1970-427-Convert with aluminum block/heads?????

[Daniel A. Yonker]

I just went to look at a 1970-427-4 spd M-22 Convert radio/heater delete no power steering/power brake ect.with a big rear with caps and large half shafts front and rear sway bars the #s we could get off the car were3933198 intake,3946074aluminum heads,no block cast #s or dates? The car was never titled and the current owner is looking for the paper work he got with the car,this car was raced its entire life never road driven and is in overall need of a total restore it has been left outside for many years,the covers that were on it have rotted and blown away(thats the only reason we came acrossed it!) I am 45 years old and have been playing with Vettes before I even had my license! I am sure by looking at it there would be some way to tell what it is ,is it real? Also it has a trim tag that reads SPEC. any help would be great, my N.C.R.S. # is28018 Thanks Dan

[Joe L.]

Re: 1970-427-Convert with aluminum block/heads????

Dan-----

There's no question that the car is real; you've apparently seen it right before your very eyes. The question is: is it original? All kidding aside, though, I expect that the engine was probably added for racing purposes. ZL-1s were sold over the counter in the early 70's. I have a good friend that owned several of them during that time period, all purchased "over the counter".

The intake manifold and cylinder heads are L-88/ZL-1 pieces. I'm surprised that you can't discern a casting number on the block. The casting number for the ZL-1 block was 3946052 and can be found in the same location as other big blocks. Also, if it's an original ZL-1 block it will have a Winter's Foundry "snowflake" located on the front of the engine block, in the area just above the timing cover. Since Winter's Foundry didn't produce any non-ZL-1 aluminum blocks, if you see the snowflake, which is readily apparent, that's as far as you have to look.

There's also the possibility, reinforced by the trim tag inscription, that this was a "special build" vehicle. Perhaps it was a "COPO" car or an engineering test vehicle that somehow got out of GM's control. I don't know of a way to verify the car's originality. However, you could check for things like the block, cylinder head, intake manifold casting date to see if they're consistent with the car's build date. You could also check to see if a "tank sticker" exists(doubtful)or if a "build sheet" was tucked somewhere under the dash. Any of this paperwork, if it could be found, could potentially authenticate the car. But, in a practical sense, your best bet is probably going to be the engine component dates. Let us know how it turns out.

[Joe L.]

Re: 1970-427-Convert with aluminum block/heads????

Dan-----

There's no question that the car is real; you've apparently seen it right before your very eyes. The question is: is it original? All kidding aside, though, I expect that the engine was probably added for racing purposes. ZL-1s were sold over the counter in the early 70's. I have a good friend that owned several of them during that time period, all purchased "over the counter".

The intake manifold and cylinder heads are L-88/ZL-1 pieces. I'm surprised that you can't discern a casting number on the block. The casting number for the ZL-1 block was 3946052 and can be found in the same location as other big blocks. Also, if it's an original ZL-1 block it will have a Winter's Foundry "snowflake" located on the front of the engine block, in the area just above the timing cover. Since Winter's Foundry didn't produce any non-ZL-1 aluminum blocks, if you see the snowflake, which is readily apparent, that's as far as you have to look.

There's also the possibility, reinforced by the trim tag inscription, that this was a "special build" vehicle. Perhaps it was a "COPO" car or an engineering test vehicle that somehow got out of GM's control. I don't know of a way to verify the car's originality. However, you could check for things like the block, cylinder head, intake manifold casting date to see if they're consistent with the car's build date. You could also check to see if a "tank sticker" exists(doubtful)or if a "build sheet" was tucked somewhere under the dash. Any of this paperwork, if it could be found, could potentially authenticate the car. But, in a practical sense, your best bet is probably going to be the engine component dates. Let us know how it turns out.