Register now to get rid of these ads!

Hot Rods Flathead build advice needed

Discussion in 'The Hokey Ass Message Board' started by Desoto291Hemi, Oct 22, 2019.

  1. Karl ,

    Oh yeah,,,,that baby sounds good .
    It sounds really strong,,,,,and I agree,,,,,,,I don’t think it will idle at 500 rpm .
    700 or so is a better target,,,,,good job,,,,,and good video,,,I really enjoyed it .

    Tommy
     
    Karl_William likes this.
  2. Karl_William
    Joined: Nov 20, 2021
    Posts: 83

    Karl_William
    Member

    Thanks!
    Thanks! About 750 is where it's happy.
     
  3. Flathead Freddie
    Joined: May 9, 2021
    Posts: 806

    Flathead Freddie
    Member

    Hi Tommy hope all is well with you today and I'm not a Merc expert so not sure if all Merc blocks are factory relieved or not but it's recommended as your #1 combustion chamber flow trick since there is a ridge between the valves and the cylinder . Some guys relieve the area all the way and I'm playing safe with staying about a 1/4 " inboard of the head gasket line as I try to alleviate detonation not enhance it so when grinding ( hot shots use a mill ) I stay away from edges and walk the bit from left to right multiple times to keep it smooth and not lumpy . Some guys say just relieving the intake valve side of the ridge makes a noticable difference .
    I marked the relief area I am using and only 1/8 " deep .
    Also detonation precautions are about the best you can do and occurs where there is a flow hangup . Aha ! Now you know why I named the engine Flo ! Recall Flo had been rebuilt with not many miles ( under 30 grand ) so when I lifted the heads I can clean up the chambers and the heavy caking was where I marked in Orange in the second picture . So I don't want to relieve clear to the edge that may make it worse so I am trying to map my spark and flow . Both matter to fast a spark quench and loss of power on stock heads so I only smooth areas in the middle like a stream and leave the sperk plug pad area sort of rough to enhance a longer explosion at top of the power stroke . I want the explosion to push the piston down so I am mapping the flow and spark hoping to regulate both for a healthy strong bang .
    For the intake runners I am not taking Flo apart as of yet ( gonna run her as is ) so am only grinding on the roof of the intake runners with a long shank steel bit I show in the picture and I have marked an orange line on each side of a intake runners for you to see that I am only grinding on material above the orange line as close to valve as safe and I do mean safe . It doesn't take much . Your not running a blower with a hemi crank so don't need alot for good breathing .
    Have a great day Tommy
     

    Attached Files:

  4. Hi Fred ,
    I don’t really plan on any real relief work on mine .
    I will probably just blend the radius around the valves,,,,and blend the chamber to make it a more smooth transition .
    After the short block is together,,,,,I’m gonna do some really close checking on the fit and clearance for the chambers .
    Since I am planning on using my factory heads anyway,,,,they are really clean and in good shape,,,,,and save a few bucks .
    I do plan on some milling work,,,,and angle mill them some too,,,,to help boost the compression number .
    From what I have learned from some experts here ,,and on the Barn,,,it seems that most cheap power is gained by strict work on the chambers and correct piston to head clearance .
    But,,,, I still listen to all advice given,,,,,,the Flathead is a complete different animal,,,,and responds to different modifications .
    I’m just taking my time, and learning as I go .
    And besides,,,if I don’t finish it,,,,,I’ll just hand it down to someone that will,,,,,LoL .

    Like the book says,,,,,” Man is not promised tomorrow “,,,,,,I’m doing what I can,,,,while I can .

    Tommy
     
    Flathead Freddie likes this.

Share This Page

Register now to get rid of these ads!

Archive

Copyright © 1995-2021 The Jalopy Journal: Steal our stuff, we'll kick your teeth in. Terms of Service. Privacy Policy.

Atomic Industry
Forum software by XenForo™ ©2010-2014 XenForo Ltd.