WHAT FUEL FOR BEST OPERATION

[ray koziatek]

HANK,i just rebuilt moter this winter and one of my intake valves was tuliped just under carb i assumed it was due to hydrolic possably water got into intake .. today i was talking to mech. who said a bulliten was sent to dealers that the 3.0 needed mid prefferd high grade gas due to pinging ,would a mid grade with octane booster work or just go with the (gulp) high test kinda thinking long run pinging might of tuliped valve as the seat was still pretty good before rebuild 125 pressure test..only went 0.20 over runs like new 4700 rpm with 17 pitch prop i know its a little high on rpm but both tanks were almost empty and my tackle box was home, Ray K.

[jimski2]

On our 31 ' Marinette , It has an 440 Chrysler, pre 1976 and we add an additive to replace the lead these older engines ran on. If you don't, you'll burn the valves out.

[traveling man]

Ray, I have a 3.0 Merc and the dealer told me to run high test. I have never tried nid grade with a octane booster. never been a big fan of additives.

[ray koziatek]

thanks , i filled er up with the good stuff and at 3/4 throttle it litterly purred ,,from the power vs throttle position and speed i can see the mpg will more than offset the cost not to mention proper operation after rebuild. did a little research on octane and gasoline and now understand the importance of high test in older moters , i ocassoinally end my post with always learning or never learning after 800.00 rebuild job i think i learnt sumpthing,,,, Ray K.

[jimski2]

Premium grade fuel is required on alot of I/O's and older inboards. You'd be surprised that it's also required in a lot of the expensive new cars.

[mlkowalski]

valves will tulip due to extreme combustion temperatures. pinging is one of the causes and can be caused from low octane, ignition timing too advanced, or a lean fuel condition. the intake valve actually gets red hot and gets pounded into that shape when closed on the seat. make sure the timing is set right and the carb isn't clogged. the smallest partical in the carb can do the same