350 temperature

Discussion in 'Small Block Tech' started by Treeboy, Jun 19, 2020.

  1. Treeboy

    Treeboy Well-Known Member

    Looking for some help! I own several Buicks and am very familiar with the 350s and 455s. I recently got a stock 350 going in a car for my son (68 special). It runs fine (kinda boring compared to my GS) but it runs warm. I live in Phoenix so it isn't unexpected, but even in the winter with a 180 thermostat it runs at 205 (all the time). It has a nice aluminum radiator (1.25 inch tubes), a factory fan shroud, and a 7 blade fan with a factory style fan clutch. The only thing I haven't done is replace the water pump. Is that my next task? Running an hei at 34 total advance.

    If I replace the water pump what do y'all recommend?
     
  2. Mart

    Mart Gold level member

    I wouldnt suspect the pump. Sounds like the only thing not factory is the radiator.
    Good non-leaking fan clutch?

    Maybe by pass the heater core & check temp.
     
  3. alec296

    alec296 i need another buick

    Recommend a fan clutch. although 205 is not an issue. But you don’t say if it runs hot stop and go or expressway, or idle stopped. Drain some coolant and add water
     
  4. knucklebusted

    knucklebusted Well-Known Member

    There are a few things you can check cheaply.

    First, are you sure the gauge is correct? I use an infrared thermometer to point at the thermostat neck to see what temp I get there and again at the return bottom hose. I want to see a pretty good drop between them. I don't remember off hand what I see on an 80° day but I'd expect 190° at the thermostat housing to drop below 160° going back into the water pump

    The second thing, maybe the first to try, open the radiator cap with it cold. Get it up to temp and look in the tank. You should see water running through the tubes. Revving the motor should cause more water to rush through into the waiting end tank.

    Third, you need to know the thermostat is opening at the proper temp. If you can easily take it out, boil some water and drop it in with a wire to make sure it opens and closes at the preferred temps.

    Fourth, you can try running the heat (if you can stand it) and see if the additional cooling drops your temp noticeably.

    Finally, you have a 7-blade fan and a clutch with a shroud. Is the fan about 1/2 in/out of the shroud? Some say 3/4 in, 1/4 out but it needs to be in the throat, not out and not all the way in.
     
  5. LARRY70GS

    LARRY70GS a.k.a. "THE WIZARD" Staff Member

    What timing does the engine idle at. I know it's 34* total timing, but what is the timing in gear, not moving? Next, what is the timing at your cruise RPM? Are you running vacuum advance? Is the vacuum advance working?
     
  6. Treeboy

    Treeboy Well-Known Member

    Thanks, I have checked the gauge and it is accurate (used my infrared thermometer). During the summer (now) it runs at 215 while driving but heats up pretty quick at idle.

    All my other Buicks run at the thermostat temp when in the winter. I replaced the thermostat once already so I don't think that is the issue (ran at the same temps).

    I don't think the shroud is correct, the fan is deep in the shroud. I will try changing that and the clutch. But in the winter it shouldn't matter, it should be running at 180 driving down the road.

    Larry, the initial timing is at about 10 if I remember correctly. The vacuum advance is not currently working (it is on the list of things to buy). I have not checked the curve since installed the distributor, just initial and total. It acted the same way when it still had a points distributor.
     
  7. Mark Demko

    Mark Demko Well-Known Member

    Fan clutch.
    205/210 is far from over heating,
    What ratio is your antifreeze to water?
    Water pumps rarely cause over heating unless the impeller stops rotating.
     
  8. MrSony

    MrSony Well-Known Member

    How many core is the radiator? Has the heater core ever been flushed or replaced at all? 205 is pretty normal imo. even 215 is ok, as long as it's stable.
     
  9. Schurkey

    Schurkey Silver Level contributor

    FIRST thing is to FIX THE VACUUM ADVANCE. Your part-throttle timing is 10--20 degrees retarded. That alone could cause overheating.

    SECOND, you need to pull the fan out of the shroud. 1/2 in, 1/2 out works. 1/3 in, 2/3 out may be even better. Find a shorter fan clutch.
     
  10. Fox's Den

    Fox's Den 355Xrs

    When I put my car together I bought a new radiator that was for my air conditioned car and it never ran over 180 with that temp stat.

    Now it has been in there 25 yrs now and I am now starting to see 190 as my running temp and it got up to 200 sitting in the waiting line to get into Quaker for the Buick Bash Which I did not see any 350's but mine.

    That is as hot as I ever seen my motor get

    I used to drive for about an hr to another track and had to run the engine at 3 grand all the way there for a hour until I put in the 4 speed auto. now I am at 2 grand but my running temp at this time is 190
     
  11. Mark Demko

    Mark Demko Well-Known Member

    WOW 10 degrees initial??
    Add another 4 to 6 degrees initial and limit your total if need be.
     

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