Couple questions for motor builders

[MyFlat6]

I have been building my first 911 motor. Most of it is going well - taking my time and learning a lot. Just finished my cam timing and started installing the remaining rockers.

- I used Stomski mechanical tensioners to keep everything tight while setting timing. I tightened them up pretty good but noticed that the tension on the tensioners made a difference to the timing result however I couldn’t find anywhere where it said how tight these should be. Again, I tightened them firmly so the chains were tight - tighter than the pressure fed tensioners will be when I install them. Should I be concerned that I set my timing with the tensioners tightened down fairly strong? I was under the impression that tighter the better for accurate readings/timing.

- I used RSR seals on the rocker shafts. I noticed that the seals were being shaved off a bit when installed in the tower bores. I read thru the forums and some said to install lubed and some said dry - tried both ways and still had the seals shave a bit off. I installed without the bolt and retainers to reduce expansion pressure when I tapped them into the bores. I tightened them to 21nm thinking I would make up for the damaged RSR seals. Wayne’s book gives a range if18nm to 25nm - I have also read a lot of folks use this range in ft lbs which I think is incorrect. Should I be concerned with oil leaks with the damaged RSR seals?

[Flat6pac]

The tension of the chain changes with the temperature of the motor in operation. The cam settings Are constantly changing.
I’ve used the rocker seals for years on builds and it’s virtually impossible to install all 24 and not pull some edge.
Bruce

[MyFlat6]

Thanks, Bruce. Being my first time, I have found myself paranoid about every step - it is a fun yet a nerve wrecking process building a motor.

I am using DC30 cams and John gave the overlap setting at 3.8mm - no range like other cams. So I was determined to nail this measurement. I used a digital degree wheel, piston stop and Stomski tensioners (in addition to z block dial caliper) in hopes to be precise. Then I realized the tension on the idler arms influenced the measurements. Maybe that is why there is normally a range of tolerance. I can see your point about timing changing through heat cycles.

[T77911S]

Do not turn the crank backwards.
Rotate 720 degrees and check again.
Do this several times

[MyFlat6]

So I removed the Stomski mechanical tensioners and installed my Carrera tensioners primed. I measured overlap again and the results changed by +0.15 mm. I am good with this but just sharing the results as the tension on the idler arms makes a difference.

[trond]

911s; why not turn cran backwards ? to do with tensioners ?