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Discussion Starter #1
I went to the junkyard today and found a 1968 Impala 4dr. It had a 307 in it (from what the emblems said may not be the original engine) and the heads on it were in great shape. They were complete, they inlcuded rocker arms, valve springs, etc. The casting number is 3927185 and they check out to have came off of a 307/327/350 and have a 70cc chamber. Please if you have any additional info tell me? Also how good would these heads be on a 350 that may be used for racing(approx 400 HP) Do you think these heads are worth $60?
 

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The 185 casting was a small runner large chamber smog head.
The intake valve size is 1.72. these heads were made for high velocity, low rpm torque to move heavy cars and pickups, and even after getting them rebuilt, installing bigger valves, and plenty of port work, they still likely wouldn`t reach your power goal, and with the money invested you could have got a aftermarket set of heads. Best place for these heads is where they are.
 

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Discussion Starter #3
I didn't know how they would be performance wise and didn't want to buy them without an opinion. But from what this book I have those heads should be thick and metallurgy whatever that means. About a mouth ago they had a 1966 Impala with a 283 in it and it had Powerpack heads but I didn't have the money to get them. Right now in my 1980 Malibu I have 882 heads on a 350 (the numbers on the block check out to be T400 police what does that mean). What would be my best bet those 185s, those Powerpacks, 882s, or maybe some double humps. How good of heads are those 882 since I already have them? I was wanting to stick to a stock performance head if you know of any other good ones give me their casting numbers and their specs and I'll check for them next time I go to the junkyard.
Thanks
 

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The power pack heads aren`t worth having either, they have the same small valve size of 1.72, 57cc chambers, and 137cc intake ports, made for low rpm torque. running these on a 350 would give a considerable compression increase, but less flow than you have with the 882`s, and flow is power. I would keep the 882`s and bowl port them, the 882`s are the best flowing smogger head out there. you could look around in your local sale papers or ebay for a set of camel humps, the casting numbers are given on mortec.
 

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see if you can find some 3974041 or 3974041X heads. These are camel hump heads from 1969 used on SS Camaros, they flow pretty well for stockers. If you are lucky enough to find the "X" version they come with 165cc runners. Both have 64cc chambers for good compression and 1.94/1.50 valves. A machine shop guy that's been doing heads for 30 years says these are the best stock casting (pre-smog era) to use on 350s if you are looking for power. A little porting and polishing on these heads and a three angle valve grind and they will out flow the new vortecs. You should easily make 400 hp with the right combo using these heads.
 

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Discussion Starter #6 (Edited)
What about 462s someone told me they were halfway decent. And did GM make stock aluminum heads b/c my dad's friend is offereing to give me a set for free. If so how good are they, my dad's friend said that aluminum heads flow better than cast.

And from what I said earlier does anyone know what T400 police means. That's what those numbers checked out off that 350.
 

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882, 461, 462, 291, 041, 186, they were all about the same in terms of airflow and portsize. The "X" heads had a few more cc's in intake port volume. 292's were angle plug heads I think and despite what folk will say, they didn't offer any advantage over the rest.

Larry
 

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Discussion Starter #8
Thanks for the info. Sorry but could anyone please tell me what T400 police means none of my dad's friends know and I can't find anything on the internet about it.

Also did GM make stock aluminum heads
 

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882 heads and it's relatives

The 882 heads are prone to crack between the valves. Check the close. I milled .033 off mine to increase the compression ratio and had no problem bolting on the intake. That,s .033 from stock. The combustion chambers on the stock heads are 76 cc,s. They ran fine. Larger 2.02 valves will get shrouded from the chamber and th emetal may be to light to open it up. you should end up with 72 cc chambersand use thin metal gaskets.

Just s passing note, 62 cc will push the compression on a .030 over bore beyond 11 to 1. That is to high for iron heads. I know the hard way. With iron heads 9.5 to 1 is pushing it. Al heads will get you another point because they absorb the heat better. I am running 11.5 to 1 on al heads with 93 octane gas and 8oz octane booster for 10 gallons of gas. Runs good but is expensive for fuel.
 

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MyMalibu said:
Thanks for the info. Sorry but could anyone please tell me what T400 police means none of my dad's friends know and I can't find anything on the internet about it.

Also did GM make stock aluminum heads
Don't know about the trans. Maybe ask one of the tranny guys in the transmission/driveline section.

GM made a boatload of aluminum heads. Most weren't much better than the iron heads aside from having smaller chambers. They didn't flow very well either. They can be made to flow good but that's a differen't deal altogether.

Save your money and buy some aftermarket heads if you have to have aluminum heads or just get those 462's give 'em to a decent shop to assemble for you.

Larry
 

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Discussion Starter #11
Naw that's what the numbers on that 350 motor checked out to be and I wonderd what it meant. Could it mean that it was a special edition police engine or something.
 
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