RE: IML: 1967 440 and trans {big valve heads}

Rodger,

What year/compression ratio 413 do you have?

Tom

From: mailing-list-owner@xxxxxxxxxxxxxxxx [mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of RODGER D. REDDISH
Sent: Thursday, February 21, 2008 7:50 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Re: IML: 1967 440 and trans {big valve heads}

Hola All

I have been thinking of swapping for a pair of the late issued heads that have the casting number ending with 452 and put them on my 413 powered Imperial. As of now the heads are the first series six bolt valve cover design. Is there an plus for doing this ( what does B-Jackson have to do with me ) ???

Rodger & Gabby

COS

----- Original Message -----

From: Frederick Joslin

To: mailing-list@xxxxxxxxxxxxxxxx

Sent: Thursday, February 21, 2008 9:20 PM

Subject: RE: IML: 1967 440 and trans {big valve heads}

Hi Tom:

There is very little difference between the 516 heads and the 915 heads that you cannot get from installing the larger exhaust valves with hardened seats into the 516 heads and doing a little porting.

The 516 heads found on just about every 383, 361, 413 and 440 from 1964-1967 have the same quench design as the 915 heads.

On most of these heads you would probably need to install new exhaust valves (1.72" are cheaper than 1.60") and should probably go to the hardened valve seats for unleaded gas so it is pretty much a wash between the very plentifully and cheap 516 heads and the very rare and expensive 915 heads.

----- Original Message -----
From: TomC
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: RE: IML: 1967 440 and trans {big valve heads}
Date: Thu, 21 Feb 2008 18:21:53 -0800

Hello All,

It is true that the 915 heads do not have the best valve size and port areas. However, and this is a big however, it has been discovered over the years that detonation is not only a factor of compression ratio, but also something called the quench area. And the 915 heads have one of the best quench areas of big block heads, due to their closed chamber design. Please see the articles linked below.

http://www.moparmusclemagazine.com/techarticles/mopp_060800_mopar_max_wedge_cylinder_heads/factory_parts.html

http://www.moparts.com/Tech/Archive/motor/15.html

If anyone would like to trade their 915's for open chamber heads, I would be happy to acquire them.

Tom

From: mailing-list-owner@xxxxxxxxxxxxxxxx [mailto:mailing-list-owner@xxxxxxxxxxxxxxxx] On Behalf Of Bob
Sent: Thursday, February 21, 2008 5:37 PM
To: mailing-list@xxxxxxxxxxxxxxxx
Subject: Re: IML: 1967 440 and trans {big valve heads}

THANKS for the info.

I was going by word of mouth. Glad theres people out there who know their stuff. I learned something today. I always enjoy reading info like that. Helps for future refrence. Thanks for the effort.

Bob H

----- Original Message -----

From: David Whitney

To: mailing-list@xxxxxxxxxxxxxxxx

Sent: Thursday, February 21, 2008 7:20 PM

Subject: Re: IML: 1967 440 and trans {big valve heads}

915 heads don't do an Imperial owner any good except for bragging rights, and the pain may not be worth it. We're talking about a compression ratio greater than 10:1, requiring great care to avoid preignition and/or detonation with today's pig slop gasoline. In addition, the larger valve sizes are of negligible benefit at an Imperial's normal RPM range (below 4000). Even racers know the 915 heads don't flow as well at high RPM as the later heads that came with larger valves. This engine combo is best suited for somebody trying to do a correct restoration of a car that came with it from the factory. Those of us who like to drive our cars a lot need later open-chamber heads. Compression ratio is lower, the valves are larger -- paint them Mopar turquoise and only an expert can tell from the outside that they're not year correct for your car.

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Fred Joslin