Pontiac GTO Forum banner
1 - 3 of 3 Posts

· Registered
Joined
·
488 Posts
Heads are definitely 1969 but the YH code 428 would be 1968 block. Did you happen to note the block casting date by the distributor? One of the photos shows that the caps are not on the block and wondering if you found them? Not the end of the world if missing but will add to the build costs finding either an original donor set or a billet aftermarket set and either will require a line bore. Original caps should be 4-bolt on a YH block which would be great. 428 blocks were some of the beefiest blocks Pontiac produced and as Jim said, looks like no core shift that plagued some of the later 455's.

Not a big fan of 46 heads, but a nice set of aluminum heads would make that shortcoming go away.
 

· Registered
Joined
·
488 Posts
Sorry, I missed both the block date and the fact that there was a YH in 1969 as Jim pointed out.

Okay, I might be really loopy tonight, but neither the crank nor the caps are anywhere near being for a 428 Pontiac. They just don't make that big of hammer to beat it in place, and I swear the only thing I've been drinking is coffee. I couldn't find 428 photos so I'll make do with a photo of 3-1/4" 455 crank and caps. The above photos in post #10 look like something for a 4-bannger engine consider the narrow width of the rod journals and the small mains (and thrust is on #3 on that small crank).
Automotive tire Motor vehicle Gas Bicycle part Engineering
Gas Automotive tire Auto part Engineering Machine
 

· Registered
Joined
·
488 Posts
Now would be the time to take a rough bore measurement since many of the blocks this old are on their second or third life. Stock bore is 4.120".

If you can, find a shop that will "shake-and-bake" the block for cleaning. This entails the block being heated up to around 450° and then tumbled in steel shot to get it squeaky clean. I use a particular shop just for this cleaning process and magnafluxing, and then use another for the actual machine work. We have a shop locally that has the old fashion hot tank still in business from the 50's and while I admire the effort it took to keep it active with all of our state's EPA insanity, it still doesn't produce the results of baking a block to rid it of paint, grease, and calcium buildup. The crank photo I pictured above was with the old hot tank method and even after an additional hour or so of cleaning after I got it home there is still rust and paint on the block. Here is a photo of a block back from the shake-and-bake but prior to my scrubbing it down. It sat out in someone's back yard for years before I rescued it and had its fair share of rust and gunk.
Motor vehicle Rim Auto part Automotive tire Gas


Pull out all the gallery plugs if you can or pay the shop to do it before the cleaning process and also have them remove the cam bearings. Unless you have the proper tool, don't hammer them out - very easy to damage the block by chisel gouges. If it passes magnafluxing, then have the shop pull all your main cap dowel pins. Those remaining in your block have been driven down almost flush and need to come out. Shops have a special tool as long as there is enough sticking up to get the tool to bite into the dowel, otherwise they will weld on a bolt to the dowel to get pull out.
 
1 - 3 of 3 Posts
Top