I just picked up a 425 Big Block for a build I am doing, putting it in a 1963 C20 pickup. The motor came with a TH400 transmission - pretty sure these are three speeds.

The engine block code is 386525A, so everything I have read leads me to believe it is a 1965 425.

Definitely need to rebuild this thing, just not sure the best route to take. I need to find a decent engine machine shop near me. I had a Ford 460 rebuilt at L&R Engine in Santa Fe Springs CA last year, but have not had a chance to get it fired up yet. They did take a long time, so hoping to find a place that may do it a little quicker.

I'm not looking for a crazy build, although I do want it to sound good. Reliability is key for me. Do you guys get pretty wild with the cams you put in your motors?
Looking for suggestions either way.

Thanks!

 

This engine has a 45 degree cam angle so be sure to get a correct cam, most Olds BB use a 39 degree.

 

If this is going in a 3/4 ton truck ( which is no kind of racecar ) probably a " torque " cam.
It's probably best to talk to a couple of cam makers, tell them what you have and what you expect to do with it.
And they can recommend the right cam.

 

If the TH400 is original to that engine it is a "Switch Pitch" variable vane torque converter, that is nice to have. Yes, they are 3:speeds
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Or get with Mark ( @cutlassefi on this site). He's sort of the forum's resident Olds engine build/camshaft guru.

 

That would have been awesome, however, it is not a switch-pitch.
It only has one prong on the electrical connector.

 

I did find the head casting number - it's only on one of the heads which I heard is normal.
N027585

 

some pics.

 

That’s not the head casting number, it’s the engine assembly number that is stamped into the head ID pad. Those are A heads which are correct for that year engine.

 

Where are the other numbers located?

 

ok - this must be it 383821.

 

Well, I decided not to rebuild this 425; I am better off buying a crate motor for my C20 pickup. I'm sure the rebuild would cost a bunch more than a crate motor.

Any idea if there's a market for a big block 425 that needs a rebuild?

EDIT: I also have a TH400 transmission (not a switch-pitch).

 

Which block do you have ? What size valve lifters ? What lifter bank angle ? 39 or 45 degrees ?

 

It's an A block, and there are some numbers in the previous posts.
I am not sure how to determine if it is 39 or 45 degrees.

 

When you get the lifter size/bank angle thing sorted, I am sure somebody will want it. There are people who will tell you the 425 is the best engine Olds ever built.

 

Now I am wondering if this is a 425 or maybe a 401? I heard from some guys that the only 425s that Buick made were Nailheads - is this true? I know I don't have a Nailhead.

The engine block code is 386525A.

 

Umm ... you mean you think maybe it's a Buick?

Could you post a picture?

 

Ok. My mistake. I got confused - was talking to some guys on a Chevelle forum, and forgot that I have an Olds big block, not a Buick.
Wow - I feel dumb.

 

Probably not as dumb as I felt a few minutes back.

 

386525 A is the casting number for 1965 Olds 425 engine with .842 dia. lifters and 45 degree lifter bank angle.

 

If I did decide to rebuild this 425, would I be better off with the stock intake manifold or an aluminum one like Edelbrock?

 

For what you're going to do, the stock manifold will be best.
An Edelbrock will be a waste of money. Unless all you want to do is look cool.