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- Carter Dual 4-Barrel Carburetor Idle Adjustment
- Carter Dual 4-Barrel Carburetor Adjustment
- Carter Dual 4-barrel Carburetors, Linkage Sticking
- Buick Cam Specifications for 401 and 425 nailheads
- Buick Cams from Kenne Bell, 401, 425
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- Nailhead cam specs and cam selection
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Thread: Need help identifying a nailhead I have.

  1. #1
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    Need help identifying a nailhead I have.

    I would appreciate any help in ID ing a 1961 Buick nailhead I am saving for a future project. It came in a 1961 LeSabre four door hardtop, and has a two barrel on it. The numbers stamped by the valley cover are what is confusing me. Stamped backwards is "3H296304", but stamped forward (so you can read it by looking into the motor room) it has "4H1065936." Why it has two numbers is what has me going.

    Pretty sure it is a 364, but not sure about the compression ratio and HP.. Anything you guys can tell me about this motor will be a great help.

    Thanks !

  2. #2
    fortunately, the 364 and 401 have different deck heights so you can figure this out without pulling a head off.

    notice the intake manifold spec at the bottom of this page:
    https://www.teambuick.com/reference/...s_nailhead.php

    364ci should be 8 7/8" between bolts while a 401ci / 425ci should be 9 1/8".

    alternatively, the 364 and 401 have different strokes. you should be able to test this simply by pulling a spark plug and running a wire ( welding rod, whatever ) down in the top of the piston. measure how far the wire sticks out at TDC and subtract how far it sticks out at BDC and you've got stroke.

    364 == 3.390"

    401 == 3.640"


    the standard engine for a 2v Le Sabre was a 250hp 364ci.

    all 401s in 1961 should have been 4v carb.

    https://www.teambuick.com/reference/...ine_number.php
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  3. #3
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    Thanks for the fast reply. As I mentioned , here is what was confusing me. According to the info below, 3H means 364 and 4H means 401. Why would an engine have BOTH numbers stamped on it ? I will do the measuring you described, but just curious as to why both numbers are on one motor.

    V-8 364*
    3H
    V-8 401* 4H



  4. #4
    i'm aware of the meaning of 3/4H.

    i have no idea why an engine would be stamped with both.
    The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
    Vladimir Lenin

    Government schooling is about "the perfect organization of the hive."
    H.H. Goddard, Human Efficiency (1920)

  5. #5
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    Indeed this is confusing for your engine, especially if the car is not available to compare the VIN. The 4H... number is the VIN of the car and the unique serial number of the engine. A 4 here indicates LeSabre series and H means 1961.

    The 3H... number is the production code number of the engine. The 3 indicates a 364 with standard compression ratio (10.25:1) with H again signifying 1961 model year.
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    What has been, can be again. (Bob Wills, 1942)

  6. #6
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    Quote Originally Posted by TODD View Post
    Indeed this is confusing for your engine, especially if the car is not available to compare the VIN. The 4H... number is the VIN of the car and the unique serial number of the engine. A 4 here indicates LeSabre series and H means 1961.

    The 3H... number is the production code number of the engine. The 3 indicates a 364 with standard compression ratio (10.25:1) with H again signifying 1961 model year.

    That clears it up completely . Thanks !!!! I figured I had the 364, but that 4H was making me think 401. You have cleared it up completely. I also understand they had two compression ratios. Is there something you see her that tells you it is the higher one at 10:25 ?

    Really appreciate everyone's answers.

  7. #7
    Is there something you see her that tells you it is the higher one at 10:25 ?


    a - the low compression engine was designated "L3H"

    b - the low compression engine was export only, because you couldn't count on quality gasoline outside the US. the L3H should be almost impossible to find Stateside.

    https://www.teambuick.com/reference/...ine_number.php
    The way to crush the bourgeoisie is to grind them between the millstones of taxation and inflation.
    Vladimir Lenin

    Government schooling is about "the perfect organization of the hive."
    H.H. Goddard, Human Efficiency (1920)

  8. #8
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    Quote Originally Posted by bob k. mando View Post
    Is there something you see her that tells you it is the higher one at 10:25 ?


    a - the low compression engine was designated "L3H"

    b - the low compression engine was export only, because you couldn't count on quality gasoline outside the US. the L3H should be almost impossible to find Stateside.

    https://www.teambuick.com/reference/...ine_number.php
    W

    Well, that is good news, I was hoping it was the higher compression motor.

    All the help you guys have provided is much appreciated........thanks. I now know what I have to start with.

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