302/408 Swap

stirling33

Member

May 14, 2005

126

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16

Grayslake, IL

Jun 13, 2006

#1

• Jun 13, 2006

• #1

I am thinking of an engine swap in the near future and I was wondering if I was to go with a 408 long block or even crate what will swap and what will need to get replaced. Will the headers still fit from my 302, can I use the same intake and distributer etc......

Thanks

 

67Dylan

New Member

May 11, 2006

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Phoenix, AZ

Jun 13, 2006

#2

• Jun 13, 2006

• #2

You will need a new dizzy, new intake, and new headers. Just don't use 302 performance parts on the 408 and you'll be all right.

 

stirling33

Member

May 14, 2005

126

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16

Grayslake, IL

Jun 14, 2006

#3

• Jun 14, 2006

• #3

67Dylan said:

You will need a new dizzy, new intake, and new headers. Just don't use 302 performance parts on the 408 and you'll be all right.

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What type of headers would I need, aren't most of the aftermarket headers for both 302 and 351 based engines?

 

Max Power

Active Member

Jul 31, 2003

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St Paul

Jun 14, 2006

#4

• Jun 14, 2006

• #4

A 408 is made out of a 351 engine. It is wider and taller, therefore, although headers will bolt up to the ports on the head, the 302 headers have a good chance of hitting the shock towers, and with the increased deck height, may hit some power steering linkage as well.

Your 408 is based on a 351 engine, so you need to get 351 speed parts. The only speed parts that will interchange somewhat effectively are cylinder heads, and there are some issues there too.

Also, quite often 351 engines will have a water pump that exits on the other side, so you may have to use a 302 water pump or a different radiator. You will probably need a different radiator anyway just to keep up with the cooling requirements.

 

LMan

Founding Member

Aug 10, 2002

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Mom's basement

Jun 14, 2006

#5

• Jun 14, 2006

• #5

Is the search feature disabled?



Just checking

 

1

180 Out

Member

Jul 23, 2005

375

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Jun 14, 2006

#6

• Jun 14, 2006

• #6

The basic thing to keep in mind is the 302/331/347 has a deck height of 8.2" and the 351/393/408/427 has a deck height of 9.5." Deck height is a measurement of block size. It's the distance from the centerline of the main bearings to the block deck, where the cylinder head sits. Both blocks (like all the old school V8's) have a 90 degree angle between the cylinder banks. So that extra 1.3" height makes the tops of this right angle block stick out that much farther. The intake that sits in the middle has to be that much wider. The exhausts have to hang down that much more.

 

stirling33

Member

May 14, 2005

126

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16

Grayslake, IL

Jun 14, 2006

#7

• Jun 14, 2006

• #7

180 Out said:

The basic thing to keep in mind is the 302/331/347 has a deck height of 8.2" and the 351/393/408/427 has a deck height of 9.5." Deck height is a measurement of block size. It's the distance from the centerline of the main bearings to the block deck, where the cylinder head sits. Both blocks (like all the old school V8's) have a 90 degree angle between the cylinder banks. So that extra 1.3" height makes the tops of this right angle block stick out that much farther. The intake that sits in the middle has to be that much wider. The exhausts have to hang down that much more.

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I know this swap has been done before, so what are guy's doing to keep there original hood? How can you guarantee that the 408 will fit?

 

jasonn

Founding Member

Sep 26, 2002

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By Rochester MN

Jun 14, 2006

#8

• Jun 14, 2006

• #8

Mine still has the cheap 1 5/8 headers and perf rpm intake. I still have the intake cause I didn't want to chop the hood and the small headers cause that is all I could afford. But still runs good! check sig.

 

L

lauras70mach1

Member

Aug 1, 2004

202

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minnesota

Jun 15, 2006

#9

• Jun 15, 2006

• #9

jasonn said:

Mine still has the cheap 1 5/8 headers and perf rpm intake. I still have the intake cause I didn't want to chop the hood and the small headers cause that is all I could afford. But still runs good! check sig.

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I heard you got a tubbed '70. Can't wait to check it out!

 

Stangninjak

Member

Apr 16, 2004

324

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Jun 15, 2006

#10

• Jun 15, 2006

• #10

Be mindful on what you put on top. Remeber that the 408 is a 351. So watch your deck hieghts when thinking of fitting your intakes and carbs. I do not know what year car you have, but I do know that on a 65~66 a Air Gap or Vic JR will not fit on a stock hood. You need an mod hood, or have a cowl.

 

jasonn

Founding Member

Sep 26, 2002

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By Rochester MN

Jun 15, 2006

#11

• Jun 15, 2006

• #11

lauras70mach1 said:

I heard you got a tubbed '70. Can't wait to check it out!

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Thanks, I'll try to get some pics this weekend and post them.FAR from perfect but it didn't turn out tooo bad.