C-70 big block swap

[russ61]

Hey bought a 1978 C-70 dump touse around the farm,350 small block (factory) 5 spd split axle.Thing is the small block is getting tired ,lobes wore off camshaft.I have a 454 that I rebuilt in a 1 ton that I would like to swap in.The small block has a front engine mount that is a cradle type.where could I find one of these to swap in the big block?Or could it possibly be moved forward to match the BB lenght?
Thanks Russ

 

[rino]

Very few of those trucks ever had the BB due to the fuel usage over the small block. In the mid to late 80's the 366 truck motor was being used more. Look in recycle yards for the 73 to 87 Chevy C 60 to C75, or GMC 6000 to 7500.

 

[d9gdon]

Huh? Most of them I've seen were big blocks like 366 or 427. Were they a different length? I know the cradle you're talking about but don't know if they were used on both SB and BB. Find a salvage yard and ask them.

 

[russ61]

When I got out of high school I drove a couple of old dumps for a farmer.One had a 427 and the other a 366.Thats one reason I wanted to go BB instead of rebuilding the SB.Just going to be a farm truck to haul gravel.

 

[koldsteele]

GM built 3 external balance motors 292 , 400 and 454 ...Make sure in your swap you use a flywheel for a 454 ...Hope this helps .

 

[d9gdon]

Swap out the crank in that 454 with one from a BB 400 and you've got a 427.

I put a BB 400 into a 3/4 ton pickup that came with a 292. I only changed the motor mounts and put in a 4 core radiator, otherwise it bolted right up. Of course I had to change the exhaust system. I thought I used the flywheel too, but this was in 1982. Doesn't seem like 30 years ago. I know BB 400 is internally balanced. I think I remember hearing that the SB 400 was externally balanced, is that the one you're talking about?

I also had a buddy that drove up one day complaining about a vibration in his motor right after his Ford loving cousin had swapped in a 427 for a 454 without swapping the flywheel. You couldn't tell at an idle, but you sure could once you hit about 1500 rpms. Felt like it was about to come apart. It was an easy fix and he didn't have any trouble after we put the right flywheel on the rig.

Back to the original question of this thread, the local scrap yard here lets me rob parts. It makes them a little more money and saves me a bunch.

 

[Dualie]

I had an old 73 C-60 with a 350 2BBL that was governed. IT was a 5+2 with juice brakes. After i swapped out the cam for an RV Cam from a local cam grinder it was a completely different truck to drive, with some mellow flowmaster mufflers it wasn't bad at all. I would look into a cam swap WAY Before i started searching the junkyards for a big block.

 

[jimson]

I've got an 84 C60 with a 366 and a 85 C60 with the 350. I will take a look at the front mount and see if i can tell a differance. I am fairly sure the front mount off the 350 will bolt to the 454 and that they in fact are identical. I bet all you have to do is bolt the mount to a different set of holes in the frame crossmember. In fact I would bet that the frame is already drilled in the right place to make the swap.

The flywheel will need some attention as mentioned. You probably get by with a "balance plate". Its a plate that bolts between the 454 crank and the 350 flywheel and is made to compensate for the external balance 454. Probably less than $20. Balance wont be perfect but probably close enough. Google speedway motors for the plate. Good luck