'26 engine knock

[TonyAus]

Ray, I think the five thou variation quoted by the manual is correct, given that it specifies this figure for a worn crankshaft and two thou for a new one.  Allowance for heat expansion and an oil film would preclude thinking in tenths of a thou as would usual manufacturing tolerances. Have you looked at the crankshaft end float - as specified in the manual?  Not that any of this is of use - I give up!!

 

Tony 

[R.White]

 

I must admit to not paying any attention to crankshaft end float as nothing had been done to change it.  I just bolted up the gears and bearings as a reverse of the way they came off and fitted the flywheel with the six bolts before attaching the pan.

 

Note:  I tried fitting the pan first because I thought it would be convenient to do that while inverted  on the engine stand but I discovered that there is not quite enough room to fit the flywheel bolts with the pan attached  (and it would not be wise to fit them the other way round) so the pan had to come off again and the engine removed from the stand to fit the flywheel then fit the pan with the engine suspended on the hoist.  There may be better ways of doing this.?

 

Ray.

 

By the way.  I just had a thought. What if there is water seeping past the head gasket?  That would cause a knock and is something I had not thought of. I can check it out.  Having had the head and block skimmed it should be o.k. but who knows?

 

 

Edited August 21, 2017 by R.White (see edit history)

[R.White]

Going back to Spinneyhill's " long shot" 1100.  The gearbox is in the engine sump and  what often happens is the idler gear rattles.  There are too many potential knocking possibilities with these engines to list but one common failing is the exhaust manifold cracks. (hidden away at the back of the engine) and that sounds like a knock sometimes.  Also, the overhead valve rocker shaft can suffer from oil starvatiion and that can cause all sorts of problems.  I once had a 1956  "baby" Austin A30 with an early 803 cc version of this engine which knocked out a big end.  Rather than have new babbitt metal poured it was cheaper to fit a highly tuned 1098  engine from a crashed rally car.  The car was transformed but looked just the same.

 

Ray.

[Spinneyhill]

Arrr, that sounds like. Idler gear. I was forgetting about the in-sump gearbox. So that is not your problem then! There was a "hot" A30 driven by one of the boys at my high school. Well it sounded hot, but I think it was just a hot-dog muffler mounted at the back.

[R.White]

6 hours ago, Spinneyhill said:

Arrr, that sounds like. Idler gear. I was forgetting about the in-sump gearbox. So that is not your problem then! There was a "hot" A30 driven by one of the boys at my high school. Well it sounded hot, but I think it was just a hot-dog muffler mounted at the back.

 

Getting way off topic but those little cars can be great fun to drive.  You may already know but they are still being raced in historic events.  Mine was a real wolf in sheep's clothing and I used to have great fun seeing off MGbs etc.  I would get through rear tyres so often that it was cheaper to pick up wheels from the scrappie  with decent tyres on.  I would then weigh in the wheels which paid for the rubber!

 

Happy days.

Ray

[herm111]

On ‎8‎/‎17‎/‎2017 at 5:37 PM, R.White said:

 

As it happens, I have been doing just that this afternoon. I did it before and found no wear which to be fair is what the engineer said.  No matter what points across the journal I choose, I can find no difference.  It measures 1.670" in all directions.   Just to be sure I have lapped in the shells with a compound specially developed for white metal bearings called "time saver".  This particular "yellow" compound does not contain any emery, ground glass, silicon carbide, aluminium oxide and will not charge into any metal surface or continue to cut so I feel happy that a near perfect bearing surface can safely result.  I shall make sure there is no movement of the shells in the rod this time.

 

The latest results are promising with what appears to be just 0.0005" taper.  I hope to finish with an overall clearance of 0.001" after taking measurements from top as well as bottom of the stroke.

 

We are, it seems, back where we started if the knock is not the big end.  I keep wondering if it is somehow a serious pre ignition knock.  Where I am flummoxed is that it is only on the one cylinder.  Perhaps there is a fault with the distributor causing No.1 to spark early?  I keep thinking about the non standard camshaft design that may have been fitted.  This throws up issues with both valve  timing and ignition timing.  Firstly, is the ignition too far advanced?  Could it be a completely different setup if the camshaft is non standard?  I could experiment to see if the distributor is a tooth out for example.

 

 What if the valve timing is wrong for this camshaft?  There were no timing marks on the crankshaft and camshaft gears to assist so I had to set it up using the method described in the book of information.  There are two methods depending on which camshaft is used.  The after market ones fitted to a number of cars in Australia to prevent premature exhaust valve failure  is a third and I have no information on that.

 

Hi Tony.  I went to considerable lengths to ensure that this rod is as straight as it can be. Interestingly,  all the other rods have masses of lateral movement and they don't make a whisper.  I am still not 100% sure where the knock is coming from.  As I said once before it seems to be coming from the head but as you know sound travels.

 

To say I am out of my depth is an understatement.  Several old car guys listened to the engine at a show I went to last year and they were also puzzled.

 

My Dad would have been able to sort it but I expect he is busy working on The Lord's car these days.

 

Ray.

When you align Rods, all 3 Positions have to be checked. Any of the 3 can cause a knock.

 

Bearing clearance should be a thousandths per inch of crank, Minimum and plus a half Maximum.

 

Herm.

[herm111]

On ‎8‎/‎13‎/‎2017 at 2:30 PM, R.White said:

The gudgeon pins that came with the new pistons are a perfect fit to the little end of the rods.  The bushing in the rod shows no signs of wear.   The set up is of the modern fully floating type with cir clip retaining clips.  The engineer was also happy with the fit. 

 

On ‎8‎/‎17‎/‎2017 at 11:35 AM, cahartley said:

Ray, did you ever mic the rod journal yourself?

Have you tried shimming the rod bearing the old school way?

Set the bearing tight enough that you can tap it back and forth with a light hammer.

Unless the rod journals are in bad shape it seems logical the mains wouldn't be either.

After all the work you have gone through and shorting #1 stops the ticking I'm as stumped as you are....... 

What is the clearance in the Bushing in the rod?

 

Herm.

[herm111]

On ‎8‎/‎13‎/‎2017 at 2:44 PM, Bloo said:

Assuming there is no problem with the small end (I was also wondering about that), you could try tightening the big end a little.

 

I have used plastigage on almost everything I have ever worked on, but was reading the other day on the VCCA, and discovered that the 4 cylinder Chevy enthusiasts do not trust plastigage, and speak of tapping the big end sideways with a tiny hammer to check for clearance. They also turn the engine by hand to make sure the bearing being adjusted is not dragging to much.  Apparently .0015 on those engines is on the high end of acceptable, and might make noise.

 

Those Chevrolet engines are splash oilers. Is your Dodge splash oiled? Here are a couple of threads:

 

http://vcca.org/forum/ubbthreads.php/topics/306467/Re:_Adjusting_tightness_of_'30

http://vcca.org/forum/ubbthreads.php/topics/243425/Connector_rod_clearance

 

There are others over there as well. Another thing I have seen recommended is to turn the crank 90 degrees and recheck in case the crankshaft is a little less than round. This is to make sure it doesn't tighten up. Good luck.

Anybody that tells you Plastigage don't work, they don't know how to use it. It can't be used dry, it will give you a false reading.

 

Herm.

[herm111]

On ‎8‎/‎13‎/‎2017 at 4:10 PM, R.White said:

 

I only wondered if the distributor could be a whole tooth out?  Yeah, I'm clutching at straws!

 

I checked the con rods for straightness when I had them out.  The engineer says he also checked.   They all look central to the  wrist pins when I look up at them! 

 

I was surprised to read that the Chevy 4 could knock at 0.0015" big end clearance.  

 

I have a theory that No.1 cylinder suffered a serious trauma sometime in the past and this noise may be related to that time, I wonder if the crank pin has been knocked about enough to cause the knock. During the rebore they found a small piece of piston ring embedded in the cylinder wall!  I couldn't feel anything but an indentation - which I believed the rings were just passing over.  It is of little consolation to be proved right.

 

It looks like I made a mistake by adjusting the bearing with the piston at the bottom rather than the top. I will have another go at it.

Checking at the bottom of piston stroke is the excepted way.

 

Herm. 

On ‎8‎/‎13‎/‎2017 at 4:10 PM, R.White said:

 

 

 

[herm111]

On ‎8‎/‎13‎/‎2017 at 4:23 PM, Bloo said:

I sort of doubt it has anything to do with the timing. Nearly all of my experience is with force fed engines, but as I understand it splash oilers need to run tighter than force fed engines. I think that rod tap-sideways test had more to do with checking the bearing clearance than the side clearance. I think their goal (on those Chevrolets anyway) is to run them as tight as they possibly can without binding, and they don't really quite believe what the plastigage is telling them. Any out of round would prevent getting the bearings very tight, as they would bind as you turned them. I don't know how much is too much.

 

If it were mine, I think I would shim that bearing as tight as I could get it without binding, and see if it still makes noise. Even if it still does, that is a huge clue.

 

It is so hard to tell about engine noises. All engines should behave about the same under the typical tests (cracking the throttle to listen for a rattle, disconnecting a spark plug and so on). In my experience they don't always. Usually, however, a small end (gudgeon pin) noise is a double knock. Usually it will change but not go away when you disconnect a spark plug. A rod knock should get quieter or go away. It is often hard to tell the difference between a small rod knock and some relatively harmless piston slap. What kind of pistons did you use and how much clearance?

 

I would also wonder about the closest main bearing. How tight is it?

 

I don't see how it could be anything to do with the camshaft. A noise there shouldn't change no matter what you do.

 

A cam gear can make a knock if it has a loose gear, or excessive end play.

 

Herm.

[herm111]

On ‎8‎/‎13‎/‎2017 at 4:40 PM, cahartley said:

Having, within the last few days, got my 1932 Chevrolet Confederate engine running I can tell you da bois at the Vintage Chevrolet Collectors Association warn that .002" clearance on a  194 six banger which has 2" rod journals WILL knock!

My Dodge had more than that before I checked the shims and it didn't knock.

Both have nearly identical rod oiling systems.

Go figure........ 

The minimum clearance is the .002-00 thousandths on a 2" crank, or not over .000-50 more.

 

I will guess at 99% that the knocks were caused by the Rods being out of Alignment.

 

Twist, Bend, and Offset.

 

Herm.

[herm111]

On ‎8‎/‎13‎/‎2017 at 4:55 PM, R.White said:

Go figure indeed.  I was always under the impression that engines that relied on splash feed should have sufficient clearance for the oil to just flow in and out under gravity and that the introduction of pressure fed systems meant that closer tolerances could be achieved safely.  There is a certain logic  to it and that the reason we can go for closer tolerances now is that if synthetic oil is used it is not just better but thinner than the old straight oils.  I am always prepared to accept that I may have got it wrong but none of the other big end bearings are tighter than 0.002"... and they don't knock.  Why just this one?

 

Ray.

 

Bloo.  The main bearings have been a nightmare.  In a previous post I related how I couldn't get them closer than 0.003" without binding.  As I say, I think this crankshaft has suffered trauma at some time. 

 

That it runs at all is probably something of a miracle.

 

Ray.

Did you have the crank checked for being sprung?

 

Herm.

[herm111]

On ‎8‎/‎14‎/‎2017 at 4:40 PM, R.White said:

Hi Bob.  On my engine the shells are trapped by the shims so cannot move around.  They are dead flush with the bearing cap and are quite a tight fit so need to be prised out.  There are also notches on the back which locate them.  As I see it, the shells cannot move in the rod when the bearings are bolted up.  I will look at it again, though, because thinking about it that might just be what is causing the knock if all the other bearings are quiet at 0.002".

 

Ray.

Has your rods been changed over to inserts, other wise they were poured solid.

 

Herm.

[herm111]

On ‎8‎/‎15‎/‎2017 at 7:26 PM, MikeC5 said:

Hi Ray, I do know that for Model T engines, when new babbit is poured the bearings are set up very tight.  A friend of mine had his engine rebuilt by a long-time Model T specialist who was close enough that we could deliver the engine to him.  He showed us a completed short block he had on stand and let us try to turn it over with a long breaker bar.  It took considerable force to get it moving.  Instructions for starting it the first time required towing the car since it was too tight to crank by hand (our only other choice).  After running for several minutes it did loosen up enough to hand crank.  I think I would try tightening up the clearance on the offending rod big and and see if it changes things.  If it helps I might be tempted to tighten up the others too.  

Setting up Babbitt bearings that you have to use a long bar on is not acceptable to any engine, if your looking for any longevity out of it

 

When a crank, or rods are set that way, and the engine has to be pulled to turn it, the first thing that happens, is the bearing surfaces will soften from the friction, not a good thing.

 

At this time there is NO room for oil, so if the bearing doesn't burn out, it often scars, and if there are any oil grooves, or oil wells, the smear will deposit in the grooves, and turns hard again. Then this smear of Babbitt starts breaking off and runs through the bearing as bad as sand.

 

Why set a bearing so tight it has to struggle, to get its self free to turn.

 

A Model T we set at from .001-25 to .001-75, and you don't need any bar, and the crank you can turn with one hand on the flywheel flange after broke loose with the other hand.

 

Sadly, there is way more misinformation on Babbitting  out there then truth.

 

Thanks,

 

Herm.

 

.

[cahartley]

2 hours ago, herm111 said:

The minimum clearance is the .002-00 thousandths on a 2" crank, or not over .000-50 more.

 

I will guess at 99% that the knocks were caused by the Rods being out of Alignment.

 

Twist, Bend, and Offset.

 

Herm.

 

From the 1932 Chevrolet Book of Specifications.

[herm111]

On ‎8‎/‎15‎/‎2017 at 9:10 PM, Bloo said:

I remember reading on some period publication, probably Dyke's Encyclopedia or maybe Audel's, about a machine used to "burn in" newly cast babbit bearings. The machine would spin the fresh engine with an electric motor until it spun freely. Sounds risky. I would want it to turn freely, if only barely.

 

 

 

 

Your right, they burnt bearings out, instead of in.

[herm111]

59 minutes ago, cahartley said:

 

From the 1932 Chevrolet Book of Specifications.

This is just what I was talking about. Most listings, in bearing books will list a bearing from .000-50  on the low side to .003, or .003-50 on the high side. That is why some people get into trouble setting bearings. Now nobody in the right mind would set a bearing to .000-50, on a 2" crank, but they do, and they say, " But It Is In The Book" you would burn the bearing out. .001-50 is better, but you will still smear, or soften the Babbitt surface. Why have  the bearing push its self free. T clearance should be .002-00 to .002-50.

 

The thing is, when the bearing is broke in, it will be bigger then that.

 

Most people don't think, that when a .002-00 inch crank gets hot, they swell about .002-00, and more. So what happens, No room for oil, so it either pushes out, or burns out.

 

Try it your self. Mic a crank that is in shade, then lay it out side in the sun on a hot day. Then Mic it again, see the difference.

 

Thanks Herm.

 

KohnkeRebabbittingService.com

 

 

[cahartley]

Yes Herm.......I'm sure the Chevrolet engineers didn't know what they were talking about.

 

[JFranklin]

The Chevrolet engineers were working on new engines, not rebuilding worn, bent & misaligned blocks. Maybe that might explain their ideas and our different takes on the information. I would send my engine to Herm any day.

Edited September 13, 2017 by JFranklin (see edit history)

[herm111]

19 hours ago, cahartley said:

Yes Herm.......I'm sure the Chevrolet engineers didn't know what they were talking about.

 

 

7 hours ago, JFranklin said:

The Chevrolet engineers were working on new engines, not rebuilding worn, bent & misaligned blocks. Maybe that might explain their ideas and our different takes on the information. I would send my engine to Herm any day.

Mr. Cahartley, 000-50 to .001-50 is a long way on a 2" crank, from where it is going to end up to at least .003-00 thousandths clearance.in 1932, as most of the car companies done was to run the engine in, either by its self, or the whole car to loosen it up under an outside source of power.

So from .000-50 thousandths to .003-00 is .002-50 thousandths, so where is .002-50 thousandths of bearing surface going that  could have been used. It will go through Mains, Rods, cam bearings, cylinders, ect.

 

In my business, we hear all the time, can't turn the engine over, had to pull it and the rear wheels would slide. About 4 years ago a man with a Model T trying to start a new rebuild, blew two new rear  tires out.  

 

That was 1932 technology, it is not done that way today. If an engine builder were to set that clearance on a Babbitt engine today, and send it out, he would be doing it over.

 

It is the same with new pistons. The paper work that comes with the pistons will say, .002-00 to .002-50 on about a 4" piston. At that size it would score right away. So we give a 4" pistion .004-00 clearance, that is .001-00 per inch, and that works.

 

Herm.  KohnkeRebabbittingService.com

Edited September 14, 2017 by herm111 (see edit history)

[dbtravis]

After reading through these posts, it seems like you've had quite a bit of machine work and testing done to ensure the work was correct.  At the risk of being laughed at, I'll offer you a completely different item to troubleshoot with a very easy solution...  Based on your description I experienced the EXACT same thing on my 1926 DB Coupe a few years back.  It ran fine, but I kept hearing an unsettling knock/tap that would disappear whenever I unhooked the sparkplug wire from the offending cylinder.  I replaced the wrist pin, tightened the rod bearing, etc, all to no avail.  I had all but resigned myself to simply drive it with the knock until something broke and then I would finally know what it was, I didn't experience any loss of power or overheating or anything that really impacted performance - it just sounded like it was beating itself to death.  Finally it was suggested to me that I start it up from cold and take some WD-40 and as the motor was running, spray a liberal amount around the exhaust manifold gasket on the offending cylinder as soon as it started up (to avoid excessive heat and potential for it to flare up).  As soon as I did this, there was a small point where the WD-40 just blew back like crazy... indicating a small leak in the exhaust manifold ring gasket on this cylinder.  It turns out that what my ears (and others) had heard as a tap or knock was simply a really strange case of exhaust blow-by through a bad gasket.  It really sounded like a tap or knock I guess because the leaking section was so small that when the pressure built as that cylinder fired it would really shoot it out of the small breach with some force and really make quite a tapping sound.  I know we don't usually get this lucky, and after all you've been through even on the chance that this is your issue it would be a stretch to call it luck, but after everything you've been through it's definitely worth a try.  My engine was apart for the better part of 6 months trying to figured out what was loose or bent, only to realize it was something as easy as a leaking exhaust manifold ring!  I felt embarrassed, but hey - if my experience can help you or someone else it will help me feel like maybe my ordeal was worth it... maybe! 

[JFranklin]

Similar situation with a suspected bearing knock, but I first pulled the fan belt so I could get my ear close without a haircut. Well, the knock went By-by. It was being caused by the fan belt and I couldn't see any reason for it. Replaced the belt and all is well.

[R.White]

On 13/09/2017 at 12:44 AM, herm111 said:

Has your rods been changed over to inserts, other wise they were poured solid.

 

Herm.

With respect I suspect you are unfamiliar with these four cylinder Dodge Brothers engines.  One of their more advanced features was the use of shell inserts.

I can assure you that I do not have bent, twisted or misaligned rods.  

 

I was not born yesterday.

 

Ray.

[R.White]

Thanks for your suggestion, dbtravis.  Fortunately, the knock has been eliminated.  There was too much lateral play on the con rod big. end journal causing it to slap.  There was also too much crankshaft end float.  All these problems could have been eliminated had I bitten the bullet and had the crank reground with new Babbitt poured; the clearances being governed by the amount of white metal at the edges of the bearing shells.

 

If only the problem had been the exhaust manifold.  This was one of the first problems that I dealt with when I got the car.  The problem with these manifolds is that the edges of the ports wear to wafer thin and fail to seal against the copper compression seals.  It is  sometimes possible to machine the surfaces back to good metal but in my case the manifold had also been broken and brazed before and looked quite poor.  I was incredibly fortunate that Ron Lawson in Oz was able to source a better manifold (among other parts).  Even with the replacement manifold I still had leaking past the copper gasket so I replaced them with compressible motorcycle gaskets which give a more positive seal.

 

One of the minor problems that has arisen since refitting the exhaust has been the manifold attachment.  There are just three studs holding the manifold to the block.  Unfortunately, the threads in the centre hole have deteriorated and are at the point of stripping so I will have to helicoil the hole to restore  maximum grab.

[dbtravis]

Great to hear you found and eliminated the knock!!  What an ordeal, but I'm sure your experience will help several others down the road if they encounter the same issue!  If by chance you happen to have a part number for the motorcycle gasket you used in place of the copper compression seal I'd be interested to have that data available for future reference incase I ever need to go that route.  Thanks for sharing about your experience online as it's always wonderful to read and learn from others - we're all better DB mechanics because of it! - Travis

[TonyAus]

10 hours ago, R.White said:

Thanks for your suggestion, dbtravis.  Fortunately, the knock has been eliminated.  There was too much lateral play on the con rod big. end journal causing it to slap.  There was also too much crankshaft end float.  All these problems could have been eliminated had I bitten the bullet and had the crank reground with new Babbitt poured; the clearances being governed by the amount of white metal at the edges of the bearing shells.

 

If only the problem had been the exhaust manifold.  This was one of the first problems that I dealt with when I got the car.  The problem with these manifolds is that the edges of the ports wear to wafer thin and fail to seal against the copper compression seals.  It is  sometimes possible to machine the surfaces back to good metal but in my case the manifold had also been broken and brazed before and looked quite poor.  I was incredibly fortunate that Ron Lawson in Oz was able to source a better manifold (among other parts).  Even with the replacement manifold I still had leaking past the copper gasket so I replaced them with compressible motorcycle gaskets which give a more positive seal.

 

One of the minor problems that has arisen since refitting the exhaust has been the manifold attachment.  There are just three studs holding the manifold to the block.  Unfortunately, the threads in the centre hole have deteriorated and are at the point of stripping so I will have to helicoil the hole to restore  maximum grab.

Hi Ray

Sorry to give you bad news but if those compressible gaskets are the steel variety you will still have problems.  I burned through two sets before finding a solution - a set of large  thick copper washers purchased from China on Ebay for about $A5 each.  I can't remember the exact dimensions (metric) but you can work that out from your old ones.  I think that the inner dimension was about 1-2 mm smaller than the port but that's not a problem.  I also applied Maniseal to both sides of the rings.  You should be able to source an equivalent exhaust sealant (which expands on heating) from an automotive parts store.

 

Tony