15 replies to this topic

[zomerzet]

Absolutely GUTTED. Just got my engine in single-handedley (NOT easy) after swapping blocks (Long story) and have no compression on cylinders 2 and 3 and have about 1 bar on on no.1 cylinder. I don't know about cylinder 4 as by the time I'd tested the frst three I was far too demoralised to continue

I imagine I've got the timing sprockets set up incorrectly, but was pretty sure I had the crank and cam sprocket 'spots' lined up ok. It was the first time I'd done this but it seemed pretty simple. I am now facing another engine extraction *sigh*. I have had this engine in and out so many time now it is almost an inevitability. Luckily, I span the engine by hand first to make sure I wasn't going to mash any valves!

I had a spark of genius earlier and wondered if it was possible to get to the timing chain while the engine was still in the car? I understand this will mean removing the radiator, engine mounting bracket and jacking up that side of the engine (Not forgetting to drain the oil!)? Has anyone done this?

P.S. If this does work and a hole was made in the inner wing grille, would it be possible to change a cam like this???

Just realised I haven't adjusted the rocker clearances so if I'm REALLY lucky it'll be that they're too tight, not allowing the valves to close fully

[miniboo]

check cylinder 4 but intial guess is that you have a dodgy headgasket between cylinder 2 and 3

[James_1]

check the tappets. this is ver very similar to what happended to my motor. turned out that i had incorrectly set the tappets one of the valves wasn't shutting perfectly.

[minididdly]

my bet will be with the rockers, past experience.

[dklawson]

Good point on the rockers. Did you loosen them off when (presumably) you refit the head? Did you readjust them properly when you were done?

I'd check all the things you can check with the engine in place first. In addition to checking the valves, re-check the torque on the head. Way back when I was a kid, I pulled the head on a car that used bolts, not studs. I didn't notice but oil had seeped down into the tapped holes on top of the block. When I torqued the head bolts, they trapped and pushed on the trapped oil. It gave a false torque reading, causing me to leave the head a bit loose. When I started the car it had no compression at all. I gave up and took it to a shop who immediately torqued it up properly and the car ran fine. I was embarrassed and out about $50 for a simple mistake.

You can replace the timing chain with the engine in the car. It does not require pulling the cam. As for changing the cam in the car... you can but why on earth would you want to? To change the cam is more than just cutting a hole in the wing. You'd need to find a way to hold the cam followers "up" so you can extract the cam without them falling. If for some reason you still have a cam and oil pump using the spider drive, there's a good chance the spider will fall out into the sump which would require pulling the engine to remedy. I would not consider changing the cam with the block in the car.

[James_1]

The engine will run if the dots were lined up. This won't stop it running. If it was a standard factory cam (MG Metro etc) then dot-to-dot is fine, this is how they were done on the assmebly line, it is only if you had a major regrind that this could be a problem. Check the rockers very carefully, this is exactly what happened to me and I got very close to getting the motor out/changing the timing before finding the tappets were wrong.

[Sprocket]

Yeh but you can get the dots lined up with the cam being 180 degrees out

[dklawson]

"Yeh but you can get the dots lined up with the cam being 180 degrees out"

Not really. The dots are supposed to be adjacent (close) to each other when the chain is fitted. The dots either line up or they don't. For the cam to be 180 degrees out the dots won't be adjacent to each other when fitting the chain, the cam dot would be far away from the one on the crank.

[zomerzet]

Thanks for all your replys guys. I've calmed down a little now as it was indeed the tappets I'm so glad I don't have to get the engine back out. I thought I'd lined up the timing OK! I'm getting at least around 150psi on EVERY cylinder now. The old block was a high miler and the new one was from a metro that had done 44k so it's obvious how much wear there was on the old cam and followers. It is just a standard MG block and cam so lining up the dots was fine.

I was asking about the cam just out of interest really. Good point about the followers, I suppose you could use 8 strong magnets! The fuel pump'd have to come off too to stop it jamming the cam on it's way out! At least I now know that playing with the timing chain is possible with the engine in place though.

[GraemeC]

dkl - Sprocket's right, you can get the timing 180deg out with the dots lined up - I've done it!

Remember the crank does 2 revolutions to the cam's 1

[dklawson]

Please explain to me how with the keys installed in the sprockets how you can fit them to the cam and crank in a manner that allows the dots to be out 180 degrees.

[dklawson]

I'm not trying to beat a dead horse, but....

Haynes (and presumably the other manuals) show a picture or drawing of the dot-to-dot timing chain installation. If you work to that picture, with the keys in place, I don't see any way to assemble the timing pulleys. There are other related components you can put together wrong like the two-piece hub on an early flywheel, or the distributor drive gear, but I don't see a way to assemble the timing chain pulleys wrong if you work to the picture.

[The Matt]

Surely, if the cam is in the right position, the distributor will fire in (somewhere) near the right position?

This '180 degrees out' confuses me???? Surely if the dots are lined up, the camshaft and distributor are still in the correct relative position. The crank doing two revolutions per one camshaft revolution is nowt to do with it, is it????

[GraemeC]

Got to admit I can't remember exactly how I did it! I seem to recall that I had the block sat on the deck face (so upside down) but then followed the instructions in HBOL as to the keys being at 2 o'clock or something.

Certainly confused the hell out of me for a while.

[dklawson]

For future reference regarding the dot-to-dot cam timing, work to the picture, not to any text about keyway positions. With the keys inserted in the crank and cam and the timing pulleys installed on them, the timing dots are to be "close" to each other with the dots lying along a line drawn between the centers of the cam and crank.

These pictures aren't for the A-series engine, but they apply nonetheless. See:
http://ourworld.cs.c...degree_08_z.jpg
and
http://www.rcdengine...ges/wetbelt.gif

Don't loose sleep over my comments about putting the dizzy in 180 out. Succinctly, if you have removed the cam, out of necessity you have to remove the distributor drive gear. After you put the cam back in , it's easy to install the distributor drive gear back in "angularly" the wrong position. It doesn't matter. We can discuss this on a separate thread if you want. Suffice it to say that putting the distributor drive gear in wrong as part of a rebuild is fairly common.