351M Timing Chain Change

[79Matt]

Have any of you swapped out just the timing chain on your 351M? I read an article that states the stock timing chain had at least 6 degrees of mechanical retard built into the timing chain for emissions purposes. If you changed it, was there a significant performance increase?

 

[Tim Cole]

Timing chain

My T-Bird has a 3023 and I have changed mine out 4 times (car has 400,000 miles on it). So, no comparison. But it does sound like you will experience a power boost with the new chain. I've owned a few 351M and they were quit peppy if the carb was tuned right.

On the other hand, the 400-2 is a dog.

 

[HeadacheGuy]

We used to rebuild a lot of these yrs ago and for the life of me can't remember if we used early model timing kits on these . Rule of thumb here. Advanced timing increases low end power, retarded is for higher rpm. Yes, it was done for emission purposes as retarded timing produced more heat which burns off excess hydrocarbons. Higher combustion temps unfortunately produced higher oxides of nitrogen....hence the need for an egr valve . Without the egr valves 351m and 400 "pinged" on light acceleration. Bottom line if you are going to do a chain consider a mild cam to go with it. That's the best way I had to curb the ping. You don't want to advance the cam timing and then "de-tune " it with ignition timing to kill the ping. Your vacuum advance is adjustable which helps if you just do the timing components. Your altitude weighs in on the ping thing as well. Good luck