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Identifying a T786 motor


austinsailor

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I believe the 377 and the 413 were basically the same block whereas the factory did a bore and stroke the get the larger cubes..similar to the 218/230  251/265 and about a dozen other mopar engines that right up to the current models are bore and stroke combos..you may have to do the storke deal...377 was 5 inch I think and the 413 was 5 5/16  this is not a very commonly discussed engine...data hard to find...even allpar does not go into many details on the larger powerplants

Edited by Plymouthy Adams
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As far as I know all the 413's used the SAE style bell housings ... but the timing plug in #6 is the only positive way to be sure of the 5-5/16" stroke.

The twin carb  intake manifolds are a bigger bore than the 377 and smaller Moly Block engine's too. They start out with a 1484... part# ..the smaller engines  intakes start out with a 1112 part # as I recall.

A pic of a typical up through 55 413 SAE bell housing....

Bell housing SAE 2 413 Flathead.JPG

SAE Bell Housing 413 Flathead (2).JPG

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The 413 block is a bit wider than the 331, although it's close enough you'd have to put a tape on it to tell. Not sure about a 377, never saw one to tell.

 

when I saw this motor I thought it would be simple enough with the factory motor number, so I didn't check other details. I regret it now!

 

not sure if it's stuck, so even if I was there checking the stroke might be a challenge.

 

i asked here a few months ago and got no answer, was hoping someone new would see this and have some info. I suppose if I get serious enough I'll just have to make a trip.

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8 hours ago, austinsailor said:

"The 413 block is a bit wider than the 331, although it's close enough you'd have to put a tape on it to tell. Not sure about a 377, never saw one to tell."

 

All the 30"  Moly Block head widths are exactly the same including the 413...all measure  nine inches"... 281, 306, 331,377 and 413's.

I just measured  a 377  head in a 1951 4 tonner to be sure. Same as a 413.

 

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Brian has a selection of molyblocks in his yard, including the 413 industrial in his truck he uses regularly. When he replaced the original 331 many years ago he found his starter pedal rubbed the block because it was wider. He and I measured several motors and found his industrial 413 was a bit wider, I think about 1/4".  Head bolt to head bolt, where we measured them, were not the same.

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Not to start an argument here Gene...Please don't kick me in the arse for this!?

I just pulled out all the different 30" head gaskets for all sizes of these engines and I did learn that the 281 CI engine head gasket is 1/4" narrower than all the other larger bore head gaskets. Head stud holes are off by 1/4" along drivers side of block too.

I did measure head widths on a 306/377/ and a 413 industrial engine.Both  Gaskets and head widths are exactly nine inches. All cooling and head stud holes align properly.

The blocks in all my B-series 1951 to 53  big trucks  all all have the same recess in the block for the starter to fit back into. I don't have a 281 engine so don't know on that engine.

1941-47 engines could be cast different... I don't know

There are several different head gaskets because of bore size differences.

Anyway 413's have bigger rod journals, hydraulic lifters ( 377's too) on the truck engines, industrial engines use solid lifters with valve rotators, and different cams of course...there are some other unique things about the 413's but I am forgetting those...

Stroke and bore is the only positive way to be sure of a certain displacement.

413 Head # is1483668

Block # 1320629

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IMG_2142.JPG

IMG_2136.JPG

IMG_2141.JPG

IMG_2126.JPG

Edited by Dodgeb4ya
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