Mustang Owners Club Australia Forum

Technical & General Discussion Area => Tech Torque Pre 1973 => Topic started by: simo on June 13, 2021, 12:41:12 pm

Title: 390 inlet manifold
Post by: simo on June 13, 2021, 12:41:12 pm
Hi Guys,
My '69 Mach1 is an S code with a 390 FE / C6 auto. The heads that are on it are from a Cobrajet motor but it's running a standard inlet manifold with a Holley 600 cfm carb. My question is would I benefit by swapping over to a Cobrajet inlet manifold or just leave it standard.
Many thanks
Simo
Title: Re: 390 inlet manifold
Post by: barnett468 on July 09, 2021, 12:23:58 pm
Hi Guys,
My '69 Mach1 is an S code with a 390 FE / C6 auto. The heads that are on it are from a Cobrajet motor but it's running a standard inlet manifold with a Holley 600 cfm carb. My question is would I benefit by swapping over to a Cobrajet inlet manifold or just leave it standard.
Many thanks
Simo

Yes,
Title: Re: 390 inlet manifold
Post by: jiffy on July 09, 2021, 04:41:31 pm
If this was in print/still available then it would be great reading and tell you what you need to know and WHY.

http://fepower.net/GFEIC.html (http://fepower.net/GFEIC.html)

Suffice to say, like Barnett says - you'll get a power increase

Have a read of this - the section by Jay (he wrote the book above) tells you all you need to know

https://www.fordfe.com/new-to-fe-engines-questions-gt390-heads-vs-428-cj-t60504.html (https://www.fordfe.com/new-to-fe-engines-questions-gt390-heads-vs-428-cj-t60504.html)

an option for the intake is the PI intake - worth reading about them on CJ heads here:

https://www.fordfe.com/428cj-port-size-compared-to-390-heads-t3553.html (https://www.fordfe.com/428cj-port-size-compared-to-390-heads-t3553.html)


Bottom line - anything will be better than the 390 intake, and headers will perk it up even more. A CJ intake is effectively a MR intake so make sure the cam will support the revs that the top end will support.

Title: Re: 390 inlet manifold
Post by: simo on July 27, 2021, 12:02:48 pm
Many thanks guys and those links were very informative.