Question: Head Identification

[eoseitz]

Hi,

I bought a rebuilt engine and have torn it apart to change the gaskets. It is an 1981 LT9 block, with mild edelbrock cam, and maybe 202 heads. When I purchased the motor I was told they were camel hump and misidentified them (they have a hump looking thing on them). I was wondering if anyone could help me identify them. I've tried to look up the casting number, but it's very very difficult to read and I haven't been able to find a match. I think the number are either 378468 or 376458. There's also a casting number GM12T

After comparing the castings to the casting numbers they look similar to 450s. I'll attach some pics. Any help would be appreciated. I'm not sure if I've gave anyone enough to go on.

 

[kpic]

This ought to help: Quick Ref: Small Block Chevy Cylinder Head Casting Numbers - EngineLabs

 

[navy2kcoupe]

From the thread in the previous post......




Andy

 

[eoseitz]

Thanks for the replies. I've tried to look them up, unfortunately, I really can't make them out. From the second picture I posted, I think they might be 354434/376450/14014416. The marks looks a lot alike. Do the casting marks refer to the marks on the front and back of the heads or the mark stamped in picture 2 with GM12T by it? The mark stamped inside the head looks like the area in the center of the front and back of the heads.

 

[Hib Halverson]

Best I can determine is that LT9 small blocks were truck engines used in the mid-80s in 20-series and 30-series full-sized truck platforms.

Typically part numbers are not cast into heads. Casting numbers are what's casted into the top of the head.

You really need to get a better fix on that casting number. Try looking at the other head to see if the number is easier to read. Also sometimes shining a flashlight at different angles can make the numbers easier to discern.

Those three casting numbers are all 305-cuin heads. Only one, CN 140144416, is a Corvette head. It was used only on 1980s sold in California, all of which had a 305-cuin engine.

Stock valve sizes were 1.72/1.50-in. Chamber volume was 59-cc. Those heads are generally not suitable for high-performance applications.

 

[eoseitz01]

Thanks for your help everyone. I found a pair of true camel hump 202 that have been rebuilt. The guy has supplied pictures of the casting numbers and marks. $450. Can't beat that with port polish, new seals, and upgraded springs.


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