Yenko 427 Engine Information

[YenkoBird]

I have a 427 L72 Yenko complete engine in my car. Does anyone have any information or links that can provide more info. It has the Yenko located in the block casting front drivers' side on an angle. The heads are cast 3946074. The intake has the winter foundry marks. I understand this block casting was from earlier blocks, possibly 69?

[LT1vette]

That Holley has an odd choke linkage on it. Is there a part number stamped on it?

[LetsFNgo]

Originally Posted by LT1vette

That Holley has an odd choke linkage on it. Is there a part number stamped on it?

It’s a 950 3 barrel list 3916. That’s the choke setup they used. A 1030(some say 1050) 4604 3 barrel is identical but uses dump tubes on the rear secondary flap instead of boosters.

[LT1vette]

Originally Posted by LetsFNgo

It’s a 950 3 barrel list 3916. That’s the choke setup they used. A 1030(some say 1050) 4604 3 barrel is identical but uses dump tubes on the rear secondary flap instead of boosters.

Hi... I've never seen one of these, thanks for the info.

[William]

Yenko sold ZL-1 block castings in the '70s, no complete engine assemblies. Disassembly would be the only way to determine build configuration.

[YenkoBird]

From what I read, the castings with the Yenko on front right were early builds like in 69? Possibly from a wrecked Camaro? Also, the head casting numbers were on 69 ZL1's, I could not find if that was a standard head for years afterwards.

[William]

No ZL-1 Camaro had a Yenko block.

Chevrolet produced the last production ZL-1 block castings [3946052] early August 1969. Lockport [LC] did some 053 castings in the late '80s.

The 2025 Chevrolet Performance catalog still lists an 053 block casting, much improved over the original.

The 3946074 head was produced into the '70s.

[luzl78]

Originally Posted by William

No ZL-1 Camaro had a Yenko block.

Chevrolet produced the last production ZL-1 block castings [3946052] early August 1969. Lockport [LC] did some 053 castings in the late '80s.

The 2025 Chevrolet Performance catalog still lists an 053 block casting, much improved over the original.

The 3946074 head was produced into the '70s.

William, I was looking for the 053 block,couldn’t find it. Do you have the part number for that block? Thanks. Jeff

[William]

The part number for the 053 block in the 2025 catalog is #12370850.

[Too Many Projects]

Online GM parts dealers show it as discontinued...