I have an '81 351M with a bad timing chain/gears. Can I simply install an after market multi indexed (-4, 0, +4) timing chain set and install it at 4 degrees advanced, and get the original power output "as it applies to valve timing" like a '70 351C / '71 400 had.
Any valve interference?
I won't be tearing the engine down to check clearances.

 

sounds like a plan.

 

mello1965, Set it at 0 degree's advanced. Never set it more than that unless the cam manufacturer says to do so.

There was a post on the 460 column some time back where a person tried setting the cam timing at 4 degree's advanced and he had a lot of trouble.

 

The 0° setting should be 4° advanced from the factory 4° retarded setting. The +4° will be 8° from where you started.

 

Larry,

Follow the advice of the other posters and set it no more then at 0 degrees. If you are going to also replace the cam then follow the manufacturer's recommendations.

The person in the 460 section that had the trouble was Dan Poelstra with a sign in name of dpoelstra. He did have trouble with the motor not running right and he changed it back to 0 beofre he did any damage.

Setting it at 0 will not make a huge difference, but you should notice a little difference with low end torqure and a smoother idle. Make sure you reset your ignition timing as part of the job and resetting your idle mixture would be a good idea.

Good luck,

Mark