New 351w Running Hot

[DirtDonk]

Did we already talk about 351 Windsors and over boring?
Seems like we did and you came back with that it wasn’t heavily overbored, and that they did check the cylinder wall thickness?
I’ll have to go back and reread! If I can!
The 351s are well known for having heating problems when bored too much and the cylinder wall gets too thin. But the typical concerns way back when, were more about general running and using in the high-performance applications. Not so much if it’s heating up at idle and staying there, no matter what. But if they could cool it down by driving it, it wasn’t as big a deal, unless it kept climbing like was said.

I guess I’ll have to go back and recheck what you were running for ignition timing as well.
Have you played with that at all since this started?
I would definitely drive it. Don’t concern yourself over much just yet if it doesn’t heat up while driving and only heats up at idle.
Yes, it’s something to keep an eye on. But I wouldn’t let it stop me from driving and breaking in the engine and playing around a bit.
How many miles did you say you have already put on the engine?

Sorry for all the repeat questions. I know most of it has been discussed already.

 

[Ol'Blue]

Will do some more testing tomorrow and rev in driveway.

When I researched the right tstat when I put the motor in I came up with 180* as best option. Cruising on the freeway it runs around 190*, in traffic is when it climbs.

Stock bore, it was an extremely low mileage 351 and all we did is put in a mild cam with GT40 heads.

I have put about 130 miles on the motor.

Timing is at 10* at idle. I have a Pertonix dizzy that has been recurved. Out of the box it had a ton of advance. After the dizzy adjustments it runs much smoother and more low end torque.

But I think you guys are right and I think Im expecting it to run too cool, but Im just concerned with overheating on a slow trail and really putting it to the test.

 

[ba123]

Hey, overheat once and you never forget the experience of being stuck at the side of the road…or worse! I know I told the story once about my ‘55 f100 when the exhaust manifolds used to glow red and I never figured out the problem until the problem eventually broke, which was a stuck oil pump that slowed down the cam to to a struggle on the oil pump shaft and that shaf ended up twisted like a wrought iron stair post…I still need to find that thing; there is no way I would’ve gotten rid of it.

Anyway, THAT was overheating and overheating to the point that the engine would shut itself off. It was an engine just to get by while I built up another engine so didn’t care too much, but just putting it all into perspective. The number of problems do have a limit and you will find it more easily than I found mine (which was driving home from San Diego in the middle of nowhere at night alone).

 

[Ol'Blue]

Yup I really want to make sure I can maintain a reasonable temp in the driveway so when Im crawling around the rocks, Im good. Did some more testing today. With the new fan it will suck a shop rag against the grill at about 900 rpm idle. Before it wouldn't hold a paper towel in place. So Im happy about the new fan.

I made a super custom almost color matched air damn out of blue painter's tape to see if that would increase airflow. Was hard to measure but it seemed to flow a little better sucking the shop rag a little tighter. Not wet t-shirt tight but still good. I still think its something I'll do even if its just for the looks.

I revved it up in the driveway at suggested, 1,200, 1,500 then about 2,000 rpm maintaining those rpms for a minute or two. It wasn't until about 1,800-2,000 when it started to cool down and the electric booster fan shut off.

How do you all think this plug looks? I only have 130 miles on it, so maybe too soon to tell but looks lean to me.

 

[ba123]

Yup I really want to make sure I can maintain a reasonable temp in the driveway so when Im crawling around the rocks, Im good. Did some more testing today. With the new fan it will suck a shop rag against the grill at about 900 rpm idle. Before it wouldn't hold a paper towel in place. So Im happy about the new fan.

I made a super custom almost color matched air damn out of blue painter's tape to see if that would increase airflow. Was hard to measure but it seemed to flow a little better sucking the shop rag a little tighter. Not wet t-shirt tight but still good. I still think its something I'll do even if its just for the looks.

I revved it up in the driveway at suggested, 1,200, 1,500 then about 2,000 rpm maintaining those rpms for a minute or two. It wasn't until about 1,800-2,000 when it started to cool down and the electric booster fan shut off.

How do you all think this plug looks? I only have 130 miles on it, so maybe too soon to tell but looks lean to me.

That’s great that the temp went down. That’s a start at least to know you can and there’s nothing out of control. And driving it should be great but crawling or traffic not ideal.

I say out in the right tstat and see what it does. What’s the radiator?

The plugs don’t look run enough to me but maybe someone else has something on that. Did you gap them or trust them? I never trust gaps. I’ve seen expensive plugs that are supposed to good for my Porsche be way off. Had a shop even put in a set right and when I asked, they said you don’t need to gap and when I pulled them out later I found the problem.

 

[Ol'Blue]

Been driving the new 351w and really liking it. About 200 miles on it now.

Still wanting to get the temps down and dial this in more.

Fan distance in shroud looks good to me on passenger side but too deep on driver side. Do you think its worth trimming the shroud on the driver side back some?

Also, I was thinking about opening up the hood more to allow under hood heat to escape. I have about 1" gap between the air cleaner and edge of hood. Air cleaner stick up past the hood about 1.5" into the scoop. Do you think opening up the steel hood will allow under hood heat to escape?

I realize this is somewhat of a different issue than coolant temps, but I also have vapor lock issues sometimes on the trails.

Thanks,

 

[73azbronco]

I did not try revving it up to see if it would cool.
Hood closed
I know 210* is not that bad but was hoping to see it below 200* at idle.
Maybe my expectations are just too high and I should just drive it for a while and see how it goes.
Yes 180* tstat
When the elec fan kicks in you can feel more airflow
You are correct on the fan in shroud. The top 1/4 its all the way in. On the passenger side halt way in and on driver side 3/4 of the way in. I didnt notice the driver side being in so far before.
Maybe next step is to cut that extension piece off the top and trim every side to half in.
Idle is already pretty high.
I have the WH 5.75 pulleys so maybe change size of motor pulley to increase the fan speed?

Use a digital IR thermometer to get a baseline for what the temps are around the cooling stuff, verify 210 is what is seen at the sensor spot.

 

[bigmuddy]

Been driving the new 351w and really liking it. About 200 miles on it now.

Still wanting to get the temps down and dial this in more.

Fan distance in shroud looks good to me on passenger side but too deep on driver side. Do you think its worth trimming the shroud on the driver side back some?

Also, I was thinking about opening up the hood more to allow under hood heat to escape. I have about 1" gap between the air cleaner and edge of hood. Air cleaner stick up past the hood about 1.5" into the scoop. Do you think opening up the steel hood will allow under hood heat to escape?

I realize this is somewhat of a different issue than coolant temps, but I also have vapor lock issues sometimes on the trails.

Thanks,

I am a fan of cutting out the inner fenders to allow heat to escape. Mine are open, but there are several companies that make covers too.

 

[gr8scott]

I am a fan of cutting out the inner fenders to allow heat to escape. Mine are open, but there are several companies that make covers too.

Ventilators Inner Fender Vents

Keeping the Bronco cool can be a challenge. Part of the problem is the lack of air flow which causes high under hood temperatures. Here's one product that will definitely help. The Ventilators are laser cut from 18 guage stainless steel. They allow the hot air to escape through the inner fenders...

www.wildhorses4x4.com

 

[73azbronco]

Will do some more testing tomorrow and rev in driveway.

When I researched the right tstat when I put the motor in I came up with 180* as best option. Cruising on the freeway it runs around 190*, in traffic is when it climbs.

Stock bore, it was an extremely low mileage 351 and all we did is put in a mild cam with GT40 heads.

I have put about 130 miles on the motor.

Timing is at 10* at idle. I have a Pertonix dizzy that has been recurved. Out of the box it had a ton of advance. After the dizzy adjustments it runs much smoother and more low end torque.

But I think you guys are right and I think Im expecting it to run too cool, but Im just concerned with overheating on a slow trail and really putting it to the test.

Based on this, I submit you have a cooling issue based on radiator and or fan not moving enough air.

 

[73azbronco]

First thing I would try is a 192-195 thermostat.

This, run at least a 190.

 

[Ol'Blue]

Yep those work well. Put them on a couple years ago. Thanks!

 

[73azbronco]

I'll get a lot of disagreements over this, but

Ol'Blu, I'm certain to get a lot of disagreement here, but the super cooling equipment available on a Bronco will cool even the strongest engines. You don't need the four pass radiator and the high flow water pump to do it. You just need to do all the stuff right. A shroud that's really a shroud, and a fan that will blow your hat off. That's the seven blade super cooling fan. It's the best, even though it's technically a flex fan.

This, dump your multi pass radiator, all you are doing is restricting water flow in my opinion. Get a standard good quality new not rebuilt water pump for direction you need.

I am not a fan of flex fans. Get the solid fan and use a clutch, heavy duty giving you 100% lockup. I am not a fan of electric fans, its another thing that blocks airflow when a good stock cooling system handles things up to a warmed over 351.

How far from the edge of the fan is the shroud? Side to side not front to back?

My system, 347 450Tq/405HP that runs at 190 up 7% inclines in 5th doing 65 with an OAT of 108f. Then, stays at 190 when I abruptly stop and idle for 5 minutes. Stock copper radiator, stock explorer water pump, WH fan shroud for 2 inch BL. Stock explorer HD steel fan and stock HD clutch. OK, full disclosure my fan clutch is off a GMC something or other to get the extended snout, but is identical spec to explorer HD. No magic, just simple.

 

[73azbronco]

What is tranny fluid temp? That will load your radiator with about an extra 10-20 degrees right there, might consider off radiator cooling radiator with its own fan. I was going to mount one under passenger floor but decided to go manual.

 

[73azbronco]

Yep those work well. Put them on a couple years ago. Thanks!

works well based on what? Look, there is a whole lot of area on sides of motor that dumps heat downward moving or stopped, I am not a "fan" of these, don't have one, I live in Az. I do not believe these reduce heat for other than post shutdown heat soaking, which is not your issue. Even then, I am unconvinced having a screen to allow air to flow out 12 inches higher than regular inner fender, gives you much except work and expense.

 

[73azbronco]

I did not try revving it up to see if it would cool.
Hood closed
I know 210* is not that bad but was hoping to see it below 200* at idle.
Maybe my expectations are just too high and I should just drive it for a while and see how it goes.
Yes 180* tstat
When the elec fan kicks in you can feel more airflow
You are correct on the fan in shroud. The top 1/4 its all the way in. On the passenger side halt way in and on driver side 3/4 of the way in. I didnt notice the driver side being in so far before.
Maybe next step is to cut that extension piece off the top and trim every side to half in.
Idle is already pretty high.
I have the WH 5.75 pulleys so maybe change size of motor pulley to increase the fan speed?

Are these the stock sized pulley, if larger, slower fan.

 

[73azbronco]

Unfortunately motor can’t be raised. Distributor is already close to the hood. Yes 1” BL. Fan farther away from radiator, might be able to squeeze 1/4” otherwise blades may hit belts and radiator hose. Current fan is 7 blade 17”. If I can get it centered and go to an 18” that should give me about 1/2” all the way around gap.

Which is the best 18” fan?

I have been playing with the mixture some while tuning and haven’t noticed a change in temps.

Get an 18, get a clutch that works with your setup., get the smaller pulley. Generally cheap fixes, you next step if this doessnt work, new one pass copper radiator. Then stock water pump.

 

[73azbronco]

Are or have you tried water wetter type additive in fluid?

 

[bigmuddy]

works well based on what? Look, there is a whole lot of area on sides of motor that dumps heat downward moving or stopped, I am not a "fan" of these, don't have one, I live in Az. I do not believe these reduce heat for other than post shutdown heat soaking, which is not your issue. Even then, I am unconvinced having a screen to allow air to flow out 12 inches higher than regular inner fender, gives you much except work and expense.

Well opinions are like....

Glad you don't need or want them but they do work.

 

[bigmuddy]

Are or have you tried water wetter type additive in fluid?

Waste of money and a bandaid fix for a stupid money.. I don't know anyone would waste their time with this product.