Engine damage question....

[adavis]

So it happened on the way home from the Flathead Reliability Run. Cruisin' down the freeway and wham! All the sudden it sounded like someone was shooting a Tommy Gun at us. I shut it down and coasted to the shoulder and called a buddy with a trailer. When I got home, I pulled the pan to find #2 rod bearing was completely gone. I also noticed some grooves in #1 cylinder wall so I pulled the engine. When I started pulling pistons to dismantle the entire engine I found a couple that had started to smear, #4 being the worst, up near the rings. I also found that #3 rod bearing was about 10 miles from disintegrating and only half there on the cap.
My reason for writing a thread about this is to get some opinions on what occurred. Here's a little back story and some more information.......
My engine is a 1935 diamond block model B. It was running when I bought the car, but after a short amount of driving I realized it was in need of an overhaul. I sent it to the local shop to have a complete short block done. They bored it to .080 with new pistons, installed new modern valves, redid the crank, and poured new Babbitt rod and main bearings. I got the engine back and had it installed and driving the car in April 2013. I drove it all last summer and put about 3000 miles on it, but noticed that it was smoking a little before I put it away for the winter. This spring when I fired it up I had serious smoke issues and quite a bit of blow-by. I took it back to the engine builder and when he pulled the head he found that #1 and #2 cylinders where scored and both pistons were smeared on one area of the rings. Luckily he was able to hone the cylinders clean and dress the pistons. HOWEVER, when he had the pistons out he noticed that the Babbitt on the rods was beginning to break out. Upon further inspection it was discovered that the crank grinder had overground the rod journals. The crank was marked 040 but the rod journals were ground 045. The new babbitts were poured for 040, so the entire summer I had driven with 005 clearance in all my rod bearings. The shop had the rod bearings re-poured to 045 and the mechanic hand-lapped them to the crank. The shops opinion was that I had too much carburation (I'm running to Stromberg 81's with stock jets) so they blocked off one carb and sent me home. I drove the car to work and back the next day and realized that one carb simply wasn't going to work.....it felt like half the power was gone. I unblocked the carb and drove it all summer......until Sept 20th.

My car is a 1931 coupe and I have a T5 transmission. I have never dropped the clutch or drag raced. I have a tach in the car and watch it like a hawk....I never try to run the car below 1700 rpm and have never revved it past 3100 rpm. I put a 160 degree thermostat in it this spring because it runs so cool. It runs at 160 cruising down the road even in 95 degree weather and pulling hills it will climb to 190-200 but then drop immediately upon cresting the hill. Its never been above 200. I have Mobile1 synthetic oil in the engine per the builder recommendations. The 2 Stromberg 81's have stock jets and the spark plugs are all mouse brown. I run a 7:1 original Winfield head.

My question to all of you is how can this happen? I've done quite a bit of research since my first issue this spring and have found that the standard replacement pistons for model A's are mostly made overseas now. The machining is perfect, but the metallurgy of the pistons causes problems. They will expand erratically and that would cause excessive heat/wear on certain spots on the piston. Has anyone seen this or have another reason why my pistons are failing?
Why would Babbitt bearings fail in such a short amount of time? I'm wondering if driving the car all last summer with 005 clearance did something to the rod journals (beat them out of round???) and because of that the new bearings failed in less than 1000 miles. Is there a way to test the bearings to see if it is a Babbitt mixture failure?
I called the engine shop before I knew there was more than just a single rod bearing out and they said that just happens sometimes and that its not under warranty, even though the rod bearings only have 1000 miles at most on them this summer.

I'm not trying to blame anyone or point fingers. My only purpose of writing this thread is to figure out if I'M doing something wrong. I built the car to drive every day and not have to worry about it. I don't want to set a land speed record or beat a new Corvette off the line....I just want to have a reliable car that get me there and back for the next several years with major engine failure. Any ideas?

[Hitchhiker]

what you running for a distributor?

[colin1928]

My 1st impression is your piston galling is from not enough clearance
bearings failure metal from pistons or clearance ??
piston clearance changes from piston maker to maker and must be checked for each make the clearances given in repair manuals are for original parts only
I have seen this a bit lately guys fitting aftermarket parts and using original specs

[James Rogers]

I agree with Colin on the clearance problem led to the piston galling but, nothing else. I would suggest you get a different "builder" since yours is a shadetree quack. The rods were never tinned correctly leading to the broken babbitt in pic named bearing5.jpg. The others were (as you suspect) ruined by the excessive clearance. When I install rods or mains, I clearance EVERY bearing individually. I never trust them to just be correct without I plastigauge them and know. This engine should have never been let out of the "builders" shop like that. I would also, check the clearances on the mains, they may be as bad as the rods. I see engines come into my shop all the time like this and worse where the "builder" left all too much to chance or trusted the other guy to do his job right. It will always get you into trouble.

BTW, 3100 is a bit high for a babbitt motor but I don't think it had anything to do with this failure. Good luck with the repairs.

[ABento]

Seeing the galling on the pistons makes me think your correct about the clearance but I had a bad expereance with pistons from EGGE one time,their pistons were cammed incorrectly,this should be looked into, they admitted their problem and made good on new pistons but wouldn't make another set, a few years down the road they advised me to use Aries from who I got forged pistons,I sent them an orginal and they built what I needed, and have not had any problems with those,if after market pistons are made overseas they are junk right out of the box just like 90 % of that crap is,those morons throw everything in the pot when they make things.

[tbirdtbird]

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let us know how you make out

[hardtimes]

"Tommy Gun" noise = rod bearing (s) destruction !!

Hey adavis,
There is an A/B engine builder, up your way, in Turlock, Ca. This guy, IMO, is a top notch engine builder. There are Barners here who have learned about this builder and have had him build them engines and who have stated that they are very happy with his engine work.
I, in your place, would take this engine to Turlock and obtain his accessment of damages/reasons/possible rebuild options, etc.. Just a suggestion for positive outcome for future.
This guy that you call 'engine builder', who messed with your engine. You've said that he does not accept any responsibility for results of his work. So , damage is done. Take him to task, if you have evidence/proof he is culpable...or move forward. A tough pill to swallow, indeed. But, I think that you can/will get some good answers/attention to you problem from the Turlock builder. Good luck whichever path you take.

[Flathead]

.005 is a huge amount when it comes to proper bearing clearance. I would have just about zero faith in this shop. How do you know if the piston clearance was done right either? It is a real shame that this happened, but you should move on to a known competent Model A machinist and get your poor engine sorted out. Good Luck to you.

[tbirdtbird]

.005 rod clearance should have been audible from the get go....should have sounded like a cement mixer

[tbirdtbird]

An A is like all engines of yesteryear: long stroke, low revving, tons of low-end torque because of the stroke.
If you never let the engine run below 1700, then you missed the entire torque ramp and peak. The torque/HP graph is very revealing if people would only study it. Even with modifications, it won't change much. The absolute HP may change but the RPM ranges will stay about the same.
If you are gonna rev to 3100 then the old school long skirt pistons with wide rings with too little clearance will let you down every time. Also remember that cyls 3&4 run about 20-30* hotter than 1&2. You can have local overheating without much overall increase in water temp. I have seen pix of cyls 3&4 so tight and so overheated that the paint on the outside on the driver's side was cooked to a brown-black color. These engines had not overheated in the usual sense of the word....it was all local.
Add this all up and you can see what happened, before you even get to the workmanship of the babbitt job

[adavis]

Thanks for all the input guys. To answer a couple of questions above......

I am running a Mallory dual point that I converted to Pertronix.

The engine builder is the only one around that does Babbitt bearings and they specialize in T and A motors. They have built hundreds of these things so I figured they knew what they were doing. He admitted it when he found the overgrind this spring, and when he put the new rod bearings in he said he hand-lapped each one for exact clearance. He did NOT pull the crank out of the block so my thought is that there was damage done to the rod journals in that 3000 miles I drove.....therefore the new bearings were destined for failure from the start.

The main bearings look good. There is no discoloration or damage that I can see. In fact they all three look like new.

The rod with the bearing completely gone was #2. The mostly destroyed rod bearing in the pictures is #3. The piston that looks the worst is actually #4. #1 piston was the second worst for smearing.

This spring, when I took the car back to the builder to figure out why it was smoking so bad, he found that #1 and #2 pistons were smeared. He cleaned that up and reused the same pistons.

I don't need to rev to 3100. I just say that I did because the engine was revved that high once when I was trying to what kind of acceleration it had. When I drive every day I'm between 1800 and 2600 rpm. I have a T5 and a 1940 car gear set in the rear (somewhere around 3.37 I think) so I don't shift into 5th gear till 60mph. I was told that it isn't good to lug a banger below 1700 for extended periods....is that incorrect??

Thanks again for all the info. I honestly am just trying to figure out what happened so it doesn't happen again.....not to blame anyone. I will look up the builder in Turlock and bounce some questions off him. If anyone else has any ideas I'm still listening.....

[tbirdtbird]

" I was told that it isn't good to lug a banger below 1700 for extended periods"

????????? Sure is news to me. As I said you missed the ramp and peak of the torque curve. Look it up and see if you don't agree. The torque curve cannot be denied, that is the physics of the engine, and that is what dictates how you drive it, as opposed to a misguided model A wannabe mechanic
http://www.modelaparts.net/dynosheet...ynosheets.html
gives you access to many dyno curves

BTW what head are you running and what cam, and is the crank counter weighted

I am beginning to understand why there are so many crappy builders out there who get away with it. Many many A drivers do not expect much from their cars or engines. Meaning there are many owners who just go to church or get ice cream with the grand kids (and that is all well and good). Crappy workmanship will take longer to show up under this scenario. By the time it does show up the car has been long since sold and nobody knows nothin' about nothin'.

Those of us who want more from the car, like long distance touring, speed higher than 30 mph, (stuff the car was capable of when new) etc, will uncover crappy workmanship way sooner

[Kohnke Rebabbitting]

Originally Posted by adavis

Thanks for all the input guys. To answer a couple of questions above......

I am running a Mallory dual point that I converted to Pertronix.

The engine builder is the only one around that does Babbitt bearings and they specialize in T and A motors. They have built hundreds of these things so I figured they knew what they were doing. He admitted it when he found the overgrind this spring, and when he put the new rod bearings in he said he hand-lapped each one for exact clearance. He did NOT pull the crank out of the block so my thought is that there was damage done to the rod journals in that 3000 miles I drove.....therefore the new bearings were destined for failure from the start.

The main bearings look good. There is no discoloration or damage that I can see. In fact they all three look like new.

The rod with the bearing completely gone was #2. The mostly destroyed rod bearing in the pictures is #3. The piston that looks the worst is actually #4. #1 piston was the second worst for smearing.

This spring, when I took the car back to the builder to figure out why it was smoking so bad, he found that #1 and #2 pistons were smeared. He cleaned that up and reused the same pistons.

I don't need to rev to 3100. I just say that I did because the engine was revved that high once when I was trying to what kind of acceleration it had. When I drive every day I'm between 1800 and 2600 rpm. I have a T5 and a 1940 car gear set in the rear (somewhere around 3.37 I think) so I don't shift into 5th gear till 60mph. I was told that it isn't good to lug a banger below 1700 for extended periods....is that incorrect??

Thanks again for all the info. I honestly am just trying to figure out what happened so it doesn't happen again.....not to blame anyone. I will look up the builder in Turlock and bounce some questions off him. If anyone else has any ideas I'm still listening.....

It sure would be nice to see pictures of the block mains, and caps to see what that babbitt looks like, as in Grooves, oil wells, wear patterns, peening ect.

Herm.

[harleytoprock]

From the looks of the piston it seems like the connecting rod is bent or the babbit was bored crooked. The piston evidence is the scores way up top but on the non thrust sides. There is a lot of clearance at the ring area. For it to scuff like that, on the sides, the piston is not straight with the bore. The increased piston drag would make the big end babbit die quicklly.

[Kohnke Rebabbitting]

Where the babbitt is loose in the rods, pry it out and take pictures of the shells, and the back of the babbit?

[Model A Man]

This is my big fear, spending a lot of hard earned money on a rebuilt only to have it last several thousand miles. I am still holding out for Tod with his new model A motors.

[James Rogers]

Originally Posted by Model A Man

This is my big fear, spending a lot of hard earned money on a rebuilt only to have it last several thousand miles. I am still holding out for Tod with his new model A motors.

How will a new block improve the build??????????

[George Miller]

Originally Posted by James Rogers

How will a new block improve the build??????????

Well I won't it all depends on material and workmanship. If he does ever thing right it will be a good engine. if he does a lot of it wrong it will be junk.

If he line bores the mains on a angle like this thread is about, the engine will have the same problems as the one in this thread.

But I think he is going to get it right.

[CarlG]

Originally Posted by James Rogers

How will a new block improve the build??????????

That's the question I've had. Only indication I've perceived is that the new block is going use all the same interior parts. For example; where are all the "new" cranks going to come from?

As happy as I would be to have a NEW engine, is it really going to be a NEW engine, or just a new block with all old components?

And then there's the question of who is going to build the engine?

I'm excited. A new Model A "crate" engine would be my dream come true.

[adavis]

Sorry....work has kept me from getting pictures of the mains. I will post pictures of the main cap bearings tonight. The block is at the machine shop so I can't get pictures of the block side of the bearings at this point. They look perfect to me, but I have never really dealt with Babbitt bearings so I don't know what I'm looking at. The grooves are perfect and the bearing surfaces are uniform with no flaking, cracking, or discoloration.

Its interesting that in just the last few days there are at least 3 threads on here regarding smeared pistons. I've seen the mention of import pistons in all the threads. I'm feeling more and more confident that the problem lies in the piston manufacturing. The Babbitt is another story and I'm researching that as well, but I will NEVER use foreign pistons again. Silv-0-lite will be all that I install from now on. I will keep everyone posted. Thanks again.