to the mark on the crank case. If you overshoot you have to turn the engine a long way backwards past the mark to allow play to be taken fully up for turning forwards again.

I can guarantee that large clearances will not make a mechanical noise on this engine. Due me mixing up imperial and metric feelers I ended up with huge clearances on all valves. On driving there was a strange moaning noise from the air intake which alerted me and I had to start over.

I kneel on the radiator to reach the back ones. I don't know the breaking force of the radiator but its more than 10.75 stone.

I use tramadol to overcome the mental stress of doing the tappets. Probably how I got the measurements muddled up.

 

[Chris]

Frank, it's lined up. I've definitely established that. My point was I couldn't find the timing mark. Not that I couldn't see it once I'd found it. Tippex isn't any good if you can't find the damn mark to begin with.

Now I've gone and had a play. I think I am good. But I do think it could be described more simply.

Frank, I took your idea about the bridge. Now, the idea here is the the bridge has to slide up and down contacting both valve stems at the exact same time. I wound the VB screw out so that the bridge travelled up and down the central guide to establish it was all clear and free. I then used the top rocker arm screw to apply pressure to the VB locking it down gently onto the top of the valves. Like you holding it Frank, but without needing an extra arm. I then wound the VB adjuster screw down until I felt it contact the top of the valve stem and stop. I locked the nut off using a spanner and wrench.
It was easy then to back off the rocker screw, slip the feeler in and set the gap for intake and exhaust

Can you see any flaw in that? The VB is balanced and the rocker arm set by doing that surely?

In terms of the cam lobe, looking at the profile, I think there's a wide area where the rocker is off cam. The back side of the cam is very 'round' meaning that in all likelihood TDC gives a fairly generous portion of non contact. I take the point that you could do this by eye on each individual lobe but it's more work than I can be bothered with given that this wasn't the main job at hand.

It's just a shame that it's almost impossible to check the clearance without actually resetting them. You simply cannot get a feeler in there anywhere. It's a shame they don't tell you the roller to cam measurements.

 

[Towpack]

I can't recall having a problem getting feelers in there. I have some narrow blade feelers which I bought for an awkward bike setup years ago so maybe that made a difference.
Do you really need any roller to cam measurements? Any wear at the roller/cam lobe end is compensated for by setting the gap at the other end. Providing the cam lobes and rollers are not heavily scored, out of round or loose in the rocker arms then I reckon you can forget about them.

 

[frank rabbets]

You're OK with that Chris. Also the base circle thing does not apply to these engines so as long as the marks are within say 10mm either way it's safe to set the clearances. It's not like the pump timing where you have to have a precise point of measurement. A measurement from cam to roller would be useful as it's much easier to measure. Generally a horrible job and not much to be gained except peace of mind.

 

[Chris]

No I meant if you could just stick a feeler in the roller and be done, it would take five mins to check the gaps. Just be a short cut. It says measure the gap first then adjust if necessary. Not a chance. Only way is to actually slacken and adjust - so I found.

So all back together, cleaned up and a bit of bling. Sounds really sweet but then it wasn't bad to begin with. I shall see how it drives tomorrow. I do think a special bridge holding tool might be something I'd make if I ever did this again.

 

[frank rabbets]

I like the go faster red paint.

 

[Chris]

Just been for a spin Frank. It was always a good engine, but there's definitely an improvement. It pulls even better at low revs and despite its weight and size, now has a bit more of its zip back when pulling away. Instead of being a lumbering tank, it's now feeling a bit more modern. It's never going to be a sports car we know that, but just resetting the clearances does seem to have spruced up the performance a little.

I just need to stick that 100 series gearbox back in and I'll be set for some more adventures.

 

[frank rabbets]

A result Chris!

Did you get the red paint from a rattle can? If so you might have thought it was tappets rattling.

 

[Iwan]

A good result to say too! Benefiting from the valves opening to their optimum and if there's an increase in response then surely an increase in mpg etc as you get to cruising speed! Awesome man!