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More Cam Installation Questions....

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Well, I have my cam "temporarily" place in the block (GP2) and I think I have it right. First, there are no areas for adjustment using a stock cam sprocket. I lined the mark up on the crank sprocket with the mark on the cam sprocket and, and that's it... What's to adjust? The first lobe on the cam (exhaust valve lobe) is pointing down and to the right (sitting on the cam and facing forward with the engine) at TDC on the #1 piston. The new chain is really tight, with much less slack than the old chain (both double rows). Do chains stretch that much? Again, there is zero way to adjust the sprocket, short of whallowing out the two mounting holes (that was a suggestion from GoodParts). I still don't have a head in yet. Thought I could drop in the cam follower and measure the rise and fall of the new pushrod with a dial guage, if that would do any good. Again, am I on the right track or is the cam in wrong? Lots of lube on the cam. Waiting for the head. Cleaned the piston tops off (bunch of carbon). Any way to polish these or just leave them with micro scratches? So many questions, so little time.....I've had a headache all weekend to boot.

Bill
 
Bill,
If your not using a degree wheel or dial indicator, the "on the rock" installation described in the Bentley sounds like what your doing. After you find TDC the instructions for your cam will describe the timing events & what they should be (degree's off lift) . At that point you'll know whether or not you need to advance or retard the cam. You could install a cam 5 or 6 degree's off & probably not radicaly affect performance. Degreeing the cam would fine tune the power band to come in early or later in the rpm range.
The chain will definitly stretch, which will eventually again retard the timing a degree or two over time, that's the job of the chain tensioner.

I'm still trying to find the exact numbers on turning the cam sprocket over to adjust timing. This method will eliminate the original timing marks, which most new gears don't come with anyway.
 
If, as you say there is no way to adjust the cam timing, the only advantage of using a degree wheel and dial indicator is to determine if the cam was correctly machined. With no way to adjust this is mostly exercise. I'm surprised that there are no after-market suppliers of adjustable cam gears. Best of luck, Bob
 
Hello Bill,

there is a four way adjustment on the cam sprocket, but it is not at all obvious. The sprocket is attached by two of the four holes, and the two sets of holes are not at 90 degrees to each other, that and the sprocket is designed to be fixed either face out giving four increments of adjustment which enables fine tuning of the timing.

Alec
 
[ QUOTE ]
I'm surprised that there are no after-market suppliers of adjustable cam gears. Best of luck, Bob

[/ QUOTE ]

Hi Bob,

Adjustable (vernier) gears are widely available for the 6-cylinder TR. They are less commonly avail. for the 4-cyl. One place that has both is www.britishframeandengine.com Moss and Victoria British also sell one for the 6.

The original solid pulley allows for quite a bit of adjustment, including turning it front to back, as already mentioned. The bolt holes are slightly off-center to give a bit of adjustment doing this. You can usually get pretty close with this, if you don't want to go the expense of an adjustable pulley.

FYI, unfortunately, some modern replacement pulleys that were made for the 4-cylinder engine have centered bolt holes, that give no adjustment when turned front to back. I don't know if this was also done with replacements for the 6-cylinder. But, it's something to watch out for in either case.

There won't be nearly as much adjustment possible with these incorrect pulleys.

One very well-made solid (non-vernier) pulley for the 4-cyl. engine is by Kent. I think they also make one for the 6. These are machined steel, so both stronger and lighter than the originals.

Alan Myers
San Jose, Calif.
'62 TR4 CT17602L
 
[ QUOTE ]
Do chains stretch that much? Cleaned the piston tops off (bunch of carbon). Any way to polish these or just leave them with micro scratches?

[/ QUOTE ]Well, chains don't stretch literally, they simply get longer as the bearing points in each of the dozens of links wear, increasing the distance between the links. As far as your decoked piston crowns, you wan't to make sure there are no sharp edges left as preignition sites. If there are, take some emery cloth to them. Be sure to rim the crown with grease first to catch debris.

As a good decoke PM, you should plan on doing a SeaFoam soak at regular intervals. A lot easier than R&Ring the head to decoke the crowns.
 
I think it is worth changing the cam chain while you're in there, as a preventive measure.
Reynolds make very good quality chains, not an expensive precaution.
Simon.
 
[ QUOTE ]
I think it is worth changing the cam chain while you're in there, as a preventive measure.
Reynolds make very good quality chains, not an expensive precaution.
Simon.

[/ QUOTE ]I agree, but add that it should be done as a complete timing set (chain, chainwheel, crank sprocket), not just the chain. The last time I checked, an authentic Reynolds chain was close to $100, not cheap.
 
I went ahead and bought a Kent adjustable chain/sprockets combo so I can dial in my new cam. A lot of money for basically a one time adjustment but would negate all the other improvements if I don't.

Bill
 
Ha - makes me feel lucky! When I degreed the GP2 CS installed after my rebuild, hit the timing right on the first try.

BB
 
Bill--You probably already know this, but the break-in procedure for your new cam/NEW lifters setup is critical. Triple check all your coolant and fuel connections (and fuel tank volume) before firing it up the first time so you don't have to shut it down. Use an assistant to watch the engine bay for problems as you sit in the cockpit keeping the engine at a steady 2500 rpm +\-. You beed to run it for at least 20 minustes nonstop to properly seat the lobes to their lifters.

[When I broke my Isky Z-19 setup in, I fitted a ViseGrip to the throttle linkage to lock its position at 2,500 rpm--no assistant needed.]
 
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