newbie needs help

Jerry1865

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hello, I'm a fresh convert to cadillac big blocks. I've gotten myself into a spot where I need some help.

have a 70 model 472 that measured .003 over so I took it to a local shop to eval and hot tank. it wound up that it was bored .040 over. when I got it back, the crank (which was only to be polished) had been sent out and ground 20/20, but the oil holes had no chamfers at all and in fact had actual burs.
the head work was done altho not quite up to spec as the series 3 shaft rocker instructions said he should be sure to cut seats so that all valve stem heights were within .010, he got them within .024.....
he honed it to .0025 over

now for the current nightmare, the pistons were mounted on rods backwards. when I assembled it I figured he had numbered the rods for a chevy so I put the rods in the wrong banks in order to make the arrows on the pistons face forward.

did the cam break-in according to isky specs (560/560 lift cam from isky) straight up to 2500 for 25 minutes, then goosed it to 5200 once then idled for bout 30 seconds and cut it off.

results, the cylinders are scored as well as the pistons. it will have to go a size up on the pistons to clean up the bores.
the guy at the machine shop said he would do the work but doesn't think he should eat the pistons and rings. claims having the pistons backwards on rods would have helped the engine.....and that me installing the rods on the wrong bank shouldn't have hurt it.
I told him that I thought it only fair for him to eat the pistons and rigs and I would eat everything else. he simply says I need to prove that any combo of those issues should cause an issue.

so my question is ...should the damage in the cylinders be attributed to any combination of rods on wrong bank, pistons on backwards or piston clearance being out of spec?

thanks in advance for any and all advice and pointers.
 

Caddylackn

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Yikes..

I got a lot of mixed feelings on this one.

His mistake, his duty to fix it. Clearly the pistons are designed to go in one way only or they would not be marked as such.

And 0.040 over Cadillac pistons are kind of like hen's teeth, are you sure he didn't put in 0.030 or 0.060 pistons in? Or pistons from another motor? 0.040 over is an odd duck for a Cadillac piston but it does match up to standard overbore sizes for other motor makes. Check the piston diameter and the compression height and report back. Did he supply the pistons? What is the model # on them? Do you have any photos to share? Are all the score marks on one side of the cylinders or all sides?

Ok, I have to ask the obvious also,
Did you have good oil pressure when breaking in? Did you prime the oil pump? Did the motor have pre-lube?

If the mistake was entirely his and he won't do anything,
I'd take him to small claims court: let him prove his own gross error didn't destroy the pistons. It is not your job to prove the other way around.
He is the expert that you paid to do his assigned service. Now he is saying that you have to be the expert to prove his negligence caused the damage? I already have the Yelp review written in my mind on this one..... At this point I would take it to another machine shop and get a quote to fix it and get their expert opinion.

On the other hand, some of the blame could be yours for installing the pistons in when you noticed the piston number did not match the cylinder bank. Assuming he was using a Chevy firing order was a choice you made without calling him to verify. If this was to go to small claims, I feel the judge could award only partial blame to the machine shop. Maybe like 75% his, 25% yours or 50%/50%.

First thing I would do though, is take the motor apart and see if there is bearing or crank damage. The crank is already at 0.020, so if its scored, its toast. If you need an overbore, another crank, and new overbore pistons, I would just start with another motor, If the pistons are not messed up it seems like just start with another block and bore it to match those 0.040 pistons. Any 472 or 500 block will work. If he will machine a new block to 0.040 for free, it seems like this is an easier path. I'd get him to buy the rings and bearings if they are toast, if you are supplying the block.

Also the other stuff that bothers me:

You sent him the crank to polish and he ground it 20/20 without authorization?, Sounds like they messed it up polishing it to me. If there was damage that bad to require a 20/20 grind, I would ask to look at it and have them show me with their measurement tools before authorization. If they want you to pay for the 20/20 grind, send it back and have them chamfer the oil holes.

And having them sink some of the valves 0.024" more than others :mad:, I would measure them myself and find out what happened. If one or two is sunk 0.024" more than the others and the others are okay, they can put in a new valve seat(s) to fix that. You are paying him for 0.010" of tolerance, if the greater tolerance is due to bad machining equipment/techniques, I would pay them less or make them fix it. What was the reason some valves were so deep? Were some of the seats messed up when you took it in, or did they mess it up? At the least you could make them shim the valve springs so the valve seat pressures are all the same. The rockers are non-adjustable, so the geometry of every valve now needs to be checked if you are going to run them as is.
 

48Austin

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Just WOW! Where are you located that something like this would happen?
 

5one9

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The pistons backwards on the rods isn't a big deal as long as you got the rods oriented correctly on the crank (chamfer out).
The scoring on the walls sounds like filth in the engine. Did you clean the passages in the block and crank before assembling? The chamfer on the crank oiling holes not a big, big deal, but burrs sticking off of them is not good at all. Ring gap right on assembly? 20/20 on a crank isn't a big deal as long as it's round.

All in all I doubt this machine shop does any better on a small block chevy. I'd go elsewhere.

Measure the bore diameters and the piston diameters and report back to us.
 

5one9

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And when I say no big deal, I mean they won't immediately cause failure. In no way am I justifying this person's sorry work.
 

Jerry1865

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thank you all for the replies and perspective. yes I will attach pics.
primed for 5 minutes at 27 psi. once started I had 55 psi at 2500 rpm and 30 psi at 900 rpm.
bearing clearance was snug, .0005 to .0009
when it goes back together it should be at .002 clearance on the bearings as I have taken the crank to a different shop to be polished

on the .040 size, yes, the shop supplied the pistons, and told me he took it to .040 to get to the bottom of a pinhole. (a pinhole that wasn't there till he bored it ).
when i took it in it measured 4.303 it now measures 4.3425
the number on the pistons is 945p
ring gap on assembly was .024 on cast rings ( I thought the gaps were a shade wide )
what I noticed on disassembly was that the scoring in the bores roughly matched the locations of the ends of the rings.
the bores themselves look like piston slap to me.
I should probably add that of the scoring in the cylinders only about 1 per cylinder can be found with a fingernail.

I do have 2 other blocks, but im hoping to get one of them to go back together with a std bore. 2) 5200's and a 6238
location = southern mn

the pics of cylinders are paired, and the all look pretty close to the same.
for the pics I turned the rings in line in order to show the ends


this is going into a 73 c10 when finishedIMG_0394.jpgIMG_0395.jpgIMG_0390.jpgIMG_0396.jpgIMG_0404.jpgIMG_0410.jpgIMG_0411.jpg
 
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Caddylackn

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I am hoping this is just a parts mismatch.

You have 0.040 over pistons, correct? They should be stamped 0.040 on top. From the pictures, this looks like a Silv-o-lite piston, AFAIK but I could not find one online with the number 945p. Here is a 0.020 over 472 piston I found that looks to be the same except for size. https://www.summitracing.com/parts/uem-1814-020/applications
I hope you have 0.040 rings. I don't know how to tell, except for ring gap. It sounds like your ring gap was too small per the directions. These are the directions I found online on Summit for a Silv-o-lite piston. Notice they do NOT show the piston numbering for a Cadillac motor. https://static.summitracing.com/global/images/instructions/uem-1000-125.pdf If these are the directions that your machinist used, he did not follow the directions.

The machine shop supplied these pistons and rings, ask for a receipt of all the parts to verify if the part numbers are the correct ones.

No way would I put these rings back in, they definitely look like they are making all the marks on the cylinder wall. What are you using for locks on the wrist pins?

I hope your cylinder walls will just clean up with a hone.
 

Darius

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I am hoping this is just a parts mismatch.
You have 0.040 over pistons, correct? They should be stamped 0.040 on top. From the pictures, this looks like a Silv-o-lite piston, AFAIK but I could not find one online with the number 945p. Here is a 0.020 over 472 piston I found that looks to be the same except for size. https://www.summitracing.com/parts/uem-1814-020/applications
I hope you have 0.040 rings. I don't know how to tell, except for ring gap. It sounds like your ring gap was too small per the directions. These are the directions I found online on Summit for a Silv-o-lite piston. Notice they do NOT show the piston numbering for a Cadillac motor. https://static.summitracing.com/global/images/instructions/uem-1000-125.pdf If these are the directions that your machinist used, he did not follow the directions.

The machine shop supplied these pistons and rings, ask for a receipt of all the parts to verify if the part numbers are the correct ones.

No way would I put these rings back in, they definitely look like they are making all the marks on the cylinder wall. What are you using for locks on the wrist pins?


I hope your cylinder walls will just clean up with a hone.
Bro. Caddylackn,

I like your thinking.

bro. d
 

Jerry1865

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thank you to everyone for the help. it was a bit of a battle but I did convince the shop to buy new pistons/rings. turns out he had bought 'badger' pistons, and they are no longer in business according to the shop guy. so I told him that he could contribute that amount toward a set of kb hypers.
he is also punching the block to .060 and he and myself will look at every single hole and piston together before it leaves this time.

I found a shop I think would do it right but he said to make the boy do the work to fix his prob,

anyway, have a set of rods coming as well as the kb pistons. fingers crossed ........

I also think the rings caused the scars, but this time around I will have a data sheet from the mfg to go by instead of simply the machinist recommendation.
 

cadillac512

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Hi Jerry

Hope the shop fits the pistons properly this time.

Do you happen to have some pics of the piston skirts of the Badger pistons? I'd be interested in the scuffing on them.

I'd make very sure the newly bored block is washed with hot soapy water and the cylinder bores scrubbed well. In addition,all oil passages brushed clean at the same time. There's going to be grit in there from the machining, and nothing but a warm soapy bath will remove it. Same goes for the crank, but solvent or brakleen and a brush will do well enough there. I've seen dozens of engines ruined by machining grit, and still see it all the time (I rebuild engines for a living).

As for the bearing clearances, measure that crank carefully. If it was really that close on clearance it will be very difficult to polish the crank enough to achieve .002+ clearance and still keep it round and without taper.

Check every thing...

Terry
 

Jerry1865

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Thanks for the reply, the first time around i took the block, heads, crank and cam to a car wash and used lots of dawn soap as well as brushes for holes and cavities.
Then went thru lots of air and towels drying.
How do i go about the “hot” water and soap in a pressure washer?
 
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cadillac512

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Jerry, if you do the car wash deal again, that works fine. I've used that method many times.

My pressure washer won't tolerate hot water so I would do the same if I were cleaning a block at home.
 

smalltruckbigcid

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Southern MN? Go to Napa in Northfield, him I trust. On the crankshaft go to crankshaft supply in Minneapolis, they know how to do things
 
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