The 340 is out....again.....

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Did I miss it? I don't see anywhere in this story a question or a statement about oil pressure. Was there a gauge? Was there pressure? Was it steady or fluctuating? Just curious.
 
LOL, no worries, Gents; I do appreciate the discussion, not taking the heat at all.
On a side note, here's some photos of the new lower radiator support from XV Motorsports, in place on the Dart:

Dart Four.JPG


Dart One.JPG


Dart Three.JPG


Dart Two.JPG
 
was it a stock shielded round pickup, they are, as has been said O K for the shield to touch the pan, cuz the screen/inlet is about 3/16" above. running a high volume pump? cuz I question if a stock pickup has a large enough area inlet for a high volume pump. performance aftermarket pickups like moroso and canton have larger area and no shield, they need to be 3/16" to 1/4" off the pan
 
Marcohotrod said:
was it a stock shielded round pickup, they are, as has been said O K for the shield to touch the pan, cuz the screen/inlet is about 3/16" above. running a high volume pump? cuz I question if a stock pickup has a large enough area inlet for a high volume pump. performance aftermarket pickups like moroso and canton have larger area and no shield, they need to be 3/16" to 1/4" off the pan
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It was a stock pickup.
The oil pressure gauge consistently showed great pressure throughout the driving time before the knock showed up and ruined the party. It gave me no indication there was a problem brewing.
 
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340_dart_power said:
It was a stock pickup.
The oil pressure gauge consistently showed great pressure throughout the driving time before the knock showed up and ruined the party. It gave me no indication there was a problem brewing.
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So, did you actually figure out what did the damage? I'd like to know if you found something on autopsy.
 
The camshaft bearings were destroyed. The camshaft dug down into them instead of riding along on top of them.
It also turned out that the old shop did an overbore of .033 instead of .030, which wasn't a really good combination to have with the .030 pistons.
It now has an overbore of .040 with .040 pistons, and the math works it out to be a 340 stroked to a 418.
Really, and I mean really, looking forward to firing it up and driving it.
 
I think you can cross the pickup off your list as being the issue; at least its position on the pan from what can be seen on the pan bottom.

How did the main and rod bearings look? This is fairly important to know to try to figure out the probable cause. I apologize if you answered this before; I have just missed it if you did.

Edit: And actually, the answer to that question has been right before my eyes all along. In the 3rd pix you show, there is a pair of rod bearings lying in front of the 2nd piston from the right. It is badly worn, down to the copper....ow! This may have actually been the knock that you heard. That same pix also shows full groove mains; they are showing the start of some wear. Both look to be due to the lack of oil.

Were all of the cam bearings damaged the same?
 
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Things I would like to know: What oil pressure did you have, cold and hot? And in particular, hot at idle? What oil weight were you using? Filter brand, part number, and size? Lifter brand and model? Were there grooved cam journals or cam bearings? Just thinking of anything that has to do with the oiling system....

Is there a new oil pump in your new build?
 
Question? Not a statement. Possible cam bearings clocked in wrong? Shows good oil pressure but starves the bearings of oil?
 
Blind Squirrel said:
Question? Not a statement. Possible cam bearings clocked in wrong? Shows good oil pressure but starves the bearings of oil?
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I know some people like to put restricters in the oil feed up from the main to cam bearings. That's a bad idea because the factory system is phase built in restriction based on RPM (time).
 
I don't have enough information but based on the limited information we have of good oil pressure, as the OP noted, and eating the cam bearings. I have to go with an oil restriction somewhere. If the cam bearing holes where misaligned with the holes in the block. Could this still show good pressure but not have any to some critical components like the cam. Is the supply for the oil pressure gauge upstream or downstream from the toasted bearings?
 
It was eating more than the cam bearings... look at all of the bearings in the 3rd photo provided by the OP in his original post, and, in particular, the rod bearing pair in front of the 2nd piston from the right. Almost all of the bearings are showing signs of oil starvation or something that was badly effecting the bearing surfaces.

I have to wonder if the oil gallery plugs have been left out of the front of the block.
 
chrysler did not put plugs in the front ends of the block, they were covered by the cam thrust plate, works for me. if the cam bearing oil holes were off, she would show more pressure on the gauge
cam plate.jpg
 
nm9stheham said:
It was eating more than the cam bearings... look at all of the bearings in the 3rd photo provided by the OP in his original post, and, in particular, the rod bearing pair in front of the 2nd piston from the right. Almost all of the bearings are showing signs of oil starvation or something that was badly effecting the bearing surfaces.

I have to wonder if the oil gallery plugs have been left out of the front of the block.
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I didn't see the 2 loose bearings laying on the table. Those look like no oil. The bearings in the rods look weird as well. The cap bearings looks bad.

If nothing else, the lifter bores may be too loose. But the oil was going somewhere other than where it should have.
 
When the motor was assembled/cleaned/ whatever during the rebuilding phase were any components Glass Beaded?

JW
 
SLOPAR72 said:
When the motor was assembled/cleaned/ whatever during the rebuilding phase were any components Glass Beaded?

JW
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That I do not know. I believe the shop which rebuilt it originally just didn't have the Mopar engine knowledge base they thought they had. Typically they are rebuilding Chevrolet/GM/Ford engines, and my guess is that they just missed some of the differences involved in rebuilding the 340.
The shop which has it now has a history of working on Mopars so hopefully this is the last time I have to pay for a rebuild.
 
Latest rebuild resulted in the same damage to the camshaft bearings after being run for awhile, so the block and heads are back at the machine shop. The current suspicion is that the Edelbrock Performance heads may be to blame in some fashion. No end in sight at this point....
 
340_dart_power said:
Well, after hearing a brand new (and alarming) knock coming from the 340, it was pulled Monday and discovered to have the camshaft bearings coming apart. Without going into the whole story, I had a garage rebuild it for me several years ago and it appears that their skills were lacking.
We're going with a new stroker kit to really strengthen it and get more ponies out of it.
I'll keep you posted as it progresses. Wish me luck. View attachment 1714967763 View attachment 1714967764 View attachment 1714967765 View attachment 1714967766
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very nice father and son photo. he'll be driving that dart very shortly.
 
340_dart_power said:
Latest rebuild resulted in the same damage to the camshaft bearings after being run for awhile, so the block and heads are back at the machine shop. The current suspicion is that the Edelbrock Performance heads may be to blame in some fashion. No end in sight at this point....
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THAT sucks!
 
How tight was the cam before you ran the motor? Did it spin easily by hand?

When I built my 340 in 2015 I knew the cam was tight but there wasn't much I could do about it at the time. Ran it for a while and pulled it and tore it down due to an unrelated knock. The cam had self clearanced and now it spun great in the cam bearings...which was not a good thing. The cam didn't want to come out. When I pulled the cam out, one of the bearings came out with it and it was NOT pretty. There were metal shavings clogging up the oil holes in the bearing and it wore down the cam journal as well. Luckily it didn't spin in the bore. When I had the machine shop install new cam bearings they had to hone the bore to get the new cam bearings to fit right because it was a TIGHT fit.

Oh, and it made enough shavings to trash my bearings!

Your issue could be non-related to oil if the cam was too tight to begin with. Just something to think about.

Good luck and I hope you find the issue!
 
RPM heads will not affect the lower end. The lower end affects the lower end. What were the clearances on this last rebuild? Was the camshaft changed during the 2nd rebuild? What had to be done to the cam bearings during asembly to allow the cam to turn? What did the mains and rods look like upon disassembly? Was the timing set re-used? Was the oil pump re-used? Was the block magnafluxed this second time around?
Two lower ends have been damaged the same way. The shop did not actually find and fix the original cause.
 
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