I just had a '76 sbc 350 removed from my '36 Ford. The old engine was bone stock, but it ran great for almost 35 years. I flattened a lobe on the cam and decided to go 350 crate engine from Jeg's. However, we did change manifold and added a 4-barrel carb. The old engine ran about 170-175 temp and would go up to 195-200 on hot days in heavy traffic. This new engine is running 210 on the highway and close to 230 in light traffic. The same radiator and water pump (Flow Cooler). Any thoughts or ideas would be greatly appreciated. If we work on the timing can we get this new engine down to 170?
What is the thermostat set at in the new motor? Lots of new motors have 200+ deg. stats. Helps with the emissions, they say.
How did you set the timing? What is it set at? Did you use a timing light? Has TDC been verified at the timing pointer/indicator? Have you set up the timing curve? What kind of distributor? Are you using vacuum advance? Is it ported or full vacuum? Is the cam bigger than stock? There are so many variables, it is impossible to say if your problem can be fixed with proper timing. My suggestion is to read up on timing an SBC. There is a plethora of info on the net. Your distributor needs to be curved correctly and total timing be in the 34-36 range. This needs to be done anyway, whether or not the engine is over heating, to make your engine run the best it can. Get this done, then see if it still over heats. I'm betting your problem is elsewhere.
170 sounds to low for me Is there a chance that some sealer has closed the small hole behind the water pump
initial timing at 15-18 and the limit mechanical so it will not exceed desired total timing number and it will cool off ---engines that don't have enough initial timing run hot after that you have to determine if issue is air flow or water flow--usually the timing is the problem--after that the #2 all time issue is no wire in bottom hose--you must have a wire in that hose or it can collapse in on itself and block flow--you stop, get out and look--it has already popped back out so you don't ever see it
Are you using the old sending units from old engine? Have you checked for good grounds on the new engine? also try one of those laser temp guns to verify gauges.
take the rad cap off and let it idle for about 10-15 minutes to see if you get any large air bubbles come out. i had air traped in my cooling system and when i got it out the temp droped about 20 degrees
make sure you have the right cover and dampner combination as chevrolet has made 3 fifferent ones of them over the years . verify the TDC to the dampner .
Had a friend who had a similar issue with his crate engine that ran damn hot. Turned out he initially had a reverse flow water pump on it, too small a radiator and a pusher and puller fan. He eventually replaced the WP and used a 160 degree thermostat. Still ran a little hot due to dual fans however he wouldn't take my advise and remove the puller fan and install a mechanical engine fan.
If the old engine had the send unit in the intake close to the water neck the temp will be correct for your gauge, If you install the send unit in the cyl head the gauge will read 35 to 50 degrees hotter
I've been told that I should try a radiator restrictor to slow the water flow in the radiator. Does anyone know if this will work and if so, does it go into the lower hose outlet or the top hose inlet?
The water not staying in the radiator long enough to be cooled is a bunch of BS. In a properly designed cooling system it doesn't matter how long the coolant is in the radiator. Gary
Bob Seward said "I've been told that I should try a radiator restrictor to slow the water flow in the radiator. " This is one of the most often stated ideas when over heating is talked about and it is also completely wrong. What is needed is high coolant velocity through both the engine and the radiator. Why do multi pass radiator work, because they increase the fluid velocity through the radiator core which increases cooling. The water flow through both the engine and the radiator needs to be at a high enough velocity to ensure that the flow is turbulent. The more turbulent the better. A good example is the Yamaha TZ750 four cylinder two stroke racing engine circa 1978-85. When it was first released it had a cooling problem, Yamaha's fix was a different set of drive gears for the pump which made the pump turn faster and pump more water. Higher water velocity through the system problem solved. Rex
Guys get way too hung up on the little things like restrictors (which are completely wrong) and other garbage. Heat rejection comes down to a very simple equation which only has 2 variable components. Q = m*C*(T1-T2) In other words, mass flow rate (coolant or air) * a constant * the change in temperature equals the heat rejection rate (BTU / hr, if you are on the western side of the pond). If you put a restrictor inline and reduce the mass flow rate of the coolant, the temperature difference in the coolant goes up, but the radiator still rejects the same amount of heat. The OP's problem is that the engine is generating more heat then the radiator is rejecting. That means that you have to reduce the amount of heat energy generated by the engine or increase the amount rejected by the radiator. That can be done by increasing the air flow through the radiator (bigger, better fan or louvers in the hood) or dropping the temperature of the air entering the radiator (drive on cold days or move north). The other option to reduce the amount of heat energy put into the coolant by the engine can be done by using many good suggestions above, like confirming the timing is correct. End of the day, the OP took out a tired old cast iron 350 that was probably making 150 or so Hp and replaced it with a newer 350 that makes better then 250 Hp. Roughly speaking from a Thermodynamics perspective, you can assume that 1/3 of the total energy created by burning gas gets transfered to the wheels (150 Hp or 381,700 BTU/hr), another 1/3 gets lost to the air around the engine and out the exhaust stream, via conduction and radiation, and the final 1/3 gets transferred to the coolant. That means that the radiator could reject 381,700 BTU/Hr, but not the 636,100 BTU/Hr (250 Hp) created by the new motor. If everything else checks out, the OP needs a larger, more efficient radiator.
Are you using the same intake you had on it or are you using the name crate intake . Some of the new manifolds have a port in man. that is not in water jacket of manifold but in exhaust . Had a guy bring by a new crate that was hot and that's where he put his sending unit . If you changed the man. do you have a air leak in the intake ? You can spray the intake around where it hits the head with mist out of a spray bottle and if rpm changes - leak . Don't know if this is the problem . Lean , timing off ,leaking valve will all raise temp . Let us know what you find .
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