How- to: Modifying the firewall for Caddy engine clearance in a 4x4 - The 1947 - Present Chevrolet & GMC Truck Message Board Network

jeffspower · 06-12-2007, 10:13 PM

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.

GREASEMONKEY72 · 06-12-2007, 10:20 PM

thats a big hole, looks good so far

jeffspower · 06-12-2007, 10:20 PM

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.

jeffspower · 06-12-2007, 10:27 PM

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

JAKES 68GMC · 06-12-2007, 10:35 PM

looks good, nice job.

GREASEMONKEY72 · 06-12-2007, 10:38 PM

nice work

jeffspower · 06-17-2007, 11:13 PM

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

Southedisto · 06-18-2007, 12:46 AM

Nice work, looks almost factory.

1969k10stepside · 06-18-2007, 12:50 AM

Quote:

Originally Posted by Southedisto

Nice work, looks almost factory.

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!

jeffspower · 06-18-2007, 01:19 AM

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

jeffspower · 06-18-2007, 01:27 AM

I think the stance looks mean from the front

**Yukon Jack** · 06-18-2007, 01:40 PM

Your mods look great.

Duallie · 06-25-2007, 02:03 AM

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.

06-12-2007, 10:13 PM	#1
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	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. Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-12-2007, 10:20 PM	#2
GREASEMONKEY72 Registered User Join Date: Aug 2006 Location: Bakersfield,CA Posts: 7,893	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 thats a big hole, looks good so far __________________ -steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME

06-12-2007, 10:20 PM	#3
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	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. Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-12-2007, 10:27 PM	#4
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	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! Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-12-2007, 10:35 PM	#5
JAKES 68GMC Aluminum slot wheels rule... Join Date: Jan 2006 Location: Maine Posts: 6,211	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 looks good, nice job.

06-12-2007, 10:38 PM	#6
GREASEMONKEY72 Registered User Join Date: Aug 2006 Location: Bakersfield,CA Posts: 7,893	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 nice work __________________ -steven Alte Seele S.S. "Allison" '72 C/10 LWB 350SB/TH350 - DD PITBULL IS NOT A CRIME

06-17-2007, 11:13 PM	#7
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	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 Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-18-2007, 12:46 AM	#8
Southedisto River life...... Join Date: Oct 2005 Location: Soldotna AK Posts: 1,078	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 Nice work, looks almost factory. __________________ I like wheelin in Dixie!

06-18-2007, 01:19 AM	#10
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	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 Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-18-2007, 01:27 AM	#11
jeffspower Well, Whoop-dee-do! Join Date: Mar 2003 Location: Easton, Mo. pop.- me & scarcely a few others Posts: 2,302	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 I think the stance looks mean from the front Attached Images __________________ '68 GMC shortbox 4x4 350/SM465/T221- bought it in '83 SOLD '72 K20 500 Cad/TH400/NP205 SOLD '92 Chevy 2500 6.5 mech TD 4L80E crusty daily driver '72 Monte Carlo... sweet low mile toy '11 Dodge Challenger IE 392 6spd... midlife car

06-18-2007, 01:40 PM	#12
Yukon Jack Post Whore Join Date: Feb 2000 Location: Rose Hill, KS, USA Posts: 12,686	Re: How- to: Modifying the firewall for Caddy engine clearance in a 4x4 Your mods look great. __________________ 1970 Blazer with a 400 sbc and 4" lift 1980 Pontiac Trans Am, 455 Oldsmobile 2012 Kawasaki Concours 14

06-25-2007, 02:03 AM	#13
Duallie Registered User Join Date: Feb 2001 Location: Nikiski, Alaska Posts: 477	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. __________________ Just as if I knew what I was doin'



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