difference in heads?

[Fondle]

is there a difference in heads between the 1997 and 1999 years? my car is a 1999 and i know of a guy selling heads from a 1997, so im just making sure im not downgrading before i pull the trigger

[cam98aro]

Re: difference in heads?

there shouldnt be any difference

[Fondle]

Re: difference in heads?

ok, i thought someone said they might flow slightly worse

[Pewter02Camaro]

Re: difference in heads?

prior to mid-1998, GM used smaller valvespring pilot seats and the heads were prone to cracking at these locations.

Someone correct me if i'm wrong but im pretty sure this applied to all mid 90's 3800 heads before 98. I think this includes L36/L67. But if someone knows for sure please chime in.

[pace2006]

Re: difference in heads?

The older castings flow the same, but they are more prone to cracking in certain spots after being ported. The later casting heads fixed that issue and that is why you oftentimes see companies requiring those for cores.

[97rs4life]

Re: difference in heads?

The older castings flow the same, but they are more prone to cracking in certain spots after being ported. The later casting heads fixed that issue and that is why you oftentimes see companies requiring those for cores.

this is correct.

[thedetailman]

Re: difference in heads?

more prone to cracking yes, but cracking in the first place is not a common occurrence with these engine heads. Cracking has only occurred with very HIGH tempts and very high compression (more so than that of which the head was rated)

more prone is just a term saying that heads before 98 were probably 5-10 percent MORE likely to crack. its not that they were bad all around.

[Blizzard242]

Re: difference in heads?

Ok, i've heard of these mid 98 heads being bad.. I have a 98. How can I tell if I have these heads that are prone to crack? I want to get some abbotts eventually but damn that's gonna be awhile.

[thedetailman]

Re: difference in heads?

your fine. the heads that we have. are fine. (as in there not any more prone to crak than other heads on gm cars. Its just the Newer cars. 98 plus. mostly 99 and plus got better castings so those heads are more crack resistant than our heads. SO i think its nothing to worry about. Unless your car gets HOT HOT alot and has 12:1 compression lol

[Blizzard242]

Re: difference in heads?

Well.. I am turbo'd. But the 160 t-stat helps.

[ssms5411]

Re: difference in heads?

Newer casting is 4781, I had a 96' head that the valve guide broke completly off and had to have it redone. This is why ZZP and Intense won't except pre 98' heads as a return becuase of their defects.

[Blizzard242]

Re: difference in heads?

Where would I look to find this number?

[ssms5411]

Re: difference in heads?

Inside of the heads, you'll have to take the valve cover off.

[nimrod.sixty9]

Re: difference in heads?

Damnit Why mid 98?!?!

Right there with ya Bliz.

Still wish I knew what that knocking was! Still no signs of it being anything to do with heads though.