The V8 Owners Forum -

[quote="ged"]You only need the valves to hit by a few thou to cause damage & this is probably the reason they weren't seated.

I would say you were lucky the lifters weren't pumped up properly.[/quote]

Thanks Ged - well I certainly hope so! - it does seem the likely cause - but really just reassurance.

Is the camshaft standard lift or is it a sporty one?

[quote="DEVONMAN"]Is the camshaft standard lift or is it a sporty one?[/quote]

Its a bog standard one from Rimmer Bros.

R0vers wrote:

DEVONMAN wrote:Is the camshaft standard lift or is it a sporty one?

Its a bog standard one from Rimmer Bros.

Those marks do tend to indicate valve contact so camshaft timing is suspicious.
Can you not check the point at which no1 inlet pushrod starts to rise.
I haven't got a book for a 3.5 range rover but the SD1 book says 30 degrees BTDC at the end of the exhaust stroke.

If you are not confident in the marks on the timing set then the keyway on the camshaft gear should be at the 9 o'clock position when the crank is at TDC at No1. The correct marks should then be close to each other ready for final lining up.

The valves were quite clearly open quite a way when the piston came up on compression / exhaust so the timing is at least a tooth out - Which is the reason for the no compression. You may have been very lucky to get away with what you have.

I would have thought you would have felt that contact when hand turning the engine after assembly to check clear rotation.

Looks like you dodged a bullet with those valves touching the pistons.
I'd double check the cam timing marks with the heads still off, paying close attention to the lobes on No1 and what they are doing. It's not unheard of that the gears could be marked a tooth or 2 out of line, causing grief like you have.

Some time ago, I bought a new aftermarket cam - said to be ideal for injection and auto - steel cogs, chain, and tappets, and the dots didn't line up. My engine is a Vitesse unit with 9.75:1 CR. The engine didn't run well.
Moved the timing one tooth anti-clock. Still didn't run well. Then tried one tooth clock wise, from the first I'd tried. Still didn't run well.

I tried to find the exact point a valve was fully open by fitting a protractor to the pulley and using a dial gauge. I couldn't get a repeatable reading, but it looked like it needed to be two teeth. tried that, and valves hit the pistons on starting.

Bought it all new again, but standard parts including plastic cog.

Dots lined up perfectly. And it ran as expected.

I did ask on here and elsewhere about a way of checking what the valve timing actually was. But the method I used as I said didn't give consistent results. Could be because I was using the magnetic fixing for the dial gauge rather than making up a proper bracket for it.

I'm not convinced any cam timing possible with the engine still turning would make that sort of difference to the compression.

BTW, although the valve obviously kissed the pistons by the noise, it ran perfectly with the new cam and no attention to the valves. So I was obviously lucky.

The whole episode put me off using an aftermarket cam, etc. If they can't do something as simple as putting the dots in the right place, how can you be sure everything else has been made properly?

Have a google search about indexing the cam off by 90 degree's

ETA

Looks like the keyway and the dot are typically 90 degrees apart on the cam wheel so I wonder if the dot has been marked by the keyway or the keyway has been lined with the crank mark instead of the dot.

Speculation - only a few bolts to find the truth.

I'd be interested in knowing how they got the valves to seat again after they have been hit by the pistons. It would take quite a lot of grinding/cutting or whatever before the eccentricity was removed from each valve. Also personally I would not want to use valves that have been hit. I've seen in the insides of a few bike engines where the head has dropped off a valve, it ain't pretty!

Er, I mentioned on page 2 of this thread that the valves may be bent. (Do I win a prize? LOL)

I've heard the engine spinning over, and can assure you it was making no odd noises. If the valves were hitting the pistons, it certain would do.

Usually, when a valve hits a piston, is is due to something like a cam belt failing. So a pretty solid whack. Just whether a valve would be damaged if it merely kissed a piston I don't know.

In my case, they suffered no damage. The engine has run many thousands of miles since.

DaveEFI wrote:I've heard the engine spinning over, and can assure you it was making no odd noises. If the valves were hitting the pistons, it certain would do.

You may not have heard any odd noises but I can assure that the valves have hit the pistons! (Well at least on the bores that the OP has posted up pictures of).

I reckon that the reason that engine did not start was because the valve timing was out, not because the valves were leaking all the fresh intake charge away. In the process of trying to start the engine the valves hit the pistons and that is why the combustion chambers failed the fluid test. Due to the angle that the pistons hit the valves it would not take much of a hit to bend the valve a few thou, it will then leak like a sieve! AJMHO!

Thanks for all of your suggestions - it seems that i have been lucky with this.

On Saturday i will set about removing the timing cover and recheck all the crank/camshaft timing, then re-assemble. I think that I can remove the timing cover without having to drop the sump!.

There has been no damage to the valves thank goodness, and when the seats were recut, nothing untoward was reported back.

R0vers wrote:Thanks for all of your suggestions - it seems that i have been lucky with this.

On Saturday i will set about removing the timing cover and recheck all the crank/camshaft timing, then re-assemble. I think that I can remove the timing cover without having to drop the sump!.

There has been no damage to the valves thank goodness, and when the seats were recut, nothing untoward was reported back.

Maybe a bit of air still in the follower saved the day.

You should be able to check the cam timing by checking when the inlet pushrod starts to lift. It should be obvious if the cam is way out.

Right. You take off the cover and discover the marks are aligned as was said. IMHO, it's pretty difficult to get them wrong, unless you didn't know they were there and just threw things together. In which case the chances are the valves would hit the pistons in no uncertain manner.

So they are lined up, but perhaps not perfectly. Trying one tooth either side doesn't make them perfect either.

So where do you go from there?

The engines that I've built have never been standard so I've always checked the timing with a degree wheel, a DTI, adjustable pushrods and solid lifters, now I'm not saying that you need to go this far with a standard engine but I guess that would be the next step if the problem is not obvious when the timing cover is removed. Doing the above will prove that the cam is timed correctly but that does not mean that the valves still won't hit the pistons if the engine is non-standard. The next thing I do is use weak checker springs and when the valves are at the critical positions (about 10 degrees BTDC to 10 degrees ATDC) I push the valve down by hand until it hits the piston. If the movement is small I then use feeler gauges between the valve stem and the pad on the rocker to find out just what the clearance is. 1.5mm being around the min that you want on an inlet valve and 2mm on an exhaust valve. Again this 'should' not need to be done on a standard engine but it should be done on an engine that is being built with mods such as skimmed heads and a long duration cam. The engines that I've built have all needed eye browse cut into the pistons in order to get clearance! The last engine I worked on had several key ways in the cam gear and the instructions were useless! Once we had worked out which keyway to use the timing was still a few degrees out. We made an offset woodruff key in the end to sort it out!

To the OP...Did the marks line up when you built the engine and was number one cylinder on TDC? Also was there more than one keyway on either of the gears?