Help with 390 heads.

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May 16, 2009 | 12:13 PM

omarb

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Help with 390 heads.

i had posted this earlier but apparently it didnt work......if it does show up after this post, i apologize for the double post.....

i need some help with rebuilding a 390. I have stock heads (i have no idea what the serial number is) and i have these to put on it: C6AE-R..thats all i know about them....

my question is: how much better are the these than the stock ones ?

any help will be greately appreciated.

May 16, 2009 | 01:15 PM

FFR428

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From: CT

The C6AR-6090-R heads are stock heads as well. You really need to post the number off the one's you'd like to replace to be certain. Or the year of the truck if your positive the engine is all original. The head casting number on most FE heads is between the center 2 spark plugs. But sometimes can be slurred and difficult to read. So see what you can find. There are also 2 types of R heads. The large R heads are a bit more free flowing. The R heads I've seen have both been lowriser type heads. But I've read there was also a R head that was the first velocity port style like the later C8-H and D2-AA smog heads. I've never seen one of those. I'd guess it has the raised exhaust ports like the later heads too?? Which can be another issue you have depending on the exhaust manifolds or headers. I'm sure more guys can chime in on that subject. I'm not well versed on the stock truck exhaust stuff.

May 17, 2009 | 12:03 PM

omarb

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thanks for your help. i want to say that the ones that are mounted on the block already are a D2-AA and something else.....not sure because to be honest with you, this is my bro-in-laws engine and he's providing me with the info....he doesnt know for sure what's on there....he just removed his 428 cobrajet and is rebuilding a 390 for his 73 F100 to make it a daily driver.

May 17, 2009 | 06:08 PM

RapidRuss

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From: Smith Mountain Lake, VA

The D2's well flow almost as well as the C4's and C6-R's with some work on them..But being it just a daily driver I'd stay with the D2's as they have induction hardened exhaust seats... But that hardening will go away with one good valve job..But if the valve are sealing good..make it easy and just use the D2's...It you feel at a later dat..you want some more HP ..and get into some porting..then my first pick would be the C4's with the throats opened up and CJ size Valve's and some port work..and 2nd would be the C6-Big -R heads to do they same with.. JMO..

~Russ

May 18, 2009 | 02:03 PM

omarb

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i had him check....he has a set of D2TE-AA.

anything to be proud of ?

May 18, 2009 | 05:16 PM

JesusRocks

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From: Waco, Tx

nope. but they work well enough. and like Russ said they already have hardened seats. they are basically the same as the C8AE-H.

May 20, 2009 | 11:55 AM

omarb

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another question:

regarding gas…..octane numbers…….

What would be the difference if he installs the C6EA-R entirely ported with CJ valves………..and……..unmodified D2TEE……..remember, it’s a daily driver and he doesn’t want high octane fuel

thanks