Tried to fire her up tonight...but no....

[ETTony]

After rewiring and completing my LHD to RHD conversion, mine would not fire.
No spark at LT leads.
The problem was the Pertronix unit was fried, probably by me some how.

Took it to the distributor doctor at Wivelscombe, where he confirmed the fried electronic unit.
The unit was overhauled (bearings) and the points refitted, i also picked up a mega jolt coil (plug gap 40 tho)

Static timing set, checked rotor arm, fit dissy. FIred up

[Durango2k]

Finally the compression tester arrived. The first I bought was a compression tester for fuel injection systems- I made a mistake clicking on it, it looked very similar on the pic, it was one Euro less then all the other identical boxes, so I made a mistake.

But at 16 Euros I could afford keeping it, and will use it on the DS iE later.


Now, I measured compression on the Jag engine and found

0-7-6-7-7-0.

Yes, thats exactly naught on no 1 and 6. I re-checked, and the hose you can screw in the plug holes does blow strongly on 2-5, but no wind on 1 or 6.

All I can imagine is sticking valves (unlikely) or of course timing offset.

Is it possible that I had the engine on 10 tdc by error and then set the cams ? Would that cause this behaviour ?

I see a head coming off in the future.

Currently, it's -11 degs, so not now, but maybe later this year or in 2017.

Carsten

[Mich7920]

Hi Carsen,

As you can look on the book, the compression for a /8 is nearly 10.9 and for a /9 it's 12.6.
So even if everybody scraches their head, you have clearly a problem with your engine.
I recommand to fit out your engine and check all, block and head because if you have this poor pressure, you have all the chance to have others things going wrong in a small time.
You can do it yourself ( with good help...) or give it to a good professionnel.
You win a lot of time and money !
Mich

[64etype]

I bent a valve while setting up the shim clearances on the bench....

[Durango2k]

I did make a wooden bed for the head, and used it, so I can say no valve was bent.

I had new guides fitted, and I was there when they checked the lapped valves for vaccuum using a special suction- plate. It was all tight. Head was checked for cracks as well.

I'll set the engine to tdc, and re-check for the valve timing tool to fit in the cams.

If it fits, head off/valve check. If it does not, line up, correct the fault, and measure again I'd say.

In my mind I cannot be much out of phase, because I can see both cams with the lobs pointing outwards.

I do have access to a cheap boroscope, so I could try to look inside.

But as the lobes are in a fixed position vs the tool slot on both cams, I'll check that first.


Carsten

[PeterCrespin]

I did make a wooden bed for the head, and used it, so I can say no valve was bent.

Carsten

I can say some valves ARE bent - maybe not on the bench but afterwards. This assumes they were correctly fitted initially, with good springs, ruling out sticking once they were opened.

Your block has been rebored with new Mahle pistons, which run tight clearances. Even with a broken ring or two on #1 & 6 you would have significant compression. The only way you can have zero compression is a bent valve in my opinion. If the cam timing was crazy then that would bend valves, as would just turning the crank or one cam and not the other before everything was hooked up.

Your engine has not run, so a major gasket blow is effectively impossible, unless you messed up fitting so badly it would probably pour coolant out as well as not holding air. I doubt that is the situation, especially at opposite ends of the block.So if you rule out valves already being bent before the head was fitted and you rule out a massive gasket problem, the only thing left is incorrect assembly technique, which is only possible by not following the book.

You would certainly not be the first one to be caught out by a DOHC hemi engine after working on pushrod or SOHC engines.

If you put # 1&6 at tdc firing stroke in turn and pressurise each one via a hose connected to an old plug body (or your compression test adapter?), you will hear where the air is comIng out - amost certainly the intake side. Strip, repair and reassemble following the book and you will have no more trouble. If you cut corners or do not follow the book - especially about valve set up in the head or head reassembly to the block, it may happen again. Those are the two most common ways to bend a valve apart from with the head on the bench, which you say did not happen. At least the engine does not have to come out of the car, although you will need new gaskets.
.

[Durango2k]

Despite the cold I just went in the shed for another 25 minutes, and set the engine to tdc, so it shows 0 degs on the crank pulley damper. The 4 inner pistons seem to be at the same height, so I am pretty shure that it's there.

Then checked the cams- both look nicely with their grooves aligning perfectly to the tool.

So, head of it is.

I have never before been caught by that on the SM engine, despite it having 4 cams, but maybe the valves are wider spaced and can't touch so easily.

To get the head off- drain water, and remove carb manifold. Remove exhaust manifolds and swing them out, or must I disconnect the downpipes at the flange ? Disconnect rear oil pipe at side of block. Remoove all head nuts, remove flame trap under coil, loosen chains, loosen 4 bolts on cams, remove toothwheels from cams, and lift head of ?

I am really curious what I will find in there....

Hopefully the weather will change to some degs plus. At the moment it is not nice. I can do it but it won't be nice.

Carsten

[paulsco]

What about the possibility of the insufficient clearance on the valves?
If they were all too tight then the valves would leak?

Seems more likely than bent/sticking valves on ALL the cylinders??

Paul

[Durango2k]

Hi Paul,

Yes will do a valve clearance check next. Thought about it when looking on it in the shed, but gave up, too cold and too late.

Carsten

[Durango2k]

Here are four pics I took tonight.

Can anyone spot anything wrong ? I can't....











Carsten

[Robsan]

1 If valves in 1 and 6 are bent [to extent of significantly keeping valve open] , wouldnt previously set valve clearance be measurably out ?
2 Is there a way of removing cams [ and attending temorarily with timing chain]...... and then do compression test......... has it been done ? can it be ? I understand your reluctance to remove the cylinder head.............. I was trying to think of a way to eliminate the cams from the query ?

[abowie]

I was trying to think of a way to eliminate the cams from the query ?

If you can slide a feeler gauge between the back circle of the cam and the tappet bucket then the cam is not preventing the valve from closing.
There are several ways that errors with shimming can lead to inadequate clearance so it is well worth checking the clearances are correct before removing the head.
As an aside, and I haven't gone back and reread the whole thread, even if a couple of valves were bent I would still expect that you should have been able to get the engine to fire, if not run roughly unless there was another problem as well. A complete lack of ANY firing at all to me implies that there is another fundamental problem.

[Durango2k]

Yes,

This cat has flees and ticks...

Carsten

[Mich7920]

Carven,

Trying to do mechanics by correspondence is anything but an exact science. Too much parameters for an engine.
Instead of trying to put a "patch" where it seems to have a fault, really it would be better to restart all.
It's very alarming that you have a problem with the head because all the people who work on this kind of engine know that is a very very important point which take the most time to adjust correctly.
If the head is like this what about the rest ?
For me the doubt is absolutly unacceptable
Mich

[Durango2k]

Hi Mich,

I am fine with it :-), because, in the end, it's an old car.

Carsten

[Hugo]

"2 Is there a way of removing cams [ and attending temorarily with timing chain]...... and then do compression test......... has it been done ? can it be ? "

No - because the engine won't be able to suck!

[Hugo]

"You would certainly not be the first one to be caught out by a DOHC hemi engine after working on pushrod or SOHC engines."

That is very true - there are a dozen ways to bend valves when assembling these engines without even trying.
BUT - there are two things to observe - 1) if you have bent valves, your valve clearances will have opened up enough to notice (unless you set the clearances after assembly of course) so first check all your valve clearances; 2) if you have no compression on 2 cyls, this should be obvious from the way it turns over on the starter. Does it sound even or is it skipping a beat every revolution?
And of course check check and check again that the compression tester is giving accurate readings. I don't really see how you could get it wrong, but it would be a shame to pull the head off just to find that the compression tester wasn't plugged in properly or was faulty!
I reckon the engine should still show SOME signs of life, even with low compression and/or no compression on 2 cyls. I have a horrible feeling that when you finally get this sorted, you will find that you have over-looked something basic and obvious.
I last dipped into this about a week ago, & I'm amazed it is still going on! Can't stand the suspense!

[chrisfell]

Am I the only one shouting at his laptop "leave the head on, it's something else"?

[64etype]

No, you're not. Most folks are suggesting a valve lash check, I believe.

[Durango2k]

Which is what I will check next.

A close friend, professional DS restorer, said that 1/2 mm bent of a valve or a minimal piece of swarf would be enough for this problem at cranking speeds, and that it may "rattle itself out" once it runs.

So, he suggested to get it running on the centre 4 - he said it still has more power on these four then a whole DS.

I'm waiting for the Pertronix, check valve clearence, and get back to this place. Praying for warmer weather as well....usually it is freaky cold, just until x-mas where it becomes 5 degrees and raining for a whole weak. Wet Santa.

Carsten