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Technical 383 sbc 235° @ 65mph 200° @ idle

Discussion in 'Traditional Hot Rods' started by Jchill40, Jun 22, 2020.

  1. gene-koning
    Joined: Oct 28, 2016
    Posts: 2,025


    Flex fans tend to flatten out as the speed increases, at what speed the flex fan flattens out would make a difference, really there probably is not much difference between a flex fan and an electric fan.

    You might want to try some of the other suggestions before you get into moving everything around like I suggested. Sealing the radiator to the grille shell would be a good start. Gene
  2. Jchill40
    Joined: Jun 22, 2020
    Posts: 15


    I’m no mechanic and my apologies I misspoke. That’s initial timing

    Sent from my iPhone using The H.A.M.B. mobile app
  3. Any chance the gauge, sender or ground connection has failed?

  4. Darin Younce
    Joined: May 8, 2019
    Posts: 576

    Darin Younce

    Had some heat issues on 47 ford coupe , has pusher fan . I removed it and ran it down road to see if it was blocking air flow , checked with Infared thermo and had no change without fan but car ran hotter at idol .
    Jchill40 likes this.
  5. Jchill40
    Joined: Jun 22, 2020
    Posts: 15


    I ran a new gauge from intake. Original temp gauge is in the head. Intake is cooler 10-20° but I feel that confirmed the head gauge is accurate

    Sent from my iPhone using The H.A.M.B. mobile app
    pprather likes this.
  6. So you have 14 degrees of initial timing. How much advance to you have at 3000 rpm?

  7. southcross2631
    Joined: Jan 20, 2013
    Posts: 4,004


    Years ago I had a big block Camaro in Colorado when I was at Ft.Carson in Colorado Springs. It always ran cool there even though it was a high compression engine.
    I got transferred to Ft. Campbell, Ky after I got back from overseas. My car started running hot as soon as spring got there and it warmed up. I had to rejet the carb and reset the timing to get it to run right and not run hot. It had a stock GM fan. It was a 396-375 .
    bobss396 and Jchill40 like this.
  8. 6sally6
    Joined: Feb 16, 2014
    Posts: 1,261


    ^^^^^^^^^ what Phil sez........Need more timing (total timing)
    Put lighter springs in that distrib. and using a timing tape crank in 34-36* timing at2500RPM (maybe even by 2000RPM).
    pitman, Jchill40 and 39 Aaron NZ like this.
  9. AHotRod
    Joined: Jul 27, 2001
    Posts: 10,671


    And there is your answer.
    Gauges in the cylinder head will always register much higher.

    Rest in peace now.
  10. Jchill40
    Joined: Jun 22, 2020
    Posts: 15


    I ordered a good digital timing light with the settings needed to set the total advanced timing correct now. I have a very old one from Sears. The numbers on my balancer got brake cleaner sprayed on them and they wiped off, a friend was trying to help.. oops. My new light will be here Monday and I really hope this cures this issue up. I do appreciate your time and help on the matter!

    Sent from my iPhone using The H.A.M.B. mobile app
  11. MAD MIKE
    Joined: Aug 1, 2009
    Posts: 554

    from 94577

    Curious if you have tried any ducting/sealing off of the rad to shell?
    Doesn't have to be fancy, some painters tape and card stock(cereal box cardboard) can be used to temporarily block off the gaps. Go for a drive and see if the temp changes.
    Even a bit of tuft testing will show if air is stalling or turbulent around the shell when you are expecting it to flow straight.
    My biggest concern would be that without a properly sealed off radiator, hot air from the back of the radiator can spill back in front of the radiator. With an open engine bay you can get some unexpected air flow characteristics.
    bobss396 likes this.
  12. I took great pains to block off the sides of my radiator where I had gaps. The areas were tall and narrow, I used aluminum angle from Ace Hardware and milled mounting slots in them. It did the trick. I was running a solid Chrysler fan and a shroud, went to a good quality flex fan and it ran 175* right away. I have an electric fan on a t-stat for when I get stuck in traffic. Have you considered a mechanical fan and shroud?
  13. Gman0046
    Joined: Jul 24, 2005
    Posts: 6,253


    Cooling Rule of Thumb. Runs hot at low speeds and idle not enough fan. Runs hot at highway speeds not enough radiator. 235 at highway speed would concern me.

    I'm betting you don't have enough radiator. Is it made in China?
    Last edited: Jun 28, 2020
    Baumi, Black_Sheep and olscrounger like this.
  14. unkledaddy
    Joined: Jul 21, 2006
    Posts: 2,864


    235 is hot, and there's no mistaking that kinda heat. It smells and feels hot.

    Is that your case? Have you verified 235 with a temp gun?
  15. What thermostat are you running?

  16. olds vroom
    Joined: Jan 29, 2010
    Posts: 937

    olds vroom

    Squeeze a couple of pool noodles between the radiator and grill shell and drive it to test blow by . It’s an east test . Also move the radiator and grill shell ahead a few inches and put a puller fan on it

    Sent from my iPhone using H.A.M.B.
    bchctybob, loudbang and MAD MIKE like this.
  17. sunbeam
    Joined: Oct 22, 2010
    Posts: 4,974


    Is this a vortec block? If so you need to run a bypass hose.
    Roothawg and bchctybob like this.
  18. koolbeans
    Joined: Apr 12, 2015
    Posts: 556


    I had same problem. Check out Flex Fan #416. The blades are flush to front face of pulley...not forward.
    Good for 8000 rpm. Will suck the hair off a frog at 100 yards. IMG_20200607_111311706.jpeg IMG_20200607_111503835.jpeg

    Sent from my XT1710-02 using The H.A.M.B. mobile app
    bobss396, loudbang and AHotRod like this.
  19. evintho
    Joined: May 28, 2007
    Posts: 1,516


    I sealed up my rad to track nose while I was building the roadster. 18 ga steel trimmed to fit and bolted to rad support. Down low I put pieces of old pond liner to seal between the axle and track nose. Flexible so it could move with the axle. I also installed an air dam underneath to help with directing the air.

    Joined: May 4, 2020
    Posts: 19

    from Goodyear

    Baumi likes this.
  21. Almostdone
    Joined: Dec 19, 2019
    Posts: 313


    Jchill40, lots of folks chiming in to help and lots of ideas.

    I’d start with differences between CO and TX. Don’t know where you lived in CO (sorry if I missed that), but elevation could be a big difference. Tuning for elevation changes jetting and timing. Several posts about checking that.

    Timing: With vacuum advance you might have 50 degrees total at low load on the highway - if you use it make sure it’s on manifold vacuum rather than ported. Otherwise you should have mid-30s degrees with just initial + mechanical when it is all in.

    Cooling system didn’t change, but maybe it was marginal to start with (?). Problems at speed are of course likely an airflow problem. Fan shroud helps immensely with this at all times - low speed with the fan (pulling !) and high speed from even without a fan. You said you didn’t have much room for a fan, etc. You may need less than you think - see the pic of my shroud and fan on a Model A with a Chevy 348. That was after moving my radiator ahead a bit with some super high-tech brackets shown in the other pic. With your AC, etc. moving the radiator may entail more than just the move.

    I see you’re looking into people’s suggestions - keep at it and let us know what you find.

    408E55C4-10C9-4DD9-AE07-9233D04F49C7.jpeg 29A470AA-1E21-4B32-AEAF-6D813463BC06.jpeg
  22. Gman0046
    Joined: Jul 24, 2005
    Posts: 6,253


    Save your time and money its not a thermostat.
  23. seb fontana
    Joined: Sep 1, 2005
    Posts: 6,602

    seb fontana
    from ct

    A good $20 dollar one like Robert Shaw in Summit Racing. I put AC in my car and thought the condensor was blocking air flow, engine temp went up by 25/30° fast or slow speeds. Chased for 2-3 yrs, fans, ducting. Put new Robert Shaw thermostat in and coolant temp went down by 40° !! I had to lower the coolant level in the radiator to get the temp back up to where I wanted it..
    Last edited: Jun 29, 2020
    bchctybob and loudbang like this.
  24. Mr48chev
    Joined: Dec 28, 2007
    Posts: 27,526


    Running hotter at road speeds and cooler when it slows down is one indication of the wrong rotation on the water pump.
    I'm guessing that the builder bought the water pump for the year model of the engine block or that it came on the crate motor and is designed for counterclockwise serpentine belt operation and you are running V belts and running int in a clockwise rotation.

    I'd be checking that water pump to see what the actual direction of rotation is and go from there.
    AGELE55, bchctybob, loudbang and 2 others like this.
  25. olds vroom
    Joined: Jan 29, 2010
    Posts: 937

    olds vroom

    Any progress?

    Sent from my iPhone using H.A.M.B.
  26. 6-bangertim
    Joined: Oct 3, 2011
    Posts: 385

    from California

    Good suggestions here, but don't overlook the water pump, if it's a stock replacement. I had a similar issue with the 283 in my '57. Had the radiator rodded, but no change. tried a Super-stant, than a RobertShaw thermostat, still no change. I happened to bump the fan while measuring for a shroud, noticed a bit of play. Called my guy at NAPA, looking for a gringo-made rebuilt or new pump. Nope! So, I settled for new rice pump from NAPA, that did the trick. Temp went down from 220-230, down to 190-200, but never a tick over 200!

    NOT all replacement water pumps are made the same. If you want a performance pump in cast iron, consider one from Steward Racing. They also offer them in aluminum, as do the usual players - Moroso, Edelbeock Wieand, etc.

    Good Luck, let us know the REST of the story!
    loudbang likes this.
  27. stubbsrodandcustom
    Joined: Dec 28, 2010
    Posts: 1,283

    from Spring tx

    Dial in TIMING first and foremost. By 3k rpm you should be at 34 deg area. If its able to be recurved, stroker motors like a faster swing in timing, all in by 2500 rpm is about right, helps heating also. Once you have the base curve set, play with vacuum advance if you have it, as that advance on chevy motors especially drops combustion temps bigtime.

    As others mentioned check the water pump, a reverse rotation waterpump on standard rotation acessories will cause the problems you are seeing also. You could have a thermostat that is not able to flow also, but for 20 bucks I would go ahead and replace just for peace of mind also. Air density and humidity differences between texas and colorado add up for sure also.

    Got to ask, when cold what temp does the motor get for first open of the thermostat? Almost sounds like he put a 195 or 210 thermostat in it.
    6-bangertim and Elcohaulic like this.
  28. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 1,323


    Those little air filters might be starving that motor. Put one big air cleaner on it and try that.. I had the same issue on my Pontiac years ago with trips. I pulled the big air cleaner for three little ones and started having all kinds of issues. Put the big one back and it ran great!

    I never had any luck with electric fans. Everytime I put the big clutch fan on everything worked great..

    I only use Stant thermostats. I had all kinds of issues with those Mr Gasket Robertshaw style thermostats.
    Last edited: Jul 2, 2020
  29. Elcohaulic
    Joined: Dec 27, 2017
    Posts: 1,323


    Every Chevy and Pontiac motor I ever had liked a faster swing all in by 2500. Especially with a 1:1 high gear and a 2 or low 3 series rear end. Its like the first thing I do when I buy a new one.. My present 454 with 781 heads loves 20 initial with 16 mechanical all in by 2500, no vacuum advance. Yesterday I tried setting the vacuum advance, that motor hates any kind of vacuum advance.. I still have the HEI on it. I have a real nice 1962, Iron, single points, distributor with a CD box going in it sometime soon. That should make tuning a snap.

    OP I would try disconnecting the vacuum advance and turning up the initial to 18-20. I hope your running a 160 thermostat anything other will make that motor run real hot in the climate you live in..
    Last edited: Jul 2, 2020
    stubbsrodandcustom likes this.
  30. phat rat
    Joined: Mar 18, 2001
    Posts: 4,392

    phat rat

    From personal experience another cause of cool at low speed but running hot going down the highway is the number of fins per inch the radiator has. The greater the number of fins the better the cooling
    6-bangertim likes this.

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