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Jul 22, 2008 | 06:49 PM

fordnut2008

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horsepower

hello everyone i am new here i have a 390gt that came out of a 1969 torino i put it in a 69 ford truck the thing ran good before i put it in i have a edelbrock 7105 intake 750cfm holley and headers c6 with shiftkit and 3.25 rear it really runs good now just like to know if any one could give me a horsepower guess all info will be great thanks.

Jul 22, 2008 | 09:03 PM

85e150

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This engine was rated at 320 horse in '69. (325 in '68 or 265 if a '68 2bbl, but I digress)

That was "SAE Gross HP", which rated the engines without pesky details like aircleaners, mufflers, tailpipes extending to the horizen, ps pumps, etc.

"SAE Net HP" came into being in '72 and is the standard today. The rule of thumb is net is about 80% of the old gross. Thus, stock, your 390 wheezed out 256 net hp. Or thereabouts.

So headers, the manifold and a 4 bbl about 50% bigger than stock are just what the doctor ordered for this engine. I would venture a wag that you are probably close to an honest 325 horse with this engine.

This engine had 10.5 : 1 cr, so let me guess, you are hating premium fuel prices.....

Good luck with it.

Jul 23, 2008 | 08:26 AM

Danger_Dave

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From: UPSTATE NY

the gt version of the 390 means you have the 4 valve heads, hang on to those because i am having a hard time finding a set, they dont seem to be too common

Jul 23, 2008 | 08:36 AM

fordnut2008

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well that sounds good to me i am really pleased with the power of this engine and yes it likes the fuel i don't get to ride it much but boy when i do it's so much fun thanks for the info.

Jul 23, 2008 | 04:51 PM

BobbyFord

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Quote:

Originally Posted by Danger_Dave

the gt version of the 390 means you have the 4 valve heads, hang on to those because i am having a hard time finding a set, they dont seem to be too common

Hey, what do you mean "4 valve heads"?

Jul 23, 2008 | 06:53 PM

78fordman

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From: Jefferson, Iowa

i have a set of the 68 gt heads, 14 bolt exhuast manifold, with 2 valves. put them on myself.

Jul 23, 2008 | 07:26 PM

85e150

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Quote:

Originally Posted by Danger_Dave

the gt version of the 390 means you have the 4 valve heads, hang on to those because i am having a hard time finding a set, they dont seem to be too common

NO 4 valve heads ever in any production American pushrod motor made from 1940 on. Prior to that, I doubt it as well, but there were some strange things done "way back" by small auto makers.

I had a Honda GL500 with pushrods and 4 valve heads, so it can be done, but it wasn't done in US cars and it darn sure wasn't done on 390s, 427s or even the SOHC 427.

GT heads DO HAVE a different exhaust manifold bolt pattern, so watch for that when working on this motor.

DON'T BE CONFUSED by heads called "2V" or "4V". These were from the 351 C engine, circa 1970-74, where the heads were different for "2V" and "4V" CARBS. V = venturi, aka "barrel", as in "4 barrel carb". These terms were the 351C only, FE heads were known by a whole set of different terms, like the GT head, SCJ, CJ, low, medium & high riser, tunnelport, SOHC and probably a couple others.