Found a 400 block. Need some opinions - Off-Road Forums & Discussion Groups
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post #1 of (permalink) Old 08-03-2000, 03:52 PM
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Found a 400 block. Need some opinions

I found a 400 today, casting # 330817. The block still has the oil pan. I can take the crank for $35 or the whole block for $100. THe guy will gaurantee it good for rebuilding. I think I will inspect it alot closer before I put any money down on it. Anything that I should look for that would be visible to the naked eye? [img]/wwwthreads_images/icons/cool.gif[/img]

77 GMC Jimmy aka the Greyghost
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post #2 of (permalink) Old 08-03-2000, 08:04 PM
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Re: Found a 400 block. Need some opinions

I'm hesitant to reply to you, remember last time? Alum/Iron?
The 400 motor is equally controversial, so we may be in for a second bout.
I haven't had any trouble with the two I've had. In fact, they are the two most powerful motors I've ever owned. I still have them, one is in the truck, and the other awaits the shoehorn into my car.
What's your plans for it? It is common to find cracks in the OEM crank. I bought a Scat crank for my truck motor. I suggest the same if you have trouble finding a good one.
The siamese bore issue is in my opinion a non-issue. I've never had any problems with it.
Anyway, that motor is my favorite and I've done a lot to it. I'd be happy to share my good luck & mistakes.

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post #3 of (permalink) Old 08-03-2000, 08:12 PM
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Re: Found a 400 block. Need some opinions

The crank is worth $35! Just make sure the center bolt hole threads for the harmonic balancer and the flywheel bolt holes are not stripped out! The whole thing for $100? Check to make sure you can turn the engine by hand! If the pistons are rusted in, that's not good! Check the block freeze plugs, if any are missing or popped out, beware! It's possible that the block was left out to the weather and was subject to sub-freezing temperatures with water in the block which could cause the block to crack due to freezing water expands and pushes against the block.
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post #4 of (permalink) Old 08-03-2000, 08:22 PM
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Re: Found a 400 block. Need some opinions

I agree with Chevota, the 400 block is a good foundation, and aftermarket cranks are fairly inexpensive, but if there is nothing wrong with that crank, I would run it. The only thing I don't like about the 400 is the short rods. Get pistons to go with longer Rods. Personally I would go with 6.0 inch rods, again they are inexpensive in the aftermarket, and stronger than stock rods. Chevota, about the head thing, it is a differance of opinion. No hard feelings on my part, and I hope no hard feelings on your part.

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post #5 of (permalink) Old 08-03-2000, 09:41 PM
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Re: Found a 400 block. Need some opinions

You really can't get burned at only $100, but remember "you get what you pay for"

Kevin

post #6 of (permalink) Old 08-03-2000, 11:25 PM
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Re: Found a 400 block. Need some opinions

That 400 properly reworked with new (steam drilled) Vortec heads would be one bad motor! Make sure to verify the correct harmonic balacer and flywheel while you are at it!

post #7 of (permalink) Old 08-04-2000, 11:50 AM
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Re: Found a 400 block. Need some opinions

Not sure if the balancer is still attached, but I know the flywheel is gone. My Jimmy originally came with a 400 and I thought that it would be nice to find one to replace the 350 that's in there now. I use my truck as a daily driver with very limited off-road excursions. I don't want to break or ruin anything and have to spend money that I would rather spend on something else. Eventually I will be back in western PA were the terrain is rather hilly and I figure that some extra torque and some better gears will help negotiate the hills with less effort. I suppose that if the crank and block check out okay I will pick it up even if it only sits in my storage room. What I am really hunting for is a 4.10 rear 12 bolt to match the front one that I already have. i currently run 3.07s front and rear, but the front is wasted.

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"Went through it's first three legs pretty quick. Thank God for the last one."
post #8 of (permalink) Old 08-04-2000, 01:10 PM
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Re: Found a 400 block. Need some opinions

<font color=purple>Check the pistons - should be stamped with an overbore amount if they are not stocked. If you're already .030 or .040 over, you're about done. If that's the case, make sure you can clean it up with just a honing.</font color=purple>

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post #9 of (permalink) Old 08-04-2000, 06:13 PM
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Re: Found a 400 block. Need some opinions

FYRBALL MT

You're going to have to ruffle my feathers a lot more than that to upset me! I enjoy a good bout, and was only kidding about being hesitant. I'm almost dissapointed that no one wrote in to slam the 400, and me. Maybe we'll get a taker here soon.

My old motor now has an OEM crank, KB pistons w/OEM 5.7 rods. The new motor has a Scat internally balanced crank, KB pistons, Eagle 6" "H" beam rods.
I pulled the old motor from the boneyard for $150 complete, and slapped in an $100 overhaul kit. I did run, and abuse it with its OEM 5.56 rods and pistons for years. The thing saw 6000r's quite a bit. When it was time for a normal rebuild (and 5.7's) the crank had bad "spyder-web" cracks in it, and those rods (OEM rod-bolts too), never let me down! It's ready for another rebuild now before I put it in the car. I'm scared to look at the crank, this one saw 7K regularly.

5.56"? What were they thinking???



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