ZL1 or Yenko Block?
 

here's the casting on the front

Re: ZL1 or Yenko Block?
 

on the back there is no plate used, the holes do not exist to bolt it on instead a soft plug is used

Re: ZL1 or Yenko Block?
 

another pic of the front casting

Re: ZL1 or Yenko Block?
 

casting number on the back

Re: ZL1 or Yenko Block?
 

also casted in on the opposit side of the casting number is 06017 on the front stamped in behind the timing cover SY30 BQ and stamp in on the timing cover surface mounting is (9578) this block also has screw in freeze plugs

Re: ZL1 or Yenko Block?
 

From Mortec website .

3946052....427.......69......4-bolt, Alum. ZL-1, Mark IV

http://www.mortec.com/bbc.htm

Re: ZL1 or Yenko Block?
 

Stitch
I think what Eddie is looking for is whats the orgin of the Winters snowflake with the letters in the middle. Was it a special block that was used and for whose Cars?? Yenko?? ZL1's or was there a racer out there that had them made and had the middle of the snowflake removed and replaced with his initials??

Re: ZL1 or Yenko Block?
 

Gotcha...............oughta learn to look before I leap eh ? [img]/ubbthreads/images/graemlins/blush.gif[/img]

Re: ZL1 or Yenko Block?
 

Sometimes leaping is the only way some of us can learn.

Re: ZL1 or Yenko Block?
 

What was the purpose for removing the center of the snowflake and putting in the initials? Was it for theft reasons? [img]/ubbthreads/images/graemlins/dunno.gif[/img]

Re: ZL1 or Yenko Block?
 

The blue ZL1 sold new here in MN. Had a yenko replacement block in it around 1984.It was rebuilt by a local machine shop.The engine builder ground off the yenko crest and put in his own initials.This may have been a common practice in the past.Earl

Re: ZL1 or Yenko Block?
 

When Yenko purchased the rights to manufacture the ZL-1 engine from Chevrolet, They started with the GM castings. Winters notified Yenko that they could not use the Winters insignia on the blocks. Hence, the W in the snowflake was removed and the aluminum foundry stamped in their initials. Yenko stamped their alpha numeric inventory number in the timing chain area of the block. These blocks did not have an inventory or date cast on the side of the block. The Yenko blocks evolved in construction and appearance over time.

Re: ZL1 or Yenko Block?
 

Thanks Ed [img]/ubbthreads/images/graemlins/scholar.gif[/img] you told me that already i should have listen to you before [img]/ubbthreads/images/graemlins/blush.gif[/img] who is the foundry that made them for yenko? [img]/ubbthreads/images/graemlins/beers.gif[/img]

Re: ZL1 or Yenko Block?
 

I believe LaPorte Indiana LP

Re: ZL1 or Yenko Block?
 

Yenko was also working with a company outside of USA to make alu blocks for him.