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Discussion Starter #1
Hello engine builders, should I be concerned? I just started my freshly rebuilt SBC 400. Motor has a new Dart SHP block, new cam, rings, bearings etc. I had it rebuilt by a reputable machine shop who only builds racing engines. I paid extra for the engine dyno and everything performed perfectly during testing. My issue is that the motor sat in my garage for about 8 months before putting it into the car and finally, I got it started 4 days ago. I left the original oil he used in the oil pan during testing and figured I would replace it after getting the motor started. Anyhow, on startup for the first 5 minutes or so you can hear a knock coming from the passenger side low in the crank area, but it goes away once everything warms up. The engine has no miss fire, it does not heat up and it pulls hard when revving the engine. Once it heats up the cam rumbles nicely, no exhaust leaks, 55lbs of oil pressure on startup and then settles in about 25-30 lbs after oil heats up, actually engine sounds great once it's warmed up. However, on every occasion, when cold, the engine knocks for a bit and then it goes away. Yesterday, I removed the oil and found a marble size buildup (oil and I guess very fine metal material) stuck to the magnet of the oil pan plug. I took a paper napkin and wiped it off. It just smudged onto the paper towel, nothing solid. Is this part of the break in ware or should I be concerned? This is my first rebuilt motor and I am not sure what to expect. My engine builder said I did not have to adjust anything on the motor, valves, carb, etc.. everything was adjusted on the dyno. But, why would knock like when it is cold. My previous motor with similar build, never did this. Anyone have any ideas?
 

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If the motor was built to racing specs, it may have forged pistons installed. Since the piston to wall clearance is greater with forged pistons, they usually take a few minutes to expand from the heat of operation, fit themselves to the cylinder bores and quiet down. Cast and hypereutictic pistons can be installed with less piston to wall gap, as they do not expand when they warm up like forged pistons do. If forged pistons were installed with tight cast piston clearances, the pistons would grow from the heat of operation and stick in the bores, ceasing engine operation from stuck pistons.
 

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I'd call the builder and tell him everything you just said here. If you open the engine he/she will possibly be less likely to deal with it. He may have some things to try over the phone or he may want to see the car since it's already installed.

The material in the pan isn't that alarming to me however the lower noise needs attention. Your engines guys will understand it's been months but they will know if you have been running it or not. It's best they see it and hear it first hand and I'm sure they will take care of it. They should anyway. If not find another one.

You may want to check the Flexplate for cracks around the bolt holes if an Automatic trans but that usually makes noise all the time or its worse in gear when the convertor loads up.

Engines should not be making noise if assemble correctly regardless of the piston type.
 

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Discussion Starter #4
Yes, SRP forged pistons. I started the engine 4-5 times wouldn't it have seized up already? Engine runs fine 30-40 minutes at a time. I'm going to call my engine builder but I wanted to inform myself some more before making the call.

Thanks
 

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Hello engine builders, should I be concerned? I just started my freshly rebuilt SBC 400. Motor has a new Dart SHP block, new cam, rings, bearings etc. I had it rebuilt by a reputable machine shop who only builds racing engines. I paid extra for the engine dyno and everything performed perfectly during testing. My issue is that the motor sat in my garage for about 8 months before putting it into the car and finally, I got it started 4 days ago. I left the original oil he used in the oil pan during testing and figured I would replace it after getting the motor started. Anyhow, on startup for the first 5 minutes or so you can hear a knock coming from the passenger side low in the crank area, but it goes away once everything warms up. The engine has no miss fire, it does not heat up and it pulls hard when revving the engine. Once it heats up the cam rumbles nicely, no exhaust leaks, 55lbs of oil pressure on startup and then settles in about 25-30 lbs after oil heats up, actually engine sounds great once it's warmed up. However, on every occasion, when cold, the engine knocks for a bit and then it goes away. Yesterday, I removed the oil and found a marble size buildup (oil and I guess very fine metal material) stuck to the magnet of the oil pan plug. I took a paper napkin and wiped it off. It just smudged onto the paper towel, nothing solid. Is this part of the break in ware or should I be concerned? This is my first rebuilt motor and I am not sure what to expect. My engine builder said I did not have to adjust anything on the motor, valves, carb, etc.. everything was adjusted on the dyno. But, why would knock like when it is cold. My previous motor with similar build, never did this. Anyone have any ideas?

If it stuck to a magnet it's from a hard part such as block, crank, rods, cam/liters, oil pump housing or gears.


What about the oil does it have swirls of metallic color. If it does that could be bearing or piston. Bearings are mostly a copper material over a backshell of steel. If you're getting both gold looking swirls in the oil and steel on the magnet it could be an advanced bearing failure.


At any rate this should go back to the builder it's one of those things that if you open it up it gives the builder an opening to say it didn't happen on his watch.


Bogie
 

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Discussion Starter #6
I'd call the builder and tell him everything you just said here. If you open the engine he/she will possibly be less likely to deal with it. He may have some things to try over the phone or he may want to see the car since it's already installed.

The material in the pan isn't that alarming to me however the lower noise needs attention. Your engines guys will understand it's been months but they will know if you have been running it or not. It's best they see it and hear it first hand and I'm sure they will take care of it. They should anyway. If not find another one.

You may want to check the Flexplate for cracks around the bolt holes if an Automatic trans but that usually makes noise all the time or its worse in gear when the convertor loads up.

Engines should not be making noise if assemble correctly regardless of the piston type.
I'm going to call my engine builder but I wanted to inform myself some more before making the call. Thank you
 

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Yes, SRP forged pistons. I started the engine 4-5 times wouldn't it have seized up already? Engine runs fine 30-40 minutes at a time. I'm going to call my engine builder but I wanted to inform myself some more before making the call.

Thanks

Mahle Pistons are among other forged Pistons that are composed of 2618 aluminum alloy with 0%-0.2% silicon. They are installed with a maximum of .006" skirt clearance. Those Pistons will have a audible piston slap when cold.
You cannot hear the piston slap when they are used in Top Fuel engines,. They should also be used in NOS and boosted engines.

SRP Pistons are among other forged Pistons that are composed of 4032 aluminum alloy with 11% silicon. They are installed with a maximum of .0045" skirt clearance. They should not slap when cold if set up with the proper clearance. Used in Naturally asperiated engines for street, professional drag and circle track.

Speed Pro Pistons are composed of proprietary VMS-75 aluminum alloy with 13% silicon. They are installed with .0035" skirt clearance. They should not slap when cold. Daily driver, high performance street and week end drag racing.

Hypereutectic Pistons are composed of 18% silicon alloy. They are installed with .0015" skirt clearance. No piston slap when cold for Daily drivers, and will meet most stringent California emissions standards.
 

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I'm going to call my engine builder but I wanted to inform myself some more before making the call. Thank you

What has my attention is that it's magnetic. Fresh engines tend to put some bearing and piston material into the oil early in the break-in. But magnetic stuff is from the hard parts which are not typically sacrificial and except for the cam lobes to lifters, rocker arm bearings or ball, and timing chain and gears you don't get much if any magnetic material unless its a super serious failure. If this is using rods that needed clearancing of the block, rods, or cam this could generate magnetic particles if the clearance was insufficient. Another odd thing with 400's is the oil pump shaft needs to be specific with an OD reduction to provide rear counterweight clearance, if the crank is kissing this shaft you'd get a tick once a revolution on the back right (passenger) side toward the pan rail. This could also be noise off the flexplate or the torque converter if this is installed to a vehicle.


For lack of clearance you'd get a tick once a revolution. For rod or pin failure there would be a double tick every revolution. For a main bearing going out there is a deep single thud per revolution, however, these crankshaft and piston pin noises don't go away when the engine warms up. Clearance issues with one part not missing another may or not change with temperature.


Forged pistons or any piston for that matter installed with loose clearances will tick when cold. Same for pistons with zero pin offset. But unless there is only one installed loose or has a zero pin offset this would be a rattle from all the cylinders all the time till warmed up. Zero pin offset pistons would probably never get really quiet.


If this has a windage tray and other oil pan windage management items the problem could be there with some sheetmetal part not quite missing the crankshaft when cold.


Without opening it up to see what's going on the possibility list remains with a lot of stuff on it.


Bogie
 

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Discussion Starter #9
If it stuck to a magnet it's from a hard part such as block, crank, rods, cam/liters, oil pump housing or gears.


What about the oil does it have swirls of metallic color. If it does that could be bearing or piston. Bearings are mostly a copper material over a backshell of steel. If you're getting both gold looking swirls in the oil and steel on the magnet it could be an advanced bearing failure.


At any rate this should go back to the builder it's one of those things that if you open it up it gives the builder an opening to say it didn't happen on his watch.


Bogie
I did see a grey swirl on top of oil in the container, I thought it might be contamination from other oil changes so I did not pay to much attention to it. I am going to remove the header to get to the oil filter to see what's up in there. Thanks for you response.

So just to be clear. This accumulation of fine metal attached to the oil plug is or is not common after a new engine is started?
 

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I may be wrong, but it seems like a small amount of swirl is normal with oil during break in, but the knocking does not. I would cut the filter open and see what you find.
 

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Discussion Starter #11
What has my attention is that it's magnetic. Fresh engines tend to put some bearing and piston material into the oil early in the break-in. But magnetic stuff is from the hard parts which are not typically sacrificial and except for the cam lobes to lifters, rocker arm bearings or ball, and timing chain and gears you don't get much if any magnetic material unless its a super serious failure. If this is using rods that needed clearancing of the block, rods, or cam this could generate magnetic particles if the clearance was insufficient. Another odd thing with 400's is the oil pump shaft needs to be specific with an OD reduction to provide rear counterweight clearance, if the crank is kissing this shaft you'd get a tick once a revolution on the back right (passenger) side toward the pan rail. This could also be noise off the flexplate or the torque converter if this is installed to a vehicle.


For lack of clearance you'd get a tick once a revolution. For rod or pin failure there would be a double tick every revolution. For a main bearing going out there is a deep single thud per revolution, however, these crankshaft and piston pin noises don't go away when the engine warms up. Clearance issues with one part not missing another may or not change with temperature.


Forged pistons or any piston for that matter installed with loose clearances will tick when cold. Same for pistons with zero pin offset. But unless there is only one installed loose or has a zero pin offset this would be a rattle from all the cylinders all the time till warmed up. Zero pin offset pistons would probably never get really quiet.


If this has a windage tray and other oil pan windage management items the problem could be there with some sheetmetal part not quite missing the crankshaft when cold.


Without opening it up to see what's going on the possibility list remains with a lot of stuff on it.


Bogie
Thanks for your very detailed thoughts. When the engine was being put together the engine builder explained how we would go in and reduce certain parts of the block for rod clearance. So, I am sure he accounted for this already. We did replace the old windage tray for a new one but he dynoed the motor so if it were hitting this should have shown up. There are tapping type noises coming from the engine on startup. But I attributed that to no oil on the first startup. That seem to be cleared up pretty quickly. Your theory of loose clearance or zero pin offset is viable. I actually recorded the noises with my phone I am wondering if I can post it here for you guys to hear.

Do you know if there is a way for me to post or send you a video?
 

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So just to be clear. This accumulation of fine metal attached to the oil plug is or is not common after a new engine is started?
Perfectly normal. More so with a FT cam. Ring and bore wear will be magnetic while bearing wear will not be. Both can be small enough to float in the oil.

Beware there is a fine line between some and too much without a good way of differing between the two except for experience. Not getting all the debri out of the engine after final machining or very dirty honing oils make the problem worse and create issues but sometimes you can get lucky too and flush it out with oil changes. Either way telling the engine guys is needed. Let us know what they say.

On a $50k engine a tiny bit is normal but should be gone by the first oil dump after it's loaded up on the dyno. Not every builder has a surgery room for assembly either so you might expect a bit more. Without knowing anything about the builder or how meticulous the assembly is it's really hard to say. One thing for sure is the should be no noise at all. I don't but the "some pistons make noise) theory if everything is spec'd out correctly.
 

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Discussion Starter #13
I may be wrong, but it seems like a small amount of swirl is normal with oil during break in, but the knocking does not. I would cut the filter open and see what you find.
I am going to remove the header to pull the filter today. I will post my findings. Thanks.
 

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Discussion Starter #14
Perfectly normal. More so with a FT cam. Ring and bore wear will be magnetic while bearing wear will not be. Both can be small enough to float in the oil.

Beware there is a fine line between some and too much without a good way of differing between the two except for experience. Not getting all the debri out of the engine after final machining or very dirty honing oils make the problem worse and create issues but sometimes you can get lucky too and flush it out with oil changes. Either way telling the engine guys is needed. Let us know what they say.

On a $50k engine a tiny bit is normal but should be gone by the first oil dump after it's loaded up on the dyno. Not every builder has a surgery room for assembly either so you might expect a bit more. Without knowing anything about the builder or how meticulous the assembly is it's really hard to say. One thing for sure is the should be no noise at all. I don't but the "some pistons make noise) theory if everything is spec'd out correctly.
I have a video recorded of the noise on my phone I would like some of you to hear it and give me an opinion. Is that possible?
 

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Discussion Starter #16
Hello engine builders, should I be concerned? I just started my freshly rebuilt SBC 400. Motor has a new Dart SHP block, new cam, rings, bearings etc. I had it rebuilt by a reputable machine shop who only builds racing engines. I paid extra for the engine dyno and everything performed perfectly during testing. My issue is that the motor sat in my garage for about 8 months before putting it into the car and finally, I got it started 4 days ago. I left the original oil he used in the oil pan during testing and figured I would replace it after getting the motor started. Anyhow, on startup for the first 5 minutes or so you can hear a knock coming from the passenger side low in the crank area, but it goes away once everything warms up. The engine has no miss fire, it does not heat up and it pulls hard when revving the engine. Once it heats up the cam rumbles nicely, no exhaust leaks, 55lbs of oil pressure on startup and then settles in about 25-30 lbs after oil heats up, actually engine sounds great once it's warmed up. However, on every occasion, when cold, the engine knocks for a bit and then it goes away. Yesterday, I removed the oil and found a marble size buildup (oil and I guess very fine metal material) stuck to the magnet of the oil pan plug. I took a paper napkin and wiped it off. It just smudged onto the paper towel, nothing solid. Is this part of the break in ware or should I be concerned? This is my first rebuilt motor and I am not sure what to expect. My engine builder said I did not have to adjust anything on the motor, valves, carb, etc.. everything was adjusted on the dyno. But, why would knock like when it is cold. My previous motor with similar build, never did this. Anyone have any ideas?

Here is a youtube video with the noise.

 

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I'd take it to them on a trailer, so its STONE cold when you get there, and let them decide to fire it up and see what their opinion is.
 

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When I built my 383 stroker I had this awful noise coming from what seems like the valve train. Thought at first I had really screwed something up. pulled the valve covers cranked it up and there was no noise. The rocker arms were touching cast aluminum valve covers. However the sound wasn't what I heard on your video. might not hurt to pull the valve cover and see what happens.
 
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