Running Main Bearing Inserts To use A 383 Journal Crank In a 440 Block

-
PROSTOCKTOM

PROSTOCKTOM

FABO Gold Member
FABO Gold Member
Joined
Oct 8, 2013
Messages
1,552
Reaction score
1,504
Location
West Central Indiana
Has anyone here done such a thing in the past? I am thinking of doing such a thing.

I know that they were produced years ago, just haven't found any link tot hem today.

Tom
 
Last edited:
What is your objective in doing this? It has been done back when they were de-stroking pro stock HEMI engines in the 70's. I think the more accepted route was converting a 400 block to run HEMI heads.
 
It's done with small blocks, to run 318/340 journal cranks in a 360 block. Don't know why it couldn't be done with big blocks too.
 
PROSTOCKTOM said:
Thanks, but I am not interested in using a 400 block. My only intent is to slow the bearing speed.

Tom
Click to expand...
Tom, this confuses me. Since the 383 has smaller mains, don't they actually spin faster than the larger diameter 440 mains would?
 
RustyRatRod said:
Tom, this confuses me. Since the 383 has smaller mains, don't they actually spin faster than the larger diameter 440 mains would?
Click to expand...
Smaller diameter = less bearing speed.

Look at it like a merry-go-round, the people out at the ends are flying, the people in center are spining but not moving nearly as fast.
 
PROSTOCKTOM said:
At 6000 rpms it slows the bearing speed down 4.55% or 270 rpms at 6000 rpms.

Tom
Click to expand...
Thanks, Tom. Immediately after I posted that, I realized I was thinkin backwards. Not uncommon for me. lol
 
If you are worried about brg speed, never run a 421/428/455 Pontiac, they have 3.25" mains!

I wouldn't do it, hardly worth the trouble for 1/8" difference. I did a quick calc: brg speed is reduced by 4.6%.
 
MOPARMAGA said:
Will you have to machine those, or are those available in the aftermarket?
Click to expand...

They apparently were available years ago, but so far I haven't found a vendor that offers them today.

If necessary I can produce them, but would be time and money ahead if I can find someone that already makes them.

Tom
 
Apart from the miniscule benefit of reduced brg speed [ friction ], using an 'insert' is more likely to cause failed brgs. The brg shell transfers heat to the block/cap. Having another layer of metal there is going to reduce the amount of heat that can be transferred.
 
Bewy said:
Apart from the miniscule benefit of reduced brg speed [ friction ], using an 'insert' is more likely to cause failed brgs. The brg shell transfers heat to the block/cap. Having another layer of metal there is going to reduce the amount of heat that can be transferred.
Click to expand...
simple solution to that.
Heat the block to operating temperature and check the bearings clearances
 
I am talking about a running engine. In a running engine, the heat in the brg shell gets transferred to the surrounding metal. Ever see a brg shell fall out of it's location? That is because it overheated & the steel backing lost it's 'spring'.

You might use brg inserts on a rare vintage engine because that is all that is available, but there is a reason that inserts are not used when the correct brgs are available....
 
Bewy said:
I am talking about a running engine. In a running engine, the heat in the brg shell gets transferred to the surrounding metal. Ever see a brg shell fall out of it's location? That is because it overheated & the steel backing lost it's 'spring'.

You might use brg inserts on a rare vintage engine because that is all that is available, but there is a reason that inserts are not used when the correct brgs are available....
Click to expand...

Well if that were true the millions of 400 SBC blocks that used/ using inserts to allow the use of the 350 main cranks would have not last 40 years.

Those Saturday night stock car and bracket racing engine have flourished at much higher RPM's than required for my intended uses.

Tom
 
Bewy said:
I am talking about a running engine. In a running engine, the heat in the brg shell gets transferred to the surrounding metal. Ever see a brg shell fall out of it's location? That is because it overheated & the steel backing lost it's 'spring'.

You might use brg inserts on a rare vintage engine because that is all that is available, but there is a reason that inserts are not used when the correct brgs are available....
Click to expand...
I think your over thinking it.
 
PROSTOCKTOM said:
Well if that were true the millions of 400 SBC blocks that used/ using inserts to allow the use of the 350 main cranks would have not last 40 years.

Those Saturday night stock car and bracket racing engine have flourished at much higher RPM's than required for my intended uses.

Tom
Click to expand...
I worked on a dirt sportsman car pit crew years ago. We ran that set-up to create 377". We beat that thing HARD every week. I saw him skip it through the infield and the telltale tach showed over 9k! Never skipped a beat. One of the fastest cars in the field every week.
 
PROSTOCKTOM said:
Has anyone here done such a thing in the past? I am thinking of doing such a thing.

I know that they were produced years ago, just haven't found any link tot hem today.

Tom
Click to expand...
Based on what I read your intentions to be, RESPECTFULLY, I feel you'd be focusing a lot energy in an area that will show NO benefit. But worse it opens up the possibilities of something else going wrong. So many other areas you can focus attention (time/$$$) on for gains. Or said differently plenty of low-hanging fruit elsewhere.
 
You must log in or register to reply here.
-

Back
Top