My Stuck 251 Engine

[55 Fargo]

Here is a pic of my stuck 251 engine, it is a 47 or 48 C38S, Royal engine, with fullflow oil filtration.

It was rebuilt in 1956 employing the Chrysler method, pistons/and or/rings .030 over, all else standard, have no idea how many miles were put on this engine after the rebuild. There was no sludge in this engine, gonna pull her out of this parts car in spring, and see whats what with it.

I just took a couple of pics a little while ago as I am bored, and getting a little cabin fever, up here in the great snowy north....fred

[Young Ed]

Fred have you put oil in the cylinders? If so does it leak past the rings on all 6?

[55 Fargo]

Fred have you put oil in the cylinders? If so does it leak past the rings on all 6?

Hi Ed, I put oil in all the cyls, it did not leak past 1 or 2 cyls, whadda ya think....Fred

[Young Ed]

The ones it didn't leak past are the stuck ones. Of course you can also have stuck valves. I think I'd take the timing chain off and see if you can get the cam or crank to rotate independantly of the other.

[55 Fargo]

The ones it didn't leak past are the stuck ones. Of course you can also have stuck valves. I think I'd take the timing chain off and see if you can get the cam or crank to rotate independantly of the other.

Ed, just went and had another look, it is 1 cyl with oil in it still from last summer, so it is most likely stuck.

I think I was able to spin a lot of valves around......fred

Edited January 27, 2010 by Rockwood

[Young Ed]

Fred I've seen guys take a 4x4(whats a 4x4 in metric) and shape it so it fits in the cylinder. You want it to be as big as possible to spread out the shock. Then you give it a wack or 10 with a hammer to knock the piston loose. Keep in mind that even if that frees up the piston it wont necessarily free the rings and you might need to take the pistons out for new rings.

[55 Fargo]

Hey Ed, lumber and most building material in Canada is not metric but the same as the US......

I am hoping this engine makes a nice rebuild candidate, even if I had to only do rings and a valve grind, that would be great.....

[Flatie46]

The last one that I "unstuck". I sprayed the cylinders and the valves with penetrating oil let that set overnight. Then the next day I took a 2x4 and a hammer and tapped on the pistons, sprayed it down and come back the next eve and done the same thing. I put a sockett on the balancer nut and very easily worked it back and forth. Patience is the big thing here, don'tforce it and don't tap too hard on the pistons. I also pulled the valve covers and sprayed oil in there. It took 4 days a little at a time but I didn't break anything. Take your time with it and you may save $$$$$.

[55 Fargo]

The last one that I "unstuck". I sprayed the cylinders and the valves with penetrating oil let that set overnight. Then the next day I took a 2x4 and a hammer and tapped on the pistons, sprayed it down and come back the next eve and done the same thing. I put a sockett on the balancer nut and very easily worked it back and forth. Patience is the big thing here, don'tforce it and don't tap too hard on the pistons. I also pulled the valve covers and sprayed oil in there. It took 4 days a little at a time but I didn't break anything. Take your time with it and you may save $$$$$.

Thanx, will try this, in spring....fred

[55 Fargo]

Remember like said, be careful with the tapping. No BFH:eek:

The crank is designed to move the pistons, not the other way around:D

Hi Shell, last summer the engine got doused with oil in all cyls, and over the valves, will try some penetrating oil this spring and will try and persuade her to move, could be a decent engine, if not a good rebuild candidate.

251 with some mild modding, maybe get a 140 hp out of her, better than the 98 hp I have now with the 218 longblock, although the 218 is a stroker as it is a shorter stroke.....

[JBNeal]

Patience & perserverance...although using the formed 4x4 would best be used with the 10# sledge, but not like driving in a railroad spike. I've used the 10# Persuader to "tap" stuff loose by having the head about a foot above the striking surface. The head will deliver the blow through the entire 4x4 as long as it is squared up. I try to have the end of the handle balanced on my hip with one hand and my other hand directing the force. This way, the head is being dropped rather than driven. This also has the benefit of applying a consistent jarring force rather than intermittent power spikes. As I understand it, penetrating oil works best when there are vibrations present between the metals. A low level but strong frequency (dropping 10# hammer) would generate a steady vibration as opposed to a high level but low frequency (striking 3# hammer) that would generate an intermittent vibration.

[knuckleharley]

Rockwood,the easy way to unstick any engine is to close both valves on a stuck cylinder and then pour the cylinder full of carb cleaner. It will eat the corrosion and allow air and oil to pass.

The quickest way to do it is after filling the cylinder with carb cleaner, screw one of those plugs into the spark plug opening that mechanics use to hold valves shut so they can change valve springs,and then hook 125 psi of air to it. Remove the crankcase oil breather cap and sit nearby and relax until you hear "blub,blub,blub" noises coming from the base pan. That noise means there is air getting past the rings.

Once all the carb cleaner has dripped down into the base repeat this process,but use something like WD-40 or a 50/50 mixture of ATF and kerosene instead of the carb cleaner The idea is to get some oil/lube on those rings and cylinder walls before they start to rust again. The thicker lube will take longer to penetrate the stuck rings,but once it does the engine should turn over by hand.

Once you do get it turning over by hand,go ahead and drain the crankcase and refill the engine with fresh oil before you try cranking it over to start it.

In fact,if it has been sitting long enough to be stuck you shouldn't try to start it right away. Either use a pre-oiler to build up oil pressure before spinning the engine with the starter,or just remove all the plugs and spin the engine with the starter until it has built up oil pressure. Then replace the plugs and try to start it.

If you don't have any carb cleaner handy,you can use brake fluid or vinegar. Vinegar is slightly acidic and eats corrorsion like nobody's business,and I use it to remove rust from small bolts and nuts. Not sure I'd leave it more than overnight sitting on aluminum pistons,though. Not sure it would hurt them,but I'm not sure it wouldn't,either.

The best thing I like about vinegar other than it being cheap is that it is safe to use and easy to dispose of. Just pour it right down your drain or use it to kill weeds in the yard once you have drained it out of the engine or poured it out of whatever container you had it in.

Vinegar is also great for removing rust from the inside of gas tanks.

Edited January 28, 2010 by knuckleharley

[Don Coatney]

Rockwood,the easy way to unstick any engine is to close both valves on a stuck cylinder .

How do you close both valves when the engine is stuck?

[knuckleharley]

How do you close both valves when the engine is stuck?

Pretty simple on a OHV engine. You back off on the rocker arms. If the valves are stuck you remove the rocker arms and tap on the valve stems with a brass hammer after greasing the stems.

If it's a flathead you have to remove the timing chain to rotate the cam. I guess it is possible for a cam to be stuck,but I have never seen or heard of it,and chances are if the engine is that dry and rusty inside you are going to have to take it apart with a chisel.

[Johnny 5]

I bought a 331 that I didn't have a history on a while back. I've bought plenty of seized engines and this was the only dud. I did the typical diesel soaking to loosen it up - no luck. When I tore it down I saw a huge chunk of cylinder wall in #1. The block was toast.

Fast forward to 2007. I bought another 331 that was stuck. It wouldn't loosen up either but when I tore it down I was able to hammer the piston out with a 3 lb hammer and a drift. Forget about using a 2x4. You'll go through a half dozen and the pistons will still be in the engine. You'll have to work it up and down a few times before it gives up. Patience is key here. Beer doesn't hurt either. It doesn't do much for car parts but is sure loosens up people.

[55 Fargo]

Hi Johnny, will see if I can get her loosened up, doubt there is a busted up cyl. This engine looks not too bad, liter camber is super clean, no sludge.

The engine was rebuilt in 1956, .030 pistons/and or rings, all bearings standard.

The nice thing, it is a 47, 251 Royal C 38S engine, just what I want. I have a 218 long block in my car, it was from a 1951 Canuck Dodge, it is rated at 98 HP, the 251 is rated at 115 hp, so 17 more HP would be nice.

The one thing about a Canuck 218 long block is this it has a 3 3/8 bore, this can be bored to about 3 1/2 if ever need be and still be in spec, at .060 over a 251s 3 7/16 bore.

The stroke on a 218 long block is 4.0, on a 251 it is 4 1/2 inches. The 218 is a shorter stroke, not sure if this means it can take more rpm or not........Fred

[knuckleharley]

BTW,guys,don't trash those old irreplaceable blocks over something like this. I guess it isn't done much anymore,but people used to put sleeves in blocs with bad cylinders. You can save a block this way and it would probably be cheaper and no doubt be easier to do than fining another block.

Hell,you can even sleeve all 8 if you want and bring it back to standard bore,or whatever bore you manage to find pistons and rings for.

[55 Fargo]

BTW,guys,don't trash those old irreplaceable blocks over something like this. I guess it isn't done much anymore,but people used to put sleeves in blocs with bad cylinders. You can save a block this way and it would probably be cheaper and no doubt be easier to do than fining another block.

Hell,you can even sleeve all 8 if you want and bring it back to standard bore,or whatever bore you manage to find pistons and rings for.

Yes this I have heard of sleeving when necessary, My Uncle has a 332 Hemi, that 1 cyl needs sleeving, that engine would certainly be worth saving...

[Johnny 5]

Hi Johnny, will see if I can get her loosened up, doubt there is a busted up cyl. This engine looks not too bad, liter camber is super clean, no sludge.

The engine was rebuilt in 1956, .030 pistons/and or rings, all bearings standard.

The nice thing, it is a 47, 251 Royal C 38S engine, just what I want. I have a 218 long block in my car, it was from a 1951 Canuck Dodge, it is rated at 98 HP, the 251 is rated at 115 hp, so 17 more HP would be nice.

The one thing about a Canuck 218 long block is this it has a 3 3/8 bore, this can be bored to about 3 1/2 if ever need be and still be in spec, at .060 over a 251s 3 7/16 bore.

The stroke on a 218 long block is 4.0, on a 251 it is 4 1/2 inches. The 218 is a shorter stroke, not sure if this means it can take more rpm or not........Fred

These engines can probably all go to 3.50"-3.56" if the sonic test shows you'll have .175" thick cylinders afterward so sleeving isn't necessary. Custom pistons might be in order over 3.50". The only limiting factor in engine RPM is rotating weight. Fuelers can rev to 8000+ with 4.75" strokes so the stroke itself won't slow you down, the heavy throws and counterweights will. From what I know old flat 6's need the cranks cross-drilled for better oiling to the middle cylinders. If I ever get around to building one myself I'm going to do this, have the crank lightened, enlarge the 2 center main oil passages in the block a little, use Venolia pistons, an Edgy head and cam, port, polish, headers, etc. I figure this will be as good as any hot rod motor and make 1hp/cid with a multi carb setup. Turbo or blower will put it into the 350-400hp range. More work will be needed for it to stay together though. Thoughts?

[Johnny 5]

I can't find St Andrews on MS Streets and Trips, just curious as I'm originally from Moose Jaw.

[55 Fargo]

These engines can probably all go to 3.50"-3.56" if the sonic test shows you'll have .175" thick cylinders afterward so sleeving isn't necessary. Custom pistons might be in order over 3.50". The only limiting factor in engine RPM is rotating weight. Fuelers can rev to 8000+ with 4.75" strokes so the stroke itself won't slow you down, the heavy throws and counterweights will. From what I know old flat 6's need the cranks cross-drilled for better oiling to the middle cylinders. If I ever get around to building one myself I'm going to do this, have the crank lightened, enlarge the 2 center main oil passages in the block a little, use Venolia pistons, an Edgy head and cam, port, polish, headers, etc. I figure this will be as good as any hot rod motor and make 1hp/cid with a multi carb setup. Turbo or blower will put it into the 350-400hp range. More work will be needed for it to stay together though. Thoughts?

Not sure what will result with being supercharged. But Earl Edgy has only got his 32 Chrysler salt racer to maybe 220 hp, at this point, and that is fuel injected I thinks...Fred

[55 Fargo]

I can't find St Andrews on MS Streets and Trips, just curious as I'm originally from Moose Jaw.

I am located 18 miles north of Winnipeg, 5 miles northwest of Selkirk Manitoba, on Fillmore Road in the RM of St. Andrews off Hwy #9.

Nice to have you on here fellow Prairie Canadian....