[beertracker]

Found a 400 with block casting number 488988? Is this one of the thin saddle blocks? I found it referenced at

http://www.wallaceracing.com/blockcastnum.htm but nothing on it's desirbility or strength.

[Bermuda Blue]

the blocks with a casting # ending in 557 (don't recall the entire number) are the ones to avoid for high HP builds. the one you reference is "good" one.

[ponyakr]

I read somewhere that some think that 488988 number was a mistake somebody made when casting that batch. Some sites show the 481988 used in early '75 models--some the 488988, then switching to the 500557 sometime later in the model year.

Here's a quote from the Wallace site.

"Block Casting # 488988 - these were possibly miscast block codes in 74?"

http://www.wallaceracing.com/enginesearch4.htm

Don't know if it was somebody's mistake or not. But, they do exist.

This site shows the 488988 was used in all '74 models, then switched back to 481988 for early '75 models.

http://www.teufert.net/pontiac/bloccast.htm

My wild guess is that some guy did make a mistake on one batch of blocks, and they were used til gone. Then, at least one more batch of 481988 blocks were cast, which were used up during the '75 model year. Then they started using the 500557 blocks. But, who knows for sure ?

Just out of curiosity, what is the date code on your 488988 block ?

The Wallace site asks for pics of these blocks.

"... email me pics of these please "

[ponyakr]

Here's another wrinkle. This Ebay engine has a 488988 casting number. But, it has a 5 0 cast in the lifter valley, indicating that it is a 350 engine. Also appears to have 350 pistons. The Wallace site shows that all '73 model 350's used casting # 488986 blocks. But, in the pic posted, that last # is clearly an 8, not a 6. So, it would appear that one of the numbers is wrong--OR, the guy posted pics of 2 different engines. He also states that it is a '74 400 engine. But the date code seems to indicate that it was cast in late '72 & used in a 73 model car.

http://www.ebay.com/itm/Pontiac-400-...-/112045842869

So, is this a 350, cast in '72, with a 488988 casting number ? If not, what is it ?

[gene simmons]

Petes book refers to a 488988 block as a early 1975 400 and 488986 as 350's.

IMO its a early 1973 350,cast number 73 by the distributor and date code K-01-2 or 11-01-2,also because of the 50 in the center and the amount of area there is between the cylinders,even at 0.030,compared to a 400. Just saying.

Ask the seller to measure the cylinder bores.

I owned early and late 1975 400's. Mid year seemed to be when pontiac went to the thin main webbing #500... The early 75 block had the thicker main webbing and the 488988 casting number