1965 426 wedge
 

A question for you guys, the NHRA specks for the 426 wedge is max bore of 4.33, the standard bore on a 440 is 4.32. NHRA shows the pistons allowed for the 426 but Im wondering if I can use a 440 block and the standard bore piston with NHRA excepted numbers. I hope I explained this right. Maybe call the tech people but I have no phone number. Thanks

Re: 1965 426 wedge
 

I do not see why you could not run the 440 block but
it will be difficult to find one that would clean up at .010
over. They all have pretty worn cylinder bores
that I can find any more

Back in the day you could buy from Mopar Perf. an unbored
440 block that could be built at .060 over for a 426. But I have
not seen one for 30 years.

Re: 1965 426 wedge
 

I have a 70 and 74 block with good cylinders so that’s not a problem. I’m thinking more about the piston numbers

Re: 1965 426 wedge
 

I don’t think it would be an issue in SS, but it’s probably a no-go in Stock as the 426W and the 440 have different compression height on the pistons. Ultimately NHRA tech would make that call.

Re: 1965 426 wedge
 

You can use the 440 block with a approved 426 piston as long as you are not .080 or more on the 426 bore and the block has the same deck height as specified for the 426 block.

Re: 1965 426 wedge
 

Just looked at both specs 426 has a 2.015 comp height .042 deck with a .020 gasket. 440 has 1.94 ch .027 deck and a .021 gasket. No 440 piston has that ch except the 6 pac but it has valve pockets, a no no. So it’d have to be a .070 over 426 piston with the right numbers on top. What a can of worms.

Re: 1965 426 wedge
 

The 413 industrial or motorhome blocks are the way to go and they are everywhere for a very reasonable price then get the correct approved 426 piston. There are 440 motorhome blocks around that have very little wear and if you get one finished to within 1-2 tenths taper and roundness with the desired hone finish at 4.325" the .005" over standard ring set will make it by a hair, you'll still need to use the approved 426 piston, they'll make it whatever size you want.

Re: 1965 426 wedge
 

Back in the mid 70s my Max had a bad cylinder so I found an industrial block out of a 60 ton crane, it was a very strong block.

Re: 1965 426 wedge
 

MH or Industrial blocks have a water hole for spark plug cooling passages that are in the MH or industrial heads. They are easy to spot.
If you find a block try to get one that has the Dash end number(-1) closer to one or zero.
The higher the dash number the more mold/casting modifications. Closer to zero or 1 is usually a block that has been cast matching the original prints. A -1 could be a lot better core than a block with a -15 on it.
Sonic testing is important

Re: 1965 426 wedge
 

I thought they only used the block castings ten
times 10 times before retiring them but that was a longtime
ago.