tiger9297
1/2 ton status
Are these the same Vortec heads that came on the late 90's trucks? I know they had Vortec heads but I'm just not familiar with the "L31" designator. I also have another stupid question: Is a 355 simply a bored 350??
CK5
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L31 Vortec heads????
- Thread starter tiger9297
- Start date
sled_dog
1 ton status
355 is just a .030 over(or 30 over) bored 350. And yes L31 is just a casting number of Vortec heads. I forget what the other designation is.
L31 is was the engine RPO for the 5.7 Vortec engine. First introduced in the 1996 trucks. in other words L31=Vortec.
tiger9297
1/2 ton status
Gotcha. Thanks for the input. I was just looking at some engine combos I was interested in and saw some 355's and some had the "L31" Vortec heads. Wanted to make sure I knew what I was looking at.
beater_k20
Banned
casting numbers will be 10239906, 12558060, 12558062, or 12529093. stay away from 12558059 as they are 305 heads with 1.84/1.50 valves.
tiger9297
1/2 ton status
Thanks again. I know these heads aren't great but I'm seeing 400+ hp and 400+ lb. ft. of torque with them so pretty good for the money. As long as you don't compare to AFR's. WOW!!! Those heads are head and shoulders above the rest. Can't justify that though. I'll wait and put those on my Vette (when I talk the wife into letting me buy one). 
mr_clean
1/2 ton status
I just ordered a set of those from Summit. got the 062 castings and they were in my house within 24 hrs for a little over $500
