[z28rookie]

a set of heads #3991492? would these be the correct numbers for a 69 Z-28...thanks

[JohnZ]

Nope, those are '69-'72 service-only big-valve heads; '69Z used 3927186 heads.

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JohnZ
CRG
'69 Z28 Fathom Green

[This message has been edited by JohnZ (edited 02-02-2003).]

[ratchetmaster]

There were actually two different castings used on the 69 302 in the z28.

As JohnZ mentioned, the 3927186 was used for the 302 in 69.

Also, the 3947041 heads were used as well on the z28 302 in 69.

Both the 041s and the 186s also came on some 350 engines in 69.

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ratchetmaster



1968 RS SS 350 M4
1969 olds 442 convertible
1972 454 ElCamino Turbo 400
1973 RS LT Z28 Camaro M4
1995 Caprice LT-1 WWW A4
1999 Firebird WS-6 T/A A4
moderator http://www.gmforums.com

[Jonesy]

The 3927041 heads did not come on the 302. They are basically the same except for the casting symbol on the front. The 041 head has a triangle and the 186 head has camel back humps. The 186 head is the correct head for the 69 302 engine.

[z28rookie]

thanks for the quick come back...that cleared up some dispute with a friend...they always told me if you really have to know ...ALWAYS CONSULT WITH AN EXPERT........jake....

[ratchetmaster]

Well,
I don't know where you guys are getting your info from, but . . .

and I can't say this topic hasn't been covered before on here and I missed it,

but the 041 heads were also used on the 302. There have been many documented cars with these heads on them.

Chevrolet by the #s book also covers this topic.

unless I missed something??

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ratchetmaster



1968 RS SS 350 M4
1969 olds 442 convertible
1972 454 ElCamino Turbo 400
1973 RS LT Z28 Camaro M4
1995 Caprice LT-1 WWW A4
1999 Firebird WS-6 T/A A4
moderator http://www.gmforums.com

[JohnZ]

The 186 heads had 2.02" valves, and were the only castings used on '69 302's; the 041 heads had 1.94" valves and were used on many '69 SS350's, 300hp Corvettes, Novas, Chevelles, and passenger cars.

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JohnZ
CRG
'69 Z28 Fathom Green

[ratchetmaster]

John
I am not trying to be argumentative, so don't take this wrong . . .

But what are your sources for your statements??

I have read several articles (including one in the year one catalogue I believe) and one in a restoration magazine that clearly states that the 041 heads were used interchangeably with the 186s.

They were also both identical to the earlier style 461s except for a redesigned combustion chamber, the temp boss, and the external mounting bosses.

For the 290hp 302 They were fitted with 202 intake and 160 exhaust valves, screw in studs and guide plates, and swirl polished valves just like the 186s.

And another fact . . . the 186s did not only come on the 302s. They also came on 300 hp 350s in chevelles, passenger cars like impalas, caprices, etc; 300hp Camaros, 300 and 350hp corvettes, and novas too.

The only "exclusive" head in this year I am aware of were the 187s which came exclusively on the 350 hp 350 corvettes.

This info comes from what I consider to be one of the best sources of info available . . .

"1965-1969 Chevrolet by the numbers . . . the essential CHEVROLET parts reference"
by Alan L. Colvin.

Now if your source is more complete . . . or can over ride this source of info making this source "incorrect", then I will stand corrected . . . but I don't think so.


[This message has been edited by ratchetmaster (edited 02-04-2003).]

[Jeff H]

Don't believe everything you read in books. A lot of those books were written way before any serious research was done. Some books say X11 could be a Z28. The 186 heads are known as the Z28 head, but they also came in the 350/300 hp engines with the smaller valves. The 041 heads did come on the 350/300 hp engines, but I'm not sure there is any real proof they came on Z28's. If there are any, I'm sure CRG would have them documented as original owner cars.

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Jeff H - Hugger Orange 69 Z28, original factory JL8 brakes, cross-ram & GM fiberglass hood, TI setup, heater and radio delete, Stahl headers, Minilite wheels - being restored - 91 SS454 pickup

[Kyvox]

I don't think screw in studs and guide plates were factory installed on any 302s. Those were added in 1970, on the LT1 as far as I know.

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_________________________
John
'67 SS/RS (RR)
'68 RS conv. (J2)
'68 Z/28 (VV)
'68 Drag Car(ZZ) (in progress)
'73 Corvette Drag Car

[JohnZ]

There are lots of magazines and books out there, written with varying degrees of research, and some of them were printed several years ago and don't benefit from more recent work. If you want the most recent accurately-researched information on '69 Z/28's, Jerry MacNeish's "Definitive 1969 Camaro Z/28-SS396 Fact Book" is the best reference.

Yup, the 041 and 186 heads were used on many other Chevrolet applications as well, in both valve sizes, but only 2.02" 186's were used on '69 302's; screw-in studs and guide plates were used on 186's starting with the LT-1 in 1970, in both Z/28's and Corvettes.

The 187 heads weren't exclusive on 350hp Corvette 350's; both 186's and 187's were used interchangeably on Corvette 350/350's in both 1969 and 1970 (source: NCRS Judging Manuals).

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JohnZ
CRG
Chairman, NCRS Michigan Chapter
'69 Z28 Fathom Green

[This message has been edited by JohnZ (edited 02-04-2003).]

[ratchetmaster]

I am not sure on the screw in studs or guide plates . . . I am afraid that was my assumption since my 73 Z28 has them. (I believe my engine is called the L82?)

I don't believe everything I read in books. But. . . I do believe what I read from reputable sources . . . otherwise, what or who CAN you believe??

I have heard many supposibly true stories from people which often times were a bunch of crap.

I think this guy (Alan Colvin) did his work and is VERY reputable.
But, then again, I can always take the other side and be a skeptic.

[ratchetmaster]

John
Just read your post . . .

I would probably bet that "Jerry MacNeish's "Definitive 1969 Camaro Z/28-SS396 Fact Book" is a very reputable source of info. I would be interested in knowing why he has chosen to exclude the possible use of the 041s in 69 z28s. Does He go into detail? Does he feel there are no "authenticated" examples of there use in the 302??
I don't have the book, so I would be interested in what the book says about this topic.

I have found the Colvin book to be very accurate. When ever something is not verified, he puts that in there.

under the 186s info he does say "Please note that the ...041 heads were possibly used interchangeably with this head through 69 and 70 . . . " and lists the 302 and 350s as applications for them.

Then under the 041s he says "This head was interchanged on some . . . 186 and ...187s." and lists the 290hp 302 as an application that was used for this head.

I looked under his "Corrections made" up to his 6th printing and there were no additional comments made or removed from what was already printed on this topic.

also . . . the 187s were only used on the corvette. Other heads came on the corvette. According to CBT#s. I may not have made that clear . . . in other words both sources seem to agree that these heads only came on That application and were not used for other applications.

one more thing . . . the 041 were used on 70 360hp 350 Z28 and the 350hp and 370hp corvette LT1 motors and had 202 valves, guide plates, screw in studs, etc. (1970-75 CBT#s)



[This message has been edited by ratchetmaster (edited 02-04-2003).]

[ratchetmaster]

Jeff H.
I agree with what you said in your post. Is the registry accessible?? Have there been any 041s? Or are you saying there have not been any registered?
Thanks

[Jeff H]

Colvin did some good work, but his research is old and not always accurate. With more than 19,000 69 Z28's made, I would think that quite a few with 041 heads would have shown up by now. First off, you would need to find a set of 041 heads that are actually 202 valves and a proper combustion chamber. The 186 heads for the SS350 with 194 valves need to have more work done than just putting in 202 valves to make them Z28 heads. There is extra machining that needs to be done to open up the chamber. I don't have any information on the data that CRG is collecting, but I would recommend going to their site and asking the same question. It's a similar situation to all the books that show a 69 302 engine with a 3 digit engine code, they are wrong. There are no known 69 Z28 302's with anything other than a DZ stamped engine.

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Jeff H - Hugger Orange 69 Z28, original factory JL8 brakes, cross-ram & GM fiberglass hood, TI setup, heater and radio delete, Stahl headers, Minilite wheels - being restored - 91 SS454 pickup