512 B Underway

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RAMM

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Picked up an assembled longblock 400 last week and after disassembly and degreasing in the jet wash--blasting took care of the paint/rust and really caked on muck. I really like clean castings to work with. Spent the morning on this block--removing dowels, tapping all holes, light deburring, clean up cam bores, stroker notches, enlarge oil pickup to 1/2" and since this is a manual tranny--I drilled the thrust bearing for oiling (1/16". I have a full 8 hours on this and the real machining isn't started. All pre-machining prep. I will weigh this one tomorrow. Some pics of the progress. J.Rob

thrustwork.jpg


holeintersection.jpg


thrusthole.jpg


blockside.jpg


blocksaddleshot.jpg
 
So I couldn't wait to see what this 400 block weighed--while I was at it I weighed a '83 318 block oh and a 1993 360 Magnum crank weighed 58 lbs. J.Rob

400blockscale.jpg


318blockscale.jpg
 
Do you drill both sides of the thrust bearing/saddle? I definitely want to do that mod on my next build.
 
Sorry,
Do not see any benefit from the extra hole. And it weakens the block, because when you drill a hole in something, you weaken it. Thrust faces already get pressurised oil.
 
Bewy said:
Sorry,
Do not see any benefit from the extra hole. And it weakens the block, because when you drill a hole in something, you weaken it. Thrust faces already get pressurised oil.
Click to expand...

Old hemi trick was to put a bigger/deeper chamfer in the oilng grooves, still tappered like stock--worked too ,and didn`t weaken anything .
Back side only.
 
Bewy said:
Sorry,
Do not see any benefit from the extra hole. And it weakens the block, because when you drill a hole in something, you weaken it. Thrust faces already get pressurised oil.
Click to expand...

No need to be sorry its your opinion. My opinion is based on experience and this is a worthwhile procedure especially in a manual transmission application.
Please explain how the thrust faces gets pressurized oil. J.Rob
 
RAMM said:
No need to be sorry its your opinion. My opinion is based on experience and this is a worthwhile procedure especially in a manual transmission application.
Please explain how the thrust faces gets pressurized oil. J.Rob
Click to expand...


The only way the thrust gets pressurized oil is to drill that hole. Otherwise the thrust gets fed by the leak from the main bearing.

So what you are doing is the most simple, easy way to get pressurized oil to the thrust. I can’t see how that small hole would cause a block failure.
 
yellow rose said:
The only way the thrust gets pressurized oil is to drill that hole. Otherwise the thrust gets fed by the leak from the main bearing.

So what you are doing is the most simple, easy way to get pressurized oil to the thrust. I can’t see how that small hole would cause a block failure.
Click to expand...

Yup, you're relying on splash and overflow just like my 3600 rpm Briggs & Stratton. A hole 1/16 or .0625" is tiny, I have zero concerns. J.Rob
 
The thrust brg ALREADY gets pressurised oil without drilling holes. The escape path for the pressurised oil that enters the journal....is past the thrust flange. If there was zero endplay & no scallops in the flanges, there would be no oil flow out of the brg, no fresh oil able to enter the brg....& it would overheat & fail.
 
Bewy said:
The thrust brg ALREADY gets pressurised oil without drilling holes. The escape path for the pressurised oil that enters the journal....is past the thrust flange. If there was zero endplay & no scallops in the flanges, there would be no oil flow out of the brg, no fresh oil able to enter the brg....& it would overheat & fail.
Click to expand...

I understand how a thrust bearing is supposed to work, I have also seen several inexplicable thrust failures, mostly in Fords (thrust on #3) one 318 and one 360. This mod ensures a good supply of oil.
Don't like it- don't do it, don't like this thread- don't open it. J.Rob
 
yellow rose said:
The only way the thrust gets pressurized oil is to drill that hole. Otherwise the thrust gets fed by the leak from the main bearing.

So what you are doing is the most simple, easy way to get pressurized oil to the thrust. I can’t see how that small hole would cause a block failure.
Click to expand...

The old way I described , works.---Tom Hoovers idea !
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How much clearance is between the back of the main bearing and the saddle ?
 
Last edited:
RAMM said:
Yup, you're relying on splash and overflow just like my 3600 rpm Briggs & Stratton. A hole 1/16 or .0625" is tiny, I have zero concerns. J.Rob
Click to expand...

What kind of trust bearing has no oil champers to the sides , all I have ever messed with do !-chevy , 440 , hemi !
 
Question Ramm. 440 Source sells a long drill bit for that they recommend to drill from galley to mains for better oiling. Don't think they mention size. Do you recommend this mod along with the added small thrust hole & 1/2" pickup? I'm about to start on 400/470 build for the drag car next week and would like to cover all the small oiling mods while the block is getting prepped for me.
 
80fbody said:
Question Ramm. 440 Source sells a long drill bit for that they recommend to drill from galley to mains for better oiling. Don't think they mention size. Do you recommend this mod along with the added small thrust hole & 1/2" pickup? I'm about to start on 400/470 build for the drag car next week and would like to cover all the small oiling mods while the block is getting prepped for me.
Click to expand...

I use a long 9/32" and I forgot to show that. Thanks for the reminder. J.Rob
 
Ramm,
I have heard of, & seen, inexplicable thrust failures...on many engine brands. I am not sure if anybody really knows the cause. Some engines with GM T400 trans seem to suffer more than those with GM T350. One line of thought is some form of pressure problem in the T400 cooling cct, that causes back pressure & some builders put a restrictor in the coolant line. many theories out there....

I do not think you are properly thinking through this mod. The mains supply that you have drilled into also supplies two rod brgs. Any bleeding off of that supply reduces oil getting to those rod brgs. If you look at used t/brgs, you see wear on both sides. Thrust clearance on Ch engines is 0.002 - 0.010". If the clearance is on the larger side & the crank is away from the thrust brg on the hole side, you have a large 'leak' through a 0.010" gap. The t/faces already get pressurised oil without extra holes, which is probably why no engines have extra holes.
 
Bewy said:
Ramm,
I have heard of, & seen, inexplicable thrust failures...on many engine brands. I am not sure if anybody really knows the cause. Some engines with GM T400 trans seem to suffer more than those with GM T350. One line of thought is some form of pressure problem in the T400 cooling cct, that causes back pressure & some builders put a restrictor in the coolant line. many theories out there....

I do not think you are properly thinking through this mod. The mains supply that you have drilled into also supplies two rod brgs. Any bleeding off of that supply reduces oil getting to those rod brgs. If you look at used t/brgs, you see wear on both sides. Thrust clearance on Ch engines is 0.002 - 0.010". If the clearance is on the larger side & the crank is away from the thrust brg on the hole side, you have a large 'leak' through a 0.010" gap. The t/faces already get pressurised oil without extra holes, which is probably why no engines have extra holes.
Click to expand...

I've done this so many times now I've lost track. I've had the opportunity to inspect the bearings many times over the years--all of them look brand new-as in never touched-no evidence of contact that I could see. As for the rod bearing concern--I ain't building 10'000 rpm engines over here, rarely above 6500rpm-again not a concern. J.Rob
 
80fbody said:
Thanks Ramm. Going to get that drill bit and add that to the list of mods to do.
Click to expand...

I still think that the crush thats designed into bearings would not leave much clearance for oil to escape thru the hole . I like the chamfer increase in the
oil pockets that are already there , leaving the farthest outward edge alone , creating a bigger oil pocket between the crank and bearing thrust surfaces. . Worked on a 6500-7000 rpm hemi , and was suggested by Mr. Tom HOOVER himself , and there was no one that knew more about a hemi than him ,the whole deal was his idea , and he was in on the development all the way .
 
There is some good info about the causes of thrust brg failure on motor.com.
 
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