How to pull the 251 engine out

[harmony]

I'm thinking about (procrastinating) having the 251 engine rebuilt on my 1948 Chrysler Windsor.  I think I'll make it a winter project.  At this point I don't think the condition of the engine is critical.  Plus I only have Vintage BC plates on the car so I can't really drive it too much and be legally insured.  So I get the car out a couple or a few times a month for 45 minutes cruises at a time.  These days I'm driving my 1930 Hudson Super 8 as my daily driver so that fills my need for that special feeling. 

 

On start up, lately I get quite a bad knock, that goes away in about 5 seconds thankfully.  But when I'm driving it, I can hear a bit of a clicking/tapping. At idle it's not bad at all, but noticeably more than it used to be in years gone by.   I have reset my valves and they seem to be pretty accurately set.  I'm also getting a slight blueish smoke out the exhaust when idling.  But I don't notice anything from my mirrors on acceleration. The compression is not too bad.  133, 130, 127, 135, 130, 130. 

I've had rich exhaust for some time and I've tried leaning out the idle mixture screw on the EV1 carter carb.  But that doesn't seen to make any difference.  Plus as I adjust the carb, the engine doesn't get rougher or smoother.  I've recently talked to a professional engine rebuilder, that mostly specializes in building hot rods and he says the black sooty smoke out the exhaust pipe is probably caused by bad rings or something related to the engine getting tired.  I will probably be getting him to rebuild the engine, since he's in my car club and club members get a discount, and he's looking forward to it.  

 

Ok so here is my question.  Can I unbolt the engine from the fluid drive?  Or do I have to remove the engine, fluid drive, trans, all at once?  I have limited height in my shop.  When the hood is open on the car, I have about another 6 inches to the ceiling.  I have removed the whole thing once before, a few years ago, on another car ( 47 Royal) and as most of you know, the whole assembly is fairly long.  Of course I'll be removing the hood and radiator.  If I remember correctly, the engine hoist was at it's maximum lift and we had to remove the front wheels to get the car as low as possible, when I did it on the 47. 

If it's possible to remove just the engine?  It looks to me like once I remove the two top bolts (engine to fluid drive assembly)  all the rest of the bolts are on the sides and bottom which I can access from under the car.  If I remove the inner fenders and front wheels,  I think those two top bolts can be accessed not to badly.  Not sure about getting a torque wrench in there when reassembling though.  Lots of linkage in the way on the drivers side. 

 

I'm not a mechanic, however I would like to do as much work as possible.  I might remove the head just to have a look. I'll probably pull out the water distribution tube, since I built a special tool to do that a few years ago using a slide hammer method.  I'll re-watch Keith's videos on rebuilding his engine.  I'm sure I'm not qualified to do as much as he did, but at the same time, I do want to learn as much as possible and what better way to do that than pulling the engine apart, but reassembly would be over my head for the most part.  But I'm not sure how impressed an engine builder would be if I bring him a basket full of parts as opposed to a complete engine.  

[joecoozie]

Yes, you can pull the engine only but you will have to remove the transmission/bellhousing/FD unit.

Removing the front floor panel ( it's bolted in) will give you all the access you'll need to make the job a lot easier.

I have done it several times this way - without removing the inner fenders.

However, in the shop manual, there is a procedure for removing the fenders/grille, etc all in one piece - if you want to do that.

 

 

[Doug&Deb]

Be careful with the fluid coupling. Pull the trans straight back. You don’t want any side load on the fluid coupling. Before removing the clutch assembly place wooden wedges between the clutch and coupling and use wire to hold them in place. You don’t want to crack the carbon seal. If you remove the trans you can pull the engine and bell housing as a unit.

[Curt Lee]

If you don't already have some, make up at least a pair of bell housing to block alignment pins, using longest bolts available to give you a straight shot going out and back in. I have several sets I made for other engines, usually by cutting the heads off head bolts and cutting a slot for a screwdriver in the end. Head bolts are almost always the same thread and pitch as the bell bolts, YRMV. Head bolts are strong enough to stay put with the weight of the trans on them for a short time, too.

[keithb7]

Now that I have a flathead engine rebuild on my resume,  if it were mine, I might need more proof that it really needs a rebuild. I learned a ton rebuilding mine. 
 

Your compression is good, (good ol’ sea level compression) what is your engine oil pressure? Pull 1 spark plug wire then fire up the engine. Does the knock go away?  No? Re-install plug wire. Let everything sit a while and go back and try the next wire. Keep going until you find which cylinder is causing the knock.  Then I’d pull the oil pan and take a look. Check bearing clearances with plasti-gauge. Check end to end thrust movement. 
 

Black soot out the exhaust pipe landing on the driveway when engine is first fired up means little.   Perhaps your carb has air leaks and adjustments don’t make an impact. Maybe your carb float is set too high? Maybe your choke is staying on too long? Bad oil rings maybe? Yet compression rings are showing very good. 

Pulling the cylinder head and measuring the top ridge, cylinder taper and out-of round will tell a ton about the engine’s current condition. Now you’ e got the head off, and the oil pan off, time to push out a piston. Pull the one with the worst looking spark plug.  Out the top and check rings rings. End gap.  
 

If you are serious about a rebuild you really need to be placing your parts order now. It can take months and months to get everything you need.  

 

Maybe let me get involved in person? Old Mopar flatheads are so much fun. I’m kinda serious. I’m not far away. Send me a message. 
 

Keith

[kencombs]

Couple of things stick out to me from your post.  First, those are good compression numbers, very good driver condition.   I've seen low mileage rebuilds lower than that.  

 

Second it would be a rare occurrence that black sooty stuff come out of an engine with those numbers   due to oil burning.   Much more likely to be carb related.   Choke not working well, float to high etc.

 

Hard to tell what the knock is long distance, but a telltale for me searching for rod bearing knocks is to rev the engine slowly up to 1500-2k rpm range and just very slightly let I drop 2-400 rpm.  A rod knock will almost always get worse during that decel period.

 

How's the oil pressure?   Loose mains will always show up a very low pressure, not so much as a knock.

 

Before committing to a high dollar rebuild, I'd first do a through examination as suggested by others.

 

 

[harmony]

Thanks everybody.  Great comments from everybody.  I think I'll follow everybody's advise.  I forgot to mention that my oil pressure seems good to me.  When I'm cruising along on a level road.  So not with adding to the pressure on the gas pedal and not letting off either, I have about 40-45 lbs.

As for performance, I really have never noticed anything sluggish or anything else noticeable.  It's strong going up a steep hill even in 4th.  I'll kick it down into third and in no time, I'm letting it go into 4th because it's climbing strong and the revs are telling me it's time to get into 4th.  As we all know the fluid drives are a bit of a dog.  But if I really want to distance myself from the guys bumper in my rear view mirror, coming off a set of lights, if I get into it, it doesn't bog down or hesitate or anything like that. 

 

I'll try that trick you mentioned Keith about one cylinder at a time to see if I can find where that knock is coming from.  Thanks for that offer of helping out Keith.  I respect your knowledge on these flatheads so that's a very nice offer.

 

I do have a spare engine/fluid drive/trans that I built a run engine stand for and wired it up just as it would be in the car with the regulator and trans relay all wired in. ( picture below) Plus the original gauge cluster is also all hooked up. I'm using an old lawn tractor fuel tank and I have the battery box all ready for the 6V battery.  I didn't have thick enough battery cables for the negative post, so I doubled up on 12V size cables that I had kicking around.  The positive cable was beefy enough.   I just wanted to see if it was any good.  I already pulled the head and 4 valves were stuck open for who knows how many decades.  I finally got them freed up and I polished the valves before putting them back in, and the head back on.  But sadly even after that, the compression is poor with the best cylinder being 65lbs and the worse being 35lbs. The valve seats were also corroded, and I've learned in one of Keith's videos that they are hardened seats, so valve lapping doesn't do anything.  So anyways I may drop the pan on that one first and maybe try all the things everyone has suggested on it first.  Sort of like a trial run. 

 

As I mentioned I don't really want to get into all this until the rainy seasons comes along in Dec.  I'm just really enjoying the luxury of cruising along in the old girl too much to put her under the knife just yet.  

  

[harmony]

8 hours ago, CURT LEE said:

If you don't already have some, make up at least a pair of bell housing to block alignment pins, using longest bolts available to give you a straight shot going out and back in. I have several sets I made for other engines, usually by cutting the heads off head bolts and cutting a slot for a screwdriver in the end. Head bolts are almost always the same thread and pitch as the bell bolts, YRMV. Head bolts are strong enough to stay put with the weight of the trans on them for a short time, too.

I know exactly what you're talking about.  I've made a set of them for the exhaust manifolds on my boat engines. 454's.  Great for lining up the gaskets and getting those monstrously heavy exh, manifolds in place.  Never fun working in a boats engine room.  

[harmony]

10 hours ago, Doug&Deb said:

Be careful with the fluid coupling. Pull the trans straight back. You don’t want any side load on the fluid coupling. Before removing the clutch assembly place wooden wedges between the clutch and coupling and use wire to hold them in place. You don’t want to crack the carbon seal. If you remove the trans you can pull the engine and bell housing as a unit.

Thanks, I may experiment with the spare set up I mentioned in my last comment.

[harmony]

6 hours ago, keithb7 said:

Now that I have a flathead engine rebuild on my resume,  if it were mine, I might need more proof that it really needs a rebuild. I learned a ton rebuilding mine. 
 

Your compression is good, (good ol’ sea level compression) what is your engine oil pressure? Pull 1 spark plug wire then fire up the engine. Does the knock go away?  No? Re-install plug wire. Let everything sit a while and go back and try the next wire. Keep going until you find which cylinder is causing the knock.  Then I’d pull the oil pan and take a look. Check bearing clearances with plasti-gauge. Check end to end thrust movement. 
 

Black soot out the exhaust pipe landing on the driveway when engine is first fired up means little.   Perhaps your carb has air leaks and adjustments don’t make an impact. Maybe your carb float is set too high? Maybe your choke is staying on too long? Bad oil rings maybe? Yet compression rings are showing very good. 

Pulling the cylinder head and measuring the top ridge, cylinder taper and out-of round will tell a ton about the engine’s current condition. Now you’ e got the head off, and the oil pan off, time to push out a piston. Pull the one with the worst looking spark plug.  Out the top and check rings rings. End gap.  
 

If you are serious about a rebuild you really need to be placing your parts order now. It can take months and months to get everything you need.  

 

Maybe let me get involved in person? Old Mopar flatheads are so much fun. I’m kinda serious. I’m not far away. Send me a message. 
 

Keith

Great idea about pulling the spark plug wires.  I appreciate your offer Keith.  I'll keep it in mind. 

[soth122003]

2 hours ago, harmony said:

But sadly even after that, the compression is poor with the best cylinder being 65lbs and the worse being 35lbs.

You said that was a spare engine. When I first got my P-15, it hadn't run in a few years, the compression was low like that. I did a wet comp check and it came up some, about 75 psi or so across the pistons with one being about 50. Letting the engine run for a while, about an hour or so the compression started going up. Now it's about 115-120 across all the pistons. Your rings are probably stuck and just need some exercise to work them out to operate properly. 

2 hours ago, harmony said:

The valve seats were also corroded, and I've learned in one of Keith's videos that they are hardened seats, so valve lapping doesn't do anything. 

As I recall in one of Keith's videos, he has those seat reamers to recondition the valve seats. Might hit him up and see if he'll come over and help you with that.

 

Joe Lee

[D35 Torpedo]

In my experience, rod knock shows up first when the engine is hot and oil is thin. Perhaps the sound you're hearing is exhaust or a belt. Something rattling as it's shaking to life.

[harmony]

8 hours ago, soth122003 said:

You said that was a spare engine. When I first got my P-15, it hadn't run in a few years, the compression was low like that. I did a wet comp check and it came up some, about 75 psi or so across the pistons with one being about 50. Letting the engine run for a while, about an hour or so the compression started going up. Now it's about 115-120 across all the pistons. Your rings are probably stuck and just need some exercise to work them out to operate properly. 

As I recall in one of Keith's videos, he has those seat reamers to recondition the valve seats. Might hit him up and see if he'll come over and help you with that.

 

Joe Lee

Come to think of it, I do remember something about his valve seat reamer.  I'll have to go back and check that out again.  I'm wondering how difficult it would be to build one accurately.  I love building home made tools.   

 

Well,,, when Keith says he's "not far away".  It's not like he's just down the street, and he knows that.  He's on the other side of the mountains. Plus, add on an hour and a half ferry ride. Plus the ferry fee (one way) is about the cost of a ticket to outer space. Total time from his place to mine "on a good day" is about 8 hours.  In the winter you need a sherpa guide to get you through the mountain pass, and make plans to be rescued. 

So his "get together" offer says a lot about his personality and love for old Mopars. 

[keithb7]

I don’t have a valve seat reamer. I have an abrasive cutter tool. featured in some of my videos. You gotta work pretty hard to get the hardened exhaust seats cleaned up. I have successfully done it on 2 different old Mopar cars.  After working on the hardened seats for a few days, the intake seats cut like butter. Your back and shoulders love intake seats. 
 

I get lots of vacation time. My wife does not. This gets me some time to myself, to do whatever I want each year.  Going to help Harmony on his Mopar, to me would be fun. Sorta like going to a car-junky amusement park. Lol.  Besides his area is pretty beautiful. Gives me a good excuse to go down there. 

[keithb7]

My valve seat tool, on ebay when I bought it 7 or so years ago. 
 

 

[harmony]

18 minutes ago, keithb7 said:

My valve seat tool, on ebay when I bought it 7 or so years ago. 
 

 

Jumping way ahead of myself on this project, but since this tool has been introduced into this posting, I've briefly started to look around.  Amazon.ca offers a set, however about 5 times what you paid.  I've also found a tool company in Windsor Ont. called Colonial Tool Group that offers a tool.  They say contact them for a quote on the tool.  That indicates a scary price.  If I do get one of these handy tools, what info do I need to know?   Like what is the exhaust angle?  Is the intake a different angle? Anything else I'd need to know besides the phone number of a good chiropractor? 

It really would be fun to get my spare engine up and running and with good compression.  Just for the fun of it. 

[keithb7]

Flathead Mopar engines; 45 degree single angle valve seats. Both intake and exhaust are the same. 

You also need valve grinding compound. Using my tool above, a 3/8 hand speed handle helped a lot with hand placement,  and exerting good downward force. Pretty much the secret ingredient for success for hardened exhaust seats in my opinion. 

Both times I did this valve work with the speed handle, the engine was in the car. My ‘53 Chrysler had tons of room under the hood. My split hood Chrysler, I removed the hood and snuggled right up to the engine. 

Edited July 20, 2023 by keithb7

[harmony]

5 hours ago, keithb7 said:

Flathead Mopar engines; 45 degree single angle valve seats. Both intake and exhaust are the same. 

You also need valve grinding compound. Using my tool above, a 3/8 hand speed handle helped a lot with hand placement,  and exerting good downward force. Pretty much the secret ingredient for success for hardened exhaust seats in my opinion. 

Both times I did this valve work with the speed handle, the engine was in the car. My ‘53 Chrysler had tons of room under the hood. My split hood Chrysler, I removed the hood and snuggled right up to the engine. 

Even though I watched those videos, I can't remember if you recorded yourself doing that procedure.

[soth122003]

Hey Keith, wonder if a low speed drill (about 20 rpm) would save the back and shoulders? Your more or less cleaning up the seats, not cutting new ones. Just a thought.

 

Joe Lee

Edited July 21, 2023 by soth122003