What type of gas?

[drrm123]

What octane gas do you use in your boat? I started mine today and hear what may be pinging when rev engine. I put in 87 octane and was wondering if most people use premium. I'll check the timing tomorrow to make sure it's not advanced to far.

 

[HT32BSX115]

Re: What type of gas?

Most stern drive type boats were designed to run on 87octane.

Some, like my former OMC 460 actually had 2 types of fuel that could be used. If you could get 89(I think) or better octane then you could time it 15* BTDC. Otherwise OMC said to time it to 10* BTDC when running 87 octane.

The answer is to check the manual for the engine you are using.

All newer Mercruisers are designed to run on 87 octane with some exceptions for the hotrod engines.

Mercury Fuel Recommendations

If yours is pinging and it's not one of the hot rods, you might need to either re-time it or or you may have seriously "carbon'ed up" plugs, valves or combustion chambers.


"Pinging " usually only occurs under load. It usually doesn't happen when "reving" the engine with no load. If it's really pinging with no load you may have other problems going on.....and it might not actually be pre-ignition "pinging".




Regards,


Rick

 

[Manipulator]

Re: What type of gas?

My manual says 89 octane or retard the timing if using 87 octane like mentioned. I ran the boat on 87 octane and there was no pinging so I left it. Seems to run fine.

 

[f_inscreenname]

Re: What type of gas?

It all depends on your motor. Mine likes 93 or better and nothing less or it runs "flat". Thank God I trailer cause your not find that at the local marina.

 

[drrm123]

Re: What type of gas?

I'll check the timing when I pull it out of storage yard again. I'm sure it detanation or preignition when I bring rpm's up slow I dont hear it. I may run some seafoam through it also. This is a used boat I bought and dont have an owners manual, just seloc manual I bought. thanks for the replys.