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Topic Review (Newest First)
11-05-2002 02:36 PM
stonedchihuahua here is what I know about the 400 it came from a truck and is in a blazer right now... the guy is supposed to be getting the casting marks on the block and heads but has not called me back because he is working overtime.... it is in a blazer right now and he is swapping it because he rebuilt a 396 he found.... he said that to his knowledge there have been no cracks or other problems but that is taking his word for it... He also said it needs to be rebuilt (I was planning on doing that anyways) and that everything is there and he wants $400 canadian... this seems like a decent deal since most guys around here want 400 for just a block
11-05-2002 12:22 PM
lozinit TM454, just a a little clarification, the 400 only had problems overheating when the wrong heads were mated up to it. The siamesed cylinder bores would generally need a couple small steam holes drilled into the block beside them (into the water jacket), and the gasket would have to be clearanced to match up with the new holes. This was to prevent steam pockets from building up and overheating the block.
I have seen many 400s run at normal temps. Some had this mod done, and some didn't.
11-04-2002 05:50 PM Stoned, invariably the heads on stock 400 are cracked , you can check 20 pairs and 18 will be cracked between the bolt hole and the steam hole, this can be repaired with a sleeve in the bolt hole. some people let the crack go and get away with it, i haven't ever been that lucky. the cranks usually are good just check the thrust bearing surface at the rear journal, no wear is allowed unless you want to go for oversize thrust type bearings that are hard to find and costly. also watch for cracks through the oil hole in the main webs of the block, usually not a problem on 400's but i have seen it a few times. stock pistons will crack in the skirts up from where the steel strut is on the sides.
11-04-2002 03:56 PM
Super Streeter The deck surface cracking problems are mostly related to poor material in the block.All 400's that came out of late 70's and later vans and pickups had this problem.I aviod them for performance use.A 73 thru 76 2 bolt passenger car engine is the best find and is the premium piece for a maximum effort buildup,the earlier 4 bolt blocks arent that bad,and will work fine up to about 600 horsepower if you prep them right,but for the ultimate in strenght,a 2 bolt block with splayed caps is the best factory block setup.Otherwise,you are limited in what you can look for.If you can hear the engine run you will get an idea of what kind of shape it is in,and you need to look for all the regualr problems.Milkshake in the oil is bad and I would pull a head before buying any engine with milkshake,and wouldnt buy such an engine unless I was sure that the problem was simply a blown intake or head gasket and not a crack in the block{even a cracked head wouldnt be the end of the world if you didnt want to use the heads}.Milkshake in the oil destroys the bearings in the bottom end so even if the problem were a blow intake gasket you shoudl still plan on a full rebuild.If you cant hear it run,I would bid way low on it on the off chance that you are only buying a good block and crank or maybe even just a good crank.If you can ehar it run you can decide if it is what you want.A little smoke aor a light knock may be a good thing if it helps you get the engine for a lot cheaper,but if you need a drop in and drive it engine then a smoker or knocker would be no good for you.Good luck,and if you pass it up let me know where it is.
11-04-2002 03:56 PM
Jason First off make sure you know how to I.D. a 400 block. Just because it has an externally balanced damper and flexplate is not enough, get a casting number. And even better a Suffix code.
I have had the same 400 for almost 15 years now. I had it bored and decked. Looking at the ridge in the cylinders I couldn't believe it cleaned up at .030. It has also had a crack in the deck from a steam hole to a bolt hole, been there for 7 years and has never been a problem, just stay away from cracks that go into the clyinders.
I have also seen people put 350 heads on 400's not knowing to drill the steam holes and overheat the block so bad it cracks. My 400 has never run hot, even at .030 over.
Heads should not be much of a concern because any 350 head will bolt on after the steam holes are drilled. You usually won't run into any unusual problems with any other parts, the crank stroke and rod length are different than any other small block but they are made of the same materials.
11-04-2002 03:36 PM
tm454 What kind of money does the owner want for this engine? Can you find a running 350 for about the same money? 400sbc do-did have over heating problems. Try and find out why this engine was pulled out. Look at how clean it is and make a decision. You are buying a pig in a poke without persional knowlege of this engine.
11-04-2002 02:21 PM
stonedchihuahua do you know what kind of problems there are with heads, crank, and con rods?
11-03-2002 04:45 PM you will have to have the heads off and a magnaflux setup to find the problems they have, they develop stress cracks toward the rear of the block between the lifter bores and the deck between 6-8 cyl or the opposite side between 5-7. if you see a lot of carbon or gunk buildup in this area pass, they also crack between the head bolts and the bore. check to see if the main caps look dark in color this means heat and a line bore is due. also chck for bore wear you don't want over .040 for a final bore oversize.

[ November 03, 2002: Message edited by: ]</p>
11-03-2002 04:15 PM
What problems should I look for in a 400 sbc?

I might be going to look at a 400 sbc this week and I was wondering what kind of problems I should look for... I may or may not be able to hear it running and I may or may not be able to pull the vavle covers and oil pan... Where are common problems with these engines?

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