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JohnZ
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« Reply #15 on: July 24, 2012, 10:17:45 AM »

There's no difference in the castings between 1.94" and 2.02" heads - they're the same casting. The difference in the apparent thickness between chambers with adjacent intake valves and adjacent exhaust valves is a result of the material removed from the side of the chamber wall when the factory unshouding cut was made. Photo below is a 2.02" 462 chamber that shows the amount of material removed; machining was the same for 2.02" 461/462/291/186 heads.
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'69 Z/28
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pjbizjak
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« Reply #16 on: July 24, 2012, 06:55:43 PM »

Dannystar, JohnZ; The pictures I have are in the form of an email that I can forward, that's the only way I can get them to you.

Pete
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pjbizjak
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« Reply #17 on: July 24, 2012, 07:00:57 PM »

Oh the other reason I'm persuing this issue is because the heads are 'date correct' for my 04A built Z/28 engine with a build date of 0329MO. The heads are dated c208 & c218, I have one original head that is dated c238.
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dannystarr
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« Reply #18 on: July 24, 2012, 09:20:37 PM »

JohnZ, I messed up my wording. Of course the casting is the same. I meant after the cutting. It seems that if the cutting is done by a machine shop, 35 years later, you can see that it's just not factory. Or at least I think I can tell. But like I told him, I am last on the list on this site for knowledge. Or close to the bottom. Because looking at your picture, that to me looks like it was a 194 casting that has been punched up to a 2.02. Just doesn't look right to me. Looks like an after market relief job. Like I said, what do I know.  Grin Huh  

pjbizjak, send them to me at this email. djc@vom.com

Then I will try to load them on here for John and the guys to see.
  Danny
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dannystarr
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« Reply #19 on: July 25, 2012, 04:36:23 PM »

Here are pjbizjak heads he is interested in buying. Are they real 202's??? Doesn't look right to me, not enough relief. The more I look at JohnZ's last picture, the better it now looks.... Danny
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TODD
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« Reply #20 on: July 25, 2012, 08:34:05 PM »

So are the guides drilled out and these new guides added? Also looks like its got scew in studs, what are your plans for rockers the stock "O" rockers?
Those new studs can cause geometry issues if they have the guide locked in the wrong position. I'd try to find a set with original studs (pressed) and no guide work. But thats just me, lots  of extra effort downstream dependant upon what you are doing.
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tmodel66
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« Reply #21 on: July 25, 2012, 11:32:24 PM »


Those new studs can cause geometry issues if they have the guide locked in the wrong position. I'd try to find a set with original studs (pressed) and no guide work. But thats just me, lots  of extra effort downstream dependant upon what you are doing.

Todd can you elaborate a little on the issues you mentioned if the guides a locked in the wrong position?
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Daniel  
'69 SS 350/4 speed  Fathom Green--POP
pjbizjak
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« Reply #22 on: July 26, 2012, 09:32:05 AM »

I'm not too concerned about the guides because they can be removed, I do like the screw in studs. I'm mainly interested in these heads because the are 'date correct' for my engine.

Pete
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pjbizjak
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« Reply #23 on: July 26, 2012, 09:38:20 AM »

Dannystar; Great job on the pics, thank you.
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1968 Z28
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« Reply #24 on: July 26, 2012, 10:28:43 AM »

I'm not too concerned about the guides because they can be removed, I do like the screw in studs. I'm mainly interested in these heads because the are 'date correct' for my engine.

Pete
That depends....in the old scheme of things the holes that the pushrods went through in the  heads served as the guides....they were shaped to hold the pushrods in alignment, ie...they served as guides.  When you convert to guide plates, they now serve as the guides and in order to keep the two methods from interfering with each other the holes in the head were reamed out to keep the pushrods from touching the head.  So now you have to use the guide plates.  It looks to me that the holes in these heads have been reamed out.

I did the same thing to my original heads and I now regret it....I am trying to restore my car to original.  But, I continued to search for the right date coded heads and I finally found a set of date correct, magnafluxed, 1.94s and with the right machinest can be converted to work and look like my originals.

So....keep looking.
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Jerry G.

Z28-1968-07C-Norwood
Ermine White, Red Std. Interior
2 Owner, 38,000 miles
dannystarr
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« Reply #25 on: July 26, 2012, 10:54:52 AM »

pjbizjak you are welcome. At least we got them posted. I had to fool with them and resize them etc. But we we got her done.
 I agree with all above info, I would skip these. The heads you see in the picture were for my Z/28. But I lost that car as some of you may remember. So I had alot of parts I collected and sold most on this site. No reason to keep them and needed the dough. Good luck in your search, I will look for a set for ya here in Northern CA. Give me all the build date info on your car.... Danny
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1968 Z28
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« Reply #26 on: July 26, 2012, 01:15:22 PM »

Well.....actually I found two sets of date correct 1.94 heads. Bought the first set on eBay cheap, a set of heads just taken off an old motor, not cleaned and magnafluxed. The set I thought looked great and took them to the machinist to be modified to the 2.02 specs.  When the machinist got them cleaned up he found that one head had cracks on two of the rocker stud mounts. So he then had to machine the stud mounts down and install screw in studs.  I didn't like the looks of the fix so I decided to keep searching for another set.

I kept searching on the internet and finally found a set at a machine/race shop in Pennsylvania that was date correct (even closer to my originals than the first set, within a couple of days), cleaned, magnafluxed, and unmolested. I did have to pay more money but at least I now have something that is good from the start.

So the moral is.....keep looking and make sure you buy something that isn't junk.
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Jerry G.

Z28-1968-07C-Norwood
Ermine White, Red Std. Interior
2 Owner, 38,000 miles
JohnZ
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« Reply #27 on: July 27, 2012, 11:56:20 AM »

The bottom photo in reply #19 is a 1.94" head that's been opened up to 2.02", without doing the unshrouding cut; the flow restriction around the outboard portion of the intake valve is very obvious.
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'69 Z/28
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pjbizjak
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« Reply #28 on: July 27, 2012, 01:33:27 PM »

Man you Guys are awesome. I'm convinced and  I am passing up on the subject heads and I'll keep looking. Thanks to all!

Pete
68 04A Z/28 Rally Green
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68Zproject
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« Reply #29 on: July 27, 2012, 02:16:20 PM »

Jerry, could you pm what you paid for the heads if you don't mind.  I have the same crack issues on my heads that I just got studs put in.
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68Z28
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