Engine stops rotating = Puzzled??

[Kevin66]

Building a 455 cid FE stroker motor (4.13" X 4.25").
- New Eagle crank and 6.7" rods
- New DSS forged pistons
- New Hastings ductile moly file-fit rings
- New Federal Mogul HD rod & main bearings
- New Cloyes Race Billet timing chain & gears
- New Bullet HR cam (250°/258° @ .050", .562"/.597" lift, 112° LSA
- New Crower EnduraMax roller lifters, new Smith Bros pushrods, Comp roller rockers/shafts/stands w/ end supports
- New Melling HV oil pump & ARP driveshaft
- New Canton 7.5 quart oil pan, pickup & windage tray
- Blair Patrick CNC'd BBM heads
- New Blue Thunder MR 4-Bbl intake
- Cometic .051" MLS head gaskets (4.155" bore)

C6ME- block had been .020" O/S previously and wouldn't clean-up at .040" in a few cylinders, so a decision was made to sleeve all eight of them. To save original cylinder wall strength, the thin Melling .0625" sleeves were used, and honed to stock 4.13" bore size. Block was align honed and decked to true. Crank & rods were checked, and entire rotating assembly was balanced. Rings were file-fitted to .018". Pistons were miked and assigned to bores. They protrude about .010" above the block deck, hence the thicker than normal head gaskets.

On assembly, using Permatex assembly lube, the crank rotated freely, although it would not 'spin' after giving it a push. I blamed this on .0015"-.002" main clearance and the drag from the lube. Pistons and rods were installed without incident, and the assembly could be rotated smoothly, with some drag. Engine was rotated numerous times by hand, and although resistance was higher than expected, nothing really caught my attention.

When the cam was installed, two things drew my attention. The first was an audible 'clunk' sound, and the rotating assembly locked-up, although it would turn backwards easily enough. It appeared that, at least on some cylinders, the rods were hitting the cam lobes. The shortblock was disassembled, and the rods were machined for the necessary clearance. Everything went back in, and as expected, nothing now stopped complete rotation of the engine.

However, an error was quickly discovered when I set out to degree the camshaft. Despite the timing marks on the gears being aligned as they should be, opening and closing points were WAY off what they should have been. Sure that Bullet wouldn't have made such a dramatic error, I looked elsewhere and quickly found the problem. It seemed that the dowel pin hole on the Cloyes cam gear was 180° off! Instead of the dowel pin being at 12 o'clock, it was pointed down at 6 o'clock. More trouble than it was worth to return the defective one and hope the next one was right, I simply put a new timing mark directly across on the other side of the gear, and tried that. Sure enough, now the degree wheel indicated that the Bullet cam was dead on the money, installing at the 107° point they wanted.

The heads were installed, along with the intake. Then began the process of setting-up and adjusting the valve train. A pair of Mr. Lykins' laser-cut .050" shims had been found to center the roller rocker marks on the valve tips, so it just remained to set the valve lash. The spark plugs were out to allow engine rotation, and only the passenger side shaft assemblies were in place. With the rocker adjusting screws backed off as much as possible, I went through the process of setting the intake valves on cylinders #1 - #4, using the EO-IC procedure. With those done, I set out to do the exhaust lash adjustment...whereupon I ran into the problem!

As I was bringing #4 around to intake closing, the engine more or less locked up, and would no longer rotate. Attempts to reverse direction were met with the same condition. Since the engine had now been rotated dozens of times, what could be causing this? Resorting to trying a 2' breaker bar, with a little more grunt applied, I found that the dampener bolt...previously torqued to 100 lbs/ft...was tightening up more, rather than the engine rotating! I again tried to reverse rotation, but the engine wouldn't budge.

Trying to think through this, I couldn't come up with anything logical. There had been no 'clunk' as I got when the rod/cam lobe issue came up, and I had neither heard any scraping noise nor felt any 'gradual' increase in resistance, it had just stopped. I finally resigned myself that there was nothing else to be done except to dismantle the engine, checking carefully for something wrong. So off came the rocker arms and pushrods, looking first to make sure there was no coil bind or other issues with clearances there. Next came the intake and the heads. Not finding anything to indicate problems...no witness marks on pistons or valves, and nothing else that seemed abnormal, I prepared to remove the oil pan, oil pump and windage tray so I could look at the bottom end.

Before doing that, it occurred to me to take one more stab at engine rotation, with all these parts removed now. Once again, I could not turn the motor clockwise, but on trying it counter-clockwise, it resisted for a second, and then turned. I continued in that direction, rotating the crank 90° each time. I went through three complete rotations, stopping with #1 at TDC. Then I changed to clockwise rotation, and turned the engine through four complete rotations. It seemed like the problem had gone away!?

Sorry this has been long-winded, but I wanted to give everyone the facts as they happened, before asking:

- What the heck went on here?
- What was likely causing the problem?
- What would YOU do next, if it was your problem?

Hopefully, with all the decades of experience and expertise on this forum, someone has an idea and can give me a clue. Thanks for your time!

[mike7570]

Pull the pan, inspect the windage tray for interference. It might be bending back out of the way on reverse rotation. Are you using a crank scraper, they can be very close and if hit one way will catch going the other.
I can’t think of anything else except piston to valve clearance and you had the problem with the heads off so it needs to be inside the block. (Timing chain area clear, cam plug in correctly?)

[blykins]

My guess is that you have a piston/valve clearance issue somewhere.   Pushrod not seated in the lifter which is giving you more lift, valve hitting piston, retainer/seal clearance, etc. 

A couple of other notes:

1.  I would not run an FE main bearing clearance at .0015".
2.  The dowel hole being 180° off on the timing gear means nothing.  It doesn't matter if the cam gear dowel pin hole is at the top or the bottom. 

[jayb]

I have never heard of a 4.25" stroke crank causing the rod shoulders to hit the cam lobes.  I've only seen this with 4.375" strokes and larger.  That part seems very strange, unless you are using something other than the standard BBC rods.  2.200" rod journal?

If you happen to have flywheel bolts in the back of the crank, sometimes they can be turned in far enough to hit the main cap or block in the back.  That could cause the issues you are seeing.

If it is a piston to valve clearance issue, you may have bent a valve by forcing the engine over.  If you do find a piston to valve clearance issue, you should pull the heads and remove the valves to check them.  A valve head can bend, and then be pulled back into position by the valve spring pressure, which makes them appear to be OK when the head is assembled or when doing a compression check.  Then when the engine is running it will bend and straighten repeatedly, and eventually the valve head will pop off, ruining your day.

Good luck on the block with 8 sleeves, hopefully you won't see cracking between the cylinders at the deck.  FYI, a lot of 428 blocks will go to .060" over with no problems.  Even some 427 blocks will...

[fairlaniac]

I had the push rod sit on top of the lifter edge and "lock things up". A little more force and a loud crack it rotated. Later down the road I had a lifter stuck in the bore. The "crack" was a piece of the lifter edge. It broke, fell into the lifter seat and got worked into the oil hole.

I should not have put the extra force into the rotation as I should have been smart enough to know something wasn't right. I paid.

[My427stang]

Remove the rockers, pull the plugs and see if it turns.  Seems to be a valve issue, stacked spring, exhaust valve hitting a bore, etc

I forget how close the oil pump bolt is, but can look later, seems to me, too long could also hit a counterweight but doesn't make sense to the description

[Kevin66]

As always, thank you for some thoughtful replies. It isn't hard to overlook some detail that others might pick up on. I'm more than willing to consider others' input, if I'm convinced it's applicable, logical, and likely correct. If it doesn't seem to be, I'll reiterate the facts as I known them, and/or ask for further explanation.

Mike I don't believe the windage tray is the source of the problem, and the only thing like a crank scraper is the one bolted into the Canton pan, a couple inches below the rail. I had noted the rod bolt heads hitting on the windage tray louvers early on, during trial assembly. There was also a distinctive metallic sound when contact was made. I marked the points of contact, and there were nine of them. So my options seemed to be to do a good bit of grinding to get the necessary clearance, or find another way. This Canton windage tray 'bottom' is solid where it connects to the oil pan rail on the driver's side, but the passenger side would be free-floating were it not for two metal straps welding it to that pan rail flange. I considered lengthening those straps to push the tray bottom lower, which might provide the needed clearance. But I had also determined that the Canton oil pump pickup was a little on the short side, the bottom sitting about 1/2" off the bottom of the oil pan. That was without the two pan gaskets and windage tray in place, meaning that there'd be over 1/4" more gap with them installed, so the pickup would need to be lengthened. At that point, I tried installing two pan gaskets between the windage tray and the block, snugging things into place with a half-dozen bolts. I could rotate the crank fully without seeing anything hitting or any sounds of that, and it appeared that there was probably 1/16" or more clearance. I thought this was a reasonable solution, so I went with that on final assembly, after lengthening the pickup by about 1/2".

The rear cam plug and front thrust plate are installed correctly, with good clearance between the plate bolts and the inside of the cam gear. There was no interference between the timing chain and the block, nor between the fuel pump eccentric and the inside of the timing cover.

Brent, as I mentioned, I only had the passenger side rockers and pushrods installed when the lockup or binding occured, with nothing on the driver's side head. The rocker adjusters were backed off fully until lash was set on each valve, and only the four intake valves on that head had been done. Pushrods seating correctly in the lifters was confirmed by both the tactile feel of the 'suction' created by the assembly lube on the pushrod balls, and by a visual inspection through the intake holes with a flashlight.

There was 1/4" or more clearance between the pushrod and the rocker arm with the lifter on the cam heel, so any valves that were open but not adjusted yet had that amount subtracted from the lift. When the lockup occured, I checked for pushrod binding in the intake manifold holes, and then looked at the valve springs. There was lots of clearance between the spring coils, even on the #4 intake valve which was partlly open. There also appeared to be good room between the bottom of the retainers and the valve seals. When the heads were removed, there was no indication on either the flat piston tops nor the valves themselves suggesting that any of them had ever made contact.

I hear your good advice about the tight main bearing clearance, and that's something I'd wrestled with myself. In the end, I didn't heed the old adage about "Why is it we never have enough time to do something right, but always find time to do it over!". Wanting to get this build finished and on the road before winter starts to set in, I convinced myself that somehow things would 'adjust' themselves during a careful break-in. Obviously now I'll be pulling the shortblock apart and taking the crank in for polishing to nearly about double that clearance spec!

Jay the rods in use here are the Eagle SIR-6700-B ones. They likely are 'fatter' where the cap screws thread into them, which accounted for the interference with the cam lobes.
There were no flywheel bolts installed in the crank flange when this happened. I experienced 'cutting a groove' in the back of a 427 block years ago, whenever the clutch was depressed, and the bolts were pressed in as much as crank endplay would allow. Not going to repeat that (!), so I definitely check bolt length too.
As for the sleeving, yes I've heard of that problem. My own experience, going back to two 428 blocks used for NHRA Stock Eliminator decades ago, was to have no problems with the decks. I realize there's going to be a considerable difference between a dedicated race-only engine and a street engine, in not only total miles driven but also in heat cycles undergone along the way. I'll hope it doesn't rear its head, but I'll also be watching for evidence of it.

There were no spark plugs in the engine at the time. And only the passenger bank cylinders had pushrods and rocker arms installed in the beginning, and those had been removed with the problem continuing. I think this pretty much rules out any of the valvetrain being the culprit.

Thanks again guys. I'm still puzzled by this, but you gave me some things to think about.

[blykins]

What are the valve spring loads and what are you using to turn the engine over with?

I've had a lot of guys who hadn't experienced it before panic when they couldn't turn an engine over with >600 lbs of spring load and a 1/2" drive ratchet.

[Kevin66]

Brent I can't say for sure. I suspect these beehive springs Blair installed wouldn't be stiffer than something like the Comp 26120...155# closed, 377# open...and likely less?
But I'd also say again that half of the valves weren't being opened at all (driver's side head), and only the four intake valves on the passenger side were adjusted right, so as to get maximum lift.
And yes, I was using a 2' breaker bar with a 1/2" drive socket on the ARP dampener bolt.

[mike7570]

On mock up my crank scraper needed some grinding for clearance and I worked on it to get a nice fit. On final assembly with stacking the scraper, windage tray, oil pan and 3 gaskets I found the rods hitting the crank scrapper again. I think I tried to get a little too close and the stacking and alignment has more wiggle room than I thought so I had to do it over again.

[brra1961]

In the original post , he states that he removed the heads and the crank would still not turn. I think that eliminates any valve problems.  I believe either crank or cam is making contact with rods or block when moving front or back with thrust clearance , I would rotate crank while prying crank or cam back and forth against thrust  and see if locking and unlocking occurs. since rod contact was already a previous problem , I would suspect that.

[My427stang]

On mock up my crank scraper needed some grinding for clearance and I worked on it to get a nice fit. On final assembly with stacking the scrapper, windage tray, oil pan and 3 gaskets I found the rods hitting the crank scrapper again. I think I tried to get a little too close and the stacking and alignment has more wiggle room than I thought so I had to do it over again.

I just had a 4.25 stroke SCAT forged crank hit a new Canton windage tray on a customer's 482, seems they have changed.  I had an older version on the shelf, louvers and shape was completely different, plenty of room with the early version.  You may be onto something

[mike7570]

In the original post , he states that he removed the heads and the crank would still not turn. I think that eliminates any valve problems.  I believe either crank or cam is making contact with rods or block when moving front or back with thrust clearance , I would rotate crank while prying crank or cam back and forth against thrust  and see if locking and unlocking occurs. since rod contact was already a previous problem , I would suspect that.

Great idea, I should have done that. It could be why I had to open the clearances a second time.

[Kevin66]

I started dismantling the shortblock later yesterday. Once I got the oil pan, pump and pickup, and windage tray off, I looked at everything. I could see nothing, and there was still considerable effort required to turn the crank. I began removing the rods/pistons, starting with #2 & #6 since they were right there and ready. As I turned the crank to bring #3 & #7 up it took the same effort as before. All the pistons slid out easily with just a moderate push. I could see only those minor marks that you always seem to get on the bearings.

Then I brought #4 & #8 up to loosen the rod bolts, and noticed something. The two rod big ends were touching each other, and there appeared to be virtually no gap against the #4 crank cheek, and only a small one against the #8?? Out came the feeler gauges, and as I'd remembered, there was .018" side clearance between #1 & #5 rods, but I could not get even a .006" one between the #4 & #8 rods. I could get it to slide down the cheek side of #8, but only a bit before it stopped, like it was hitting against the bearing shell or something. So really wanting to have a look at what was going on there, I removed the cap from #4. As I went to rotate the crank to push the piston up to the deck, I noticed an immediate, significant reduction in the effort required now. Obviously this was where the problem originated!

Again the piston came out easily, but when I looked at the bearing half still in the rod, I could see damage. The same thing showed on the lower half of the bearing...significant burnishing near the edge of the bearing nearest the crank cheek, but also at the parting line? When I removed the #8 piston, I saw much the same things. The only good thing was that I could now rotate the crank, with the #1 & #5 pistons still in their cylinders, by just turning the dampener with my hand...no 2' breaker bar required.

So I'm thinking that now I'll need to look at the width of that crank journal, and the width of those two rods. But also, the diameter of the journal, and whether or not it's round like it should be. But I'd welcome other suggestions about what to check too.

[Kevin66]

Sorry, I meant to include this one too.