discovered 241's on my 1998 z28

**Destroy Everything** · 03-12-2014, 03:09 AM

Quick question, I bought a 1998 z28 and received a spread sheet from the previous owner. Every bolt that he turned is documented however in his notes I noticed "inspected heads, center bolt valve covers, 241 heads, not 1998 engine." Now correct me if I'm wrong but the previous owner assumed the engine was replaced because the heads are not original when in fact chances are only the heads were swapped. The computer is still a 1998 model if that means anything. Is this a good thing I have 241's? What are the original heads? Do you think I still have the original block?

**kingls1** · 03-12-2014, 03:31 AM

98's came with 806 heads perimeter style bolt pattern. 241 heads have center bolt and flow a little better. better than them were the 243's. the only way to tell if block is original you need the number from the block.

**Destroy Everything** · 03-12-2014, 03:33 AM

thanks

**zmg00camaross** · 03-12-2014, 04:29 AM

May have been a late production engine going into 99.

**Destroy Everything** · 03-12-2014, 05:57 AM

I guess it doesn't really matter how they got there, just wanted to confirm what I had when ordering parts. Going to bring it in to a gm dealership at some point hopefully they can clear everything up for me.

***SMWS6TA*** · 03-12-2014, 06:35 AM

How many owners of the car besides you 2?

It's possible the heads were swapped out. Almost anything is better then the 806 heads.

The only non performance difference with center bolt vs perimeter bolt is the valve covers. You can easily remove the coil packs as a unit instead of individual units.

**Destroy Everything** · 03-12-2014, 06:54 AM

I am the third owner, 123,000 miles. Previous owner purchased it with 89,000 in 2010 and set it up for auto cross.

**Destroy Everything** · 03-12-2014, 07:17 AM

I'm wondering if zmg is right.. when the second owner bought the car it was bone stock. I doubt the first owner would have swapped heads without any other mods

**zmg00camaross** · 03-12-2014, 04:16 PM

I bet it's factory just late 98 model year.

**Firebirdjones** · 03-13-2014, 05:10 AM

241's didn't come out until the 2001 model year, so that would be pretty darn late

After 98 they came out with 851's, center bolt valve covers. Those heads stayed through 2000 production (my 2000 SS has them) then the switch to 241's was made late that year for the new 2001 models.

241's are said to be better than previous versions because they went through a sand casting process (not all 241's, just the ones cast in Mexico) which provided a smoother surface and more uniform shape from port to port. This provided slightly better flow numbers. From what I've seen and read, it's not much more than 5 cfm. Nothing to get too excited about.

**Destroy Everything** · 03-13-2014, 07:53 AM

So the motor was swapped at some point or I may have early 851's from the factory? Like I said when the previous owner got the car it still had the stock exhaust, lid, wheels ect.. That being said I can safely rule out the first owner swapping heads. I wish I could just drive down to the dealership but I travel for work, I've been on the road for a month straight and I don't know when I can get back home. I've been really curious ever since I left lol.

**zmg00camaross** · 03-13-2014, 09:33 AM

O yeah I forgot they came out in 01 I thought it was 99. My bad lol my 00 ss has 241.

Thread: discovered 241's on my 1998 z28

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