Register now to get rid of these ads!

Technical Ford Flathead Timing and Heat

Discussion in 'Traditional Hot Rods' started by blowby, Mar 9, 2014.

  1. blowby
    Joined: Dec 27, 2012
    Posts: 7,516

    blowby
    Member
    from Nicasio Ca

    My flatty sems to run cooler in stop and go traffic (idling mostly) with the ignition timing advanced from stock (as shown in link below). Pancake distributor, vacuum brake connected and adjuster screw out all the way. About 17 inches of vacuum at idle.

    Is it possible, or a good idea, to limit the centrifugal advance? I used to do this on GM distributors with a bushing. Any idea what timing I might want at idle for optimum cooling?

    http://www.vanpeltsales.com/FH_web/FH_images/FH_engine-pics/Flathead_Distributor_timing.jpg
     
  2. 38 coupe
    Joined: May 11, 2008
    Posts: 155

    38 coupe
    Member
    from Texas

    I have found the stock distributor timing to be about optimal for a flathead. The advance curve limiting feature in these distributors doesn't wear out like an old chevy distributor (usually, nothing is impossible). I usually run the advance adjustment halfway between 0 degrees and full advance.
     
  3. blowby
    Joined: Dec 27, 2012
    Posts: 7,516

    blowby
    Member
    from Nicasio Ca

    Thank you. I'm going to be doing more testing today with another fan setup. Anyone else have experience with initial timing and heat?
     
  4. I'm no expert but frome some personal experience with flatheads, are you running thermostats and what degree? Some flathead cooling problems come not from timing so much as how fast water runs through the radiator. At idle it runs slow and has a chance to cool off more.
    At higher speed the water runs through the radiator faster and espicially without thermostats, run too fast and it doesn't get a chance to cool off.
    Just a possibility and an easy fix.
    I run my stock Merc with 160 degree stats with no trouble at 50-60 mph even at 90* degrees, even with no fan.
    Good luck.
     
    RonaldR likes this.

  5. flatjack
    Joined: Feb 13, 2007
    Posts: 932

    flatjack
    Member

    Here we go again. No such thing as flowing through the radiator too fast.
     
  6. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,019

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL


    That statement requires a sound explanation...especially in regards to running without thermostat(s). With thermostats, I can understand the water flow would be controlled....but without.....why couldn't it flow too fast to cool adequately?
     
  7. Purely an opinion, but way back in the day some guys say they would add washers into the radiator hoses to slow down waterflow so that the water stays a little longer in the radiator. also thermostats add some restriction to flow that running without stats doesn"t.
    Also long ago guys would even remove every other vane on the water pumps to slow down water flow. I'm just offering information picked up from the real old timers_ even older than me! haha
    From my own recent experience, my stock Merc flatty has been driven regularly in all weather for 4 years or more with 160 degree thermostats, Speedway water pumps and no fan at all! It only gets up to boiling in very slow traffic on veryhot days.
    Just relaying info.
    I'm no physicist just telling what works for me.
    tony
     
  8. Hnstray
    Joined: Aug 23, 2009
    Posts: 12,019

    Hnstray
    ALLIANCE MEMBER
    from Quincy, IL

    I didn't go into it in my above post, but I've seen, even owned, flathead heads that had a big washer tack brazed to the water neck to limit water flow in place of thermostats.
     
  9. I rest my case!
    Not implying you are an old timer Hnstray!!
     
  10. Mike51Merc
    Joined: Dec 5, 2008
    Posts: 3,856

    Mike51Merc
    Member

    I can tell you that retarded timing will definitely result in overheating at idle.
     
  11. choppedtudor
    Joined: Nov 28, 2009
    Posts: 683

    choppedtudor
    Member

    the myth of water traveling TOO fast in a radiator can be de-bunked by considering that the SAME water, if slowed-down, will then spend more time in the block, thus absorbing MORE heat than if it had been moving quicker. This is not always a good thing, higher water temps are never good. In addition, a block can be cooled TOO much, creating other issues. The real trick is to get it flowing at the correct rate to maintain a determined temp for optimal run conditions...and thats the job of the thermostat(s). If you have overheating issues, check timing first, thermostats next, then air/water flow through radiator. I have a degree in Mech. Eng. applied to heating/cooling systems and this is textbook stuff...
     
  12. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member

    The crab distributor is a little misunderstood.
    After building hundreds of these over the last few years i have found that its the best ever made for the flathead ford.
    The Vacuum brake needs some load ( never removed or turned out) as the brake makes the advance unit stable at start up and retards timing when using light acceleration. Remove the piston , make sure there is a leather washer for drag on it. Lube and re-install turning adjustment in three turns an a minumum.
    The centrificial unit is very functional ( assuming its clean and lubed) offering a very crisp advance rate ( 22 degrees at 2500). Dual points are used with the drivers side controlling timing and the pass side controlling dwell or coil build up.
    Again properly set up they are the best ever made...
    Built set up units $150 with core.....
     

    Attached Files:

    Ric Dean likes this.
  13. blowby
    Joined: Dec 27, 2012
    Posts: 7,516

    blowby
    Member
    from Nicasio Ca

    Thanks for the replies guys. I disassembled my crab distributor and found everything to be in excellent condition. I turned the leather 90 degrees to give it some fresh area, however I was under the assumption that even all the way out there was still pressure applied, I'll have to address that. I have timed it with a strobe at 24 degrees total, so I suppose with 22 degrees of advance I should be at 2 at idle. Perhaps 6-8 might be better for cooling.

    I thought I had a handle on the overheating but it got hot again last night (220). I don't have thermostats, however I tried washers with 1/2" holes, no help. I'm still running iron heads but about to install these Edlebrocks, the water outlet is much smaller, about an inch diameter (v8-60). I have heard it is possible to put Pinto thermostats in the hose.
     

    Attached Files:

  14. flatjack
    Joined: Feb 13, 2007
    Posts: 932

    flatjack
    Member

    Heat transfer is a function of the cooling medium, the temp difference and the flow rate. Increasing the flow rate will increase the heat transfer. Laws of thermodynamics.
     

  15. okay, and since the cooling medium and flow rates are constant between the radiator and the engine block the temperature difference would be the variable. At higher engine loads the cylinder temperature vs coolant temp would increase at a higher rate than the coolant temp vs ambient temp you could theoretically transfer more heat to the coolant than you could remove.

    also things like heat transfer rates of materials and surface area also play into this but again are constant so probably not worth bringing up in the discussion.

    so getting back to the OP, you can advance the ignition timing too far and increase the cylinder temps higher than the stock system was designed to cool. he didn't give any specs on the engine or vehicle but if it's stock and is supposed to have thermostats or flow restrictions then he should install some if he doesn't currently have them. if its modified then it will produce more power and heat than stock so increased cooling would be needed, i.e. larger radiator or increased radiator air flow. this is "assuming" that all equipment is in good condition, a clogged radiator, restricted air flow and other system problems can cause the overheating as well.
     
  16. flatjack
    Joined: Feb 13, 2007
    Posts: 932

    flatjack
    Member

    The stock cooling system has plenty of extra capacity. My 39 Ford has a 276 in. engine which probably puts out quite a bit more power than the original 221 in. engine did. I have a stock original non pressurized radiator , stock engine driven fan and stock Ford water pumps and have absolutely no cooling problems.
     
  17. harleyjohn45
    Joined: Aug 27, 2012
    Posts: 190

    harleyjohn45
    Member

    If I was running hot, I would worry about a crack in the engine. Flatheads are famous for cracks.
     
  18. Flat Ernie
    Joined: Jun 5, 2002
    Posts: 8,406

    Flat Ernie
    Tech Editor

    All else being equal, there's only two ways to increase cooling: bigger radiator or more flow. Period.

    As to your overheating problem, generally if it's good at idle and slow speeds, but overheats at high speed, it's a radiator flow issue. If it overheats at idle, but is fine in cruise, it is often an airflow issue and a good fan shroud will help a lot.
     
  19. flatjack
    Joined: Feb 13, 2007
    Posts: 932

    flatjack
    Member

  20. johncard
    Joined: Nov 15, 2013
    Posts: 5

    johncard

    When you set up the early Ford V8 distributor, do you apply vacuum to the vacuum brake to check it? Is it on-off, or does it apply and release gradually?
     
  21. 19Fordy
    Joined: May 17, 2003
    Posts: 7,188

    19Fordy
    Member

    I would think that using washers would create lots of cavitation. Not good.
     
  22. GMC BUBBA
    Joined: Jun 15, 2006
    Posts: 3,385

    GMC BUBBA
    Member


    Its hooked to direct manifold vacuum and is either on or off ...As vacuum increases when the engine is started its off the leather, when vacuum drops when the engine is loaded it would return to the contact position causing some retard..
     
  23. Not to throw a monkey wrench in or hijack this thread but, what about when one side runs hotter than the other?
    my right side at low speed driving runs between 200-220 while the left is steady at 180. once i am driving at speed (+30mph) the right side comes back down to match the left at 180. both sides run the same when parked at idle ('30 ford coupe, mild built flathead, no hood, six blade mech fan, new griffin radiator, 180 thermostats)
    thanks
    Chappy
     
  24. Bruce Lancaster
    Joined: Oct 9, 2001
    Posts: 21,682

    Bruce Lancaster
    Member Emeritus

    And the crab piston can be understood as slowing down the rate of advance rather than actually changing timing itself. It is usually run backed off considerably with modern gas, since you can't obtain gas as crummy as the prewar stuff!
    It brakes against a sort of floating disc on the advance and needs SOME, not very much, tension as noted above as drag stabilizes the rotational position of the brake disk. If you completely kill its function, the disc can drift radially and so give you a bit of continually varying timing.
    The whole setup gives very rapid advance of idle. Brake would be used to tune out pinging, but unless you are running period correct gasoline you really should be fine.

    Thermostat function is to keep engine running warm enough at low power range. Yes, too cool is quite possible even on a flathead when engine is loafing, and yes that is a very serious problem...plenty of bad stuff is going on a cold engine. You are throwing away power and engine life.
     
  25. Relic Stew
    Joined: Apr 17, 2005
    Posts: 1,136

    Relic Stew
    Member
    from Wisconsin

    Late ignition timing leads to higher exhaust temperatures. Peak temperature/pressure ideally occurs 15°-20° ATDC. Later than that, less energy is converted to useful work and more is dumped to the exhaust. The exhaust ports transfer that heat to the cooling system, especially the convoluted ports in a flathead.
     
    teach'm and blowby like 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.