The Stovebolt Site Forums The Shop Area Engine Shop Heads

Went to a cruise in at our local DQ last night. Was standing by the Sub with the hood open and this guy comes walking up and he says, " I see you have Power Pack heads on your 283, those are semi-rare"and are 10/1 compression". Now I have not heard of power pack heads. My engine was built up out of parts I scrounged from various sources including a couple of junkyards that I visit frequently just for entertainment. Any body know what this guy is talking about? With all the small block historians on the Stovebolt I figure maybe someone can tell me what I have here. Thanks in advance.


Weeds

The Power Pac heads are what i believe we call the Corvette heads over here. They have oversized valves and a larger combustion chamber to get more power out of the 327 engines.

Weeds,

This is out of my league, but the Power Pack heads (on 265s and 283s) topic has come up a few times recently. Here is a little information. Looks like 9.25:1 compression ratio with flat-top pistons (vs 8.0:1).

also
Small triangle on top of the a rectangle on front of heads is indeed a Powerpack head. They'll also have no accessory holes I believe.

"Power Pack" on the 283 was an option package [different than on a 327], higher compression [I remember it as "around" 9:1] heads with smaller chambers, single 4 bbl and dual exhaust, not specific to vettes, high school bud of mine had a 57 convert with the power pack 283 - nothing special compared to more modern options unless you're trying to build a "numbers matching" show piece .... the casting numbers would say what you have and you'd likely find a lot of discussion on early muscle car forums .... that's a good engine link Tim

Diagram "B" in the attached chart is the end view of a 283/327 Power Pack head. Since they're 50+ years old, assume most of them you find these days will have been reworked, possibly several times. The 58CC 305 heads are probably a better choice if they can be found for anything other than a "numbers-correct" restoration.

http://www.fastnuf.com/Headguide.html

Jerry

I kinda went through this a while back myself in my '61 truck, Weeds. The heads on the '65 327 I have are from a '55 283. Here's a pic of the triangle which was referred to above:
http://rides.webshots.com/photo/2111263150055391021rqhWkI

HotRod, thanks for posting that diagram. That's pretty handy.

The only thing I can add to the subject other than that is if you ever replace the valve covers you will need to get one with an "offset" bolt pattern. Also, gaskets for them are not as plentiful as the others. You can find them with two holes on one side and they are advertised to fit both regular and offset. However, I found out that the holes were not placed correctly and required quite a bit of redoing. So, my advice is to take care of the gaskets you have.

Husker, Jerry, Squeeze, Joker, Tim and 49chevtrcknIN, you guys know everything! Thanks for the education. As for the heads it seems they are more of conversation pieces than hop up speed parts. Their inclusion on the engine build was purely accidental.

Weeds

Thank you for the compliment, and you're welcome. But I will have to "bow out" of that honorable spot. I may very well know the least about old trucks as anybody in here. I'm here to learn from the gurus. You just got lucky with your question.

By the way, I came to the same conclusion as you. The heads are an interesting conversation piece. If I ever run across someone who is rebuilding a '55 car and they are in need of matching heads I'd consider selling them these. But for now, I'll just enjoy the "uniqueness" of the "heinz-57" engine. LOL

Hotrod, great link! Had to print that one off for future reference. Thanks a bunch!