302 and 351W Block

Reply Subscribe

Thread Tools

Search this Thread

Oct 18, 2008 | 11:07 PM

#16

doug1222556

Posting Guru

Joined: Mar 2007

Posts: 1,649

Likes: 2

Quote:

Originally Posted by MBDiagMan

Why is the 351 block 3" wider? The deck height is only raised an inch or a half inch. Even if the deck height were raised an inch, it is at a forty-five degree angle, so 1 inch up would only move the head out a half inch on each side, adding one inch to the width at the outer corners of the block deck.

Is there some other part of the block that protrudes out adding the other two inches?

The 351W has a 9.5 deck height, the 302 an 8.2, which is a difference of about 1.3". That's on a 45* angle to the crankshaft, and it is on each side. Looking at the motor from the front and imagine putting 1.3" taller valve covers on it and you can see that that will make the motor as much wider as the height of the valve covers, (pretty much). It's pretty much the same thing, only happening under the heads instead of on top. The 302's intake is about 9" wide, the 351W about 11". This is where and how the width varies on the 2 motors.

Another way to look at it is as a right triangle turned sideways: A squared + B squared = C squared.

8.2 squared= 67.24 ..... 67.24 + 67.24 = 134.48 ...... square root of 134.48= 11.59
9.5 squared= 90.25 ..... 90.25 + 90.25 = 180.5 ....... square root of 180.5= 13.43

13.43- 11.59 = 2.94
So looking at the width as the long side of a right triangle, you can see how it will get wider, the 45* rule you are thinking of will apply to height in this instance, the motor will get much wider, but not that much taller.