Overheat

[skinny mike]

Hope this is right place to post. Finally took the car for a drive. Got real hot and took a while to cool down. Very old 350, flushed the motor but who knows what lurks inside. Am running an electric fan with a full shroud I made. I'm going to assume the shroud is blocking air flow while moving, so will remove it and test drive again .While sitting with the fan running to let it cool down I noticed the fan didn't seem to be moving much air. So, any recommendation on a strong fan? My wife wants to go for a ride. It's been one thing after another.

 

[Indycars]

Check out this article by PotvinGuy. Also more details might help, like what radiator do you have? When does it overheat, while moving 40 mph or just at idle? What is ignition timing on your engine at idle and total advance?

Cooling secrets

 

[SRM1952]

is the running the right way --- if the wires are switched it will run backwards ???

 

[skinny mike]

It's an after market, 4 row radiator. Timing is 12-16 degrees at idle. Hard to see. Overheating while moving, not sitting. Got it up to 45-50 for a short stretch. Believe wiring correct but will check. Again what's a good, STRONG fan?

 

[Spanky]

I've heard this one moves a lot of air . . .

SPAL 30102049 SPAL Electric Fan

 

[Indycars]

Spal, Derale and Flexalite are all excellent fans. Try to get at least 2000 cfm or
more and it should be a puller fan. Some fans in the links below can move over
3000 cfm.

But it's not your fan, if it's NOT cooling while you are driving 35 mph or more.

https://www.summitracing.com/search/part-type/fans-electric/puller/yes/product-line/derale-high-output-single-rad-fan-and-shroud-kits?N=4294949187+4294447526+4294924122+4294949129+4294499216+4294499214+4294895632+4294868431+4294927288+4294882447+4294839672&PageSize=50&SortBy=BestKeywordMatch&SortOrder=Ascending&autoview=SKU&keyword=cooling fan&ar=1

https://www.summitracing.com/search...2+4294499234+4294499214+4294499222+4294499199

 

[Neshkoro]

You could have a water pump that is wrong for the engine (running backwards). The engine or the radiator could have an air pocket. A weak radiator hose could be collapsing during acceleration causing a restriction.

 

[skinny mike]

I figured the fan isn't a problem...going down the road, only while sitting. Doesn't seem like much air flow behind it..while sitting. I suspect my shroud isn't allowing enough air flow, plus the fans blades, while the fan isn't running, while moving. Will remove the shroud and reattach the fan to see if that's one problem. Then the fan itself while idling, the second problem. Two of a long list of issues .Have no idea what total advance is since not a degreed balancer or advance type timing light. The waterpump is stock for that motor. I'll check out those fans suggested. I realize some don't put out advertised cfm, probably the one I have.

 

[Indycars]

The waterpump is stock for that motor.

Don't just assume the water pump is right, Neshkoro could be on to something there. How do
you know it's right, just because an Auto Parts store sold it to you doesn't prove it's the right one.
If you have a borescope, you could pull a hose and check the impeller I suppose. There have
been lots of guys assume they know .... including myself, we are all guilty of it. Just try to deal
in facts and not assumptions. Maybe the impeller is loose and not turning like it should. I'm not
trying to criticize, just wanting to help.

A four row radiator should have NO problems cooling a SBC, something is wrong. Has this car
ever cooled properly, what's the history, anything changed recently.

They make timing tapes that can be installed on any balancer to give you the total timing. The
outer ring on a balancer can slip, so you really need to confirm TDC, then apply the tape.

https://www.summitracing.com/parts/sum-161589/overview/


Try revving the engine while you are outside the car and can see if the lower radiator hose is collapsing?
Thanks for the idea Neshkoro !

I realize that finding TDC is a major undertaking, so yes, start with the fast and easy things first. But at
some point, you will have to go there if the problem still exists. Let us know what you find and

Good Luck !!!

 

[skinny mike]

You bet I'm assuming a lot. The condition of the very early sbc,the old paint on it and the pump...leads me to believe. It's an old short one, "looks stock".Will check it. Yes...will have to pull the rad to do the shroud anyway, so can get tdc, apply tape. Just went in garage switched on the fan. Hmmm. A weak air flow behind and some small amount at the rad edges in front. I THINK the edges of the blades are pushing some air to the sides, in the shroud ,and it "stacks up" and moves to the front. Not good. Will can the shroud. Am going to spring for a strong fan for idle and slow speed cruising. How many times this old fart has had to redo things. And my wife thinks I know what I'm doing. I REALLY appreciate the feadbacks. THANKS!

 

[Guy]

My 350 had a few heat problems, one was lower-radiator hose would collapse, I purchased a spring to go in the hose , then temperature would have fluctuations running from 170-220 . Then I removed the new thermostat and installed a 160 degree one , now she runs cooler all the time warms up to 170-180 and I am in Florida never used the fan as of yet. I have had a few times it was 98 and I still went out . I would replace less expensive items first. It maybe something simple

 

[skinny mike]

I've done two things so far. I removed the thermo as one check, and I skeletonized the fan shroud for max air flow thru the rad. Still wonder about how much the fan blades might restrict the flow. Trial and (lots of) error. Both rad hoses are heavy wall silicone joined in the middle with a metal tube sealed at the joint with Gates shrink-wrap type connectors. Stiff! While under yesterday I looked at the back side of the damper. The rubber bond-don't-look-so-good. Soooo.

 

[Indycars]

I've done two things so far. I removed the thermo as one check, and I skeletonized the fan shroud for max air flow thru the rad.

And what was the outcome ???

Still wonder about how much the fan blades might restrict the flow.

Not enough to matter, if it did, electric fans would NOT be in wide spread use.

Both rad hoses are heavy wall silicone joined in the middle with a metal tube sealed at the joint with Gates shrink-wrap type connectors. Stiff!

Yeah, that doesn't look like your problem then. But have you watched the hose while
bringing the RPM's up to 3000 ?

While under yesterday I looked at the back side of the damper. The rubber bond-don't-look-so-good. Soooo.

The timing reference on the timing chain cover has had more than one position, yours
could be way off it's the wrong one. Maybe it's time to document TDC.

 

[Island Girl]

The timing reference on the timing chain cover has had more than one position, yours
could be way off it's the wrong one. Maybe it's time to document TDC.

You might really want to research this . . . if you're still having heat issues . . . .

The sbc had one timing cover with the pointer at about 12 o'clock position, nearly in the center of the cover . . .

Most have the pointer way over on the driver's side.

Different dampers and/or keyway positions in the cranks

The damper outer ring may also have shifted if the rubber is going bad, giving you a false timing indication.

Time to get a degree wheel and start verifying what you really have before you run off all over the map guessing at stuff.

I guess you could also use an infrared thermometer to make sure the rad isn't plugged up before doing anything too intrusive.

 

[PotvinGuy]

Bad timing is a real common reason for overheating. Gotta find out what your timing is. Timing lights are cheap. Do you have vacuum advance? My crate SBC runs 20 initial, 15 speed and 15 vacuum.

 

[Island Girl]

Bad timing is a real common reason for overheating. Gotta find out what your timing is. Timing lights are cheap. Do you have vacuum advance? My crate SBC runs 20 initial, 15 speed and 15 vacuum.

That truly sounds like an excessive amount of initial, about 12* is pretty normal for a sbc, as the engine loads, the vacuum drops away and essentially gets replaced my mechanical, but 15* of mechanical seems rather on the low end.

How much boost do you run, and do you have methanol cooling.

My blown BBC has the MSD boost timing retard, but no methanol.

 

[skinny mike]

Thanks all for the responses. Yes I do need to establish the timing. The radiator is new and I established it's height to be visually even with the cowl. It's kinda low so I had to fab the two hoses. The very heavy material and the tube connector in each makes them very strong but, no, I haven't looked to see if the lower is collapsing. Any thing is possible. My wife has been very patient with all the problems I have encountered but, she wants to ride, so yesterday after reinstalling the shroud , off we went for a short drive. Not long enough to see if it would overheat but, the temp rose very slowly. Will need to get it out longer. Sitting still the fan just seems so weak. It's a 16 inch so I'm thinking of one suggested here but an 18 inch to cover the rad better.

 

[PotvinGuy]

That truly sounds like an excessive amount of initial, about 12* is pretty normal for a sbc, as the engine loads, the vacuum drops away and essentially gets replaced my mechanical, but 15* of mechanical seems rather on the low end.
How much boost do you run, and do you have methanol cooling.
My blown BBC has the MSD boost timing retard, but no methanol.

The crate SBC has low CR and I hardly ever get into boost, so I can use lots of advance. If I really stomp it I can see 5# for a few seconds, then I'm going waaay too fast! And my Mallory MaxFire dist has boost retard just in case. I have a real-time advance gauge and idle at 35 and cruise at 45. I could do less initial and more mechanical, but the motor fires instantly with one of those nice geared starters, and I'm too lazy to change things. Funny you mention methanol; I'm working on a system to squirt some nitro/alky/water just for fun. I call the mix "moxie." We do love the smell of nitro in the morning...

 

[old round fart]

I have a question. HOW DO IT KNOW?

 

[old round fart]

When I pigged my long car I saw a pegged 10 lb. pressure gauge as long as I stayed in it but like you that wasn’t very long!!