Ravoll

Hi All.
Have a quick question.Pulled the heads off my 350 and during my valve job prep,found they were both cracked across the 4,6/3,5 cylinders exhaust valve seat.Just purchased a brand new pair today, Hecho Mexico,
Cast # 462624 2.02/1.60

Just found out that heads with these Casting '#s are crack prone.
I also saw that the new heads have pressed in seats for the exhaust valves,not ground into the casting like my busted ones .Is this a fix for the cracking problems.
I'm just trying to gather some info before I run these things.It's a "peace of mind" thing.

BLOCKMAN

Those heads are a smog head, Years ago when I worked for State Police we had a memo from GM that said if we found cranks in those heads and they were not using anti freeze put them back on as the cranks were most likely just in the induction harden seat.

I think that was a valid point as we would pressure test them valve job put them back on and never seen any issues.

Pessure test would be key!!

I would go to a better head like an aluminum head rather then spend money on seats and guides ETC.

Ravoll

Due to a minor stipulation in my registrating I cannot add Alu heads and still retain my historical vehicle status.Vehicle must keep an outward "original" appearence.

On the heads that are cracked the cracks run from inside the combustion chamber,through the valve seat, and out the exhaust port.

The question is ,with the new heads having pressed in valve seats, will I have to worry about them also developing the same cracks in the future?

63mako

Made in USA Aluminum heads with chevy orange paint would be my choice for an "outward original appearence".
.
Edit: I guess that ugly blue color in your case.

Shark Racer

I agree, and if the car has the alternator and A/C hooked up, it will be next to impossible to see the head.

TheSkunkWorks

After going thru several "crack-o-matics" on my '78 L82, I finally fixed the problem by putting a 427 BB in it.

That said, if anyone would like to have a spare on hand I do happen to have one good bare #462624 w/o apparent cracks. $25USD plus shipping (states only), else it's going to be tossed out with spring cleaning.

vanice

Ravoll

Actually its been repainted ."Ford" blue.
Not really.I'ts dark ultra marine blue.Was cheaper than getting that ugly faded chevy blue,and looks better.

Rich's'78

Both engines used the 624 heads with the L48 using the smaller valves and the L82s using the larger valves (2.02 + 1.60). I believe the cracking problem was only with the larger valves since there is less casting material left between them.
So either use the smaller valve 624s (I don't think you will give up much flow, they both flow poorly compared to modern heads) or get a set of good flowing cast iron heads and grind the brand name off them. You will pick up at least 20 hp, more if you made other mods.
The potential problem with aluminum heads in your case is no matter how you hide them they will not be magnetic, so if they go to that much trouble to verify cast iron heads, you are sunk.

scottyp99

I was looking at your pics, and it looks like you've made some drivetrain mods, nobody says anything about that? Just engine oriented mods are prohibited?


Scott