engine problems

[dmulhall]

Here's the story...

6 years after my original 218 spun 2 rod bearings I found a re-built (so called) industrial 251 out of a Massey combine for it. This engine looked pretty good (other than being repainted with a brush and it has been sitting outside under a tarp for the past 8? years. With a limited budget (young family) I brought this engine home, pulled the oil pan (clean), switched over everything from my old engine (flywheel, carb, both manifolds, dissy, coil, cap (new), wires (new), put brand new plugs in it, and plopped it in.

When I first started it, it was blowing out the carb (enough to get the pass side windshield dirty), running rough, and I thought to myself stuck intake valve. So I pulled the covers (clean inside) and found a stuck intake valve on number 1, stuck a big screwdriver in there and PING, down it came. I then let it run and watched all the springs and tappets, all were working well.

I had a old friend of mine come over and set the points with a "dwell" meter? (Kinda over my head) and we set the timing to 2 degrees btdc. It was still idling rough and will not rev above around 2,000 rpm. We also did a compression test and found #1-32 #2-37 #3-62 #4-57 #5-65 #6-55

My old mechanic friend thought I might have a few stuck rings, and maybe some rust on the cylinder walls. He said dump some seafoam in the crank case and drive it for awhile and it will probably straighten out.

I've put 54 miles on it now (idling around town basically) and it has improved some what, but it has a exhaust sound out the carb when you rev it up a bit. It stumbles under load, bogs out, and doesn't do over 35 miles an hour. It is starting pretty good, idles better than it did (still misses and vibrates a bit.

Could this be from the cylinders with low compression? Why would it have the exhaust noise out the carb when you rev it up? Intake valve? I had the head off thinking it was a burnt valve and they all look good, and are seating properly when it turns over with the starter, cylinders look good (no ridge to feel),.

If I do order rings for it, do I get .010 over and trim them to fit need be? It doesn't have any oversized piston numbers stamped in them?

I did not pull the pistons out yet to look at the rings yet.

I'm kind of pulling my hair out...

Timing chain off one notch?

The only thing not new in the ignition is the coil, but does it sound like a faulty coil?

I also noticed that when its idling, the ammeter needle will bounce a little bit back and forth when it stumbles, is this normal?

Sorry for the book, just a little frustrated...I love this truck so much and havnt been able to touch it since we've had kids...

Thanks guys in advance for your past help and much more in the future (as I foresee)

[dmulhall]

I forgot to mention, it has 40+ pounds of oil pressure on a consistent basis, even hot =o)

[mechresto]

Sounds like late cam timing. if you have a vacuum gauge, get it running and take a reading. assuming that your ignition circuit and carb are tolerably in adjustment, your vacuum reading will give you your answer. This is probably the most important tool you will ever use when it comes to tuning and diagnosis

Bryan

[MBF]

I agree-it sounds like valve timing, or valves set to tightly with the low compression readings you're seeing. Have you checked the valve lash (tappet adjustment) with feeler gauges while the engine is hot and running? If they're set properly within tolerences, and you're valve timing is correct, the next thing I would check for would be to see if a valve job was done during the rebuild. Mike

[Plymouthy Adams]

As Mike states, if your timing is correctly set, the possibily of other valve issues come to mind. The low compression indicates such a possibility..investigate close, check lash, seat and valve face..lap if necessay..this lapping action will quickly show a warped valve if there is one..best time spent as you will not be guessing later if they are or are not warped..do it once and do it right, peace of mind is worth it...

[mechresto]

Both good suggestions however, when reading the original post he states that "it has a exhaust sound out the carb when you rev it up a bit." and "will not rev above around 2,000 rpm". both symptoms will get better with an increase in rpm if the valves are set too tight or simply leaking. Valve reversion is negated by RPM wheras late timing is magnified by RPM.

Bryan

Edited March 21, 2012 by mechresto

[B1B Keven]

Just a silly question.

Does it have a vacuum advanced distributor in it?

[dmulhall]

Yes, it has vacuum advance...checked that yesterday...I don't really know what to check for, orher than being dirty, stuck, or grimy...it moves freely seems to working good...clean

I briefly checked the tappet valve clearance..if anything they had too much clearance...

I have a feeling that the cam isn't timed properly...maybe a few notices out..but I'll have to find a friend with a puller to pull the cover off...

With the exhaust noise in the carb it has to be something like that...I guess its the most logical place to start...???

[ptwothree]

Another silly question...Industrial engine-does it have a governor on it??

[dmulhall]

I'm young and dumb

If it did have, where would they put it?

I don't think it does, I think its valve timing because it bogs out so bad if you step on it, you can't floor it or it will probably sputter and stall...if you give it gas lightly it still has the exhaust noise through the carb

If I had sticky valve guides, would I have noticed it when I was watching the tappets?

Would the valves not be really noisy?

I'm a truck driver so I have too much time to think haha

Most of the time I way over think these things

One guy also told me that the rotor might be shorting out down the shaft? He said mopars are famous for this? I don't know...never heard of that, but like I said...young and dumb or "inexperienced" haha

[Dodgeb4ya]

A rotor shorting through the center will not cause low compression. Maybe weak valve springs, tight valve clearances- but what is the history of this engine, a combine rebuilt engine? Why did they take it out? It was sitting under a tarp outside?

It could also have pitted valve faces and seats.

The head probably should come off and have a professional check it out. As for the chain and gears being off, could happen but I have purposely set them 1 tooth off just to see and it's obvious because the dots will be off centerline of the cam and crank by at least 1/4-3/8". Timing marks would not easily line up either.

Bob

[ptwothree]

Does the throttle on the carb open all the way when you floor it? Accelerator pump working?

Does the ignition timing advance when you rev the engine? check with a timing light...............

Is the timing chain loose? Check by moving the crank pulley back and forth while watching the rotor for movement. You can measure the difference with the timing marks if you are clever.

The governor is usually associated with the carb and or linkage.

Also..Industrial engines usually have a very limited advance curve because they run at limited or fixed rpm's......

[Rusty O'Toole]

If you have the head off measure all the cylinders diameter at the top and at the bottom. This will tell you if you have stock size cylinders (3 7/16") and how much they are tapered. .007 taper or less and you can rering, no problem. More than that and it becomes questionable although, you can get away with it up to .010 although the job will not last as long.

Get new rings of suitable size, standard if your pistons are standard, or whatever oversize you need. I have a set of NOS .040 over Perfect Circle rings if you need them.

Hone the cylinders with a bottle brush hone. Fit the new rings (you may have to file them a little, I can tell you how to do this if you don't know). Grind in the valves. While you are at it you can check your bearings with Plastigage but if you have 40 pounds oil pressure they are probably OK.

Another thought comes to mind. If the engine was rebuilt maybe the rings are not even worn. Maybe you can take the pistons out, work them free, and stick them back in. If there is no ridge on the top of the cylinder, in other words no cylinder wear this is quite possible. Are the piston tops clean or do they have a coating of carbon about as thick as a business card? If they are clean it can't have many miles.

Yet another thought, 54 miles is not enough to free up anything. Try driving it more. Drive it long enough to get thoroughly hot, like for an hour. Even if you just tool around the country roads. Then see how it performs. If the engine is getting better and faster keep driving, it may take several hundred miles to free the rings.

You could also try tuning the engine up. The tuneup is a lost art in the age of fuel injection and electronic ignition. It does not have to cost money. Adjust valves, check ignition, clean points and plugs, set their gaps, set timing, inspect and test plug wires and finally adjust carb. That is another thing, the carb may need to be cleaned and adjusted.

These suggestion seem to be in reverse order lol. It is so hard to know what to do without being able to see the engine. I seriously doubt there is anything wrong with the cam timing. It sounds like the engine is just gummed up and out of tune. Maybe it just needs to be driven, maybe it needs a tuneup, maybe a ring and valve job. Hard to say without seeing it.

[dmulhall]

Thanks to everyone for your input and suggestions.

Ya, when I had the head off to check the valves I should have pulled the pan and popped out a piston. I can always still do that again, but when I had it off the cylinders looked good, no carbon on top of the pistons, except for a slight bit on #4, but the spark plug was clean. I also fogged the engine with seafoam so that probably took care of a lot of the carbon (if there was any). There isn't really any ridge to speak of. There is a little discoloration where the ridge would be, but nothing that I can feel or pick at with a fingernail.

Do you think if I do have a few stuck rings (low compression) it would cause the stumbling, bogging out and exhaust noise through the carb?

Thanks again

Dave

[lugnut123]

If it is poping threw the carb you have a valve that is not closing all the way. Probly the valve spring is weak or the valve itself the stem is gunked up . Pull the side pan off the moter and take a look. I hope somthing helps.

[dmulhall]

So when I did the engine swap I changed the crank pulleys (thin belt to thick) and when I removed the head today to check the valve's (again) I noticed that when it is at TDC on the pulley, the piston isn't right to the top yet

Then when #1 is at TDC the mark is about 2 or 3 inches out...??

Is that because the crank pulley is from a different (218) crank?

So then when it is at TDC this throws my timing way off...

No sticking valves that I can see..??

I'm going to try and figure out how to post pics from my blackberry

[John-T-53]

Either the pulley mark or the tab on the chain cover might be different. You might have a mismatched set, if that's possible.

Make a mark on your pulley when #1 is at TDC and use that to time the engine, then figure out the rest from there.

[dmulhall]

In the few minutes I had to "play" last night I marked the pulley

With a felt marker, then tried to line up #1 wire on the cap...the points are closed however and aways from being open

So I'm going to have to play some more...maybe tomorrow when I'm home again

Thanks

[Rusty O'Toole]

You can get a timing tape to put on your balancer. Don't know if they make one specifically for your engine but if the balancer is the same diameter it will work.

http://www.jegs.com/p/JEGS/JEGS-Timing-Tape/1336612/10002/-1

[JBNeal]

when I first started working on my '48 back in jr. high, somehow I knocked the timing pointer off of the cover and reattached it with some JB Weld. This was all with the engine in the truck and the fenders attached, so I had to stand on my head to line it back up with the shadow lines of the cover paint. Eventually I read somewhere that the oil pump has to be carefully installed so that the distributor rotor would be in the correct position for ignition timing. So there might be a cumulative effect with engine performance if the crank, cam, and distributor aren't synchronized properly.

[John-T-53]

Oil pump installation is critical. I screwed this up a couple years back and was off a tooth on first start up. The engine ran, but timing was way off and had no top end. After fixing this simple thing, it ran like butter!

when I first started working on my '48 back in jr. high, somehow I knocked the timing pointer off of the cover and reattached it with some JB Weld. This was all with the engine in the truck and the fenders attached, so I had to stand on my head to line it back up with the shadow lines of the cover paint. Eventually I read somewhere that the oil pump has to be carefully installed so that the distributor rotor would be in the correct position for ignition timing. So there might be a cumulative effect with engine performance if the crank, cam, and distributor aren't synchronized properly.