External appearance of 2-bolt vs. 4-bolt 454

[Mike E.]

On a 454 motor that's buttoned up with pan, etc, how do I tell the difference between a 2-bolt and 4-bolt? I'm asking specifically about a 3963512 casting. Seems I remember something about the machining where the oil pressure line attaches. Please fill me in on that and anything else to know. Thanks

[Mike T.]

Re: External appearance of 2-bolt vs. 4-bolt 454

Mike - To determine a 4-bolt Bigblock from a 2-bolt Bigblock, the area to look at is where you mentioned...at the oil passages just above the oil filter pad. I have a January #512 427 block that I just installed into my 65 L78 Roadster and it's a 2-bolt. The pic will show the smaller drilled/tapped hole that I used for the oil pressure line. The last pic, if they stay in order, is the same area but on a 1966 #942 4-bolt 427 and you can see that center hole is much larger.IMG_4890.jpgDSCN5967.jpg

[Mike T.]

Re: External appearance of 2-bolt vs. 4-bolt 454

Meant to include a pic of the raised casting numbers on the 69-vintage #512 2-bolt block.DSCN6383.jpg

[Mike E.]

Re: External appearance of 2-bolt vs. 4-bolt 454

Any idea why the 4-bolt was machined with the larger hole?

[Mike T.]

Re: External appearance of 2-bolt vs. 4-bolt 454

The story that I've heard for a long time was that the 4-bolt blocks could be used in racing events and the larger
passage was for an external oil cooler.

[Patrick B.]

Re: External appearance of 2-bolt vs. 4-bolt 454

Also notice in Mike's photo of the 66 4 bolt block also that the boss next to the large pipe plug is drilled and tapped for a smaller pipe plug. These two pipe threaded holes would be the in and out ports for an oil cooler or remote oil filter. The tell tale for a 4 bolt block it there are two pipe treaded holes by the oil filter not just one smaller hole for a oil pressure gage fitting.

[Terry M.]

Re: External appearance of 2-bolt vs. 4-bolt 454

On a 454 motor tMikehat's buttoned up with pan, etc, how do I tell the difference between a 2-bolt and 4-bolt? I'm asking specifically about a 3963512 casting. Seems I remember something about the machining where the oil pressure line attaches. Please fill me in on that and anything else to know. Thanks

Mike

RTFM If you don't know what that means a rough transition is Read The F****** Manual. That abbreviation is increasingly used on Judging score sheets where space is limited. It is appropriate here.