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Technical Intake/ coolant temp affect on starting engine?

Discussion in 'Traditional Hot Rods' started by Deyomatic, Jul 3, 2017.

  1. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    This past winter, at the same time I swapped in a Power Master starter, I also went from a 180 degree to 195 degree thermostat. I had thoughts that it would make a fuel mileage difference. The jury is still out.

    The OLD starter was a POS and after dealing with it for years not starting (not turning over with hot engine- even with remote solenoid and heT shields) after the engine was warmed up, I bit the bullet and got the new starter.

    Now, the starter spins (but also clunks) but I almost need to have it at WOT to get it to start. Is there a hard and fast rule that a colder intake will start easier? If it were 15 degrees cooler would the fuel be less apt to evaporate after it is at operating temp.?
     
  2. joel
    Joined: Oct 10, 2009
    Posts: 1,649

    joel
    ALLIANCE MEMBER

    I assume you have a carb. WOT is usually used to clear an over rich situation ( too much choke etc.). If the engine is warm and the fuel is vaporizing in the fuel bowls ( not uncommon) you should need less air to get it to start. Are the floats set too high or the needle and seat not holding? What kind of carb?
     
  3. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    It is an Edelbrock 600 (my FIRST problem) on a 350. I set the float level years ago. I don't think it's vaporizing in the bowls, I was thinking it was vaporizing in the intake plenum when I prime the carb. If I don't prime the carb it just cranks and cranks, if I pull the choke (when hot) it just cranks and cranks. I just need to do a combo of cranking and pumping and it will work eventually.

    I'm just beginning this WOT trial but it seemed to work today.

    I will admit to this: PART of the problem is the distributor. I believe it is WAY advanced at startup because when I set the timing after getting the truck together it ran like crap...someone asked my total timing and (once I learned what it was) I found out mine was down around 22 degrees BTDC (I had set it to 8 degrees BTDC at whatever the idle RPM was. I cranked it up to 34ish Total and it's run great ever since, save for not firing up as quickly. I just didn't fee like fooling with the advance weights...because I'm lazy AND it will only mess something else up.
     
  4. joel
    Joined: Oct 10, 2009
    Posts: 1,649

    joel
    ALLIANCE MEMBER

    If you added 12 deg to your total (34-22) then you added 12 deg to your initial. which should now be 20 deg at idle. Do you have a vacuum advance on the distributor? that needs to be disconnected before you set timing. With todays shit gas, it's not uncommon to need 12-16 deg initial timing.
    For the carb, I'd add a non metallic spacer( insulator) under the carb to keep heat away and set the idle mixture screws 1 1/2 to 2 turns out from lightly seated. Changing weights and springs in the dist. changes the rate (rpm) the advance comes in. On a Delco dist.,there is a stop pin on the underside of the rotor mount that moves in a slot to limit travel.
    When the engine is hot and slow to fire , look into the carb and pump the linkage by hand. If the accelerator pump is good and there is fuel in the bowl you can see it coming out of the pump nozzles.
     
    Last edited: Jul 3, 2017
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  5. joel
    Joined: Oct 10, 2009
    Posts: 1,649

    joel
    ALLIANCE MEMBER

    FYI I have 327 with a Holley 750, with a 1/2 in. composite spacer under it and the heat riser passages in the manifold blocked.
     
  6. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    Thanks Joel...

    I set the idle with a vacuum gauge (this engine has never gotten more than 11" at idle), so I'm not too worried about that. It's always seemed to run rich, so I hoped that the higher T-stat would cure that.

    My OCD kicked in so I headed out at 11:30 and drained the coolant, replaced the thermostat with the 180 that was in there a few months ago. We'll see if that helps.

    Since you seemed to have solved the problem (percolation), it makes more and more sense. I read an old Popular Mechanics article on it and they describe almost the exact scenario that I have when attempting to restart it...I can always get it to start, so it probably could be much worse, but it still sounds similar.

    I have always used those .320" insulating carb gaskets, but when I had to replace my intake gaskets last year, I didn't have any, and the parts fool didn't know what I was talking about and made no attempt to find out, so I stuck with the bum gaskets that came with one of the carbs along the way- the one that's as thin as a cereal box.

    Sounds like a perfect storm- didn't use my go-to gasket, added heat...

    So, having just changed the oil about 50 miles ago...should I do it again if the boiling fuel has basically been dumping down my intake? That's how the Popular Mechanics article described it.

    Thanks.
     
  7. Mr48chev
    Joined: Dec 28, 2007
    Posts: 26,880

    Mr48chev
    ALLIANCE MEMBER

    Outside of installing the insulator plate I'd highly suggest setting the timing with a light at the specified idle speed and then check the advance mechanisms at the prescribed rpm to make sure they are working right. Setting the "total timing" at a certain degree and at a specified rpm is what you do with a race motor if you want it to put out it's max for you but that may not be ideal for all around street driving.
    Most good shop manuals for the engine you have will give the base timing and what the vacuum and mechanical advance should be at what rpm. You didn't say what mods you have in the engine but I'm thinking it is stock or pretty mild with just the carb change. and that leaves you with setting the timing and what not at stock specs or slightly improved but not radically changed from stock specs.
     
  8. joel
    Joined: Oct 10, 2009
    Posts: 1,649

    joel
    ALLIANCE MEMBER

    I forgot to ask why the thermostat change, but you're right that could be a contributing factor. The idle vacuum sounds a little low unless you have a lot of camshaft. On mine I was trying to get it to idle at 750 rpm and could only get about 11 in. on the vac. gage so I changed the power valve ..twice. That really didn't seem to help; then I noticed that if I raised the idle rpm to about 1000 the engine really smoothed out and I got 12.5 to 13 in. vacuum. I readjusted the mixture screws and finally settled at 950 rpm ( then went back to 6.5 power valve). I have a manual trans so no converter to deal with. If you have an automatic you're limited to what you can set the idle at.
    With todays fuel I think it goes out the vents and as the float drops it allows fuel in the lines to enter the bowls and vaporize out. I never find any fuel lying on the throttle plates or any evidence of leakage else where. I doubt the oil change is necessary. Good luck.
     
  9. southcross2631
    Joined: Jan 20, 2013
    Posts: 3,753

    southcross2631
    Member

    I make my spacers from marine plywood. Great heat insulator and cheap too. Just use a carb gasket for the pattern .
     
  10. Truck64
    Joined: Oct 18, 2015
    Posts: 4,056

    Truck64
    Member
    from Ioway

    It's worth taking the time. 34° is reasonable for total mechanical timing, but this is always measured with vacuum advance port disconnected and plugged. The weights only determine "when" the timing is advanced, not "how much". An OEM distributor may have such stiff springs full advance may only come in above 4000 RPM.

    Letting the initial or crankshaft timing fall wherever it may in order to get this 34° total timing is reasonable, except when this causes starting problems. Usually around 20° can start to cause problems. Starter kickback esp. in hot weather can be a problem. Stock OEM type distributor curve are slow to come in on the road (stiff heavy springs) and excessive advance. By limiting the amount of distributor advance inside the distributor somewhat, this allows for more "room" to play with when setting the initial timing. It sounds though a little like this may already be the case. Usually 10° to 12° to 14° crankshaft advance should be right in there. Unless you have a performance cam the engine vacuum should be high and steady at a low factory idle. Once the mechanical timing is where you want it, after some "test driving", re-connect vacuum advance and dial that in. This is important because the vacuum advance does not factor into "total" timing.
     
    Last edited: Jul 4, 2017
  11. I had an Edelbrock 600 on my El Camino and one day on the way home from work, I stopped to see the wife at O Reilly's where she worked. I shut the engine off and heard a strange noise under the hood, it turned out that the fuel in the float bowl was boiling. I was running one of those thin carb gaskets that come with the carb. At home I had an old 1 inch phenolic Moroso carb spacer left over from my drag racing days, once installed, it cured my long hot crank time. The engine also had a little more power too. It was a stock 350 with a small cam, aluminum intake and headers.


    Sent from my iPhone using H.A.M.B.
     
  12. With my 355 SBC my initial timing is 12* BTDC, total timing is around 36*. I have a 1" Moroso phenolic spacer under a Holley 700 DP. It always starts well, hot of cold. A little harder when hot, which is sometimes associated with an aluminum air-gap intake manifold. I would knock down the initial timing as suggested and get a spacer under the carb. I think most of your problems will go away. I also run a 180* t-stat.
     
  13. Engine man
    Joined: Jan 30, 2011
    Posts: 3,476

    Engine man
    Member
    from Wisconsin

    Another thing that can help is to use a bypass type filter with a return to tank line that will allow a constant fuel flow to bring cooler fuel from the tank. The fuel doesn't have to sit in the line when the float is closed so it isn't as warm when it goes into the carburetor.
     
  14. If the engine is stock, or nearly so, it should be making more than 11 in. of vacuum at idle in neutral. Probably something more around 18 inches or so, give or take. A "funny" camshaft will reduce manifold vacuum, as will retarded ignition timing. Are you sure the vacuum gauge is plumbed to a source of full manifold vacuum and not a ported vacuum source on the carburetor?
     
  15. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    The engine is not stock...not wild, but the cam is definitely not stock, it has a very lopey idle, and it never made more than 11" when there was a Holley 750, 600, or even this Edelbrock on it. It used to ALMOST stall when I ran power brakes.

    UPDATE:
    I put in a 1" wooden carb spacer and swapped the 180* thermostat back in. (I tried the 195* just to see if it ran any better, now I know). It runs better, starts quicker, but I still think there is a problem with underhood heat while parked.

    If I shut off the ignition and start it right back up, it fires off without any throttle input, it less than a second of cranking. If I wait 20 mins, it requires a full throttle input to fire back up.

    The truck is a '60 F100- there is little to no air circulation under the hood, as evidenced in the photos below. Whatever heat is being made rises to the hood and has nowhere to go. The only openings, aside from beneath the frame rails, are a small hole the size of a quarter on the passenger fender, and a square hole low on each fender, about 3"x3" or so. (I didn't measure it).

    Seems like it needs to get some heat out of there. I am tempted to take a hole saw to the inner fenders and see if I can make some kind of escape hole for the heat.

    I also read a few forums where people have removed the weatherstrip at the rear of the hood and this gave the air a place to go. I just don't want to do that and have other problems, like the hood vibrating or water messing something up. That same forum suggested using washers between the hood hinge and the hood to create a gap that could allow air to escape...sounds like it may look terrible- also at the back of my hood is a flange that is 90* to the top, so that would probably need to be trimmed for it to work, too.

    Any ideas?
    Thanks. Driver Fender.JPG Pass Fender.JPG Flange rear of hood.JPG
     
  16. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,151

    BamaMav
    Member
    from Berry, AL

    Just louver the hood, heat problem solved! :D
     
  17. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    Bama,
    That is my favorite option BUT, I am not sure how it would look with the truck at stock height. Maybe I am wrong but I feel like louvers belong on cars that are more modified aesthetically.
    All that matters is how it looks from the driver's seat, I suppose.
     
  18. BamaMav
    Joined: Jun 19, 2011
    Posts: 4,151

    BamaMav
    Member
    from Berry, AL

    Ford used a cast aluminum hood scoop on some of the larger trucks, I don't know if it was for carb/breather clearance or a vent, but one wouldn't look too out of place since they are kinda short and small and are a factory piece. Look for F600 series or something like that.
     
  19. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    Well, if the 3 3/8" holes I drilled into the inner fender today don't work. I got three on the driver side, and between recharging batteries for the drill and having some family stuff to go do, I never made it to the passenger side. once I get the other side done I'll cross my fingers and see what happens. Then if that doesn't work, I may explore louvers.
     
  20. You never mentioned what motor you are running, could probably help with taking a crack at solving

    As for engine heat escaping, I have a couple of those early Ford Trucks with 460's in them, a motor that is notorious for running hot and Never had a problem with under hood heat. Look at model late model cars, they have far less air space around the motor, which flows down around the motor past the frame and out under the truck when you are driving.. Yes heat rises but the vacuum created when driving sucks it out the bottom.

    The idea of propping up the back of the hood or removing the weather strip will just make YOU hotter in the cab as all that hot air will go right in the cowl vents and into the cab.

    Edelbrock carbs are known for having fuel evaporation problems. Insulator spacers help a whole bunch. So do Electric fuel pumps as the refill the float bowls before you start the motor, just make sure you are using a Low Pressure pump as they flood easily with a high pressure (over 5psi).

    You mention "Priming" the carb. Do you mean pumping the pedal before starting? If so this is not uncommon for carbureted vehicles, as long as you aren't pumping it a bunch of times - Once should be sufficient. Multiple times can flood it, requiring holding it wide open as you indicated.
     
  21. Diavolo
    Joined: Apr 1, 2009
    Posts: 810

    Diavolo
    Member

    2 things. First, especially Edelbrocks are very sensitive to fuel pressure. If you aren't running a high quality fuel pressure regulator and setting it to around 2 lbs, there's your biggest issue. This can contribute to excess fuel in the intake and WOT start condition.

    Second, go to the Edelbrock website and make sure you are pulling vacuum for the distributor from a ported source on the carburetor. The website should tell you but a cheap gauge and a piece of tubing will also tell you. You should be pulling almost no vacuum at idle and increase as rpm increases.
     
    Last edited: Jul 10, 2017
  22. Deyomatic
    Joined: Apr 17, 2002
    Posts: 3,095

    Deyomatic
    Member
    from CT

    Just to answer the questions... It's a 350 and the vacuum advance isn't hooked up. It's running a regulator set to 4.5 psi, and that shows just under 5psi at the gauge.

    I drove it around today- first to dinner, after about 40 mins it touched right off with just the key, then to Home Depot, and after about 10 mins it gave the same treatment. I then drove home and let it sit for a little under 10 mins before starting it again to park in the garage and it fired right off again. If I stick my hands inside the holes in the inner fenders from the wheel wells there is noticeable heat getting out now, at least it feels that way. It starts easier than it ever has. I will report back if this changes.
     

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