[abefromen]

This vid is right after the cam break in..........

https://www.youtube.com/watch?v=6gMrPfenKjU

Zero miles on this engine. Break in went well with 30 weight break in oil for 25 minutes at 2K RPM.

Filter cut open after break in. Other than a lot of dirt and grit that shouldn't have been there I didn't see anything problematic. Obviously it was poorly cleaned.

This thing rattles and knocks so much at idle it's obvious it isn't right. I've heard diesel engines that were quieter.

Engine was bored .040 over and fitted with SRP forged pistons part number SRP153983
These are 4032 pistons and SRP recommends clearance for these at .0030-.0035 with a 4.200 to 4.600 bore range.....and .0020-.0025 with a 4.000 to 4.200 bore size.

Even though this is a low compression stock cammed grocery getter engine, bone stock in every way, and telling the builder I wanted quiet pistons, the builder for whatever reason set these up with .005 clearance.....I questioned this and was told:

"Tight piston clearance cause many issues such as over heating, the potential for rings to stick, loss of power and premature wear.
You need to have confidence in my ability to engineer a quality engine build. The extra clearance built in was .001”.

That's all fine and dandy but these were set up beyond recommended specs.

Unfortunately it has to come out and done over because the noise is extremely objectionable.
Oil pressure at hot idle is an ok 20 PSI with the 30 weight break in oil. Changing it to 10-40 after break in yielded a few extra psi.

Rods and mains are also set a little on the wide side too at .0028 and .0032 respectively.

I would like opinions as to the noise although I am guessing it's the pistons, idk.

Before I ran it I contacted a few builders who specialize in Pontiacs, including Butler, and ran the piston clearances past them.........they all questioned why it was done this way on a low perf non race engine and said I may hear them.

It was run with belts off too and the converter disconnected and it was the same, although I knew that was not the issue because the accessories and torque converter were run on the engine before it was removed for the rebuild and everything was totally quiet.

[PontiacJim1959]

Hmmm. the .040" bore puts you at 4.160" so that falls into the 4.00-4.20" bore and clearances of .0020 - .0025" Looks like he has doubled it. If you plan on running nitrous which really heats pistons up and needs extra wall clearance, I think you have too much. He is correct on his reasoning if the pistons were too tight. But, doesn't seem yours are.

The .028" and .032" on your bearing clearances are also a bit on the high side for a grocery getter. With those numbers, in my opinion, you will want at least a 15w-40 oil or even a 20w-50 oil. The 30w oil may be too thin, but then as you go thicker on the oil, such as 20w-50, you can have issues with the hydraulic lifters not bleeding down fast enough depending on the brand. The thicker oil will up the oil pressure as you found out. 20 hot should be fine at idle, with idle not being too low with those bearing numbers - might want to try something like 750 RPM if manual trans or in Drive if automatic as long as the car does not creep or you have to use some effort to keep the car from moving forward. Pontiac rates their oil pressure at 2,600 RPM's where you should see 55-60 PSI hot if you have the 60 psi oil pump.

[abefromen]

Originally Posted by PontiacJim1959

Hmmm. the .040" bore puts you at 4.160" so that falls into the 4.00-4.20" bore and clearances of .0020 - .0025" Looks like he has doubled it. If you plan on running nitrous which really heats pistons up and needs extra wall clearance, I think you have too much. He is correct on his reasoning if the pistons were too tight. But, doesn't seem yours are.

The .028" and .032" on your bearing clearances are also a bit on the high side for a grocery getter. With those numbers, in my opinion, you will want at least a 15w-40 oil or even a 20w-50 oil. The 30w oil may be too thin, but then as you go thicker on the oil, such as 20w-50, you can have issues with the hydraulic lifters not bleeding down fast enough depending on the brand. The thicker oil will up the oil pressure as you found out. 20 hot should be fine at idle, with idle not being too low with those bearing numbers - might want to try something like 750 RPM if manual trans or in Drive if automatic as long as the car does not creep or you have to use some effort to keep the car from moving forward. Pontiac rates their oil pressure at 2,600 RPM's where you should see 55-60 PSI hot if you have the 60 psi oil pump.

No nitrous or racing. It's nothing more than a highway cruiser.

Oil pressure seems ok at idle and raised RPM.....goes up to around 70 psi when the rpm's are brought up.

[punkin]

Do you have oil flowing up through all rockers? Any chance you forgot to install the rear oil galley plug on the back drivers side...the one hidden under the water jacket plug.

[abefromen]

Originally Posted by punkin

Do you have oil flowing up through all rockers? Any chance you forgot to install the rear oil galley plug on the back drivers side...the one hidden under the water jacket plug.

Yes no problem with oil flow........plenty when primed with drill and when covers were removed after break in. The noise is ALL bottom end.

Hidden plug is in.

[PunchT37]

Sounds exhaust to me. Cracked manifold, doughnut gasket, heat riser rattle, etc.

[abefromen]

Originally Posted by PontiacJim1959

If you plan on running nitrous which really heats pistons up and needs extra wall clearance, I think you have too much.

Exactly what the piston manufacturer told me:



"If we recommended .0030 - .0035 then I would have set the clearance up at what we recommended unless you are planning to add a bunch of nitrous or boost"

[Jay S]

Sorry your having issues. FWIW...I was looking at a Ram AIR 4 that was being racing with a set of TRW domed forged pistons. Someone had it set up for .010-.011 pistons clearances. Also have had some race engines run quietly yet at .004-.005 oil clearance.

If you have decent oil pressure I think the rotating assembly might be the the wrong place to lay blame. Usually bearings noise get louder or change sound on acceleration or deceleration.

While it could be something in the bottom end, make sure you have no exh leaks, no valve terrain issues, and nothing hitting somewhere.

Could take a valve cover off and make sure oil is getting pumped up to the top of the engine and make sure nothing is loose.

[PunchT37]

Top engine sounds fine in the vid. Sounds like a stock 400.

[Scott Thelander]

I am no musician...
but
I seem to hear 3 noises ....
a come and go heavy knock
a consistant softer ratle knock .... my 400 chevy makes
and a possible exhaust leak muffled tick

[abefromen]

Originally Posted by PunchT37

Top engine sounds fine in the vid. Sounds like a stock 400.

Agree. Standing up top and listening it's quiet........move to the side by the wheel and down low near the ground and it's rocks in a coffee can in a clothes dryer.

Raise RPM a bit and it seems to quiet down. Back to idle and it's terrible. Almost afraid to run it more to check some things.

[abefromen]

Originally Posted by Scott Thelander

I am no musician...
but
I seem to hear 3 noises ....
a come and go heavy knock
a consistant softer ratle knock .... my 400 chevy makes
and a possible exhaust leak muffled tick

One thing is certain, at least to me......the noises are not side specific. It's equally as noisy whether I am on the left side of the car or the right side....or the front of the car.

[PunchT37]

Maybe dump a small stream of trans oil down the carb while it`s running. Get a good light and check for smoke coming from around the doughnuts or the manifold gaskets. In the dark with the light might be a good time to do this.

[mgarblik]

The rotating assembly sounds loose to me, from what you said the clearances are too from the sound on video. If you think there is any chance exhaust leak is involved, see if you can borrow an EVAP smoke machine and smoke the exhaust system for leaks. Much less intrusive than dumping ATF or something in the carb. If you don't mind, what pistons are you using, manufacturer, type and part number would be great. Cast pistons at .005 clearance will be noisy and could break skirts down the road. Typical forged pistons at .005 may make a little noise cold but will quiet down when they heat up. If you want to do a little experiment to isolate piston slap from bearing noise, drain the oil and refill with straight weight SAE 50 oil. Start the engine. If it's bearing noise, it will be much quieter at least until it gets up to operating temp. If it piston to wall noise, there will be very little change . Sorry you are having trouble.

[PontiacJim1959]

Can you ask the engine builder to swing by your home and have him listen to it? Might be better than trying to figure out what it could be. I am sure he would rather listen to it and have to pull it down than to keep running it and it blow up and do damages that you may not be able to find later and him blaming you for one thing or another and not accepting any responsibility.

I'd give him the benefit of the doubt at this point. Myself, I have a tendency to over react and wind up with egg on my face or both feet in my mouth.

[mchell]

“ Filter cut open after break in. Other than a lot of dirt and grit that shouldn't have been there I didn't see anything problematic. Obviously it was poorly cleaned.“

Wo...... I wouldn’t be surprised that it’s ratting based on the above statement.....hope the builder stands by his work

[Dragncar]

Originally Posted by mgarblik

The rotating assembly sounds loose to me, from what you said the clearances are too from the sound on video. If you think there is any chance exhaust leak is involved, see if you can borrow an EVAP smoke machine and smoke the exhaust system for leaks. Much less intrusive than dumping ATF or something in the carb. If you don't mind, what pistons are you using, manufacturer, type and part number would be great. Cast pistons at .005 clearance will be noisy and could break skirts down the road. Typical forged pistons at .005 may make a little noise cold but will quiet down when they heat up. If you want to do a little experiment to isolate piston slap from bearing noise, drain the oil and refill with straight weight SAE 50 oil. Start the engine. If it's bearing noise, it will be much quieter at least until it gets up to operating temp. If it piston to wall noise, there will be very little change . Sorry you are having trouble.

The 461 I am doing right now calls for .004 piston to wall with Ross pistons. Instructions say if hard blocked to add another .002. My block is filled so I had it set up at .006. I expect to hear the pistons until it is warmed up. Dan told me I would. I have to add another .002 ring gap for the filled block too.
Instructions also said is spraying it to add another .002 clearance. Good thing I hate NO2.
I plan on running 15-40 or 20-50 oil.

It sounds like the OP and builder may have got their signals crossed. Hope it all works out.

[steve25]

Please explane fully what you mean by dirt & grit?

In my time I have seen motors rebuilt in which the shop that did the cleaning and machining work left glass bead in the block & oil passages .

Many times the glass bead was stuck to sludge in the oil galleries that did not get hot tanked out with the result that the glass bead came loose once oil was pumped over them and within 10 minutes of the new motor running took out the Bearings , chewed up the Pistons skirts and wipped out the rings!

[abefromen]

Originally Posted by mgarblik

If you don't mind, what pistons are you using, manufacturer, type and part number would be great.

Engine was bored .040 over and fitted with SRP forged pistons part number SRP153983
These are 4032 pistons and SRP recommends clearance for these at .0030-.0035 with a 4.200 to 4.600 bore range.....and .0020-.0025 with a 4.000 to 4.200 bore size.
When I contacted the manufacturer they stood by these specs for my particular application.

Even though they are set up well beyond spec there is an awful amount of down low racket for pistons set up too loose......I wouldn't think they would be this loud but what do I know,,,,,,,but for sure something is wrong somewhere obviously.

[abefromen]

Originally Posted by steve25

Please explane fully what you mean by dirt & grit?

I'll post a pic of the filter media.

I'm just sick over all this. A lot of time, money and effort went into all this over almost a full year. Now it looks like I still won't be able to enjoy the car this summer. Not to mention pulling engines out and putting them in is getting harder and harder for me to do alone.

Pulling it again is the last thing I need.

If anyone has a decent 400 short block for a reasonable cost I can use as a temporary engine while this one is sorted out PM me. Otherwise the car will sit again for a long time and I want to enjoy it. I'm in NW Illinois.