Compressed thickness of stock steel head gasket

Home Page Forums Discussion Topics – Ask the Experts Compressed thickness of stock steel head gasket

This topic contains 7 replies, has 3 voices, and was last updated by  joe_padavano 7 months, 3 weeks ago.

Viewing 8 posts - 1 through 8 (of 8 total)
  • Author
    Posts
  • #14447

    jensenracing77
    Participant

    Does anyone know what the compressed thickness is of the stock steel head gasket? The FelPro head gasket is .040 to .042 and I know the originals were thinner than this. I want the original compression on my 4 speed car and if I use the FelPro gaskets I will have to mill the difference off the heads. I would rather not mill them at all but I really want the 10.25 compression.

    I also have a set of NOS head gaskets but don’t really trust them if I don’t have freshly machined surfaces, this would end up with to much compression.

    #14448

    JimNoel
    Participant

    The 1963 Oldsmobile Parts manual lists 1961-1963 F-85 head gaskets at 0.020″ thick for all 215 cid engine applications. These gaskets are all steel, #578813.
    The automatic transmission Jetfire’s are 10.25:1, and the manual transmission Jetfire’s are 10.75:1.
    If you had 0.020″ milled off the head to clean up the surface, the FelPro 0.040″ should give you the correct compression ratio?

    Attachments:
    #14450

    jensenracing77
    Participant

    I did not know the parts book give the thickness. I had not looked these up. As far as compression, I thought I read it was only the automatic 63 Cutlass that had the higher compression? That also confuses me because I can’t find anything in the parts book that is different for them to gain that compression? Did they have special heads with less cc’s? I have not looked up the heads yet.

    #14451

    jensenracing77
    Participant

    OK, Just found it, It has a separate part number for the 4bbl heads of the 63 manual trans and the 4bbl heads of the 63 hydromatic trans. Looks like the Jetfire all have the same heads so I believe all the Jetfire would be 10.25

    #14455

    JimNoel
    Participant

    Yes, you are correct. The compression ratio difference is between the 1963 4bbl carb auto 10.75:1 & manual trans 10.25:1. All Jetfires were 10.25:1
    A copy of Dan LaGrou’s head listings attached

    Attachments:
    #14457

    jensenracing77
    Participant

    Very cool, I never seen that document before.

    #14458

    JimNoel
    Participant

    Attached is the NHRA spec sheet for the 215cid.

    Attachments:
    #14460

    joe_padavano
    Participant

    Keep in mind that the NHRA numbers are the minimum blueprint spec, not the as-cast numbers. I’m not sure about the 215 heads, but later iron Olds V8 heads tend to run 2-4 cc larger chambers than the NHRA blueprint numbers in the as-cast state. Obviously this also depends on how much the head has been surfaced, how much the valves have been cut, etc.

Viewing 8 posts - 1 through 8 (of 8 total)

You must be logged in to reply to this topic.

Recent Articles

Turbo System Safety Checks

Turbo System Safety Checks

The safety components of the factory designed turbo system have some interactive groups of safety "c...(read article)

Engine Front Drive Pulleys

Engine Front Drive Pulleys

The standard drive pulley has one groove. It drives the water pump/fan and alternator or generator. ...(read article)

1961-1963 F85 Car and Option Prices

1961-1963 F85 Car and Option Prices

Attached to this article is PDF file containing an extensive list of car and option pricing for 1961...(read article)

Recently Active Members

Profile picture of oaklyss
Profile picture of johnsage
Profile picture of jensenracing77
Profile picture of captiannapalm
Profile picture of doctorg

OldsJetfire Forum