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MG MGB Technical - Offset woodruf key source?

I've just timed my new cam in and found it around 6 degrees out so I need an offset woodruf key. I've just been looking for suppliers from the usual suspects but don't see the offset keys listed. Any idea where I may be able to get one. I presume I need a 3 degree offset to correct for 6 degress at the crank. It's been a real pain doing the timing. Finding TDC is easy enough as the engine is smooth at that point (least piston movement). However finding the top of travel for the cam lobe is a lot more difficult as there is a lot more stiction happening as the pistons need to be moved (new pistons and rings!) I've checked it twice. A couple more times perhaps to be sure.
Steve Church

According to my parts books, the woodruff key is the same as A-series engines, so should be available from the like of Minispares, Minisport, etc.

What is the timing at the moment?
Dave O'Neill2

Also Advanced Performance Tecnologies in USA. Mike
J.M. Doust

Hi Steve

Are you checking half a thou before full lift to half a thou after full lift and dividing by two? Six degrees seems a lot on a billet cam. If it is six degrees you need a six degree offset key.

Peter
Peter Burgess Tuning

At the moment I'm getting 102/102.5 degrees. I've checked it four times, both for piston TDC and cam peak.

Peter, I have not checked at 1/2 thou. I used anything from 4 thou to 10 thou (but always the same same figure before/after). This was mainly due to the difficulty I described earlier in overcoming the stiction of the the new piston rings. I will try with 1/2 thou if I can achieve this. My dial gauge is only marked in 1 thou increments though. I also thought 6 degrees out was a bit much as well especially in view of your comments that billet cams should be better in this respect than reprofiled ones which was one of the reasons for getting a billet.

I'll check again tonight just to be sure.

I'm assuming that the offset key goes in the camshaft not the crank.(Just to be sure).

Steve Church

Dave,
I agree that the cam key is the same as the 1275. However when it comes to offset keys doesn't the diameter of the camshaft where the keyway is have a bearing on the degree offset for any given offset key. For instance a six degree offset key will give a different degree offset for a shaft diameter of 2 cm to that for a 4 cm diameter. So next question. Is the mounting hole in a 1275 timing sprocket the same as for an 1800?
Steve Church

We use MiniSpares offset keys they are marked with the degree they will offset. They go in the cam shaft.

We have had an odd occasion where the original gears are not perfect but this would be a first so far out on standard gears.

I check where the max lift is and set the zero of the dial gauge so it is approx 1/2 thou (halfish of your 1 degree increment) exactness not important from max lift. You turn the engine in direction of rotation till you hit the zero, take a reading, go past zero and back to zero and take second reading.

Peter
Peter Burgess Tuning

Peter,
Minispares it is then. Your comments make me wonder even more that I may have done something incorrectly. I will go back and check how I've put the gears on. If I was 20 degrees out then I'd know I'd done something wrong but 6 degrees is in the right ball park (albeit on the fringes!). I don't think my method of measurement is incorrect, having read various write ups including Peters.
Steve Church

Just a thought. I didn't use a new timing chain as the PO said he fitted a new one along with a new tensioner. The timing gears look good. The tensioner is in. Could a stretched chain account for a few degrees out. When installing the gears I would not have said there was any slop in the chain. I'll check that without the tensioner. How much side to side movement would there be on a new chain?
Steve Church

Hi Steve

A worn chain may leave the cam a little retarded. You are reading advanced.

Peter
Peter Burgess Tuning

Steve,
You can get them from Moss.
N
Neil22

While we are on this subject of degreeing a camshaft. How often is it that an engine from the factory is out in its timing? Commonplace? In other words, is it worth degreeing any and all engines? Mike
J.M. Doust

if you dont measure it you would never know.

Peter
Peter Burgess Tuning

It's so much like the A series that the comp tuning book says " do not use mini cooper gears, as they give the wrong timing".
I don't know how much wrong.
Mike not rare at all, depending on how close you want to be. I check all of them Record is 14 out from the factory on a Spitfire.
Or when I was a kid a flathead Ford V 8 that had two sets of marks, 180 apart!

FRM
FR Millmore

Cool! so really, that is a tuning mod in itself. Don't go straight to porting, gasflowing, intake, exhaust, carbs, air cleaners, until you have checked the cam timing???? and this could be done with the engine in the car? Mmm, sounds like a nice weekend job.
PS, course, one might find it's spot on!! Mike
J.M. Doust

Indeed. The Spitfire showed about 15% increase in fuel mileage and about the same in power by butt dyno. That's the owner's butt and he did not know what I did; my hutt said the same. Timed 2 deg advanced over stock with a new chain, ie about +16 over where it had been. I've had similar experience on other cars just by replacing the chain and timing the cam in, even on pretty clapped out engines. Notable decrease in oil consumption and smoke too. I believe this is a major factor in the "really good" or "real pig" phenomenon in otherwise identical cars.

Of course, this is just an extension of "make sure all stock settings are right before you screw with it". The factories are not populated by idiots, although the bean counters interfere sometimes.

FRM
FR Millmore

If a cam is "out" when new, could it be that all lobes are out the same amount, or can they be all different?
Art Pearse

Generally the error is in initial indexing of the blank, at the keyway. After that the nature of the cam grinder tends to keep all cylinders in the correct relationship. When I have checked multiple cylinders, they have all matched. I frequently check 1 & 4, more as a check on my setup. But I suppose if something can get screwed up, sooner or later it will be!
FRM
FR Millmore

I've fitted a new timing chain and rechecked everything again. With the dots lined up and the sprockets fitted the dot on the cam sprocket sits a little clockwise of the crank dot. Anyway I measured again and have 102.5 to 103 degrees so will go with a 5 degree offset key. I presume if I can get withing one degree it will be close enough?
Steve Church

Hi Steve go for a 4 and leave the cam a little advanced.

Peter
Peter Burgess Tuning

I'm happy to take your advice on this Peter. What does this achieve exactly (as an engineer I have to have a reason for everything!).
Steve Church

It tends to give slightly better bottom and mid range, where you usually drive, at very slight loss on the top, where you don't. And, as the chain wears in, it leaves it very near spec for the rest of the engine's lifetime.

You can expect 1 or 2 degree retard as the chain beds in, in the first few thousand miles. Another 2 deg might take 50,000 miles or more, if the engine is well maintained.
+ or - 2deg doesn't make much difference, but if you start out dead on, then 4deg wear leaves it 4 late, which is very noticeable.

FRM
FR Millmore

Spot on :)

Peter
Peter Burgess Tuning

4 degree offset key installed. Now between 106 and 106.5 degrees. Now I can get on with the rest of the engine!
Steve Church

Brill, good luck

Peter
Peter Burgess Tuning

This thread was discussed between 26/02/2012 and 03/03/2012

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