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What Radiator For Boat Towing?

buddybbuddyb Member Posts: 4,779 ✭✭✭✭
edited June 2009 in General Discussion
After 28 years and 320,000 miles I had to put a rebuilt engine in the old El Camino.When I fired up the new engine with the intent to run it at about 2000 rpm for 20 minutes to break in the cam,the radiator boiled over after less than 10 minutes.The new coolant was filthy in that short run time.I know I screwed up by not replacing the radiator when I replaced the engine.The engine is a almost stock 305 with a RV cam,Edelbrock 500 cfm carb,Edelbrock performer intake and shorty headers.I plan to use it to tow a 19 ft bass boat.What radiator should I use? I dont know whether to use stock or if the double or triple core would be better.Thanks


  • armilitearmilite Member Posts: 35,381 ✭✭✭
    edited November -1
    I would get the biggest one I could find an afford. Not only do you have to have the extra cooling capacity for the engine but it helps cool the transmission also. I would also install a transmission cooler to. I used to hall a heavy fiberglass 16 ft (circa 1961) bass boat with my 79 Ford LTDll and it didn't take much of an incline in the road to watch the engine temperature rise. The car didn't have air so it was the standard radiator, so I went and put one in from an air conditioned car and it made a big difference. In fact if I remember right I took an automotive air conditioning condenser removed all the AC fittings and hooked up the trans cooler lines and used that as a trans cooler. Also make sure you have a heavy duty fan blade as that can make a differnce also.Good Luck
  • catpealer111catpealer111 Member Posts: 10,695
    edited November -1
    Don't go too big though. When I use to race, I pulled my 18 foot car trailer behind my '93 F-150. With the stock radiator it was always over heating, so I replaced it with one for a truck with AC. Now my truck never heats up and I have a 190 degree thermostat in it and yes the thermostat works. I still have card board on my radiator and it's getting to be summer. So, for normal duty, you can go too big on your radiator.
  • 38anup38anup Member Posts: 42 ✭✭
    edited November -1
    I ran a radiator for a g-body with air in my monte.It had a built 350 in it with no problems. Use some water wetter with your coolant and it will drop engine temp about 20 degrees.
    When you were breaking the cam in what oil were you using?There was alot of talk awhile ago on nastyz28 and montecarloss about cams going flat.Seems that newer oil doesnt have the additives (phosphates)it did a few years back.The fix was to run 15-40 deisel oil in it for cam breakin.
  • brier-49brier-49 Member Posts: 6,741 ✭✭✭✭
    edited November -1
    The coolant should have been dirty, you just ran it thru a new engine and got all the junk out. Back flush the radiator, refill with new antifreeze and run it again. Half you radiator was clogged with crud.
  • slipgateslipgate Member Posts: 12,741
    edited November -1
    It shouldn't have over-heated because of an undersized radiator. When I rebuilt my LeMans 326 engine, when I first started it, it shot up to 180 within 2 minutes but stayed there and did not overheat. I used a custom 4 core radiator. Perhaps your timing is off? Too lean?
  • LesWVaLesWVa Member Posts: 10,490 ✭✭
    edited November -1
    Who did the rebuild?
    Sounds as if it is setup to tight if it overheated in less than 10 minutes. It takes longer than that for a new factory car/truck engine to reach full operating temp. Also running a rebuild engine at 2000 rpm from the get go is not a bright idea either. The cam manufacture may recommend it. But piston rings, rod and main bearings are more fragile at start up than the cam and it's related parts.

    At 2 grand you can not watch the engine and get accurate timing, Carb vacuum (14.7 ratio) settings, oil pressure or water temp readings. And you sure can not get it if a "camper cam" as we call them is used.

    Flush and refill the cooling system with 75/25 (3 parts coolant, 1 part water) mixture.

    Restart the engine and check everything as it comes up to temp while idling at no more than 1000 rpm.

    Use a light to check the timing.
    Vacuum gauge to check the fuel/air ratio.
    Watch the oil pressure as the temps raise.
    Watch the water temp.

    If you are using a clutch fan. Use a large box type fan to keep cool air passing through the radiator. If using an electric fan hard wire it directly to the battery or other power source so that it runs continuously until you get all of the settings checked and rechecked.

    That new engine may sound cool sitting there thumping and roaring away. But it is doing nothing but destroying itself if the settings aren't correct.
  • bigtirebigtire Member Posts: 24,800
    edited November -1
    Yep, Go with the biggest one you can.
  • buddybbuddyb Member Posts: 4,779 ✭✭✭✭
    edited November -1
    The engine builder(they have been building engines for 40 years) stressed with flat tappet cam use oil for pre-1988 engines because they contain zinc,plus use a zinc addative.Newer oils have had zinc removed because as the engine wears and it gets a little blow by the zinc will kill the catalytic converter.At start up run it at 2000 rpm for 20 minutes and dont let it idle during that time.If there is a problem,turn it off.If its a roller tappet,just start it up and go.LesWVa brought up something I was wondering about on the timing is how would you know if it was too high contributing to the overheating with the engine at 2000 rpm.
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