Page 1 of 1
Unleaded fuel 1984 PCM 351 engines
Posted: January 25th, 2022, 6:21 pm
by Justright
Apologies if this has been addressed but my searches found nothing. I recently purchased a 1984 Riviera with twin Pleasure Craft Marine 351 Fords. Information plates on the valve covers indicate that leaded fuel is required. It has obviously been running on unleaded gas for many years. I'm wondering what changes, if any, were required to run unleaded. Thanks
Re: Unleaded fuel 1984 PCM 351 engines
Posted: January 26th, 2022, 11:32 am
by Cooler
I don't believe any changes were required for unleaded fuel. You would be hard pressed to find leaded fuel at any marinas anyway. You would need to use an additive to provide the leaded condition. The thing you want to avoid is unleaded with ethanol. Try to use non-ethanol, especially if the fuel is going to sit in the tank for any length of time. There are a number of members that are extremely educated on fuel formulas, so assistance will be here shortly.
er
Re: Unleaded fuel 1984 PCM 351 engines
Posted: January 26th, 2022, 12:03 pm
by bud37
Lead was added to gas to help keep valve recession under control and had the benefit of boosting the octane.
Now in the early to mid 70's most engine manufacturers changed cylinder head design to include hardened valve seats because of the new EPA rules to go to unleaded fuel. So my guess, your engine being just a factory crate from 83 or so has the seats so all is well.
Now I can tell you that even engines with the so called soft seats ran for years on unleaded with little or no recession that would have required the heads to be rebuilt and hardened seats added .......a non issue.
Re: Unleaded fuel 1984 PCM 351 engines
Posted: January 29th, 2022, 1:02 am
by tomschauer
I am really surprised a 1984 engine is labeled as requiring leaded fuel. Unleaded was started in the mid-seventies in the US and leaded was pretty much phased out by the mid-eighties I do believe.
So, I am pretty sure those engines have not seen much, if any leaded fuel.
Re: Unleaded fuel 1984 PCM 351 engines
Posted: February 20th, 2022, 11:30 am
by Justright
tomschauer wrote:Source of the post I am really surprised a 1984 engine is labeled as requiring leaded fuel. Unleaded was started in the mid-seventies in the US and leaded was pretty much phased out by the mid-eighties I do believe.
So, I am pretty sure those engines have not seen much, if any leaded fuel.
I appreciate all the replies to my question. It's comforting to know. I was surprised too. I might have a photo of the label and send it.
Thanks