[DK03]

I went to an estate sale and noticed a pile of parts in the corner of a barn. A couple of VW motors, heads, intakes and transmissions. At the bottom of the pile I noticed what looked like a Pontiac block. It was laying upside down and covered by the other parts. It had #46 heads on it. I was able to look at the engine code, but wasn't able to determine what it is. The code was 29P248521. I talked to the owner. He said he thinks its a 421 out of an old car his Dad used to have. Is there anyway to confirm this by the engine code? I wasn't able to see the casting numbers or any other numbers on the block. Let me know what you think it may be.

[mysticmissle]

Not enough info there for
Me to decode but it’s it’s likely a 400 but it could be a 428 assuming the drapes
Match the carpet
Most
Likely
It will
Be cheap. Don’t leave it regardless. It will
End up in a dumpster

[Singleton]

Probably a 1969 428 YH block if heads are original

[77 Canamman]

29P248521 is the partial VIN stamp on the block

2- Pontiac Motor Division
9- last digit of year. Since there is suspicion that this is a 428, the year would be 1969
P- Pontiac MI assembly plant
248521- last 6 digits of the vehicles ID number

[b-man]

It’s probably as already mentioned above a ‘69 428. The standard Bonneville 360 hp 428 had the low performance #46 small valve heads with press in studs, the block had 2-bolt main caps and 3 core plugs (freeze plugs) per side.

A 421 would have 4-bolt mains and 2-core plugs per side.

[unruhjonny]

double beat to the punch!!

That partial vin was a good thing to record;
The "9" indicates the model year;
If my memory serves me the number 46 was used in 1969 and 1973 - in both instances for a small valve configuration.

[DK03]

Originally Posted by b-man

It’s probably as already mentioned above a ‘69 428. The standard Bonneville 360 hp 428 had the low performance #46 small valve heads with press in studs, the block had 2-bolt main caps and 3 core plugs (freeze plugs) per side.

A 421 would have 4-bolt mains and 2-core plugs per side.

It did have 3 core plugs. Is there any other way to determine if it is a 428 or a 400? Going to try to make him an offer tomorrow.

[b-man]

There should be a ‘2’ and and ‘8’ cast in the lifter valley to designate 428 or ‘0’ and ‘0’ for a 400. Sometimes the side of the block will have 428 cast in it too, but if it’s too filthy you might not see it.

The main journal dialeters are 3” for a 400 and 3.25” for a 428, of course without bearings in place those measurements will be a little larger. Might be a good idea to bring a set of calipers with you to check the mains and also the bore size, 4.120” is standard for both 400 and 428 engines.

[hobbygto65]

There should be a 2 letter code just below the vin. That will tell you what it is.

[b-man]

Probably a YH code if it’s a 428.

I have one stashed under my work bench for a spare, probably should sell it.

[433lemans]

The 69 YH 428 blocks I've seen with two bolt mains were still drilled for 4 bolt main caps, 400's were not.

[DK03]

Originally Posted by hobbygto65

There should be a 2 letter code just below the vin. That will tell you what it is.

I looked for the two letter code, but there was none. That is what confused me. I wire brushed the entire front of the motor looking for it. Did they make any without the two letter code?

[Singleton]

Originally Posted by DK03

I looked for the two letter code, but there was none.

Look near the deck of the block above the timing cover

[1_Wild_Cat]

How about the casting numbers on the block next to the distributor hole? That should be easy to cross-reference.

[thepontiacman]

Casting number behind passenger head close to where trans/bellhousing bolts up to block. This will tell you for sure. take mirror since its upside down.

428 may be under or near motor mount.

400 or 428 worth getting/saving.

[johnta1]

As pontiacman said look for block casting # on bakc part of block, would be 9792968 if 428.

As Singleton says also, the engine ID on front is stamped so may be hard to see if paint covers it. (it would determine what it is also)

Having a partial VIN on it, it would probably have the engine ID code plus the EUN above the code. ( EUN = 7 digits)

[DK03]

Originally Posted by DK03

I went to an estate sale and noticed a pile of parts in the corner of a barn. A couple of VW motors, heads, intakes and transmissions. At the bottom of the pile I noticed what looked like a Pontiac block. It was laying upside down and covered by the other parts. It had #46 heads on it. I was able to look at the engine code, but wasn't able to determine what it is. The code was 29P248521. I talked to the owner. He said he thinks its a 421 out of an old car his Dad used to have. Is there anyway to confirm this by the engine code? I wasn't able to see the casting numbers or any other numbers on the block. Let me know what you think it may be.

Here is a pic I took of the engine code. The motor is sitting under a ton of stuff. I only had access to the front and part of the driver side. It is upside down, so was not able to see the casting numbers. Did they make a motor without the two letter code?

[johnta1]

Did they make a motor without the two letter code?

Not really? (for factory installed engines)

Here is a pic of where the info stuff is:

[bdk1976]

I'd assume it's a cracked 350 and pay him like its a boat anchor unless HE can confirm otherwise.

[Big Bear]

Looks like vin that is vertical beside timing chain cover and cover is missing. Code is on the passenger side just below the head.