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Old 03-07-2010, 09:26 AM
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Sbc 350 Over Heating

HI, sbc 350 I put together 30k ago, with new vortec heads, rebuild the 80 chevy mini Winnie m/home
runs great stared getting hot check temp/ 225-250 turn off.
rad. now new, t-stat, water pump. ect. new no difference- no head gaskets signs! check temp engine block 170, left head 170, right head 225+ within 10-15 minutes of start up. confimed with infrared temp gauge and mechanical temp gauge in head. restarted project again- confirm temp again. thought
poss. build up in block or pass plugged in Cly. head. tear down- no evidence of leaks, cracks, gaskets very good- no cooling sludge- ports all clean and wide open-will take both heads for pressure check in on Monday and insight
to what I may have missed! I am a 20+ year Import tech. play with old iron for fun! Thanks for your input, Bob.

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Old 03-08-2010, 06:00 AM
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I work for a cooling company and get this question all the time. Is the water pump being overdriven? by that I mean is the pump pulley smaller then the crank pulley? is the rad copper/brass or aluminum? how much HP does the motor make? what kind of fan you running? electric or belt driven? does the bottom hose have a spring in it? with these questions answered I may be able to help
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Old 03-08-2010, 07:15 AM
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FWIW, there are bypass hoses to redirect coolant (The image is not my engine. There are other- possibly better- set-ups that are plumbed to the water pump), but if this is something that just began, it won't be anything that'll help repair what's wrong.



Any chance the exhaust (possibly a heat riser or cat-con) is restricted on that side?

Depending on the intake, there might be a lean condition originating from one side of the carb- but I suspect you'd have heard the pinging associated w/it if that were the case.
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Old 03-08-2010, 03:36 PM
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Quote:
Originally Posted by MYSPEEDBUGGY
HI, sbc 350 I put together 30k ago, with new vortec heads, rebuild the 80 chevy mini Winnie m/home
runs great stared getting hot check temp/ 225-250 turn off.
rad. now new, t-stat, water pump. ect. new no difference- no head gaskets signs! check temp engine block 170, left head 170, right head 225+ within 10-15 minutes of start up. confimed with infrared temp gauge and mechanical temp gauge in head. restarted project again- confirm temp again. thought
poss. build up in block or pass plugged in Cly. head. tear down- no evidence of leaks, cracks, gaskets very good- no cooling sludge- ports all clean and wide open-will take both heads for pressure check in on Monday and insight
to what I may have missed! I am a 20+ year Import tech. play with old iron for fun! Thanks for your input, Bob.
What is the intake?

Bogie
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Old 03-08-2010, 04:43 PM
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thanks for the responce! 350 sbc over heating

thanks for the response.
this ran very good pull small trailer and pass everyone on the big mt passes with on problems. then suddenly getting hot- only on one side right Cly. head. left head and radiator stays cool- until left head reached 225-250
Intake is a vortec carb intake by edelbrock. 2116
the water pump pulleys are all stock just installed a new high flow for better flow. new 4 core radiator oe style with oil cooler. old one 3 core, oe fan clutch operation normal- with good fan shroud.
heads will be checked at the machine shop soon will respond to status then.

thanks for your time!
Bob
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Old 03-08-2010, 05:56 PM
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Quote:
Originally Posted by MYSPEEDBUGGY
thanks for the response.
this ran very good pull small trailer and pass everyone on the big mt passes with on problems. then suddenly getting hot- only on one side right Cly. head. left head and radiator stays cool- until left head reached 225-250
Intake is a vortec carb intake by edelbrock. 2116
the water pump pulleys are all stock just installed a new high flow for better flow. new 4 core radiator oe style with oil cooler. old one 3 core, oe fan clutch operation normal- with good fan shroud.
heads will be checked at the machine shop soon will respond to status then.

thanks for your time!
Bob
Have you had a chance to check the intake manifold bolt torque (11 ft/lb)? The gaskets will take a set and need at least one re-torquing and possibly more before it settles in.

Edelbrock also advises against using manifold end seals. They say to "Use RTV silicone sealer instead. Apply a " high bead across each block end seal surface, overlapping the intake gasket at the four corners. This method will eliminate end seal slippage."

Are you using the OEM bolts? If so, these bolts are designed to bottom out to prevent the OEM-type gasket from being over torque or squeezed too much. If they bottom prematurely, there might not be enough clamping force to maintain a good seal.

ARP bolts do not have the rounded "ball tips" that the OEM bolts have. The OEM bolts can be ground down if they are suspected of being a problem.

GM bolt on Left, ARP Right

What type intake gaskets are you using? If they are the stiff, OEM-type, they are said to be leakage prone in the best of circumstances. This isn a common problem that's reported here often.

The Edelbrock #7235 gaskets are said to work well on your intake manifold. MS98000T is Fel-Pro's version of this gasket, I believe. Jegs' intake gaskets for the Vortec that might be OK (need to verify this) is their #555-210003.

These problems could cause a lean condition if the intake is pulling vacuum at the gasket. Are the headers showing a lot of heat?

One quick and dirty test for vacuum leaks is to spray WD-40 on the head/intake interface, or base of the carb, etc.- where ever a vacuum leak is suspected. But if the leak is under the intake, this won't show it.

A vacuum gage might show an abnormally low reading, and the plugs could also show if there's a lean condition- or if they're oily from the intake pulling oil from the underside.

Last edited by cobalt327; 03-09-2010 at 04:29 AM.
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Old 03-08-2010, 06:33 PM
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Quote:
Originally Posted by MYSPEEDBUGGY
thanks for the response.
this ran very good pull small trailer and pass everyone on the big mt passes with on problems. then suddenly getting hot- only on one side right Cly. head. left head and radiator stays cool- until left head reached 225-250
Intake is a vortec carb intake by edelbrock. 2116
the water pump pulleys are all stock just installed a new high flow for better flow. new 4 core radiator oe style with oil cooler. old one 3 core, oe fan clutch operation normal- with good fan shroud.
heads will be checked at the machine shop soon will respond to status then.

thanks for your time!
Bob
I was hunting to see if this was a 360 degree manifold where an error in fuel flow on one side could influence all the cylinders on that side to run lean which the 2116 isn't.

The Chevy does tend to put more coolant into the passenger side of the block than the drivers and it tends to run drivers side a bit warmer as a result which is why the temp sensor is usually found there.

I suppose the possibility of some internal casting mal-formation, or trapped manufacturing crud could be in a head.

I could also guess that a vacuum leak from the manifold not clamping the gasket adequately on that side would have to be considered in play.

Also, Chevy's will sometimes trap air in the back of the head, I suspect the result of casting core shift. Cobalt showed a picture of lines off the rear of the head to under the thermostat return. This is fairly common distance racing mod done to the SBC to help insure steam and air doesn't get trapped back there. The fact that you can buy a thermostat adapter from any speed catalog that has the necessary return holes already tapped may say something about how common a problem this is. When the Chev blows, its often 5 or 7 that do it because they run hotter than the other cylinders. This is also a symptom of the ignition sequence that has 7 firing just 90 degrees behind 5. Ford FEs have a similar porblem it's just in their numbering sequence, its 7 and 8.

When I set up a distance race car I gauge both heads and the common return. That, however, takes up a lot of panel space. For a street vehicle, you could use one gauge, three senders and a switch to keep track of things if so inclined. I like gauges and switches, brings out the flight engineer in me.

The LT1 heads I blogged about that I had welded up by Heads Up in Auburn to convert them to conventional cooling are for a distance racer. The returns are cut into the front of the heads ala original Chrysler Hemi and the old Smokey Yunick NASCAR kit that Moroso used to sell. I use a 1 inch aluminum adapter block with a thermostat and a conventional Chevy water return for each head. The original LT bypass holes where a steam vent using banjo fittings; these are retained on the rear. They get retapped to NTP fittings. Then a hard line is run off the back of each head into the thermostat adapter to provide an escape for anything caught back there. Each side then routs up thru coolant return hose to a tee fitting, with a single line from there to the crossflow radiator. Why all the messing around, because rules, rules, rules. This is a class that requires a 23 degree production head with no porting. OK, I can work with that. Oh the thermostats will eventually get replaced with restrictors once I see what each side wants to even out the temps overall.

For a street engine, venting the rear of the heads can be accomplished by putting fittings on the back of the intake and using this for the usual return source Chevy does thru the heater core. If you had an old Chevy, you've seen this before, at least on one side.

Bogie
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