403/455

[bdub]

>-- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
>
>hummmmm
>
>first you say you will and then you won't
>
>and then you do
>and then you don't
>
>your undecided now so whata yah gonna dooooooooo?
>
>I wearing out the eraser on my web page.
>I guess if "us experts" can't tell the difference between a 403 and a
>455
>there must not be much difference.
>sounds like they are all doing great.
>
>the greatest answer I ever saw was
>>
>gene

hahahaha,

My feelings excactly! I'm thinkin there's not enough difference in these 2
engines to matter. But perhaps one of you web guru's could ( if we ever
figure it out conclusivly ) post an 'official' document on your site for
posterity.

gigglin
bdub

 

[herm beeck]

This is how I discovered that my '78 Eleganza II had a 455 in it.

I went down to the local speed shop and bought an Edelbrock intake
manifold for my 403. Then, when installing the manifold, it fell right
into the engine.

This is how I found out.

>

> >-- [ From: Eugene Fisher * EMC.Ver #2.5.3 ] --
> >
> >hummmmm
> >
> >first you say you will and then you won't
> >
> >and then you do
> >and then you don't
> >
> >your undecided now so whata yah gonna dooooooooo?
> >
> >I wearing out the eraser on my web page.
> >I guess if "us experts" can't tell the difference between a 403 and a
> >455
> >there must not be much difference.
> >sounds like they are all doing great.
> >
> >the greatest answer I ever saw was
> >>
> >gene
>
>
> hahahaha,
>
> My feelings excactly! I'm thinkin there's not enough difference in
these 2
> engines to matter. But perhaps one of you web guru's could ( if we
ever
> figure it out conclusivly ) post an 'official' document on your site
for
> posterity.
>
> gigglin
> bdub
>

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[zachary zehnacker]

I think an easy way to tell the difference between the 403 and the 455 is
by looking at the heads. The Olds heads on big blocks (455) are designated
by a letter. On most GMC's with 455's, you will unfortunately find the
smog restricted "J" heads. The Olds heads on small blocks (403) are
numbered. I am not sure what number is common for the 403 GMC's although
it is probably listed in the www.442.com faq.

For finding the letter or number on the heads, I will quote the www.442.com
faq.

"Scrape the oily goo off and read the letter at the lower left corner of
the head, near the #1 or #8 spark plug hole, a letter about 1.5" high
indicates a big block, while a number indicates a small block. Some
have an additional letter (an A or B), about 1" high, right next to the
letter (or number)."

While the head is a very good indication if the engine is a 403 or a 455,
it should be noted that any of the heads can be bolted on and run on either
of the engines. The big block heads will reduce the compression on the
small blocks though, which would probably make a 403 with 455 heads on it
noticeably lacking in power.

Zachary Zehnacker
Seemann Motorsports