What is better to run in a 4kc motor without putting stainless steel valves in, unleaded or premo unleaded?

In my experience unleaded yeilds the best results. I found that running premium you accually lost power. I BELIEVE this is because of the short stroke and premium doesnt have enough time to complete a full burn.

 

I ran unleaded for 6 months or so before an engine rebuild. Upon inspection of the valves there was minor pitting...nothing too severe (alebit this was a 30 year old motor in 100% original factory condition...just worn out so the pitting may not have been from the unleaded).

 

Most of the guys here run unleaded or premium unleaded with no problems what-so-ever. If your concerned about running unleaded you can put in some stem lube but in my honest opinion they don't need it.

Irokin is right. No mods are required on a 4K-C for them to run unleaded (except maybe a tweek to the timing..). Unless it's a grunter engine, save your pennies and use unleaded.

Cheers for that. it helps me out a bit. as it is getting harder for me to find a servo that still sells lead-replacement fuel :jason:

Agreed. I have a strong dislike for Shell. I tend to only buy Caltex and BP. If I buy premium I only ever buy BP Ultimate. Its the shiznat. (cept for 110LL)

I mainly use BP ultimate in my car. Probably cause its the closest servo to my house. But i'll use any premium if I'm running on emtpy. havent tried regular in it yet, probably cause its tuned to run on that 100ron jap rocket fuel they have.

Iv'e been running Vortex in my car and it loves the stuff! sheers :insane:

I try to only use BP Ultimate, but there isnt one to close so i sometimes have to use no name PULP. Can def. feel the difference between bp and no name.

I wouldnt waste my money on vortex...

My rolla gets treated to BP ultmo every time.

 

:doublebird:

Mine pings like buggery on regular.

 

and no i wont change the timing :doublebird:

My Nova gets a nice does of Unleaded fuel :lol:

You could also put Fuel Additives into your tank when refueling for those extra K's and if adding the right stuff you can get more power outta your car :lol: