Bf-42 replacement /Autolite 45's - Ford Muscle Forums : Ford Muscle Cars Tech Forum
 
LinkBack Thread Tools
post #1 of 9 (permalink) Old 04-13-2008, 09:22 AM Thread Starter
Subscriber
 
Join Date: Sep 2006
Location: Vancouver, Canada
Posts: 1,704
Bf-42 replacement /Autolite 45's

Is the heat range of the Autolite 45 close to the original Bf-42 or is there a better choice. I have to change the plugs and the shop recommened NGK V Power .

Greg
foleysfriend is offline  
Sponsored Links
Advertisement
 
post #2 of 9 (permalink) Old 04-13-2008, 10:43 AM
Registered User
 
Join Date: Feb 2001
Location: SoCal
Posts: 493
Re: Bf-42 replacement /Autolite 45's

By the book, today's Autolite 45 is the same plug as the old BF-42.
I use a step colder non-resistor Autolite 34 in the 289 in the GT. I always
found the 45's to be too hot. Unfortunately the 34's aren't available anymore.
(AR 33, which is an Autolite racing plug, is pretty close - just a bit cooler than my favored 34's)

66GT289 is offline  
post #3 of 9 (permalink) Old 04-13-2008, 11:14 AM Thread Starter
Subscriber
 
Join Date: Sep 2006
Location: Vancouver, Canada
Posts: 1,704
Re: Bf-42 replacement /Autolite 45's

What is the difference in the two plugs when it comes down to performance and does it effect idle quality to go to a colder plug or type of octane you can run

Greg

Greg
foleysfriend is offline  
post #4 of 9 (permalink) Old 04-13-2008, 01:46 PM
Registered User
 
Join Date: Feb 2001
Location: SoCal
Posts: 493
Re: Bf-42 replacement /Autolite 45's

Quote:
Originally Posted by foleysfriend View Post
What is the difference in the two plugs when it comes down to performance and does it effect idle quality to go to a colder plug or type of octane you can run

Greg

Greg
Colder plug = higher compression & the attendant need for higher octane fuel
Hotter plug = stock compression, stock engine, or worn out engine

If the plug reads "hot" for your combination, you'll need at least a range cooler. (The temperature of the plug is how fast if transfers heat from the tip)

As far as idle quality, colder isn't a problem as long as it isn't loading up and fouling out..... that would be a problem, as you can probably imagine.
Octane requirement is mainly a function of compression.
It's always safest to be too cold and foul plugs, than to have the plugs be
too hot and have pre-ignition/detonation issues.

66GT289 is offline  
post #5 of 9 (permalink) Old 04-13-2008, 04:36 PM Thread Starter
Subscriber
 
Join Date: Sep 2006
Location: Vancouver, Canada
Posts: 1,704
Re: Bf-42 replacement /Autolite 45's

Excellent information. I have a 289 that has been worked on and the compression ratio is 9.5-1 on the shop work order. My fuel of choice has been 94 octane and as I try lower octane the engine idles poorly. The 89 octane is a disaster. Recurve on the dizzy works well on the 94 . The car has a very slight miss which may be a timing or pre-ignition problem or plugs.

Thanks
Greg
foleysfriend is offline  
post #6 of 9 (permalink) Old 04-13-2008, 08:09 PM Thread Starter
Subscriber
 
Join Date: Sep 2006
Location: Vancouver, Canada
Posts: 1,704
Re: Bf-42 replacement /Autolite 45's

Found the AR-33 spark plugs today and they are around $5.00 each. Not much in stock so I wonder if they don't sell too many or they may be on the discontinue list. May be able to negotiate a price with them.

Greg
foleysfriend is offline  
post #7 of 9 (permalink) Old 04-14-2008, 07:24 AM
Registered User
 
Join Date: May 2007
Location: Orting, Washington
Posts: 1,126
Re: Bf-42 replacement /Autolite 45's

This is link to a cross reference chart.

http://www.cvproducts.com/cv/technical/sheets/spark/Autolite.pdf
McCutcheon4 is offline  
post #8 of 9 (permalink) Old 04-14-2008, 04:51 PM Thread Starter
Subscriber
 
Join Date: Sep 2006
Location: Vancouver, Canada
Posts: 1,704
Re: Bf-42 replacement /Autolite 45's

The chart shows the Autolite 45's near the top of the chart and the 33's down near the bottom as a cold plug, nothing just after the 45's.

Thanks
Greg
foleysfriend is offline  
post #9 of 9 (permalink) Old 04-14-2008, 07:29 PM
Registered User
 
Join Date: Feb 2001
Location: SoCal
Posts: 493
Re: Bf-42 replacement /Autolite 45's

Quote:
Originally Posted by foleysfriend View Post
The chart shows the Autolite 45's near the top of the chart and the 33's down near the bottom as a cold plug, nothing just after the 45's.

Thanks
Greg
Yeah, the "hole" in the chart is where the discontinued 34's go.......
I hope they don't discontinue the AR33's..... that would piss me off.
Particularly after they did away with the 34's......
(really stupid because if you have a cold plug that fouls, you can always
use an MSD to minimize the problem, but if all you have is a hot plug
available & you need something cooler, you're SOL)

Try Sparkplugs.com, they have AR 33's cheaper than $5 ea.

66GT289 is offline  
Sponsored Links
Advertisement
 
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Ford Muscle Forums : Ford Muscle Cars Tech Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in









Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page



Similar Threads
Thread Thread Starter Forum Replies Last Post
Holley or Autolite ? condor4 All Ford Techboard 3 04-22-2007 05:28 PM
Anyone tried the Autolite XP plugs? f100cleveland All Ford Techboard 3 09-13-2005 01:01 PM
Autolite saves the day. ScreaminC All Ford Techboard 2 09-12-2005 05:00 AM
Autolite sparkplugs PONY1 All Ford Techboard 0 10-29-2002 07:14 PM
autolite 2100??? 64 TBOLT All Ford Techboard 21 10-29-2002 04:33 AM

Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome