Big block swap 73 k10

[Mike_The_Grad]

Hey everyone, I'm going to be swapping a 427 big block(454 block with 396 crank) into my buddy's 73 k10. His 350 sbc gave up the ghost. He picked up the 427 on impulse. So it's happening one way or another. I explained to him the kinds of changes he needs to make for this to happen. Obviously exhaust, motor mounts, and compatability with his drivetrain. The 427 is a long block. It has pro comp air gap manifold, oval port heads, and tall valve covers. That's pretty much the extent that I know so far. P.o. said it made about 425 horsepower and it was originally going to be put into a old hot rod style coupe with side lift engine covers.

So, I know I need to find out what cam it has in it to make sure it's not some crazy high rpm style race cam and that it makes enough vacuum for power brakes. But I also need to find a powersteering bracket/pully setup and an alternator bracket that will clear everything and align properly.

Any tips on motor mounts/frame brackets or engine crossmember modifications? Any thoughts on a accessory drive setup that's not chrome or billet aluminum shiny stuff? Hopefully more along the lines of factory. He does use his truck off road and it's lifted pretty high. Not sure how much of a lift or how tall his tires are or his differential gear ratios. But I can find that stuff out relatively easy.

Any input is appreciated. Thanks.

[kwmech]

Will literally bolt into the same spot. Clearance will be needed for the oil pan though at the x-member. Which transmission are you trying to blow up?

[Mike_The_Grad]

That's kind of what I was thinking was needing to happen. It's either a th350 or th400. I asked him to send me a picture. He lives about 20 minutes away from me. But when I pull his small block out the trans and transfer case is coming out with it and going to the shop for rebuilding on both units anyways. So I'll have the trans shop beef up what they can. I'm friends with the trans shop owner so it shouldn't be too bad to do. My buddy doesn't have a lot of experience with these trucks. So I'm kind of his eyes and ears through all this. I told my buddy we should just pull the cam and put in one that we know would be more in line with what he wants to use the big block for. Plus it'll give us the opportunity to check out the internals. I have boroscope I plan on putting into the spark plug holes. Plus check main and connecting rod bearings. And timing set.

[kwmech]

Automatic in the K10 will be a T350. It can be built up with some performance parts. T-case could possibly be an NP203.

[Mike_The_Grad]

I'd agree with that assumption. But also it seems that someone had done some work to the truck before it came into his possession. It's already got headers, and some kind of cam in it. Roller tipped rockers. It might even be a stroker motor already. He thinks it's a th400 behind the small block. I asked him to snap a picture of the pan on the transmission just to confirm. I understand it that gm never put a th350 behind a big block in anything factory. Of course there's always exceptions to anything considered standard equipment. so I won't speculate until I see a picture of the pan. I think he'd be better off with a th400. But I'm sure we can build the th350 enough to live behind the big block.
This truck is not a daily driver. It's his "off road hot rod" so to say. He wants it to sound as big as it looks. He is asking about exhaust cutouts for the import guys at the stoplights. He's a marine with a bunch of military diesel mechanic training. But knows nothing about gas engines especially v8s. So I'm thinking a 4x4 RV low end torque cam would be more usable in his situation. It's not a rock crawler, it's not a mud truck. It's more of a backroad, streams and trails, mud puddle romper. If that makes sense. He actually uses his truck off pavement and wont wash it for weeks at a time. I'd say the suspension lift on it puts the top of the hood about chest height to me. I'm 6 foot tall.

[57NAPCO]

Not to Jack your thread but thought I’d ask KW, I have a 454 sitting in the shop, I was thinking about putting it in my old 78 K10 350/Sm465 205 transfer. Do you know if it would be an easy swap ? Or am I gonna have to mess with drive shafts and X member.

[blazer2007]

I had to do nothing but exhaust on my 78 blazer. 454 in place of a 350.

[Mike_The_Grad]

Im guessing your 454 came with all the brackets and pulleys to drive the water pump and power steering and alternator. Do you have a picture of the front accessory drive on the 454?

[kwmech]

Yeah, it'll bolt right in. No driveline work needed, just a trip to the muffler shop. Only clearance to check would be the oil pan. Even then I don't think anything would be needed. Recently did a swap into a 74 K5 with a 502 and a turbo 400.

[kwmech]

Also converted to 3/4 ton axles. Ton of work done to this rig.

[Mike_The_Grad]

So here's an update, I did a compression test on all 8 cylinders yesterday. Results were 168psi on the lowest cylinders(#1) to 180psi on the highest cylinder #6. The engine has the higher compression 063 100cc cylinder heads. So it put this engine at least at 10:1 static CR. So my next move was to knock the rear cam plug out of the block to look for a cam number and this is what I was able to find. 330885. A quick Google search found nothing based on the number off the cam.

And a picture of the engine.

[Mike_The_Grad]

Couple more of the cam number.