How to I.D. a 400 cid

[Dafey]

I think I have a 400 according to the Vin ,the 3rd letter is a R.How can I tell with out seeing behind the drivers side of the motor (I'm disabled ,its too hard for me to crawl up in there )I haven't done a tune up yet,but it runs smooth it just has less power than Id expect from a 350 let alone a 400....Esp with headers and a 4barrel.My guess is the PO didn't re-gear it [which I haven't had time during the day to check either ].If some one has a clear pic of a certain part of the motor for me to compare it too Id be very grateful

 

[goldwing2000]

Look for an externally balanced harmonic balancer, something like this:

Also, some 400s have three core plugs (freeze plugs) on the sides of the block.
Not all 400s have three but all that have three are 400s.

That's about it, short of getting the casting number or yanking off one of the heads and looking for steam holes.

 

[4X4HIGH]

The balancer on a 400 is 8" diameter and so are many 350's. The way to tell is by either looking at the backside of the balancer for a piece that is cast irregular (external balance) or the flexplate will have a weight welded to the engine side of it (external balance).

 

[54inches]

Well 400's only came in vehicles between 1970 to 1980.

Casting #'s:

330817......400...72-80...2
3951509....400...70-71...4
3951509....400...74-80...2
3951511....400...70-73...4

This is the best I can do for ya.

 

[Dafey]

Sorry 54 , mines a 77,so it still could be...I hope so.
And thanks guys !!

 

[Beast388]

Probably the easiest way for the novice to determine if he has a 400 or not is to look at the harmonic dampner, which is what all of the crank pulleys bolt too.

Since the 400 is externally balanced, the dampner will have some material removed around one side to act as part of the crankshaft counterweight.

Here are a few pictures of harmonic dampners for externally balanced engines:

This is what a dampner looks like for an internally balanced engine:

Hope that helps!






Edit: Dang I'm slow.

 

[goldwing2000]

Well 400's only came in vehicles between 1970 to 1980.

Casting #'s:

3951511....400...70-73...4

That's mine!

Out of a '72 Caprice. I still can't figure out why they put 4-bolt mains under a 2bbl carb, but I ain't complaining!

 

[Dafey]

Thats perfect Goldwing & Beast.Thanks!!
Shouldnt be hard to figure out. Getting under the front if I need to isnt hard.

 

[54inches]

You are very welcome....compliments of moretec.com

 

[4X4HIGH]

Thats perfect Goldwing & Beast.Thanks!!
Shouldnt be hard to figure out. Getting under the front if I need to isnt hard.

Geeze, thanks. I gave you the most accurate info and i'm not even recognized. Guess i should have posted a pic to go along with what i said, goldwing2000 had to edit his post to make himself look good though since i posted in this thread.

 

[goldwing2000]

Geeze, thanks. I gave you the most accurate info and i'm not even recognized. Guess i should have posted a pic to go along with what i said, goldwing2000 had to edit his post to make himself look good though since i posted in this thread.

Awww... poor widdle baby didn't get a pat on the back.

Whatever.

And just fyi, smartass, I edited my post after I went to summitracing.com and started looking up dimensions on harmonic balancers so I could make sure I wasn't giving erroneous information.

Yes, you should have posted a picture.
And no, your information wasn't any more or less accurate than anybody else's.

I don't know why you go around looking for shít to bitch about. Worse than a damn woman.

 

[Dafey]

The balancer on a 400 is 8" diameter and so are many 350's. The way to tell is by either looking at the backside of the balancer for a piece that is cast irregular (external balance) or the flexplate will have a weight welded to the engine side of it (external balance).

LOL sorry I was actually laying on the couch and dictated that to my wife to post,she told me two people posted pics and I told her to thank them...PLEASE forgive me

These are the best pics I could get today,does it help?

BTW does anyone know who this is,or I should say who made this trans?

Im thinking the PO just put in a 350ci/th350 combo to replace the blown up pair that was in there.Beacuse the tag in the glove box says it had a 400ci and a M40 turbo hydramtic in it [ is that a th400?].

And BTW again anyone know what a "UA1 4000 watt HD Delco F " is?

{more questions to come tonight when I figure some stuff out }

 

[Dafey]

LOL I think I need to make a "Questions/build" thread... What do ya think?

 

[3 on the tree]

I believe the 4000 watt Delco refers to the OE battery. For some odd reason, they used to rate them by watts.

 

[54inches]

If you look at the harmonic balancer, you can see where it is reliefed on one side, so this makes this an exterally balanced engine.....400.....

 

[Dafey]

I believe the 4000 watt Delco refers to the OE battery. For some odd reason, they used to rate them by watts.

Thanks 3 !

so this makes this an exterally balanced engine.....400.....

So I really do have a 400? COOL!!! Thanks dude!!!

Ok So what are these 3 other things guys? Besides the 4000 watt thing.
EDIT:Is that the tires? Also whats the N41 Variable raito power?The steering?

 

[4X4HIGH]

His picture does not show any relief on the balancer. He needs to rotate the engine 180* and snap another pic to confirm for sure.

 

[54inches]

I can see two reliefs in both pics and none 180 degrees from those reliefs which would indicate balancing.

 

[Dafey]

His picture does not show any relief on the balancer. He needs to rotate the engine 180* and snap another pic to confirm for sure.

Ok I`ll do that tomorrow and feel behind it also for the relief.I couldnt feel any on the flywheel , but I wasnt that far under it either.

 

[54inches]

Just as the 1st pic posted by beast 338 shows.

Small drilled relief.

Fairly clear to me, unless I am seeing something else.