Thread: SBC 350 overheats !!!!

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SBC 350 even before i added the weiand supercharger my car overheats not standing still but the faster i drive shouldnt it overheat standing still? You would think but it doesnt .

I have a datsun 280z with this 350 sbc im running no hood and its only 68 degrees outside . Ive made sure the thermostat works and it does what its supposed to do . The entire setup is only 8 weeks old from jegs crate engine and all .

I cant run a clutch fan as there isnt enough room so i have a electric fan the pulls through the radiator at about 3,300 cfm with a shroud that covers the entire radiator . Hold a piece of paper in front of the radiator about 14 inches away and it will suck it into the radiator so it seems to pull air decent .

Nothing is in front of the radiator seperate trans cooler in a different place no place near the radiator . Cools fine in traffic sitting still but get going and it hits 200 then 210 and thats with a 190 degree stat . I tried a 160 degree stat and same thing 200-210.

7 inch water pump pulley and 6 inch crank pulley milodon high flow pump tried all kinds of coolant additives still nothing

Originally Posted by SBC DATSUN

SBC 350 even before i added the weiand supercharger my car overheats not standing still but the faster i drive shouldnt it overheat standing still? You would think but it doesnt .

I have a datsun 280z with this 350 sbc im running no hood and its only 68 degrees outside . Ive made sure the thermostat works and it does what its supposed to do . The entire setup is only 8 weeks old from jegs crate engine and all .

I cant run a clutch fan as there isnt enough room so i have a electric fan the pulls through the radiator at about 3,300 cfm with a shroud that covers the entire radiator . Hold a piece of paper in front of the radiator about 14 inches away and it will suck it into the radiator so it seems to pull air decent .

Nothing is in front of the radiator seperate trans cooler in a different place no place near the radiator . Cools fine in traffic sitting still but get going and it hits 200 then 210 and thats with a 190 degree stat . I tried a 160 degree stat and same thing 200-210.

7 inch water pump pulley and 6 inch crank pulley milodon high flow pump tried all kinds of coolant additives still nothing

sounds like the water pump belt is slipping the more rpm's you turn. if you an turn it with your hand its to loose.

Checked the belt and its plenty tight kinda sings when it spins not really but its tight

Say Lt1S10 what kind of fan do you run ? clutch or electric if electric what brand ive got one from jegs the black magic fan with shroud but still the same problem happens

Originally Posted by SBC DATSUN

Checked the belt and its plenty tight kinda sings when it spins not really but its tight

just make sure its not bottom out in the pulley. if its not sitting up in the grove it want do what its suppose to do.

hey guy. i ran into this same problem on a engine awhile back and it had me going for some time, antway what i finally found was that the water pump had a slipping impeller (inside) . i don't know if this is your problen or not but it's an idea that you might want to check. let us know how it turns out

If she ain't overheating in traffic then it surely points to slippage somewhere. Unless the Z is not channeling air through the rad when you are moving, but that I have not heard of before.

Meanwhile my '97 454 truck runs at 200-210 normally. Albeit I'm in Austin and it's normally ~100 F this time of year.

It is common for the V belt to not fit the aftermarket pully grooves right. Make sure it is wide enough and not bottoming out or it will slip.

What coolant mixture are you running? For hotter blooded apps I rec 65% water and 35% glycol. Lastly you did not mention what radiator you are using?

Regards, Kitz

Im using a cross flow radiator brand new out of a 85 camaro with a 305 chevy in it a fan with 3,500 cfm rating . Checked belts tried different water pumps still the same thing . No hood no grille no bumper nothing restricting air flow tried hood and bumper same thing just gets hot quicker .

Sitting still on a 93 degree day 195 is as hot as it gets get over 2,500 rpm and 210-220 is what it hits with a 190 degree stat . Milodon water pump stock pump high flow non high flow same thing .

tried straight watter 50/50 mix and with coolant additives same thing . I was told by Jegs who i got the crate engine from 2 months ago that this is normal that a 350 chevy runs 200-220 degrees with no problem bull is what i say i want no more then 190 . Even in the rain on a 64 degree day it runs 210 degrees .

Jegs told me it was timing so i checked 18 degrees advanced at idle with a super charger and 38 degrees at full advance . The fuel mixture isnt lean im running fat 12 to 1 air to fuel a bit fat but better then burnt valves .

Originally Posted by SBC DATSUN

Im using a cross flow radiator brand new out of a 85 camaro with a 305 chevy in it a fan with 3,500 cfm rating . Checked belts tried different water pumps still the same thing . No hood no grille no bumper nothing restricting air flow tried hood and bumper same thing just gets hot quicker .

Sitting still on a 93 degree day 195 is as hot as it gets get over 2,500 rpm and 210-220 is what it hits with a 190 degree stat . Milodon water pump stock pump high flow non high flow same thing .

tried straight watter 50/50 mix and with coolant additives same thing . I was told by Jegs who i got the crate engine from 2 months ago that this is normal that a 350 chevy runs 200-220 degrees with no problem bull is what i say i want no more then 190 . Even in the rain on a 64 degree day it runs 210 degrees .

Jegs told me it was timing so i checked 18 degrees advanced at idle with a super charger and 38 degrees at full advance . The fuel mixture isnt lean im running fat 12 to 1 air to fuel a bit fat but better then burnt valves .

why 18 degrees base timing? thats hi.

All things considered, sounds to me like the temperature is OK. Blown motor is going to run hotter than natural anyway.

IMO 18 advance at idle is pretty high. 38 degrees total and no detonation is good with a street blower.

Regards, Kitz

you can run double the timing at 6,000 ft above sea level and im running 8 lbs of boost with the supercharger you can even use mid grade gas as the thin air makes it act like high grade gas strange thing thin air .

a 9.1 compression engine at sea level will be 7.5 to one up here with a 29% power loss all around it sucks .

Ive fixed the problem i bought a 18 inch clutch fan never gets over 190 now no matter what who would of thought strange now im just having a custom shroud made as i cant just buy things for this crazy conversion

Thanks for all the help

you really shouldn't need a lot of fan at 60 mph. sounds like you elec. fan stopped turning some time or another and acted as a restriction. who knows with a car. glade you got it fixed. my elec.fan does great.

I agree, at 60mph ya should'nt need much (if any) help from a fan, and remember puller fans really suck.

Got the problem worked out the temp sender electronic unit is getting heat soaked by the hot air the fan throws at it . I got to 210 degrees then put a luke warm damp cloth on the sending units top side and it droped to 160 degrees driving down the road .

Tried a ice cold rag well ya can guess that one . So somehow i got to keep it from getting hot from the hot air not sure what to do but at least im in the rite aera .

Oh its a Phantom electric water temp unit from autometer . It was worse when mounted to the side of the head wow header heat soak really threw it off .

Jason

Originally Posted by SBC DATSUN

Got the problem worked out the temp sender electronic unit is getting heat soaked by the hot air the fan throws at it . I got to 210 degrees then put a luke warm damp cloth on the sending units top side and it droped to 160 degrees driving down the road .

Tried a ice cold rag well ya can guess that one . So somehow i got to keep it from getting hot from the hot air not sure what to do but at least im in the rite aera .

Oh its a Phantom electric water temp unit from autometer . It was worse when mounted to the side of the head wow header heat soak really threw it off .

Jason

something else is wrong there jason. out side temp. shouldn't effect water temp.