In bench racing I posted concerning a 400 small block I came into. In preparation for pulling the engine I drained the oil pan. What came out was about 1/2 clear liquid and 1/2 oil. It had a definate separation so I assume it is water. The rad had antifreeze in it so I was a bit surprised that it was clear. 70isfine stated that 400s are famous for cracked blocks and heads. I am going to pull the engine apart tomorrow. Where should I look for suspected cracks in the block? Are there any internal places it could crack that would not be evident on a normal tear down inspection?

Thanks in Advance

If has been overheated the blocks can crack between cylinders (where the cylinders are siamesed), between a cylinder and the water jacket near the siamesed area. However, cracks in these areas would have likely led to catosrophic failure of the entire engine.

Aside from obvious neglect or abuse, they tend to crack in the webbing between the main bearings and the pan rail. This area is actually weaker on a 400 than on other small blocks because they had to remove the amount of cast iron in this area to make room for a larger crank.

If it is a 4-bolt main block, look for cracks near the outer main bolt holes of the block. On the heads, check for cracks from the steam holes to the combustion chamber and between the exhaust and intake valve pockets. They may not be visible by the naked eye, you might want to have it all checked by a professional at a machine shop. They can find cracks you'd never see yourself.

Concerning the clear liquid in the engine; had it sat for quite a while? Could rain water have collected inside the engine? If so, I would expect ugly things inside that engine.

Take a look in the lifter valley. A common spot for SBC is along the sides of the cylinders.

thanks guys. yes it did set for about 3 years but it is free and was inside tof the van.. Could it be condensation???? I wouldn't think it could be that much... it is supposed to rain tomorrow, if it does I might be able to get it torn down...

later... septic system took a dump (pun intended..) happy holidays to me.. septic truck is here now.. dig dig dig...

later

Ok, we pulled the heads an everything looks great. Some minor scratches on 2 or 3 cylinder walls. The heads look clean and no cracks or fluid in the cylinders or anywhere. No internal rust. I'm stumped. Also, I don't see much trouble in the heads.

One question. Would it be better to do the heads for the 400 or use vortechs? The reason I ask is that the 400 heads seem to have huge valves. Is there an advantage over the 400 heads with the vortechs? Sorry for dumb questions but this is my first 400.

TIA
rick

I don't know which would be better. But with the small chambers in the Vortecs, the CR will get very high, very fast with flat tops pistons. You'll need dish pistons. I suggest using reverse domes rather than the common full circle dish. They will more closely match the chamber shape and provide a good sized quench area.

"Gary at GMPP" has put some pretty big valves in the Vortecs. You might try a search on his username. Of course, by the time you put big valves in and do the studs (if needed) and springs pockets (if needed) and trim the valve guides, and get the Votrec manifold, you could buy some nice aftermarket heads with large ports, good springs, and big valves already in them.

Rick,
First of all, on the heads. What is the casting date? If the casting date is later than July 74 (letter G for July), they are probably for a 75 model car. As a result, on 75-later SB engines, they had thinner cast heads and SHOULD NOT be used. But, if they are 70-74 model heads (74 heads, ON ANY SB, was the LAST year for the good, heavy heads), and they do not have any cracks, then they are a good core for a street engine. AS I SAID, NEVER USE SB HEADS FROM A 75-LATER MODEL ENGINE, if they are not cracked, they will be!
SB400 heads came with 1.94/1.5 valves and any machine shop can open them up for 2.02/1.6 valves. If the 70-74 heads show no signs of overheating, I would not hesitate to use them. You can have your machine shop port match them to the intake manifold that you will use and do some clean up/light polishing to the bowls, and they will make great street/performance heads. With the 76cc chambers and flat top pistons and a .030 bore (406), this will give you 9.5 to 10. compression, just right for todays pump gas.

I really suspect the water, since it is clear and the radiator had antifreeze in it, is somehow the result of either water getting in from the outside (rain water or whatever) or possibly condensation (but that's a LOT of condensation inside a closed up engine).
As mentioned, tear it down and have a good machine shop check the block/heads for cracks. I have seen several SB400 blocks with cracks between the steam hole and head bolt hole between the cylinders. I've used them (I have 2 blocks with these kind of cracks in 2 cars) and NEVER had a problem. But, a crack between a steam hole and the cylinder wall is bad and the block is not any good.

If the block/heads proves to be solid, even with some rust on the cylinders, the machining processes and boring will make it a good engine to build.

Thanks for the suggestions but I'm a little confused. The engine is out of a 78 van. The block # is 3951509 and the only numbers I find on teh head are 888820 and D 110.

Now, as for inspection. I tore it down. No rust in the cylinders at all. Oil in pan has some sludge but black goo not the white froth I would expect if it was running with water in the engine. I see no rust on the crank or rods. The one thing that does puzzle me is that the cam seems to have 1/4" or more of play front to back. I don't have the balancer off yet so I was rolling the engine over to check cam lobe. I then noticed this play.

A visual inspection doesn't seem to suggest any cracks or really anything unusual. I don't see any cracks between valves or cylinders and like I say. Even witht he liquid that was in the oil the crank and journals all were coated nicely in oil and the lifters were all full of oil as usual.

Weird... never saw this kind of liquid in an engine and not have the internals all rusted up. Can't believe there would have been this much water in it just from condensation...

Originally posted by DZAUTO:
Rick,
First of all, on the heads. What is the casting date? If the casting date is later than July 74 (letter G for July), they are probably for a 75 model car. As a result, on 75-later SB engines, they had thinner cast heads and SHOULD NOT be used. But, if they are 70-74 model heads (74 heads, ON ANY SB, was the LAST year for the good, heavy heads), and they do not have any cracks, then they are a good core for a street engine. AS I SAID, NEVER USE SB HEADS FROM A 75-LATER MODEL ENGINE, if they are not cracked, they will be!
SB400 heads came with 1.94/1.5 valves and any machine shop can open them up for 2.02/1.6 valves. If the 70-74 heads show no signs of overheating, I would not hesitate to use them. You can have your machine shop port match them to the intake manifold that you will use and do some clean up/light polishing to the bowls, and they will make great street/performance heads. With the 76cc chambers and flat top pistons and a .030 bore (406), this will give you 9.5 to 10. compression, just right for todays pump gas.

I really suspect the water, since it is clear and the radiator had antifreeze in it, is somehow the result of either water getting in from the outside (rain water or whatever) or possibly condensation (but that's a LOT of condensation inside a closed up engine).
As mentioned, tear it down and have a good machine shop check the block/heads for cracks. I have seen several SB400 blocks with cracks between the steam hole and head bolt hole between the cylinders. I've used them (I have 2 blocks with these kind of cracks in 2 cars) and NEVER had a problem. But, a crack between a steam hole and the cylinder wall is bad and the block is not any good.

If the block/heads proves to be solid, even with some rust on the cylinders, the machining processes and boring will make it a good engine to build.

Without the valvetrain in place and distributer in, the cam will move back and forth. I wouldn't worry about it.

400's are very prone to cracks in the lifter valley. Id spend a couple of bucks and have it magnaluxed. Nothing worse than spending lots of money for machine work on a bad block.

OK guys another question.

Lets say that I drill my vortech neads for the steam holes and use them on the 400. If at a later date I decide to use them on a 350 could I or would drillig them for the steam holes screw them up as far as using them on a 350?

DZ... thanks for your insights on the 400 heads. I cannot see witha visual inspection any problem with the heads but they are post 75 heads. Would it be better to drill the steam holes onto the vortechs or hunt around for a set of pre-75 400 heads?

thanks again for all your help

If you want to run on pump gas...I think that you are gonna find that you'd have to run a hell-of-a dished piston with those small chamber vortec's on a 400.

Heads drilled with steam holes for a 400 type block will work on a 350. Although I dont think its an ideal setup.

Originally posted by Professor_SS:
OK guys another question.

Lets say that I drill my vortech neads for the steam holes and use them on the 400. If at a later date I decide to use them on a 350 could I or would drillig them for the steam holes screw them up as far as using them on a 350?

DZ... thanks for your insights on the 400 heads. I cannot see witha visual inspection any problem with the heads but they are post 75 heads. Would it be better to drill the steam holes onto the vortechs or hunt around for a set of pre-75 400 heads?

thanks again for all your help =
The drilled holes will cause no problem putting the heads back on a 350
The early 400 heads were 350 heads with holes drilled in them, same casting, so you do not need to find "400 heads" but as Tom said you should look for the pre 75 heads (350 or "400") as they are a thicker casting & the later ones will be cracked or are waiting for the crack to happen after you put them back on :D

My thoughts exactly to all of the above.
Either locate a set of 74-earlier 350-400 heads, or, buy aftermarket iron such as World or Dart.
That's my story and I'm stickin' to it.

So in order to run the vortech heads I'd have to change pistons? I thought there were several guys here that are running this combo on pump gas but maybe I'm mistaken...


Originally posted by DZAUTO:
My thoughts exactly to all of the above.
Either locate a set of 74-earlier 350-400 heads, or, buy aftermarket iron such as World or Dart.
That's my story and I'm stickin' to it.