Just joined? Please introduce yourself.
Page 4 of 8 FirstFirst ... 23456 ... LastLast
Results 31 to 40 of 75

Thread: Track times

  1. #31
    Registered Member
    Join Date
    Nov 2015

    Member #:2764
    Posts
    649
    Quote Originally Posted by markm View Post
    I have seen several 454s run very low 7 second 1/8s with those pistons and 781s with the aforementioned oversize valves. I already posted I damn near made the high 6 second club with them. Currently you should have 2.06/1.72 real gain to be had with 2.19/1.88s.
    Do my heads have room for larger valves?
    Attached Images Attached Images

  2. #32
    Banned
    Join Date
    Nov 2015

    Member #:2775
    Posts
    1,426
    Quote Originally Posted by 55 Tony View Post
    Do my heads have room for larger valves?
    Looks like the intake seat is toast, so I would guess no.

  3. #33
    Registered Member
    Join Date
    Apr 2012

    Member #:571
    Posts
    4,671
    Disagree on the no, the new intake seat will be .065" further out, and the old seat cut away.

    Looks like there's lots of room between the valves. The 2.19" intakes that markm mentioned should fit fine. Same on the 1.88" exhausts.

  4. #34
    Banned
    Join Date
    Nov 2015

    Member #:2775
    Posts
    1,426
    Quote Originally Posted by Rick_L View Post
    Disagree on the no, the new intake seat will be .065" further out, and the old seat cut away.

    Looks like there's lots of room between the valves. The 2.19" intakes that markm mentioned should fit fine. Same on the 1.88" exhausts.
    I believe it's a BBC, and I see cracks in the intake seat, and valve. Just a guess. but it looks like a leaking valve.

  5. #35
    Registered Member
    Join Date
    May 2012

    Member #:625
    Posts
    3,409
    I BBC seen many a 781 & 049 head machined to accept the 2.19. 1.88 valves with no issues. I agree with Rick the larger valves will be on new metal.
    Last edited by markm; 10-24-2018 at 03:46 PM.

  6. #36
    Registered Member
    Join Date
    Nov 2015

    Member #:2764
    Posts
    649
    That picture is from before they were installed. I don't think there is a leaking valve, I get 205 to 210psi cranking compression all around. On the valve I think you see a mark in some carbon from a wire brush. I do see the little cracks in the seat though, or is that in the casting? I haven't the slightest clue how big around the hardened seats are but it sort of looks like the cracks stop at the seat?

  7. #37
    Registered Member
    Join Date
    Apr 2012

    Member #:571
    Posts
    4,671
    What I'm seeing is that there are radial marks on the outside of the pressed in seat, but they stop short of the outside diameter of the valve. So I don't see anything on the actual seating surface. They may or may not be actual cracks.

    What you may be up against if you go to bigger valves is that you may have to start over and replace the pressed seats for bigger ones. A little measuring would confirm or deny this.

  8. #38
    Registered Member
    Join Date
    Nov 2015

    Member #:2764
    Posts
    649
    Quote Originally Posted by chasracer View Post
    What you can do is possibly obtain some valve checking springs and check what your clearances are currently with the cam you have - that should give you some idea of how much more cam you can go with but you would still need to check the new cam during installation.
    How do you use valve checking springs?

  9. #39
    Registered Member chasracer's Avatar
    Join Date
    Mar 2018

    Member #:3718
    Location
    Montpelier
    Posts
    230
    They are just light weight springs. You replace your normal valve springs on one cylinder, use the same retainer and valve locks. This way you can rotate the engine to different degree settings and push the valve down with your finger. I use the back end of a dial caliper to see what the reading is. Your're looking for the difference between full height and open height touching the piston.
    Remember the "13"


  10. #40
    Registered Member
    Join Date
    Apr 2012

    Member #:571
    Posts
    4,671
    Rotate the engine to 10° BTDC on overlap. Put a dial indicator or caliper on the exhaust valve and get a zero reading. Push down on the exhaust valve retainer with your fingers until the valve hits the piston. Measure again. The distance the valve moves is your clearance.

    Rotate the engine to 10° ATDC on overlap and repeat the procedure on the intake valve.

    On a solid lifter engine you don't even need checking springs. Just use the regular springs and the lash adjuster.

Page 4 of 8 FirstFirst ... 23456 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •