fuel needed?

[Farmall m 421]

Looking at building a 421 m. Gonna have 12:1 compression. 450 lp head. 1920 high idle. Cammed for max torque about 1500. Typical 421 type build.

What type/octane fuel will I need for this type of engine? What do you guys recomend? VP110? Q16? Something else?

Thanks
 

[buickanddeere]

What if any quench in that engine combustion chamber? Are you planning on 25-35 thou of cold clearance between the piston and head? That will increase power and reduce detonation .
The cam duration can vary the compression pressure from requiring fuel from 87 to 115 octane . Tell you cam grinder what you have as a combo and they will grind to match.
 

[Farmall m 421]

A cam that would allow me to run 87 octane fuel would have overlap to the point that it would barely even run at 1500 rpm. If I want max torque at 1500 then I am going to have short duration and very high cylinder pressure. I want to know if I can run something in the 100-105 octane range, 110, or do I need something better like Q16? 87 aint gonna do for this.
 

[ss409]

110 did just fine at 300psi cranking psi, under full load, at 180 degree temp for 3 minutes on dyno.
 

[Farmall m 421]

Thanks. What brand? VP110 or something else?
 

[Superih]

[ss409]

vp works fine. you was talking about cams there,,,, i dare ya to start with a 450 cam grind. if ur turning 1500 n under rpm, in my experiences, the 450 cam grind did very good in my engine. itll lug clear down to under 1000rpm n still chug out triple digit power. try it as a baseline n work ur way up.
 

[Farmall m 421]

Do you have the stock 450 cam specs?
 

[buickanddeere]

What do you mean quench doesn't matter?
If you take a little extra time and care instead of just slapping
an engine together. Keeping the quench at 25-35 thou will
reduce the engines tendency to suffer detonation. The engine
will also make more power due to the improved combustion
chamber turbulence and mixing.