[GoneNova/406]

several yrs ago i bought a 413 dodge engine from an old guy that came out of a 71' superior motor home to put in a 70' dodge swept side camper special that i was going to do a project on.well after getting a few books and the engine cleaned up and apart,it turned out to be a 426 industrial engine,but it is indeed bored to a 413.block numbers are 2658836,date code 7-14-70,stamp pad 1971 GT 413 followed by an upside down "A".now who knows what the cylinders can be bored to?i'm hoping 426,.030,.040 or .060.it also has the normal 426 steel crank.not a truck crank.i have the info that describe's the difference. can anybody tell me why they call it an industrial block instead of a regular big block?.i am assuming that it simply means it didn't come in a production vehicle.

[techinspector1]

I recall from my youth that these motors as well as hemi's were used to power generators, sirens, water pumps and who knows what else. As far as how much it can be bored, I personally wouldn't trust anyone's word. Take the block to a shop that can sonic test the cylinder wall thickness. You want 0.130" of wall left all around after boring and honing to size. I'm a little confused by your post, but I think you're saying that the block is actually a 4.1875" bore (stock 413). If that's the case, then the walls would have to beep at 0.162" now in order to suffer the 0.03125" per side cut to the new 426 bore of 4.250".

[GoneNova/406]

i have an 8th edition mopar engine book as well as others and they say the 413,426,& 440 can safely be bored to .060" and i understand what you are saying about sonic testing but i would once and for all like to get sorted out why they used a 426 block for a 413.it appears to me that at the factory when they were building the motor home that this engine went into that for one reason or another a 413 block was not available to them when they needed it and they simply used a 426 since they are the same block.they just bored it to a 413 spec. instead of 426.the old man i bought the engine from has had the motor home since it was new and always thought the block was a 413.he sold it to me as such.i didn't figure it out til i got it home and apart.he wanted a 440 to replace it.all the same i wish i could find some clarification.is it a 413 or is it a sheep in wolve's clothing?

[woodz428]

I'll speculate on why it is a "426" block. The 426 wasn't made after the mid 60s and you have a 197o date code. I would guess that they were using the old castings for a 426 to cast up 413s. Probably a little heavier and durable for heavy usage especially in the smaller size. If it had an earlier casting number I would think it didn't meet specs for the 426 and was used as a smaller truck engine. The late casting number would suggest that it was never intended as a 426. A block casting, if you have never seen one is an elaborate set of pieces that include a section for the cylinders. It may be that the external casting is of the 426 and the cylinder pattern is for a 413. Ford did that commonly with various FE engines, the Mopar engine is of the same era.

[GoneNova/406]

yes thats all good and well but it is an industrial block with 426 nuumbers.the only difference between the two blocks is the cylinder notching for huge valves"which being a motor home motor and needing torgque instead of h.p. it did not get.also the oilpassages were drilled bigger but i don't yet know how to tell the difference unless i also had a 413 block in froint of me.",so being an industrial as far as i know only means it wasn't used in a regular production vehicle.they are used in all kinds of stuff.and i think you actually said the same thing as me in that it is a 426 used as a 413.if so why can't it be bored to a 426?check the casting #'s for yourself and see what it says.i'll try to email BOB MAZZOLINI RACING,HE SOMETIMES HAS THE THE REULAR 413 MOTOR HOME blocks for sale.

[sam-missle]

if i remembr right the production 426, had the #2,3 & 4 main caps cross bolted.

sam-missle

[BOBCRMAN@aol.com]

Your block can be bored.

I just did a 426 from a motorhome. This engine is destined for a late sixties Dodge convert.

426 stock type pistons are not available in the aftermkt. I called all my suppliers and only spendy custom pistons are available.

Sooo, after a sonic check. The block got std. bore 440 pistons and went together like a dream. Car isn't done yet, so I haven't heard it run.

[GoneNova/406]

i was hoping to here something like that .thanks.now i have something to go on.thanks for getting back to me.