1957 1958 X58 cast into 997 heads?

[John R.]

My car has 997 heads with X58 cast into them. Does anyone know if these are correct for very late 1957 and very early 1958 vettes? Or just one year or the other? Normally the X58 is seen on the 770 heads. Thanks for any input, John

[Gary C.]

Re: 1957 1958 X58 cast into 997 heads?

John, what's the VIN of your '57? Gary....

[Tom P.]

Re: 1957 1958 X58 cast into 997 heads?

This issue was just recently discussed.
As I recall, there REALLY was NO acceptable resolution as to why the 58 was cast into the 997 heads.
But, one thing for sure that has been concluded by almost everyone is that the 997 heads were 57 ONLY. Both Vette and pass car engines.

And this brings up another issue----------------even though it was not asked----------------, the 539 heads.
In the past, a LOT of people (I sympathize with those poor folks) have paid BIG BUCKS for (1957) 539 heads because they are 57 FI heads! Well, not exactly so. The 539 heads are (or were) more or less common as dirt, because this was the head that was used on all 57 Chevy pass cars with the "Power pack" 283 engine (4bl 283). Thus there were (and still is to some extent) tons of cheap 539 heads, but a lot of people didn't do their homework and thus unnecessarily paid exhorbitant prices for them just so that they could have a set of real FI heads on there 57 FI engine.
So, the next time you see a set of 57 "FI" heads priced at the national debt, be skeptical about their past, because they could have come off of a 57 4dr wagon with a 4bl carb 283.

[Joseph T.]

Re: 1957 1958 X58 cast into 997 heads?

This issue was just recently discussed.
As I recall, there REALLY was NO acceptable resolution as to why the 58 was cast into the 997 heads.
But, one thing for sure that has been concluded by almost everyone is that the 997 heads were 57 ONLY. Both Vette and pass car engines.

And this brings up another issue----------------even though it was not asked----------------, the 539 heads.
In the past, a LOT of people (I sympathize with those poor folks) have paid BIG BUCKS for (1957) 539 heads because they are 57 FI heads! Well, not exactly so. The 539 heads are (or were) more or less common as dirt, because this was the head that was used on all 57 Chevy pass cars with the "Power pack" 283 engine (4bl 283). Thus there were (and still is to some extent) tons of cheap 539 heads, but a lot of people didn't do their homework and thus unnecessarily paid exhorbitant prices for them just so that they could have a set of real FI heads on there 57 FI engine.
So, the next time you see a set of 57 "FI" heads priced at the national debt, be skeptical about their past, because they could have come off of a 57 4dr wagon with a 4bl carb 283.

Passenger car = sand cast pyramid head marking and two digit year code

Corvette = machined pyramid head marking and single digit year code

[John R.]

Re: 1957 1958 X58 cast into 997 heads?

Gary, my cars assembly date was Aug 31, 1957. Assembled in the last few days of production. Appreciate all the information that every one has provided. Thanks, John

[Jim L.]

Re: 1957 1958 X58 cast into 997 heads?

Passenger car = sand cast pyramid head marking and two digit year code

Corvette = machined pyramid head marking and single digit year code

Two digit year code indicates Tonawanda origin while single digit year code indicates Flint origin. Nothing more. I've seen plenty of Flint (single digit) heads on unmolested. passenger car engines.

Jim

[Mike M.]

Re: 1957 1958 X58 cast into 997 heads?

Passenger car = sand cast pyramid head marking and two digit year code

Corvette = machined pyramid head marking and single digit year code

joe: the tonowanda heads, sand cast and double digit cast date year, were never used on 57 vettes BUT lots of 57 pass car chevys were equipped with the Flint machined single digit cast date as well as the tonowanda heads. mike

[Tom P.]

Re: 1957 1958 X58 cast into 997 heads?

Two digit year code indicates Tonawanda origin while single digit year code indicates Flint origin. Nothing more. I've seen plenty of Flint (single digit) heads on unmolested. passenger car engines.

Jim

That is exactly correct.

[Tom P.]

Re: 1957 1958 X58 cast into 997 heads?

joe: the tonowanda heads, sand cast and double digit cast date year, were never used on 57 vettes BUT lots of 57 pass car chevys were equipped with the Flint machined single digit cast date as well as the tonowanda heads. mike

That is exactly correct.

Now, what about the 58 cast into 1957 997 heads?

[Jim L.]

Re: 1957 1958 X58 cast into 997 heads?

Now, what about the 58 cast into 1957 997 heads?

I bet that's nothing more than the foundry's way of keeping track of pattern updates as the casting evolves.

I used to have a "739" block that had the numbers "739" AND "548" embossed in the casting under the timing cover area. It was an early "739" block and I just figured some of the pattens from '57 were still applicable to the next generation casting.

Jim

[Joseph T.]

Re: 1957 1958 X58 cast into 997 heads?

joe: the tonowanda heads, sand cast and double digit cast date year, were never used on 57 vettes BUT lots of 57 pass car chevys were equipped with the Flint machined single digit cast date as well as the tonowanda heads. mike

Mike & Jim...

Thanks for the finer point.

Joe

[Tom P.]

Re: 1957 1958 X58 cast into 997 heads?

John Neas called me last night to tell me he has ONE 997 head with the 58 cast in it below an exhaust port---------------------but he didn't tell me the cast date code!