1929 Chevrloet 194 question

[theterrym]

Good day all. I finally got to the engine on my 29 Chev coupe. Once I got all of the years of oil and grease off I discovered it is the original to the car.  I only started the car once when I first purchased the car a few months ago and the began disassembly. The motor didn't smoke, but had a bottom end knock. I know a bunch of good mechanics, but they are more specialized in 350 and 454 performance engines. I don't think their advice applies to my project. The motor has been apart before and is bored .60 over. Pistons and timing gears look to be almost brand new.

I took one piston out and measured the crank for out of round and it was a difference of.002. When I pull on the connecting rods one of them I can feel has a bit of movement in it and would guess this is where my thump is coming from. They all have some side play. The worst has .15 side movement. Of course the advice I got was not to worry about that, but advice from those who don't know what they are talking about is just an opinion.  Im the same as the guys who are giving me advice. I have no experience with engines this old so im looking for input from those who know what they are talking about. Luckily for me there is a guy not to far from where i live that does re babbitting.  Anyone with some advise would be most helpful. Thanks in advance.   

[cahartley]

The 1934 repair manual at the linked page states .004-.011"  >>> http://chevy.oldcarmanualproject.com/shop/1934/34crm006.htm

Pretty much everything there will be pertinent to yours.

Poke around the site........there is loads of cool stuff there....... 

[herm111]

4 hours ago, theterrym said:

Good day all. I finally got to the engine on my 29 Chev coupe. Once I got all of the years of oil and grease off I discovered it is the original to the car.  I only started the car once when I first purchased the car a few months ago and the began disassembly. The motor didn't smoke, but had a bottom end knock. I know a bunch of good mechanics, but they are more specialized in 350 and 454 performance engines. I don't think their advice applies to my project. The motor has been apart before and is bored .60 over. Pistons and timing gears look to be almost brand new.

I took one piston out and measured the crank for out of round and it was a difference of.002. When I pull on the connecting rods one of them I can feel has a bit of movement in it and would guess this is where my thump is coming from. They all have some side play. The worst has .15 side movement. Of course the advice I got was not to worry about that, but advice from those who don't know what they are talking about is just an opinion.  Im the same as the guys who are giving me advice. I have no experience with engines this old so im looking for input from those who know what they are talking about. Luckily for me there is a guy not to far from where i live that does re babbitting.  Anyone with some advise would be most helpful. Thanks in advance.   

Your Engine is the same from 1929, like you have, to 1931. The mains are bronze backed, and Babbitt lined. and use .032-00 thousandths shims. It is a stepped crank, all 3 journals, are a different O.D.

 

The Rods have .006-00 thousandths brass shims, and a X groove oil groove. Standard bore is .002-00, or a little more, for the correct clearance. The width of the rod I don't know as I need your forging number on the rod? It is either 1.625, or 1.625 - .010.

 

Any thing else, let me know.

 

Herm. 

[wayne sheldon]

A quick warning about piston fit. These engines are known as the "cast iron wonder" and with upgrades were used by Chevrolet from 1929 into 1953 (and a few beyond). One of the reasons for the nickname, is that they used cast iron pistons originally. Original type cast iron pistons in these are usually fine, because they are a lightweight design (yes, that is possible).

The problem comes about because many replacement pistons for these engines for going on eighty years now, are aluminum pistons. Aluminum expands more than cast iron does due to higher temperatures. This is called the coefficient of expansion. Many specifications you will see for these engines are the original specifications for the cast iron pistons (which expand with running temperatures about the same amount as the cylinder itself does). Cast iron pistons for a proper fit, should be at about .002 to .003 (inch) total clearance from the cylinder walls. Aluminum pistons get a bit more complicated. Modern engines, with full water jackets, and high pressure oiling, can run as close as '004 inch. Your Chevrolet should ideally be set at about .006 inch (largely due to the half water jackets) if it has aluminum pistons.

Those Chevrolet engines are amazing. I had a worn out '52 many years ago. A quick and dirty overhaul with too much wear in the cylinders (you likely wouldn't believe me if I told you how bad it was), only burned oil at somewhat over 60 mph,  and was driven daily for more than 60,000 miles before the transmission gave out.

[Dave39MD]

Good advice so far, it would not hurt to ask on this site as well. Lot's of early Chevy experts there.

 

Dave

 

http://vcca.org/forum/ubbthreads.php/forum_summary

[Gunsmoke]

When I (not a mechanic, just a tinkerer) refurbished the "noisy" bottom end of my Chev's 194CI 5 years ago, it was recommended by VCCA tech experts that rod caps be adjusted with a clearance of about .001 on journals (they say factory settings were between .0005 and .001). This is accomplished by removing shims if any are still in place between the cap and rod. Rather than using plastigage it was recommended I do one rod at a time, removing shims  and tightening rod to point crank will not turn, then adding .001 of shim each side of cap and torgue up. This repeats for all 6 rods. Turns out my rods had about average .004 clearance on journals, causing most of the "noise" in my car. There were about .005 of shims on each cap. As for the 3 bearing points, these still have some play and I removed all remaining shims on those. They are not as tight as I would like, but to correct that would require sending engine for rebuild involving re-babbitting, correcting crank journals, re-boring etc, min $2000-$4000 I'm guessing. Finally, some piston slap is also present, but again without a rebuild, cannot be eliminated. My rods had a small lateral movement, but since I was not planning a rebuild, I did not measure it. Cheers

[theterrym]

Thanks everyone. This is exactly what I needed to hear and why I asked you guys before I took it apart any further. I knew about the shims, I just hope they are still there. If so i will be on easy street. If not im sure Ill have many more questions. Thanks everyone.

[Gunsmoke]

The Vintage Chevrolet Club of America (VCCA) gave me great guidance on this refitting exercise. While none of it was rocket science, there is a great deal to learn including the nature of the gravity drains on the end bearings (they have a small ball stop), ensuring dippers are on correctly (mine had been installed backward by a PO!), ensuring oil distributor and pump/screen are all good etc. Finally, installing a new oil pan gasket involves a tricky procedure in area where it rounds end bearings. If not done correctly, oil leaks are likely. Cheers

[herm111]

14 hours ago, wayne sheldon said:

A quick warning about piston fit. These engines are known as the "cast iron wonder" and with upgrades were used by Chevrolet from 1929 into 1953 (and a few beyond). One of the reasons for the nickname, is that they used cast iron pistons originally. Original type cast iron pistons in these are usually fine, because they are a lightweight design (yes, that is possible).

The problem comes about because many replacement pistons for these engines for going on eighty years now, are aluminum pistons. Aluminum expands more than cast iron does due to higher temperatures. This is called the coefficient of expansion. Many specifications you will see for these engines are the original specifications for the cast iron pistons (which expand with running temperatures about the same amount as the cylinder itself does). Cast iron pistons for a proper fit, should be at about .002 to .003 (inch) total clearance from the cylinder walls. Aluminum pistons get a bit more complicated. Modern engines, with full water jackets, and high pressure oiling, can run as close as '004 inch. Your Chevrolet should ideally be set at about .006 inch (largely due to the half water jackets) if it has aluminum pistons.

Those Chevrolet engines are amazing. I had a worn out '52 many years ago. A quick and dirty overhaul with too much wear in the cylinders (you likely wouldn't believe me if I told you how bad it was), only burned oil at somewhat over 60 mph,  and was driven daily for more than 60,000 miles before the transmission gave out.

"AGREE"

[herm111]

9 hours ago, Gunsmoke said:

When I (not a mechanic, just a tinkerer) refurbished the "noisy" bottom end of my Chev's 194CI 5 years ago, it was recommended by VCCA tech experts that rod caps be adjusted with a clearance of about .001 on journals (they say factory settings were between .0005 and .001). This is accomplished by removing shims if any are still in place between the cap and rod. Rather than using plastigage it was recommended I do one rod at a time, removing shims  and tightening rod to point crank will not turn, then adding .001 of shim each side of cap and torgue up. This repeats for all 6 rods. Turns out my rods had about average .004 clearance on journals, causing most of the "noise" in my car. There were about .005 of shims on each cap. As for the 3 bearing points, these still have some play and I removed all remaining shims on those. They are not as tight as I would like, but to correct that would require sending engine for rebuild involving re-babbitting, correcting crank journals, re-boring etc, min $2000-$4000 I'm guessing. Finally, some piston slap is also present, but again without a rebuild, cannot be eliminated. My rods had a small lateral movement, but since I was not planning a rebuild, I did not measure it. Cheers

All Babbitt bearings should be set to .001 per inch of crank, Rods, or Mains, Plus a .000-50.  A  2-1/2 inch crank would have a .002-50 thousandths clearance minimum, and or a Maximum of .003-00.  Both Fine.

 

Herm. 

[mike6024]

http://www.repairengineering.com/coefficient-of-thermal-expansion.html

 

Thermal expansion coefficients - Gray Cast Iron      5.8,      Aluminum      12.8

[theterrym]

I found the cause of the bottom end thump. The middle main cap had been put on backwards at one point in the cars life and is quite worn. Every other babbitt  is in very nice condition. To get this repaired can I just remove the copper insert from the block and send the cap and insert for rebabbitt? or should this be done right in the block?

[Guest]

The man that did my bearings wouldn't rebabbit the old replaceable bronze shell.  He said there was too much of a possibility that it was distorted on removal.  He cast new bronze shells and then babbited them.  Perfect job.

[herm111]

On ‎9‎/‎23‎/‎2017 at 6:29 PM, theterrym said:

I found the cause of the bottom end thump. The middle main cap had been put on backwards at one point in the cars life and is quite worn. Every other babbitt  is in very nice condition. To get this repaired can I just remove the copper insert from the block and send the cap and insert for rebabbitt? or should this be done right in the block?

You can't just do one main, as the other two have to line up with that one. They also have to be Align Bored, and the crank touched up.

The way that main looks anyway, the others are wore past what they should be.

When crank mains wear, they do Not wear in Alignment.

Who ever grinds your crank, make sure they stay with the true center line, and not indicate off a front, and rear crank journal, it won't work.

 

Herm.

[herm111]

On ‎9‎/‎23‎/‎2017 at 9:13 PM, Tinindian said:

The man that did my bearings wouldn't rebabbit the old replaceable bronze shell.  He said there was too much of a possibility that it was distorted on removal.  He cast new bronze shells and then babbited them.  Perfect job.

Bearing shells do distort, all of them distort, you just have to know how to bring them back.

Unless, your Bronze inserts were cracked, they would pour and machine like any other.

His new shells would not be any better then what you had with the originals, and might have distorted worse.

 

Herm.

[Cabnut]

On ‎9‎/‎19‎/‎2017 at 3:13 AM, wayne sheldon said:

A quick warning about piston fit. These engines are known as the "cast iron wonder" and with upgrades were used by Chevrolet from 1929 into 1953 (and a few beyond). One of the reasons for the nickname, is that they used cast iron pistons originally. Original type cast iron pistons in these are usually fine, because they are a lightweight design (yes, that is possible).

The problem comes about because many replacement pistons for these engines for going on eighty years now, are aluminum pistons. Aluminum expands more than cast iron does due to higher temperatures. This is called the coefficient of expansion. Many specifications you will see for these engines are the original specifications for the cast iron pistons (which expand with running temperatures about the same amount as the cylinder itself does). Cast iron pistons for a proper fit, should be at about .002 to .003 (inch) total clearance from the cylinder walls. Aluminum pistons get a bit more complicated. Modern engines, with full water jackets, and high pressure oiling, can run as close as '004 inch. Your Chevrolet should ideally be set at about .006 inch (largely due to the half water jackets) if it has aluminum pistons.

Those Chevrolet engines are amazing. I had a worn out '52 many years ago. A quick and dirty overhaul with too much wear in the cylinders (you likely wouldn't believe me if I told you how bad it was), only burned oil at somewhat over 60 mph,  and was driven daily for more than 60,000 miles before the transmission gave out.

Okay so if you look at the aluminum pistons supplied these days you will notice that the lands for the rings are progressively smaller in diameter with the smallest at the top where the most expansion will be. These newer pistons are designed to allow for the extra expansion of the aluminum nearest the combustion and the tolerance at the skirt should be as stated by the piston supplier which was 2 to 3 thousands from the supplier I bought from. Also, yes aluminum pistons expand more but they also conduct and release heat more efficiently then cast iron so extra clearance at the skirt is not necessary. If the suggestion to allow 0.006" at the skirt is followed then very quickly piston slap may occur as the cylinder walls wear in.

[herm111]

15 hours ago, Cabnut said:

Okay so if you look at the aluminum pistons supplied these days you will notice that the lands for the rings are progressively smaller in diameter with the smallest at the top where the most expansion will be. These newer pistons are designed to allow for the extra expansion of the aluminum nearest the combustion and the tolerance at the skirt should be as stated by the piston supplier which was 2 to 3 thousands from the supplier I bought from. Also, yes aluminum pistons expand more but they also conduct and release heat more efficiently then cast iron so extra clearance at the skirt is not necessary. If the suggestion to allow 0.006" at the skirt is followed then very quickly piston slap may occur as the cylinder walls wear in.

Piston slap is ONLY caused by Rods being out of Alignment! Clearance should be a .001-00 per inch of bore. If the engine was to be used in a heavy pulling truck, a  4" bore would not be uncommon to have .010-00 clearance.

Piston Rattle is noticed with pistons that are solid skirted, rather then split skirt, with the proper clearance.

 

Herm.

[herm111]

On ‎9‎/‎23‎/‎2017 at 6:29 PM, theterrym said:

I found the cause of the bottom end thump. The middle main cap had been put on backwards at one point in the cars life and is quite worn. Every other babbitt  is in very nice condition. To get this repaired can I just remove the copper insert from the block and send the cap and insert for rebabbitt? or should this be done right in the block?

[Cabnut]

6 hours ago, herm111 said:

Piston slap is ONLY caused by Rods being out of Alignment! Clearance should be a .001-00 per inch of bore. If the engine was to be used in a heavy pulling truck, a  4" bore would not be uncommon to have .010-00 clearance.

Piston Rattle is noticed with pistons that are solid skirted, rather then split skirt, with the proper clearance.

 

Herm.

So reading my original Chevrolet repair manuals 1919 FA and FB engines with Lynite (aluminum) Pistons the spec for piston clearance is quoted at 0.003". By 1926-28 spec for aluminum piston Chev engines was 0.0025 to 0.003" ( I would suspect this is from improved piston design). Also both manuals state piston slap as caused by excessive wear to cylinder bore resulting in extra clearance. I tend to go with manufacturer information as being correct which is why I try to get the manuals for the cars I work on.

[cahartley]

8 hours ago, Cabnut said:

So reading my original Chevrolet repair manuals 1919 FA and FB engines with Lynite (aluminum) Pistons the spec for piston clearance is quoted at 0.003". By 1926-28 spec for aluminum piston Chev engines was 0.0025 to 0.003" ( I would suspect this is from improved piston design). Also both manuals state piston slap as caused by excessive wear to cylinder bore resulting in extra clearance. I tend to go with manufacturer information as being correct which is why I try to get the manuals for the cars I work on.

 

Replacement Aluminum pistons are likely cam ground in which case the old rules don't apply.

[herm111]

7 hours ago, Cabnut said:

So reading my original Chevrolet repair manuals 1919 FA and FB engines with Lynite (aluminum) Pistons the spec for piston clearance is quoted at 0.003". By 1926-28 spec for aluminum piston Chev engines was 0.0025 to 0.003" ( I would suspect this is from improved piston design). Also both manuals state piston slap as caused by excessive wear to cylinder bore resulting in extra clearance. I tend to go with manufacturer information as being correct which is why I try to get the manuals for the cars I work on.

Mr. Cabnut, since 1919, technology has changed just  teen-z, teen-z  bit.

 

Your book of 1919 stating .003-00, and 1926-27 .003-00 top clearance is only .000-20, or 2 tens of a thousandths difference Now seeing that an average hair Mic's at .002-00, you, or others should be able to see that .000-20 tenths is very small indeed.

 

So your Chevy 4 cylinder has a bore of 3-11/16's, or 3.687-50 standard. I said in my post that clearance should be .001-00 thousandths per inch, which is .000-20 tenths larger, or a total of about .000-70 tenths. So, if you want to take a chance on 7 tenths, extra clearance on piston, behave at it, as my customers don't care.

 

Also both manuals state piston slap as caused by excessive wear to cylinder bore resulting in extra clearance. "END QUOTE"

YES, that statement is true, but you have taken the wrong meaning from it.

 

A Piston with .003-70 thousandths will NOT wear a cylinder more, then a set of rings before it. A piston, with a straight rod will not wear a bore, the rings will, or a piston with the Rod out of alignment, and it does not take much, in a very short time to wear bore, piston, and rings.

 

Most People do not know they have to check Alignment, or even know what it is, trust me. 

 

I will post pictures to read.

 

Anybody with questions, just ask.

 

Thanks,

 

Herm.

8 hours ago, Cabnut said:

So reading my original Chevrolet repair manuals 1919 FA and FB engines with Lynite (aluminum) Pistons the spec for piston clearance is quoted at 0.003". By 1926-28 spec for aluminum piston Chev engines was 0.0025 to 0.003" ( I would suspect this is from improved piston design). Also both manuals state piston slap as caused by excessive wear to cylinder bore resulting in extra clearance. I tend to go with manufacturer information as being correct which is why I try to get the manuals for the cars I work on.

 

[Cabnut]

Well looks like more was read into my post. Bottom line someone stated 0.006" for piston clearance which I believe is wrong. And for cam ground Pistons I am sure they would be fit tighter. I am well aware technology has advanced and had pretty much stated that. These engines don't run at temps and RPMs like modern engines. I am aware the rod alignment needs to be checked by the way. That's all I have to say. Bye.