Anyone know how to tell if a 289 engine has been rebuilt with hardened valves to accept unleaded gas or not? Previous owner did not know. This is an A- code. Use regular unleaded gas? Premium? Thanks...Ed

 

Its the seats that get hardened for unleaded. No way to tell unless you take it apart. They wont get hurt too bad if you arent racing, towing, or driving up huge hills/mountains. Daily driven they will last a while, at least they have in most of my engines that didnt get new seats.

 

I used premium gas and lead additive on my stock 65 289 for years, until gas prices started going out the roof. I never had a pinging problem or any indication that my valve seats were getting hammered on by the unleaded gas. But, here recently, I started using regular 87 octane gas, and have not noticed a bit of difference. I guess it is in all how you have the engine tuned. I am running mine a tad more advanced than stock. But, yeah, you aren't going to know if the seats have been hardened until you tear into it, and even then you may not be able to tell. Just for insurance, I would use a cap full or two of lead additive in each tank full just for insurance. I use Redline, but I suppose they all have the same basic saline solution.

 

I have an A-code which calls for premium fuel. Do you think I would have a problem with regular gas vs. a C-code 2-barrel? I hope to adjust the timing to accept regular.

 

Try it and see if the regular gas works for you. Take the tank down to almost empty then add a few gallons of regular and see how the engine reacts.

 

Thanks for the advice Soaring...I will let you know how I make out.....ELT

 

had an A code in my 67 Cougar, it ran fine on the cheap stuff. It doesnt have 10:1 compression, so save some $$, it probably wont need the premium.