1969 z 302

[brent396]

I just acquired a 1969 Z28 car born with 302 DZ motor I have a question about cylinder heads has anybody ever heard of a 3947041 it's dated d17 of 9 the other head a 3927186 dated d25 of 9 and their factory DZ block is dated d18 of 9 the motor is all original do you think the head was replaced or would it come factory 202 with a 3947041 head everything else on the motor carburetor distributor alternator radiator trans rear everything's been untouched

[Lynn]

Theoretically, it is possible. However, if it did turn out to be the original heads, I believe it would be the first known example of an 041 head on a Z/28.

I tore down a L48 in a 69 Impala that had one 186 head and one 041 head, and still had the factory steel shim gaskets with no sign that it had ever been apart. That was in the mid 90s. However, as you know, the L48 had 1.94 intakes.

I don't believe there has ever been a documented case of an 041 head with 2.02 valves from the factory. Quite a few have been modified for 2.02 intake valves. You might try a boroscope, but it would be really hard to tell if the head was machined for 2.02 intake valves from the factory without pulling it.

The date would make one believe it is likely original to the car. Hate to say never.

What is the assy date on the engine? Does it predate the D25 9 head? If so, most likely both heads were replaced at some time.

[brent396]

V0512dz

[brent396]

Dist 9D2, carb 943

[brent396]

Car car 05E

[brent396]

Alt 9C7,rad CH D ,rear 0515, trans P9E05

[Hotrodpaul]

From what I have seen the 041 head was cast in Tonawanda and primarily used on the 300 Hp 350 applications to help supply the Flint plant due to high demand. It may be possible they could have machined a batch of 2.02 heads to replace the 186 heads in Hi Po applications. My 70 SS Camaro 350 was a 3970014 block cast in Tonawanda and used 041 heads.

[William]

I an aware that Camaro High Performance has seen 041 heads used on May built 302 engines. Also, a 350hp '69 Corvette.

Rare, but did happen.

[rszmjt]

I 50+ years being involved with machining/building SBC motors & a lot of 69 DZ302,s , I have personally never seen a 041 head that is a factory 2.02 x 1.60 . Not to say it didn’t/couldn’t happen but it would be interesting to see if that 041 head has machined/relieved combustion chambers around the intake valve as the factory production big valve head did. The factory relieved combustion chamber around the intake valve is hard to duplicate exactly even with today’s Serdi/Quickway type tooling.

[Tracker1]

I'm always learning on this site...it's why I love it. :)

[Jonesy]

I 50+ years being involved with machining/building SBC motors & a lot of 69 DZ302,s , I have personally never seen a 041 head that is a factory 2.02 x 1.60 . Not to say it didn’t/couldn’t happen but it would be interesting to see if that 041 head has machined/relieved combustion chambers around the intake valve as the factory production big valve head did. The factory relieved combustion chamber around the intake valve is hard to duplicate exactly even with today’s Serdi/Quickway type tooling.

Totally agree. I have never seen an 041 head on a z28. I would have to see this to believe it was the original.

[jdv69z]

From what I have seen the 041 head was cast in Tonawanda and primarily used on the 300 Hp 350 applications to help supply the Flint plant due to high demand. It may be possible they could have machined a batch of 2.02 heads to replace the 186 heads in Hi Po applications. My 70 SS Camaro 350 was a 3970014 block cast in Tonawanda and used 041 heads.

If I remember correctly, John Z, a GM engineer who was involved in the manufacturing of these cars when they were being built, stated that the tooling required for 2.02 head machining only existed at Flint. So if an 041 was a Tonawanda casting, it would have had to had made its way to Flint to be machined. I believe that did occur with some Tonawanda block castings when demand was high and Flint's block supply was behind, so it could be plausible.

[RALLY]

I just acquired a 1969 Z28 car born with 302 DZ motor I have a question about cylinder heads has anybody ever heard of a 3947041 it's dated d17 of 9 the other head a 3927186 dated d25 of 9 and their factory DZ block is dated d18 of 9 the motor is all original do you think the head was replaced or would it come factory 202 with a 3947041 head everything else on the motor carburetor distributor alternator radiator trans rear everything's been untouched

I have read on different GM car sites when people removed the valve covers they found two different cast numbered heads installed from the factory. Is it true this happened during engine assembly, it would be interesting to talk to some former people who assembled the GM engines to find out. I also was told by a retired GM engineer when engines were assembled at the Flint plant, the line workers didnt pay attention to cast dates, they just grabbed what they had on the lot or skid and installed them on the engines. Hope you can find your answer.

[Lynn]

I 50+ years being involved with machining/building SBC motors & a lot of 69 DZ302,s , I have personally never seen a 041 head that is a factory 2.02 x 1.60 . Not to say it didn’t/couldn’t happen but it would be interesting to see if that 041 head has machined/relieved combustion chambers around the intake valve as the factory production big valve head did. The factory relieved combustion chamber around the intake valve is hard to duplicate exactly even with today’s Serdi/Quickway type tooling.

That's what I meant when I said:

"You might try a boroscope, but it would be really hard to tell if the head was machined for 2.02 intake valves from the factory without pulling it."

Probably would need to pull the head to inspect it well enough to tell.

[Kurt S]

Like Bill said, there's at least one other Z known to have a 041 head.

[rszmjt]

Like Bill said, there's at least one other Z known to have a 041 head.

Kurt or William - Any idea if that 041 head had/was ever off that Z28 that Camaro High Performance documented to see if it was indeed a big valve head?, or was just the casting number & date documented?

Brent396 - Is that Z motor going to be disassembled? If so can you post pictures of the 041 combustion chamber? Also obviously the valve covers were off , did the heads retain the original pressed rocker studs?

Like I said in my post I’m not saying it didn’t/couldn’t have happened , but it would be a rare anomaly for sure IMO .

FWIW - When I worked at the Corvette Shop we once had a 66 327/350 HP Corvette that had never been apart and upon disassembly it had the correct 462” casting heads but 1 head was a 2.02/1.60 head the other was a 1.94/1.50. The casting dates were very close & it still had the GM installed steel shim gaskets, so weird stuff did happen.

Would be interesting to find out regarding if 041 heads ever came with the bigger valves , I have never seen any personally.

[Kurt S]

I don't know....