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post #1 of 3 (permalink) Old Oct 5th, 14, 03:58 PM Thread Starter
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Location: arkansas
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I have a 69 Camaro with a 3963512 dated j-28-68 hi-perf the car build date is 01A the mechanic I have said its a 427 could someone tell me what heads it should have on it im new at this and don't have a clue.thanks gtyler
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post #2 of 3 (permalink) Old Oct 5th, 14, 04:51 PM
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Re: heads

That block was used for 427s in 1969. What heads were on it would depend on what the application was for the engine. Look on the pad to see if there are any codes there. That will tell us what the engine originally was and we'll know what heads were on it. See here: http://www.camaros.org/drivetrain.shtml

Experience...... It's what you get when you didn't get what you wanted.
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post #3 of 3 (permalink) Old Oct 6th, 14, 09:29 AM
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Re: heads

Well we all know that the number of 427's installed in a Camaro by the factory were very limited (and almost all have been accounted for, with those few missing ones assumed wrecked beyond repair).

That leaves you with a 427 block casting number. It could be a 390 horse out of a big B-body or pick-up truck, or a 425 or 435 horse hi-perf motor with cast iron or aluminum heads off of a Corvette. A magnet will tell you if you have painted aluminum heads or not.

In 1969 the factory used a 320 cc intake rectangular port head with 2.19 inch intakes and 1.72 inch exhaust valves. It would be a closed chamber head at around 102 cc in volume with a large dome on the piston to match the head. These engines ran 11.25:1 compression which back when new burned 104 octane Sunoco 260, or 102 octane American white pump gasoline (today that is considered race gas).

Since I doubt you have been burning race gas we have to assume the motor has been rebuilt with either new flat top pistons, or a set of open chamber heads that were not introduced until 1972 (or both).

I can tell you that I used to own a 427 Camaro or two (or seven) and the rectangular port heads are a dog on the street unless you are running 4.56 to 5.38 rear gears like I used to do back when gas was only 43 cents a gallon for high test gas. This is because those huge ports and small displacement meant that the air flow was sluggish until you were above 4,400 RPM. Those same heads on top of a 540 are very responsive and streetable.

This is the real problem. Restoration guys would scream about even having a 427, and they foam at the mouth if you build a 540 or larger BBC motor. So originality is out the window. I personally moved away from the 427 once the 454 became available because I could get the same power without having to spin it to 7,800 RPM to get it. A four bolt main forged crank 7/16th Boron bolt rod forged piston 427 will spin that RPM all day long, but it wears the motor out quickly. A larger displacement BBC yields the same power level with less wear because you are keeping the piston speed down.

So do you want a resto mod or all out performance street rod? A 427 with those date codes might be more valuable to another Camaro owner, or a Corvette owner with deep pockets. Just like with the small block head technology has made tremendous strides in the past 45 years. The aftermarket can sell you a set of oval port heads that will flow as much on the street as those high performance old school cast iron heads had to be spun to the moon to deliver. This is why cast iron Hi-Perf heads are selling for $500 a set now but used to sell for $750 each before aluminum import heads hit the market.

If you want to keep the heads a new set of valves, valve guides, and valve seats with new springs will go far to improve their ability to preform. They have probably already been ported at least once before, though I have no idea as to how well. Just like with head design, porting has improved from the old days of bigger is better.

Larger Dave
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