52 replies to this topic

[Steve TPF]

Have to change the camshaft timing on a 202 black as the previous owner got it backward. (It's blowing through the carby instead of sucking.)

Problem 1: I can't get the crank timing cog off, using a puller.

Problem 2: When I had the cam replaced to what looked right (aftermarket timing gear with multiple keyway slots) the engine would turn and then jam. Turning it back the other way it would turn almost a full rotation, then jam at the same place. I'm confused.

The dizzie oil pump and rockers/lifters have been removed. The camshaft slides easily into place, the engine turns smoothly, then jams hard. Is it possible for the cams to hit the conrod big ends if not timed correctly?

[76lxhatch]

Not sure if there is any way to get the cam gear off without damaging it - the easiest way is to drill a hole in the steel collar next to the cam so that most of the steel collar is cut through and it will relax its grip. I've seen the remains of a fibre gear removed without doing this (after smashing the entire fibre part) and it took a 10 ton hydraulic puller to achieve it.

Check whether you're in the neighbourhood by turning the cam to the point where #1 exhaust rocker has just closed the valve and the intake is just cracking open - the crank should be at TDC for #1 somewhere around there, then you have to fine-tune.

If the cam slides in then the lobes can't hit anything as they are smaller than the journals. Sounds like something is getting stuck in the valve train?

I vaguely recall there being a difference between aftermarket red and blue/black motor timing sets? Perhaps the dots are in different places due to a changed method of setting the timing, this could be confusing if the wrong timing set is installed...?

[Steve TPF]

Thanks for the input.

76lxhatch[/url] "]If the cam slides in then the lobes can't hit anything as they are smaller than the journals. Sounds like something is getting stuck in the valve train?

I vaguely recall there being a difference between aftermarket red and blue/black motor timing sets? Perhaps the dots are in different places due to a changed method of setting the timing, this could be confusing if the wrong timing set is installed...?

The valve train has been completely removed, lifters,rods and rockers. Spark plugs removed also. The engine turns smoothly on its own, but when the camshaft is in place it will jam.

Timing gear is a rollmaster straight-cut set with multiple keyway slots. I have a single mark on the cam cog, but nothing on the crank cog to align it with.

Sounds like you have the timing backwards, rather than the cam. Sounds like you have timed it to the intake stroke, rather than the power stroke, so the fuel is igniting, and blowing back through the inlet valve, the inlet manifold and popping out the carby.

It wasn't backfiring through the carby, it was blowing. Removing the rocker cover and turning the engine by hand showed the inlet opening at the start of the up stroke, and the exhaust opening at the start of the down stroke. It was literally pumping backwards.

So, with the dizzie, oil pump and valve train removed, how could it possibly be jamming?

[76lxhatch]

So, with the dizzie, oil pump and valve train removed, how could it possibly be jamming?

If you haven't taken the cam gear off maybe it is something to do with the cam retainer?

Otherwise perhaps bent cam...? Or maybe some internal damage...?

[Steve TPF]

It was turning over quite smoothly before - just with the wrong timing.

[Steve TPF]

I don't have an option as to which keway to use because I can't get the crank timing gear off. AS to going back to basics: my engine now has nothing but the crank,pistons and head. I'm quite happy to start from the beginning, but I need to figure out why it jams with the camshaft in.

Removed the cam entirely and looked down the cam journals with a torch while turning engine. The big ends of the conrods can be seen as I turn it over - they must be scraping against the cam lobes. Perhaps the cmshaft isn't going all the way in, but it certainly seems to be.

[FastEHHolden]

Are you using a new cam or an old cam that been laying around? 202 and (149-161-179-186) cams have a different thickness shaft...the 1/4 inch of extra stroke caused the rod bolts to hit if you use an early cam in a 202 block...aftermarket cams are all releived to clear...however it is possible you have a really really old (pre 1971) cam or you have a remanufactured early cam.


I'm willing to bet the crank gear is fitted the wrong way around and that is the reason you cant see the timing mark...look on the back of the gear. if its there count the number of teeth from the 12 o clock position on the gear and remark the same distance from 12 o clock on the other side of the gear. ie if you find the mark on the back of the gear is in the 2 o clock position.....mark a dot in the 10 o clock position.

Put the number one piston at TDC. Fit the cam...does it turn over now?

[Steve TPF]

It's the cam that came with the engine, installed. It cranked over happily, no jamming. Far as I know it's an original or reground cam.

I can't look on the back of the crank gear because it's still attached to the crank. All attempts to remove it have failed.

[FastEHHolden]

Does the cam look like a 1 inch round bar with lumps on it...or does the the shaft that is between the lobes have flat sides?

Straight cut gears?

[Steve TPF]

Round bar, no flat sides. Yes to straight cut gears.

[FastEHHolden]

that is a stock 202 cam....note the releived bit....a 186 cam doesn't have this.





here is a pic of a set of str8t cutz, even if your crank gear is on backwards there is a 1/4 inch gap that should still enable you to see the timing mark....no matter put a mark between the 4th and 5th tooth to the left of the 12 o clock position on the crank gear.


is your crank gear fitted to the middle keyway?

[Steve TPF]

MY timing gear is a little different. Multiple holes in cam cog. It's not on backwards as far as I can tell. There are a couple of numbers visible, -6, -4, and possibly -2.The keyway in use is the one on the right lower, going by your pic.

No relief groove in camshaft, but like I said, it cranked happily before, so it must be something I'm doing wrong.

[FastEHHolden]

can you post a pic of the crank gear from end on?

[Steve TPF]

No digital cam or phone, sorry.

My timing gear looks like this:

Edited by Steve TPF, 13 June 2011 - 06:03 PM.

[FastEHHolden]

they are the same design? multi key is on the crank

[rodomo]

Where do you live?

[Steve TPF]

Yes, same design. Keyways on crank cog.

I live in Craigieburn.

[Steve TPF]

Okay, with #1 at TDC I fitted the camshaft counting back 4 cogs from 12 o'clock Engine jams at 9:30 position, same when turning other way. So it's jamming at 1 point only. If the big ends were hitting the camshaft itself I wouldn't get more than 1/2 a turn before one of them contacted.
Removing camshaft again and looking down cam journals:

1: When engine is at 9.30 position, big ends 1 and 6 are closest to the camshaft.

2: No.1 big end has scrape marks on the bolt housing. Which would seem to indicate it is the problem, but I can't find any marks on the camshaft to indicate contact.

I'm out of ideas. Surely if the camshaft was that badly bent I wouldn't be able to take it out?

[Steve TPF]

Yes, plenty. But that wouldn't affect the camshaft.