Big block motor mounts for a 4x4

[mikep684x4]

Ok,first of all, are they real?, I was told that a big block was not offererd in the 4x4 trucks, All the big block 4x4 trucks I have are on 73 or newer frames.This is my first stock 4x4 frame so I'm not certain.I know I can make something work but could use a little insight. Thanks

[Classic Heartbeat]

Big Blocks were not offered for any of the 4x4s from 67-72. WES www.ClassicHeartbeat.com

[mikep684x4]

Thanks Wes, I guess its time to get creative.

[breeh]

I used the small block crossmember and some high quality polyurethane motor mounts when I put my 427 in. It has been over a year now and no problems. The BBC is longer than the SBC but the mounting dimensions are the same.

[hllblly1972gmc]

I dont know how much help I can be because I changed a lot on my truck. Its a 1972 GMC 4x4 1/2/ ton short bed. I built all the cross members, sirewall, linkages, etc.... I copied this from another post I replied too, maybe it will help some of you. Or some of you will think Im crazy.

I have a 1972 gmc 1/2 ton 4x4 short bed. Still building, but should be done in the next few years I think. I built a 520 CI BBC. For headers I have the Hookers Super Comp, or Pro Comps cant remember. They fit good so far, but may run into some issues around the transfer case. Also these headers kinda suck because they have thin mounting flanges, I will build new flanges for them where they mount to the heads. I did trim the frame a bit. I am using Merlin heads, so the exhaust ports are a little higher than stock heads, about a 1/4 inch or so. I moved my firewall back 2 1/4 inches. I cut out my firewall and fabbed a new one. The firewall sits about 1/4 inch from the plastic heater box inside the cab. I built a new crossmember, and am using big block mounts. I lifted the body 1 1/2 inches, I cut three inch blocks in half because I didnt want too much lift, already have a six inch suspension lift. As far as the question about the clutch linkage, I ground the old bracket off the frame and moved it so it would match the pivot ball. Then made up new rods for the linkage to adjust for length, also due to the firewall change, my clutch linkage off the pedal is also different, it goes through the floor about two inches further to the driverside. I use tall merlin valve covers and have no clearance issues with the brake booster or heater box, this is a non a/c cab.

I know this reply is long, but theres been a lot of work here.

Im the Be-Cool radiator. My engine is very large displacement, If anyone wants info on it just let me know. Its naturally aspirated, should dyno out at about 620 to 650 horsepower, when I get the truck together I will dyno it at my work, its nice to have a dyno. Also am going to be running a 250 hp nitrous kit, not added into the hp numbers above. Be-Cool makes a radiator for our trucks that will cool up to 900 hp, I think it was about 500 dollars, give or take a little, but not much.








Maybe this will help someone. I am going to alot of work but I want it to be right. If anyone has any questions of anything I did, or maybe something I did wrong

[ryanroo]

i used a factory v8 crossmember and small block motor mounts. i think you can get big block mounts for these trucks from a 2wd that work, they are the same basic design i beleive just a higher durometer rating in the rubber for the big block power i did have to modify my crossmember with the gas axe to make the BB oil pan fit
Ryan

[hllblly1972gmc]

the mounts themselves do not matter. Odds are you wont break the small block mounts with a big block unless they are completely rotten. The towers are the issue, you can use BBC towers off a two wheel drive, with some modifications. the BBC towers are made to offer a little more exhaust clearance. But if you have to modify the two wheel drive towers, why not make your own? Show some creativity. Its a diffcult swap to do right, Im doing mine to look like the engine belongs there, not just is there