Register now to get rid of these ads!

Technical Flathead Porting: Soup to Nuts . . . Pictures, Details and Opinions

Discussion in 'Traditional Hot Rods' started by Bored&Stroked, Nov 22, 2009.

  1. banjorear
    Joined: Jul 30, 2004
    Posts: 4,479

    banjorear
    Member

    John:

    I did the same (Well Ronnie S. in CT did them for me). He is no stranger to building a stout flathead either.

    BTW: How are you doing? I haven't talked to you in a while.

    Tim
     
  2. Pete1
    Joined: Aug 23, 2004
    Posts: 2,254

    Pete1
    Member
    from Wa.

    "Guides...is anyone out there semi-permanently setting in the guides and treating them as part of the block?? Copper plating, etc., to lock them in one orientation."

    I have copper plated guides and pressed them in since the early 50's.
    This is a quick and relatively easy way to get by for a "so-so" street engine.
    On a race engine, I make guides from scratch so I can leave material on top for flow contouring. Leading or building up with epoxy works good also and from my flow tests gives
    enough increase to warrant the extra work.
    I use bronze liners in the guides and titanium valves. 5/16 stem valves with 30 degree seats.

    I use 5/16 stem valves that I cut the keeper grove in so I don't have to use any spring shims. I use Chev. single springs with a damper. Titanium retaniers and keepers. Aluminum spring seat on the upper end. These springs are larger in diameter so you have to assemble from the bottom, a task that you get pretty fast at after doing it a few times.
    Many years ago I kept hearing about cam flex and valve float associated with either too much or too little spring pressure. I made a setup from an old block so I could run an installed cam with a variable speed electric motor and then observe the valve train with a strobe. Amazing, so little cam bending/flex you could not see it. You could measure it with an indicator but it was not enough to even consider. As far as valve float, the cam determines how much you need for a certain redline. A 404A needs 100 on the seat for 7000 rpm. That is assuming titanium valves and retainers and drilled lifters.
    Spring flutter can be a serious problem with some springs. This will cause premature valve float. You will never know you have it unless you can observe with a strobe. Generally double springs or springs with a damper will be OK.
    Dale has the porting thing pretty well covered. The only difference I find is that bigger is better on BIG engines. (over 315 ci) I go to the maximum on all ports and the top of the intakes are squared to get more area. I have a way of putting the center ex baffle in without welding. Welding on cast iron is asking for trouble unless it is torch welding with a furnace to heat the whole block.
    A part of the porting should include reversion dams on the header flanges also.
    Every little bit helps.
     
    Last edited: May 28, 2010
  3. Flatman
    Joined: Dec 20, 2005
    Posts: 1,975

    Flatman
    Member

    A must for the Tech Archives. Great stuff!

    Flatman
     
  4. HotRodMicky
    Joined: Oct 14, 2001
    Posts: 1,783

    HotRodMicky
    Member

    Hi pete,
    so as a cam grinder, what is your option on duration versus lift?
     
  5. Sixcarb
    Joined: Mar 5, 2004
    Posts: 1,503

    Sixcarb
    Member
    from North NJ

    As far as shaping the contour after the guide is in I was going to go with JB weld, at first discussion it sounds pretty hoakey but I know Flatdog did the top of his guides this way after turning them to fit flush of course. My fear of this is if any pieces happen to come loose and get down in the cylinder it may cause a problem or maybe just do this on the exhaust side, how many guys just massage the block a bit more after the guide is installed to get the uniform flow that is desired.
     
  6. Pete1
    Joined: Aug 23, 2004
    Posts: 2,254

    Pete1
    Member
    from Wa.

    "so as a cam grinder, what is your option on duration versus lift? "

    Hotrodmicky:
    The cam needs to be chosen for the specific job it has to do.
    A cam for a circle track engine generally has to have maximum breathing
    at the mid to upper end of the hp range.
    The rate of lift has more to do with it than the duration. A cam curve with a flat
    top and straight sides will make more power over a wider range than a curve with a sharp peak. The sharp peak curve will produce more power in a very narrow range though.
    We are talking flatheads here.
    An example of a cam with a broad flat top curve is a 404A or a #4 Offy. Approximately 255 duration with .010 per degree squared rate of lift.
    An example of a sharp peak cam would be a 6355 H&C. 284 duration with .006 rate of lift.
    Both have .400 lift.
    Roller grinds will generally excell in the upper rpm range unless they can be ground with an inverted flank.
     
  7. HotRodMicky
    Joined: Oct 14, 2001
    Posts: 1,783

    HotRodMicky
    Member

    Yeah especially with light flathead valvetrain you can run some good cams.
    Problem is that no cams cards mention the rate of lift , you will only see it
    if you have the cam in your hands.
    So which good/high rate of lift cams can you recommend?
    Lets say for a small, medium and big engine

    I`m building a 284 ci and a 304ci engine right know. Scat/Ross parts with German and french block.Both for light Hot Rods .Over 9:1 compression. Ported and polished
    3x2 with 97s
    No Bonneville or Drag Racing, i thought Schneider 270F 0,395 and 278F 0,425 lift.

    What cams would you recommend?
    TIA
    Michael
     
  8. Pete1
    Joined: Aug 23, 2004
    Posts: 2,254

    Pete1
    Member
    from Wa.

    The high lift rate flat tappet cams all run radius lifters so they are generally
    not used for street engines although I have run a 404 on the street many times
    and since I got masters for the #4 Offy I think it is slightly better than the 404..
    You just have to keep close watch on things for wear.
    The radius lifters require special tools to install the keys in the lifter bores.
    Probably a very good cam for either of your engines would be the 425 Potvin.
    It has about the highest lift rate of the flat tappet cams. (.008)
    It also has superb spring control ramps. One reason it will turn 7500 if need be.
    It will idle under 1000 rpm and be very drivable on the street.
    I drove one for years with 4 48's and a mag. One year I drove it to Bonneville, raced it
    and drove it home.
    I recommend 48's over 97's. You need all the air you can get.
     
  9. Hey Pete . . . glad that you tuned into this post! Pete and I have worked on a few cam related adventures (which is what they are in the flathead world). I trust just about any dang flathead thing he says . . . so those of you who show are on this post, listen up!

    I've spent quite a few years graphing cam profiles and the speed of the ramp is a big deal in the overall performance of a flathead cam (especially on the track). The Isky 404-A and the Potvin 425 have very fast acceleration ramps - and given the fact that we have no rocker arm to magnify the ramp, this is typically a good thing (as long as it is not erratic and causes float or harmonic issues). As Pete noted, about the most you'll see is .008 of lift per degree of cam rotation (typically at the upper mid-lift stage). Keep in mind that back in the day, the valve spring technology could not take much more than than rate of acceleration. Today -things are different . . . at least outside our "flat" world. Not time to ponder this now! There are multiple approaches to achieving fast lift rates --> as Pete noted, a radius lifter is one of them, an inverse or hollow flank on a roller profile is another and an increased lifter diameter is another (mushroom - though the situation here is a bit different - so I'll stay out of it for now).

    Enough for now . . . need to go to dinner . . .

    B&S
     
  10. Bearing Burner
    Joined: Mar 2, 2009
    Posts: 1,107

    Bearing Burner
    Member
    from W. MA

    Speaking of light valve trains. Has anyone tried stock FORD lifters in a modified engine and ground the valve ends for correct clearance?
     
  11. flatjack
    Joined: Feb 13, 2007
    Posts: 975

    flatjack
    Member

    With a higher lift cam, you won't be grinding the valve stems, but will be adding weld to the lifter to make it longer.
     
  12. This is a great thread! I've built a few Flatheads in my life both stock and performance, but you can always learn something new. Thanks. :D I'm gonna bookmark this one.
     
  13. This is the stuff I'm on the H.A.M.B. for!
     
  14. Pete1
    Joined: Aug 23, 2004
    Posts: 2,254

    Pete1
    Member
    from Wa.

    33 grams for the drilled lifters.
    For the valves, if you use titanium valves, they come about half an inch long so there is no welding involved.
    If you elect to use stainless valves, the John Deere ones have way oversized heads that you cut to the size you want and the 5/16 stems come about 3/4 inch long. They have chrome stems also...A good choice for an economy engine.
     

    Attached Files:

  15. fullhouse296
    Joined: Jan 30, 2009
    Posts: 404

    fullhouse296
    Member
    from Australia

    I prefer to gas weld "Stellite"to the top of the lifter , then grind down in a nifty jig that I made to fit my bench gringers stone side ,gets it spot on with no heavy adjustables to keep adjusting . set and forget.
     
  16. HotRodMicky
    Joined: Oct 14, 2001
    Posts: 1,783

    HotRodMicky
    Member

    I`ve done it.
    Works good.
    Michael
     
  17. banjorear
    Joined: Jul 30, 2004
    Posts: 4,479

    banjorear
    Member

    I've been processing this thread over and over for the past few days. Somewhere in this post Dale talks about taking the guide and adding softer material and blending it into the port vs. keeping it the stock shape.

    John Lawson (JWL on Fordbarn and Bill B.'s Flathead Techno Source sites) is an incredible machinist and engine builder. He wrote a book a few years back that details changes done to a motor and what improve to flow, h.p., and torque. All real info. and no B.S. or tall tales.

    In his book, he machined a set of steel guides that had a "ski jump" style top to it so it could be blended into the port. I'll dig out his book and note what he said about doing this.
     
  18. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    What are the specs on the Potvin 425?
     
  19. That would be cool to see - I've only heard about brass and lead. I was even wondering if something like epoxy putty would bond and not come loose? Heck, they use it in other cylinder heads. The only drama is that you'd have to permanently install the guides - and that is a pain to work with. I'd love to see pictures from JWL's motor -- he is a heck of a smart guy and has done lots of dyno work as well. I know that we was going to Bonneville - wonder if he ran that motor there and how did it do?
     
  20. banjorear
    Joined: Jul 30, 2004
    Posts: 4,479

    banjorear
    Member

    Dale:

    On Monday I'll scan it and mail it to you. PM me your snail mail address.

    Also, I know Mike Davidson from Australia makes some concaved port "ramps" that use a set-screw the secure them. They are supposed to lay in the bottom of the intake port, right where it makes the turn to enter into the valve port/pocket.

    He also provides some dyno time for these things but I'm not sure if I'm in agreement of placing anything more into that already fairly crowded port.

    You, JWL, Ron H., Pete1, Mike B. & Mike D. certianly have light years of experience over me, but like most things flatheads a lot depends on your own theories and logical progression of figuring this crap out.
     
    Last edited: Nov 28, 2009
  21. Maybe we all have it wrong . . . we just need to keep putting blowers on these dang things - tends to take the "kinks' out of the intake ports:D
     
  22. banjorear
    Joined: Jul 30, 2004
    Posts: 4,479

    banjorear
    Member



    Funny. Sad, but true.
     
  23. saltracer
    Joined: Jan 4, 2006
    Posts: 293

    saltracer
    Member

    Works for me! Just noticed my timing marks on the distributor were off. Bonneville 2003, ran 146 with blower. Before ran 125 without.
    [​IMG]
     
  24. haroldd1963
    Joined: Oct 15, 2007
    Posts: 1,154

    haroldd1963
    Member
    from Peru, IL

    Great Thread! Keep the tips coming.
     
  25. What did you find out on your timing? What initial and total were you running and how many lbs boost? Are you planning on running again?
     
  26. saltracer
    Joined: Jan 4, 2006
    Posts: 293

    saltracer
    Member

    We didn't have a timing mark on the lower pulley as I made it for the blower drive. If I remember right we timed it with a vacuum gauge and we had 9 lbs. of boost. It ate the main bearings for any of many reasons, the motor had not even run before we got to Bonneville, it still had the break end oil...... really not prepared. Oh, we are going back in 2010 with a new rear engine modified roadster.
     
  27. My brain is trying to soak all this info up, lots to be digested, thanks to all involved thus far.

    Mooving back to Cams for a moment if I may, was there a 'preffered shortlist' of 'street' blower cams? (28rpu, T5, 8BA, EAL heads, 7:1 compression, 4/71, 6 pound boost, vertex mag)?

    Keep this thread coming, appreciate the info.

    Cheers,

    Drewfus
     
  28. phlip
    Joined: Jan 8, 2007
    Posts: 185

    phlip
    Member

    Thanks! Great thread!!
     
  29. HotRodMicky
    Joined: Oct 14, 2001
    Posts: 1,783

    HotRodMicky
    Member

    Schneider 270F with 115° lobe centers
    Michael
     
  30. flattyefi
    Joined: Dec 31, 2007
    Posts: 11

    flattyefi
    Member

    Hi
    I'm in the process of building my first Flathead. Attached my solution for the brickwall at the end of the port. I have overbored guide and bowl and pressed in custom guide. Don't know how good it works yet no flow bench. Attached a couple of photos some not to clear. D shaped port didn't work so good as the water passage follows the shape of the port just needs more rounded corners at the top. Really excellent thread.
    Thanks
    Grant
     

    Attached Files:

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.