You just answered your own question. Every person I've known that owned one of these cars in the 60's and early seventies had the same thing happen (although a lot of people spun mains). My next door neighbor owned a 69 W30. He sold it and the kid that bought it had it blown up in a week. One missed shift.

 

The reason that you spun the rod bearing was from lack of oil. These engines used a very high volume pump which would suck the pan dry at extended high RPMs. You have to open up the drain passages to get the oil to return faster to the pan and reduce the flow of oil to the rockers (you can purchase restricted push rods and cam bushing to assist). Also notching the sides of the con-rods helps to allow the oil to escape. Doing this will eliminate the starvation of oil in the pan during high RPM operation.

These engines will produce high hp/torque, great for the street and keeping your car original.

I will be switching to a lower highrise intake so I can run the original air cleaner in a couple of weeks, will let you know the dyno results at that time.

 

This was a big block problem not just a 400 big block problem.
I always felt that our 400 spun up quicker than 455 that we had.
I'm looking at a 69 442 on the weekend with the a original 400 engine. If I buy it I will take it to the track in the summer and see what it will do after some tuning.

 

Have you read BTR's engine building book? I just got a copy today its a good read.

Look forward to your dyno results and track times

 

What pistons are you using in your 4.00 inch bore 400 G block, custom or other ?

 

Diamond pistons, and I should be putting it back on the dyno next week, will let you know. Won't be going into the car until May or June when the body is completed.

 

Let me know what BTR's theory is in regards to the 400-455 spinning bearings?
and also if they mention the amount that the 400 can be bored out to safely?

 

For the engine not to spin bearings clearance must be larger than stock. Factory block,crank are weak and heavy pistons and rods + rods are soft. As engine rpm goes up the block flexes the crank flexes and the rods stretches. You end up with no oil between the rod bearing and crank or main bearings and crank. You have metal to metal contact. So to compensate for this flex,stretch,movement you need larger clearances.


This is my interpretation of what I read in the book.

I would get the book and give it a read and make your own interpretation!

The next engine I build will be with the guidance of this book
When Bill talks about weak he is talking HP engine builds not factory stock engines that stay with in normal rpm range.

 

Makes sense, I will let you know how my engine works.

 

Had the engine on the dyno on Friday and it pulled 455hp and just over 500 ftlbs of torque. strong pulls and oil pressure stayed in the mid 40 psi range.

Will post video and dyno spec sheets soon.

 

Very nice numbers for any Olds build.

 

Those are great numbers. I guess there is hope for that block I have sitting in a dark corner.

You should start another thread with the build details and dyno results.