I'm doing some wheeling and dealing on a shortbox '78 4x4 with a mildly built 429 in it bored 30 over. I'm gonna be making this pickup into my off-road monster. Gonna be running 37 or 38" Goodyear MTR's (37 MTR) or 38 Super Swamper TSL Radials. I know this doesn't sound good but I may be running a GM 14 bolt rear-end and a Dana 60 up front. Plan on runnin 4:56 gears with Detroit rear-end locker and an ARB up front.

Now here is where I need some help. It has an Edelbrock Performer RPM intake on it with an Edelbrock 600 cfm carb. What should I upgrade to? This truck will see high elevations and alot of steep angles.

Also the exhaust needs some work, if I have clearance I will run headers and 2.5" into a dual in single out 3" muffler (flowmaster, Xcellerator, type muffler) and dump it in front of the rear axle.

Also will be running a 6" lift just in case you were wondering on how I was going to clear those big meats. If I have clearance problems with the 38's i will run a 3" body lift if necessary.

So what do you guys think of this set-up and what would you do for the intake/fuel system?

 

I hear good things about the Holly Truck Avenger off road carbs, i think the biggest one you can get is 650cfm. 600 cfm sounds sort of small for a 429. I am planning on running a 750cfm carb on my not so mildly built 408 stroker. That is the size that was recommended by Edelbrock.

-Jon

 

I'm wondering if a 6" lift on a half ton will clear 38's. I doubt it, unless you did some fender trimming. Might want to go with a bigger lift or a body lift if your hell-bent on running 38's. If you have 8-9 inches of lift, then you shouldn't have any problems clearing 37-38" tires. As for the powertrain, what I wouldn't give to get my hands on a 429!! Too bad that swap isn't exactly a bolt-up or a smog legal one! At any rate, they do make carburetors that are designed for the off-road enthusiast in mind. The Truck Avenger is only one that I know of off hand, like Ford4ever said. It flows 670 cfm and will set you back $390 from Jeg's. It can maintain idle at a 45 degree incline, according to the specs. I know with a fuel injection system, you could be driving upside down and you wouldn't have any issues. But a conversion would be rather costly. I would look into the offroad carb/s that are available. And yeah, 600 cfm is pretty small for a 429, especially if you're planning on running 38" meats. But I guess it just depends on how much performance you want and how much fuel mileage you're willing to sacrafice.

 

The fenders on the '78s are pretty good sized and I don't think I'm gonna rub the 38's unless it really starts to flex, then if we have problems we will add a 3" body lift.

My buddy that is helping me build the truck up made the cover of Petersen's 4 Wheel & Off Road last year (April 2002). I also posted a picture of his pickup in the off roading section.

I have been giving thought to the Holley Truck Avenger. I kinda want a 700 cfm but may have to sacrifice and go with the 670. Right now the truck has 3:73 gears and 35" BFG MT's. It has plenty of power to turn those tires, but for what we are gonna use it for the 4:56s will work better

 

I don't know anything about the holley avenger carb, but from my experience with a cj-7 I built with a 68' 327, elec ignition, all the goodies. I started with the quadrajet and every freakin time I climbed steep hills or bounced around pretty good the damn thing would start puffing soot and runnin rich. I screwed around with that carb for a while and someone suggested edelbrock performer carb and I love it, its been almost straight up and down and I even laid the jeep on its side once, everytime we tipped it back over that carb was perfect and man did it make the power. Mine was like a 750 though. Its a shame you only got a 600 cause I think they're fine carbs. My .02 worth. Good luck on you're build, 429's are strong and gettin hard to come by

 

Well I have some bad news. The deal I had going with this guy involved me trading my snowmobile for his pickup. Well the guy emailed me today and backed out. We were supposed to do the trade Friday nite

My buddies have another rig on line for me right now though! This one is a '76 F-150 short box, 4x4, with lift already, and a 400 in it.

We'll see what happens!