Recess firewall

Iam running a 351w in my 1939 ford hot rod. If I buy a recessed firewall which recess will be better? 5" or 3"?

 

Are you sure you even need a recessed firewall?
Most guys that recess use a sbc and need the clearance for the dizzy.
Your dizzy is in the front.

 

Im pretty sure you will not need a recess, last mod I did to accomodate a SBC in a ford was as previously mentioned to clear the dizzy.

 

I think you may want to move the engine back a little for oil pan/ crossmember clearance and or sit the engine higher. mustang II could make it possible to leave the firewall alone.

 

No setback is required for a Chevrolet just run a small dist. not the big ugly HEI.

 

When I put an Olds into a 30 Model A I made a firewall recess slightly wider than the valve covers. I rolled about a 3" radius at the edges of the setback panel. I then welded nicely rounded corners cut from a Chev p.u. gas tank into the corners of the panel. I think it looks pretty neat. Greg

 

The OP isn't talking about a Model A,,there is more room to work with a 40 Ford.

I did recess my firewall in my 39 Ford coupe with a 302 although I did change the oil pan to a rear oil pickup to gain clearance for the cross member. HRP

 

A 351W OR 351C ARE LONGER THAN A SBC FOR THAT MATTER. Knuck From Indiana.

 

You do not need to recess the firewall in a 1339/40 Ford with a 302 or 351W. Use the Ford Motorsport shorty water pump conversion (Explorer water pump?) or get the Shorty water pump conversion from www.snowwhiteltd.com. Move the radiator forward by notching the top radiator support member and if you want an electric fan, run a Cooling Components Inc 16" shrouded fan which is only 2 5/8" deep at the motor. I run this setup in my 1940 Ford Sedan Delivery and it works out fine....