340 rings

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Johnschummer

Johnschummer

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Gentlemen,
Just got call that my 340 is done at the machine shop for my new to me 72 cuda. Block was .30 over prior and it was sonic checked and cleaned up at .40 over. I went with KB243 pistons and on Mancini website they call for 4000AM8 rings. Searching these rings I notice they will list at 4000AM8.030 which shows for bore of 4.030. I am assume I will need 4000AM8.080 since 340 is 4.04 +.040 over bore. Am I correct it saying this?
 
Also I will note, not sure if the pistons came with rings. When I got them I just made sure there was an .040 on the pistons and gave them to the machinist. Could have been underneath them in box but I doubt it.
 
Johnschummer said:
Also I will note, not sure if the pistons came with rings. When I got them I just made sure there was an .040 on the pistons and gave them to the machinist. Could have been underneath them in box but I doubt it.
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A standard 340 has a 4.040" bore... At .040" over it will be 4.080" diameter...
 
Copy that and thanks. While I go you guys around how about bearings? On Mancini website for mains I see clevite 77 p series and sealed power being the cheaper. Building street motor, what do I need? Not afraid to buy more expensive ones. Same with rod bearing, they list clevite 77 p series and h series which say it’s nascar stuff. What are your thoughts on them.
 
I typically use full or half groove main bearings. Clevite brand bearings are my go to bearings. 65'
 
Johnschummer said:
Copy that and thanks. While I go you guys around how about bearings? On Mancini website for mains I see clevite 77 p series and sealed power being the cheaper. Building street motor, what do I need? Not afraid to buy more expensive ones. Same with rod bearing, they list clevite 77 p series and h series which say it’s nascar stuff. What are your thoughts on them.
Click to expand...

If you are using stock rods, they have an oil squirt hole... Not all new bearings have the notch for the squirt hole, make sure you get a set with the notch for the oil squirt hole to keep the bores oiled well...
 
krazykuda said:
If you are using stock rods, they have an oil squirt hole... Not all new bearings have the notch for the squirt hole, make sure you get a set with the notch for the oil squirt hole to keep the bores oiled well...
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I cut the notches into mine with a small file since they were missing.
 
CFD244 said:
I cut the notches into mine with a small file since they were missing.
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You have to be careful not to raise a burr when you do that so you don't score the crank...

A burr in the front side will score the crank, a burr on the back side will make the bearing tight and cause more resistance for the crank to turn or even lock the crank up...

It doesn't take much for a bearing to get tight, I've seen a small speck of dust or string from a cotton glove lock up a crank due to the interference it causes with the bearing on the front or back...

It's best to get them from the manufacturer...
 
krazykuda said:
You have to be careful not to raise a burr when you do that so you don't score the crank...

A burr in the front side will score the crank, a burr on the back side will make the bearing tight and cause more resistance for the crank to turn or even lock the crank up...

It doesn't take much for a bearing to get tight, I've seen a small speck of dust or string from a cotton glove lock up a crank due to the interference it causes with the bearing on the front or back...

It's best to get them from the manufacturer...
Click to expand...
Absolutely agree. I did this with the precision of a surgeon using needle files. Always stroked away from the inner side, and cleaned up the back side when I was done. It took me a while that's for sure.
 
The machine shop should have used the new pistons to bore and hone the block to size correctly. And then file fit the rings for each piston for each bore for you.
 
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