Flywheel hitting Block Plate? UPDATE: 3/29/14 with Dyno Sheet!

[4EYED85]

I don't see how the balancer would pull the crank forward unless it was hitting the front cover and you would know that for sure. How much endplay is on your input shaft? Well, just thinking out loud, if it worked on the 302, it should work on the 347. Did you guys line the thrust bearing in the block? Have you checked the line bore on the block?
Clevite makes a bearing that is .010 over, I think. Put it on a piece of glass and sand .002 off of it and let the thrust clearance go back to .002 and wear to .006-.008. Yank that crank out and polish the thrust face as well.

[Hissing Cobra]

[QUOTE=4EYED85;1602622]I don't see how the balancer would pull the crank forward unless it was hitting the front cover and you would know that for sure. [/QUOTE)

I'm kind of in agreement with you on this front and my pulleys are all in alignment.

How much endplay is on your input shaft? Well, just thinking out loud, if it worked on the 302, it should work on the 347. Did you guys line the thrust bearing in the block? Have you checked the line bore on the block?

I'm not sure how much endplay is on the input shaft as we didn't check that. However, it's been behind the 302 for the past 3 years without any issues. I'm not sure what "lining the thrust bearing in the block" is but I'll ask my brother. As for the block, it was line bored.

Clevite makes a bearing that is .010 over, I think. Put it on a piece of glass and sand .002 off of it and let the thrust clearance go back to .002 and wear to .006-.008. Yank that crank out and polish the thrust face as well.

Good to know. I asked my brother about oversized thrust bearings and he's aware of them being available but he's not sure if that will fix what's going on.

On a side note, is it normal for the thrust clearance to grow and then stop after initial break in? In other words, could it have grown to .010 and won't grow any larger? Does a measurement on a cold engine (.005 on the floor before it was installed) vs. a hot measurment (.010 in the car after a 25 minute drive) differ due to the heat changes of cold vs. hot?

[4EYED85]

To align the bearing, torque the center cap to 10 ft. lbs. and the others to 35 ft. lbs, pry crank back and then forward and torque center cap to spec, then torque the remaining caps. This may not be exactly how some say to do it but it does work. My 351 was 105 ft. lbs., not sure on a 302. Is this Eagle or Scat crank? I would try the oversize bearing and polish the crank thrust face. Set it tight and keep the rpms LOW for a few hundred miles and let it wear in. Worth a shot at this point. Your so good at R&R should only take a few hours or so. Just poking at ya a little. Hope it works out.

[Hissing Cobra]

Thanks. Good advice. I'm not sure how my brother torques the caps down but he's been building engines on a daily basis for 27 years and in that time he's only seen this problem less than five times. This one is driving him nuts, just it's driving me nuts. I'll talk to him about the oversized thrust bearing. Thanks for your input.

[mustangxtreme]

Wow Pete, you just can't get a break on this engine. Hopefully you can figure out what is going on with it. Good luck.

[Zap's 85 GT]

Jeez Pete. I missed the post before my last reply that said you were having this issue again. I'd like to think I could offer some advice but with the myriad of things that it could be, who knows at this point.

Even when I built my 408 my thrust clearances were on the tight side of .003"-.004". Been like that for at least 6-7 years now and there have been no issues. With that, it sounds like your setup/build clearances were in line with the specs. It would stand to reason some external influence is causing your issue. But I will leave it up to you and your brother to deduce.

[Hissing Cobra]

Thanks Mike. It's frustrating for sure. Perseverance will pay off and we'll get to the bottom of it. My brother builds motors every damn day and never has this problem. In 27 years, I think he's only seen it two or three times and each time he was able to fix it. In the meantime, I'm off to try and learn more on the subject.

[grabbergreen84]

keep the rpms LOW for a few hundred miles and let it wear in.

No matter what else you do, this is great advice. It just takes a bunch of will power and discipline to follow it...

[Hissing Cobra]

It is but I don't think I'll be driving it anymore until I get some sound advice on what's going on. If I have to pull it back out, I will.

[86 50CPRI]

No one has mentioned clutch adjustment. Are you using the adjustable cable? how about a firewall adjuster? Not enough freeplay can contribute to a wiped out thrust bearing... just my 2 cents, sorry about your frustrating situation, and hopes it gets resolved quickly.

[Hissing Cobra]

Good thought Pete. We thought that the cable and fork may have been a contributing factor so I replaced both of those with brand new Ford Motorsport units. The clutch was adjusted and feels fine so I don't think it's that either.

[Ethyl Cat]

When you checked end play again, where was the indicator mounted, where were you prying and what were you prying with?

When I assemble an engine:

First thing I check thrust bearing clearance with a feeler gauges and the crank on the bench so if something is way off I can get good new parts before I get too far into the build.

Next I put the upper thrust bearing in the block with the two ends bearings that I used to check crank runout and check end play then.

Final endplay measurements are taken after the upper thrust has been installed .

If the first and the second end play measurements are different, then I know that the upper and lower thrusts are not aligned and need adjustment.

I would put more miles on the engine and see if endplay continues to grow. It can't really hurt anything more and you need something to work out your frustrations with. Go drive your hot rod!

The worst thing that could happen is your are right and it needs to come apart and be repaired.

Steve

[Ethyl Cat]

[QUOTE=Hissing Cobra;1602630]

I don't see how the balancer would pull the crank forward unless it was hitting the front cover and you would know that for sure. [/QUOTE)


On a side note, is it normal for the thrust clearance to grow and then stop after initial break in? In other words, could it have grown to .010 and won't grow any larger? Does a measurement on a cold engine (.005 on the floor before it was installed) vs. a hot measurment (.010 in the car after a 25 minute drive) differ due to the heat changes of cold vs. hot?

This is a good point, I have never checked one hot before. One would guess that the crank thrust surfaces would grow further apart when hot. Does the bearing expand at the same rate? I don't know.

It is not the same materials on the outside but it does have a steel backing you would think is similar.

Everyone go out and check you endplay cold, go for a drive and remeasure it again. Lets solve this mystery!

Steve

[Zap's 85 GT]

It would be curious to see the thrust bearing from before and now to see if there is force being exerted from the front or the rear of the rotating assembly.

[Ethyl Cat]

He could tell that from the old crank.

[306gt]

The old crankshaft was wiped out on the rear of the thrust facing the back of the engine. The front was perfect. The new crankshaft had .005 end play without the caps installed. Once the caps were all installed and torqued EXCEPT for the #3 cap the thrust clearance was still .005. Now I then whacked the crank backward with a dead blow hammer then whacked again forward to seat the bearings and square them up. I then. torqued the cap down to 10 ft lbs thrust clearance was still .005. I then loosened the #3 cap bolts and checked again still at .005. I then pried the crank forward with a prybar and torqued the bolts down to the final torque in 3 stages. End play was still at .005. Now we have main studs installed and while torquing the caps they don"t lean forward or backward. The block was also align honed with the studs.
I am 99.9% sure the problem is no longer in the bellhousing area. The transmission endplay was also checked when the trans was opened up. all is ok there. I am going to look at the pulley alignment on the front of the motor very carefully. If the overall length of the Romac balancer is shorter then either a stock balancer or the fluid dampner that Pete has then the crank pulley could possibly be closer to the front of the motor and alignment could be off. This would usually show up on the side of the belt and the belt could be pulling the crank forward enough for the belt to try to align itself on the grooves of the pulley's. But there is no evidence on the belt. But we will check that too. I am running out of idea's. It is pretty crazy.

[4EYED85]

He can just measure it cold if he measured it hot, have no idea if it would expand in that way. I wonder now where it was pride on to measure end play. We do know the previous build had too be pulled apart due to failure.

We posted at the same time.

Is the engine still in the car?

[gmatt]

"I then pried the crank forward with a prybar and torqued the bolts down to the final torque in 3 stages."
Could this have put a 'preload' on the thrust bearing or end up with all the clearance on one side of the bearing?

[Hissing Cobra]

The engine is still in the car. I'm pretty sure the prior bearing went bad due to the wrong depth on the Pilot Bearing hole which created a situation inside the bellhousing where the input shaft was pushing on the pilot bearing. That has been fixed so that is not a concern at this point.

[306gt]

There is no preload on the bearing. The crankshaft moved back and forth .005 after the thrust cap was torqued. just like it did when no caps were installed. The prybar was used too ensure that the thrust bearing stayed aligned while torqueing the bolts.

[Ethyl Cat]

There is no preload on the bearing. The crankshaft moved back and forth .005 after the thrust cap was torqued. just like it did when no caps were installed. The prybar was used too ensure that the thrust bearing stayed aligned while torqueing the bolts.

When you checked end play with the engine in the car, how did you do it?

Indicator on the balancer/balancer bolt, on the the flywheel?

[306gt]

When you checked end play with the engine in the car, how did you do it?

Indicator on the balancer/balancer bolt, on the the flywheel?

End play was checked on the balancer. Used rubber hammer and tapped crank pulley back towards rear of car to seat crank against thrust bearing. Pulley is bolted to the inner hub of balancer. Mounted indicator on a 1" thick piece of steel bolted to the waterpump studs and squared up indicator tip on the outer ring of the balancer and zero'ed indicator. Used prybar slipped in behind the inner hub of balancer and timing cover and pulled balancer forward with the prybar without touching the outer ring of balancer.

[Ethyl Cat]

End play was checked on the balancer. Used rubber hammer and tapped crank pulley back towards rear of car to seat crank against thrust bearing. Pulley is bolted to the inner hub of balancer. Mounted indicator on a 1" thick piece of steel bolted to the waterpump studs and squared up indicator tip on the outer ring of the balancer and zero'ed indicator. Used prybar slipped in behind the inner hub of balancer and timing cover and pulled balancer forward with the prybar without touching the outer ring of balancer.

It is surprising how easily things people think are stiff will flex. Do you think there maybe a possibility of you having measured some deflection of the assembly(from prying) by not measuring in the center of the crank?

[FM2NOTCH]

it's not rocket science to set/check crank end play, it was checked before during and after the build, either the crank itself is causing the wear or some external force like the clutch,input shaft, etc. I read one thread that said the crank may not be finished correctly on the thrust surface. crank to bearing shouldn't wear if it has oil on it, seems to me something is closing the tolerences and/or wiping the oil off it or not alowing oil between the bearing and crank

A second thought is drive it normal a while longer and recheck it, see if the clearance is growing

[Hissing Cobra]

it's not rocket science to set/check crank end play, it was checked before during and after the build, either the crank itself is causing the wear or some external force like the clutch,input shaft, etc. I read one thread that said the crank may not be finished correctly on the thrust surface. crank to bearing shouldn't wear if it has oil on it, seems to me something is closing the tolerences and/or wiping the oil off it or not alowing oil between the bearing and crank

A second thought is drive it normal a while longer and recheck it, see if the clearance is growing

I agree with you but sometimes things aren't so easy as one might assume. This is something that my brother's never really had an issue with during his 27 years of building engines. He's seen it less than a handful of times. Right now I feel as though I may not have damaged the crank due to the clearance being .010 and from what I'm seeing on multiple websites the "safe zone" on a small block ford is .003 - .012. Nothing is etched in stone though so maybe I did? I won't know unless I either pull the motor and look or continue to drive it and see if it gets worse. That's why I'm trying to "educate" myself now - before it costs me another $1,000.

I've also got this posted over at yellowbullet.com in the "Engine Building" section and I'm getting advice from a lot of the pro's in this area. From what I'm learning, this measurement should always be checked when the engine is cold. We have not done that yet so that will be done this coming weekend when my brother comes over. Some are saying that the thrust measurement will never change during break in while others say that it's common to see it change .001 or .002.

One thing we're definitely sure about is that the transmission is no longer an issue as far as we can see. Everything has been addressed inside the bellhousing.

More to come later.