" Wedge" engine

[chev1171]

Could someone explain to me what a "wedge" 340 engine is and how it differs from any other 340 engine if in deed they are different.

Also what is the difference between "J" and "X" heads ?

Thanks for your info and time .

 

[340wedge]

There is no difference. That started with the 1971 Duster 340 Wedge because of the hood decal which is an appearance option. The Wedge refers to the shape of the engine.

 

[70Duster440]

Wedge refers to the shape of the combustion chamber - just as a hemi does.

Here's a quick overview.

 

[Locomotion]

318, 360, 383, 440, etc are all "wedge" engines. On the other hand, there is the 426 Hemi. I believe the Ford Boss 429 was a ""semi-hemi". The New Hemi isn't a "true" Hemi because the chamber isn't in the shape of 1/2 of a sphere.
But it's close and good for marketing. There are many other variations across the brands.

X heads are 894 castings and have OEM 2.02"/1.60" valves only. J heads are 915 and can have 2.02/1.60 or 1.88/1.60. The 915 2.02 heads were also used on 340 Six Pak motors with offset pushrod holes and rockers.

I forgot if 587 heads have a J on them! But they only came with 1.88/1.60 valves. They started with an EGR hump in the exhaust port which eventually got drilled. But all the 340/360 heads were pretty similar otherwise.

 

[ocdart]

Just to clarify a bit - the 'wedge' refers to the shape of the combustion chamber. Take a look at a cross-section diagram of the combustion chamber, it forms a wedge shape above the flat surface of the piston.

 

[chev1171]

thanks a lot to all of those who responded. Much appreciated.

 

[Petzschler]

if yah talk to some of the Old School Guys... it has more to do with the 18deg valve arrangement (relative to the center of the cyl. bore).
X and J heads differ in prices. x head you'll get raped.. j heads not so much. the 2.02 vs 1.88 intake valve sizes gain you next to nothing on stock
heads.