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timing and replacing timing gears & chain

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recordsj

Jedi Warrior
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I have a 1500 MG Midget.

I am ordering replacment crankshaft, camshaft timing gears and chain, do the timing gears typically have the timing punch mark on the gears already there?

If not how do I do the timing?

If the timing pump marks are there how do I check to make sure they are accurate (is there some kind of double check that I can do)? I would rather not compare them to the old ones, just in case the old ones are innacurate.

Since I have part of the engine open (the timing cover off) but still in the car, is there anything else anyone would recommend I replace at this point that would allow easy access?
 
I have not worked o a 1500 but I would expect the timing marks to be there. Your new camshaft will come with a spec sheet that spells out what the exact, optimum crank angle you need to set it for. The timing gear dots may be close enough but likely won't. To get the valve timing set exactly right you will need a degree wheel, a dial indicator and stand, and either offset ground keys for the pulleys or adjustable timing pulleys. Since you've already bought new pulleys, using offset ground keys will be less expensive.

The process of dialing in the cam isn't difficult and it is well outlined in most engine building books. Rather than try to describe it in detail here, I encourage you to visit the local library and browse through a few texts. Step-by-step pictures are much better than words alone.

The degree wheel MAY have been supplied with your cam. If not, they are available from most auto parts stores that have machine shops. The dial indicator and base can be had from places like Harbor Freight (yes... lower quality, but good enough for occasional use). Various LBC part suppliers should have the offset ground keys. For the 1500 I'd like to think that The Roadster Factory would have them. The only problem with using offset keys is that you have to measure what angle you have now with regular keys, determine the offset ground key you need, then buy that key and install it. It's a bit time consuming.

If for some reason your new pulleys came without ANY marks on them, the procedures used to dial in the exact cam angle could be used to properly set the cam timing.
 
Having the various offset keys to hand ahead of time is a good idea, they're cheap enough. And a degree wheel/dial indicator would be THE way to determine cam timing. And to confirm/adjust the "factory" timing cover reference, too.
 
Having been through that process recently, it's not difficult but I'm wondering why you are replacing the gears? I replaced the chain but the gears were in good shape.

Feel free to disagree with me y'all but I don't think the tolerances on a 1500 are so tight that you're going to get any better performance from new gears - unless the old ones are chewed up somehow.
 
Agreed, JP. But I have seen some well worn gears in my time, too. Chewed, wallowed out keyways as well.
 
I am not replacing my crankshaft or camshaft, just the crankshaft timing gear and camshaft timing gear along with a new timing chain.
 
My mistake, I read that as you were replacing all of the above. So... you won't necessarily have the specs for your existing cam. Again, I've not worked on a 1500 so hopefully someone will post the preferred angle. If not, trust that your timing pulleys are marked close enough.

If you do decide to read up on dialing in a cam and the use of degree wheels... I found I still had a template online that you can print out and glue to cardboard to make your own cheap degree wheel. Print it out as large as you can while maintaining the aspect ratio.
https://home.mindspring.com/~purlawson/files/DegreeWheel.doc
 
Hello records,

the standard Triumph cam wheel can be fitted in four different positions giving about a 4 degree setting tolerance which should be adequate for a street engine. The camwheel has four holes two of which are used to secure it to the camshaft. The four drillings are slightly offset so that by using one of the pair and turning the wheel back to front gives this marginal adjustment.
Aim to achieve equal lift on valves 7 and 8 when the number one cylinder is on TDC firing position.

Alec
 
The new sprockets will NOT have marks.

mark
 
No marks... Hmhh. Thanks for the information. I'll make a mental note about that for the future. Does this also apply to the smaller Triumph 4-cylinders?
 
I imagine they would have to be unmarked - perhaps if sold in pairs but otherwise the reference would be meaningless
 
dklawson said:
No marks... Hmhh. Thanks for the information. I'll make a mental note about that for the future. Does this also apply to the smaller Triumph 4-cylinders?
Click to expand...

Yes.

All the Herald, Spitfire, etc., engines have unmarked gears. Also the sixes derived from them are usually unmarked (GT-6, TR6, etc).
And many used gears will have unfathonable punch marks from previous owners all over them (mine did).

Alec has given a good suggestion.
Also, many cam vendors (such as Kent) will provide a setup sheet to get the cam timed. Generally, you'll need a dial indicator to do this with accuracy.
 
By the way, here's an added comment I found elswhere.

It is basically the same approach as Alec's:

The Spitfire cam sprocket has 4 holes but only 2 bolts. The holes are slightly off set from each other and if you turn the sprocket over that gives you 4 different settings. Set the crank so 1 & 4 are exactly TDC. Set #7 & 8 valve adjustment at .080" and set the came so that #7 & 8 valve are in their "rocking" position. Rock the cam back and forth until the clearance of both valves are exactly the same no matter what that clearance is. Then slide the crank sprocket in place and the chain on and put the cam sprocket in the chain and check to see that two of the bolt holes line up. DON'T move the crank nor the cam. If the holes don't line up then take the sprocket out of the chain and rotate it 90 deg. and try again and if it don't line up remove the sprocket and flip the sprocket over and try again. If it still don't fit rotate 90 deg. One of the four possibles will fit. Then check the ignition timing as you could get that out of whack setting the cam timing.
 
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