comp pcm holley timing tip

[lbagby]

My '86 comp has always run well for the last 26 years. Last season while quite bored, I glanced through the pcm owner's manual and noted that the timing when using premium 93 (research) octane is 6 degrees BTC. However, it also states that if regular 90 (research) octane is used the timing needs to be retarded to 2 degrees BTC. Yikes, I've been using regular gas for at least the past two decades without retarding the timing. I guess, unlike a car, a boat doesn't put enough load to cause detonation (or at least, I can't hear it). Anyway, I had the timing checked for 6 degrees (it's never been changed) and started using 93 octane gas. What a difference. I can really feel the increased power. So, if you've been using regular check the timing try a couple tank fulls of premium and enjoy her new found youth.

86 comp Original Owner

[86 century]

If you get a big power gain just by going with the better fuel I would bet the farm it was spark knocking before.

If you still have the plugs from last time you ran the cheep gas look down the side of the electrod with a magnifing glass I bet you will see little white markes.

This will tell you if it was detonating.

[cadunkle]

If you're engine was detonating it would not have lasted 20 years. If it was not detonating, there would be no difference in performance... If anything a nearly immeasurable drop in performance as higher octane burns slightly slower.

Your boat engine is under comparable or more load than your truck while pulling your boat. 6* is not much timing, and in a low compression boat engine will not detonate.

[Hagman]

He may have purchased premium fuel with no alcohol