VCCA Home Forums TECHNICAL - 1945 AND NEWER 1958-1960 283 power pack question?

I have a 1958 impala and was wondering if anyone can tell me the difference between a 283 and 283 power pack. Is it just a 4 barrel carb and dual exhaust or are the heads different. I had a guy at the Redding car show try to tell me that the heads on my 283 power pack weren't 283 power pak heads. He said power pack heads had a little triangle on the front of the head. Does anyone know if this is correct? Any pictures or links to info about this would be appreciated. The passenger side head has a rectangle across the bottom front of head with no triangle on the top of the rectangle and the driver side has an L shaped raised area across the front outside edge and half of the bottom front of head. He said he didn't know what they belonged to without checking the numbers but definitely weren't correct heads for the 1958 283 power pack. Thanks for the help.

You are correct about the 4-barrel and the dual exhaust. The symbol he is talking about looks like a rectangle with triangle sitting on the top.

Thanks for the info. I need to find some power pack heads. I was told that it was a numbers matching power pack 283. Looks like they may have been mistaken. I need to talk with the previous owners and find out what is up with the heads. Thanks for the help.

In 1958 the dual exhaust wee not part of the power pac engine. The duals were optional on a 283, including the 2 Bbl carb. version. Most that ordered the 4 Bbl engine ordered the dual exhaust.
I had a wierd dual exhaust 2 Bbl. car. That was until the right muffler blew out, then it became a single exhaust car.
The dual exhaust option for a 283 was #220.

Hi Cap,

There were three different cylinder heads used in 1958

Casting Number 3743056
55 cc chambers and it had what appears to be two towers on top of a rectangle. I refer to this head as the twin towers since it looks like the buildings we all miss in New York City
There is controversy tied to this head since it was confused with 1957 Corvette applications which have since been debunked.

Casting Number 3748770
59 cc chambers and it has the pyramid on top of the rectangle - as in the photo posted in this thread. This is known as the only head used in 1958 with the Powerpack engine.

Casting Number 3748772
69 cc chambers and all it has is the rectangle. No towers, no pyramid.

All heads used the same sized intake/exhaust valves of 1.72/1.50"

Thanks for the info. It is greatly appreciated.

The 1959 parts book lists the 3743056 as a 2 ton truck head
The 3748770 as a power pac head
The 3748772 as a 2 barrel car head
comments?

Hi Gene,

Good to get a chance to chat with you! :)

Interesting about the 2 ton truck head.
The head seems to garner quite a bit of controversy. It has a production history of being spec'd for the passenger car engines.

According to Alvin Colvin, "the head could have been used in passenger car and Corvette production. Some reliable sources in the past have listed this head as the 1957 Corvette fuelie head and then later retracted the validity of the application for unknown reasons.

My intent was to provide known casting numbers to the member so that he can ferret out which head he has, what he may need, and of course, "load the gun" for him with the seller on his engine history.

As the value and rarity of certain parts have become more prevalent, it seems some people can be somewhat creative and create parts that have a questionable history. It would not be the first time I saw JB Weld used to make the head appear correct.

The odd thing is the head shows a smaller combustion chamber and the trucks ran a lower 8.00 to 1 C.R....I can't remember if the trucks had dished pistons or even forged pistons. Neither are mentioned in the Engineering Manual. The 2 ton truck did have a different part number for its pistons.
Another one of those mysteries

57 corvette FI engines used two different heads: the 250 HP FI engine came from Flint with cast # 3740997 and its casting symbol was a rectangle with a single tower(this 997 head was also used on all other 57 corvette engines except the 283 HP vette engine). the 57 283 HP vette engine's head's casting # was 3731539 and its casting symbol was a triangle on the rectangle.I also believe these Corvette FI heads were used on the 57 chevy pass car FI engines.Mike

Hi Gene,

You would think the 772 head was used on the trucks due to the larger combustion chamber. Based on the parts info, I would think the pistons were different due to the much lower CR...

Thanks Mike for the Corvette info.