How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

If you want to put a Caddy engine in a 4x4 without moving the transmission forward, here's how I do it. This is what i have found to be the easiest way. Moving the engine forward creates it's own problems (engine crossmember has to be moved forward, "big" oil filter won't clear, exhaust manifolds won't clear the frame rails with the engine positioned correctly for the fan shroud, etc). with the engine in the "stock" location, you can't use the mechanical style gas pedal. There isn't room to clear the cylinder head. Even with the cable- style pedal, the three nuts welded to the firewall won't clear the head. The first one I done years ago, I just hammered that area down about 1/2" and cut out the clutch rod hole & welded in a pocket for head/ exhaust manifold clearance. Even with a 3" body lift, it won't clear without doing this. This time, especially since I'm using a '69 cab, I am going to remove the pedal area & recess the area another 1/2". This will also give me a clean slate to install the gas pedal just where I want it.

I can see where this same mod would work good for a BBC or diesel conversion.

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

thats a big hole, looks good so far

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

I trim the panel to the rough shape & size, but leave a little extra all the way around. Then I tack it in place, then cut/ grind for a nice fit.

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Be sure the firewall insulation is pulled back & secured good- it is VERY flammable. Ya need not ask me how I know!

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

looks good, nice job.

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

nice work

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Thanks for the complements! Here's some progress pics. I pulled off the 36" hummer tires & put on new 33/12.50/16.5 BFG AT KO's this weekend too :metal:

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Nice work, looks almost factory.

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Nice mod,and I agree,it looks almost factory.Are you going to eliminate the body lift on it when you finish swapping the body from the donor 2wd? I'm not a fan of the BFG All Terrains because gravel tends to get stuck in the tread but those tires look better on it than the previous hummer tires!

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Yeah small rocks and gravel can be annoying with them. But I plan on alot of road time with this truck (at least in comparison to the 15k miles or so I have put on it since 1995. Hopefully they will last awhile. The cheapest mud radial I could find was a generic for $180 a pop. I got these for $140 each. The rims have quite a bit of dish to them- I think I need the body lift to keep them from rubbing in a bound- up turn. I also have another complete engine I have been collecting parts for a buildup. Arias forged 10.5 pistons, 7" Olds rods worked over, big valves & '70 heads, a 460 intake & adapter, etc. Std. headers would be a botch job at best, I think modified 460 fenderwell exits will be the way to go. The body lift will make that easier.

If I can pull it off, I'll have the new 514 Caddy done next year :metal:

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

I think the stance looks mean from the front

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

Your mods look great.

Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4
 

I "massaged" the tunnel out to the hole for the clutch rod, welded it shut, and left the brake booster reinforcement alone. I have 1/4" clearance between the corner headbolt and the firewall. I used a cable throttle pedal, too.
I also clearanced the top of the framerail for the passenger side exhaust manifold.