Richard@WCCH

iTrader: (3)

While working on our L92 CNC program I discovered at least 2 different casting numbers. Some heads are cast number 2716 and others are cast number 5364. I've discovered that the exhaust port core of the two heads are different. The 5364's have a bulge in the roof of the port just after the guide boss merges into the port roof. The 2716 head doesn't have the bulge. I'll try to get an image of the two posted up later today.
Are there any other L92 heads with different casting numbers than the two I have? I'm hoping someone from GM might be able to shed some light on this.

Richard

dame

iTrader: (3)

nice info....... does the "bulge" help or hurt a porter in anyway?

sprayjunkie

Actually, I'd love to know which of the two will flow better as cast?
Hmmm...

dame

iTrader: (3)

Thats another good question

<------ on is way outside to try and locate his casting numbers

2c5s

iTrader: (11)

5364 here.

StingrayCrazy

iTrader: (5)

Hey Elwood, what casting #'s did you get from SDPC last week?

NoMoreFWD

iTrader: (1)

Good info - thanks.

Ellwood

iTrader: (1)

How can I tell? Where is it marked on the head?

Dragaholic

iTrader: (180)

The casting numbers are usually on top of the head (not inside where valvetrain is), at the end(s).

Ellwood

iTrader: (1)

Ok... on top, not under the valve cover, if I had one installed, in the same spot my LS2 heads say 243 is 823. Just under that, on the machined surface where the exhaust flange will bolt up is a 16 digit # that ends in 2714.

Do I need to go take another look? Anybody got a picture?

StingrayCrazy

iTrader: (5)

No I think you got it... Thanks. I'm interested in finding out what the differences are.

SUTTERERMAN85

iTrader: (42)

hmmm...any idea how much airflow with differ between the 2 castings? like to see some pics my heads will be here tomorrow hopefully

adams2003

Will you be able to run the same cnc program on both part #s?

Richard@WCCH

iTrader: (3)

Great question Adam. As of now our current program will leave an untouched section of the port roof on the 2716 heads and give full cleanup on the 5364 heads. I'm uploading some pics to show the main differences.

Richard

2c5s

iTrader: (11)

Hey Richard,

Did you notice any flow discrepancies between the two different part numbers?

I may be up your way this Tuesday, I'll try and pop in and take you for a blast.

Richard@WCCH

iTrader: (3)

Here's a couple of pics I promised of the visual difference in the two castings and exhaust ports. I doubt the bulges cause much if any flow loss, but the more important thing is the finished ported casting thickness. It looks like engineers have tried to facilitate circulating more water between the port roof and the underside of the spring pad on the 5364 heads.
I also included an image of where to look for the head's casting number.

This is the 5364 casting and associated as cast exhaust port. Note the bulged area circled.



And this is the 2716 casting's exhaust port. Not bulged. There is a higher roofline in this head's as cast configuration. It looks to be approx. .050" taller in this local area.



It should also be noted that the port exit size and shape are near identical on both heads. At the moment I have no seats installed in the 2716 head so I can't test any flow differences or check any runner volumes. More will follow..........


Richard

moregrip

iTrader: (8)

excellent info Richard! thanks for the 411

Richard@WCCH

iTrader: (3)

Thanks Grip. I'm trying to get a better understanding of these new heads and in the process share some of what I find with the forum.

Stay safe at sea partner

Richard

StingrayCrazy

iTrader: (5)

https://ls1tech.com/forums/showthrea...=639090&page=2

Here's a pic of Elwood's L92's posted on this thread. So we have another casting number of 823? Elwood, do you have a pic of the other side of the head?

slt200mph

iTrader: (42)

Thanks for the undate on the casting numbers Richard..