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Engine rebuild

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Healey Nut

Healey Nut

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So Im rebuilding the engine on the the 64 BJ8 prior to it going back in the car .
Is there an easy quick way to determine if the valve timing is correct .
I have both the original owners manual and the Haynes manual and it shows the dots on the timing gear wheels in different positions .
I had the the keyways of both the crank and cam at 12 o'clock , #1 cylinder (water pump end) at TDC (head off) and that puts the crank dot at between 6 and 7 oclock and the timing gear wheel at between 12 and 1 o'clock .
There are no bright links on the timing chain so thats no help to me .
I vaguely remember someone telling me there should be 7 links between two point but cant remember what the two points are .
Help appreciated :smile::eagerness:
 
Do you still have an old timing chain with "bright links" for comparison? I've got one somewhere...

Number One cylinder @ TDC should see both valves "rocking" in other words, valves fully closed with clearance between cam/lifters/pushrods/rockers to valve tips. How much they "rock" will be dependent on what you have the static slack set at.
 
No bright links on the old chain either and the head isnt on so Im not concerned about valve rock right now . Im just confused as to the position of the dots on the timing chain gears as the manuals are different . I put the gears on with both cam and crank keys at 12 o'clock etc .
 
Healey Nut said:
No bright links on the old chain either and the head isnt on so Im not concerned about valve rock right now . Im just confused as to the position of the dots on the timing chain gears as the manuals are different . I put the gears on with both cam and crank keys at 12 o'clock etc .
Click to expand...
See if this helps?
 

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There are 15 links between the dots including the ones at the dot positions and counting clockwise from near the top of the cam sprocket. The dot on the cam sprocket is at the top and the crank dot is at the bottom. The timing can only be out by multiples of about 17 degrees as that is one tooth. If it is just a little out then that is as good as it gets.

If you want to get it spot on, borrow a DTI (dial test indicator) and actually measure the timing, even when new they were up to five degrees retarded. About 2 deg advanced is a better position as it considers chain stretch over time. A and B series engines are much the same and there is a 7 degree offset key available to correct the timing but I haven't seen one for the 6 cylinder.

I reset my cam timing by filing the key and filling the back side with shim metal. It is quite a bit of pissing about for a minor gain (mostly fuel economy) so that may not be your thing...

Andy.
 
Thats a great help , tks guys .
But if you put the gears on with both the cam and crank keyways at 12 o'clock would you not automatically have 15 links dot to dot ?
 
Even with the key-ways in the 12 o'clock position, it is very easy to get it wrong. I always think of it in terms of 13 FULL links between the dots. In order to have 15 links, you have two half links and 13 full links between the dots. There are photos in the factory manuals and the Bently manuals that illustrate this exactly...so you can count the links and the position of the dots.

If I remember correctly, getting it off by even one tooth results in a 6 degree change.
 
Update ... I put the head and valve train on then with the plugs out turned it over and checked the valve positions with #1 cylinder at TDC and the valves rock at the right point and the timing mark on the crank pulley lines up perfectly and the distributor drive gear is in 8/2 position so I'm pretty sure I got it right .
Time to paint it up and make it look pretty ......Well not so fast flywheel clutch gearbox blah blah blah then paint it up .:cool::encouragement:
 
Healey Nut said:
Update ... I put the head and valve train on then with the plugs out turned it over and checked the valve positions with #1 cylinder at TDC and the valves rock at the right point and the timing mark on the crank pulley lines up perfectly and the distributor drive gear is in 8/2 position so I'm pretty sure I got it right .
Time to paint it up and make it look pretty ......Well not so fast flywheel clutch gearbox blah blah blah then paint it up .:cool::encouragement:
Click to expand...
With the distributor at 8/2 you can have the distributor timing still off 180(different than the cam & crank timing chain). There's a offset key you need to be aware of but it's easy to turn the distributor gear 180 if it's wrong.
 
If you're valve timing any engine, the simplest double check is to make sure that numbers one and six are at TDC, then rotate the camshaft (in the direction that it rotates normally) until the exhaust of number six is closing and the inlet is opening, "on the rock" we call it. In exactly the mid point, put the timing chain on and you'll be spot on. If it's a racing engine, do the same and then with a timing disc, refer to the actually degrees of opening and closing and check what you have against what you should have and if necessary average it all out. A four is the same and with a twelve (and presumably a V8) just do the same on A bank.
 
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