underhood heat

[Glenwood]

I could use some schoolin' on fine tuning my RB.
I built this motor in the spring and did the cam break-in afew months ago and it now has approx 500-700 miles on it (speedometer/odometer is closer to kilometers when I checked against a gps). First oil change last week to dino 10w40 with a zinc additive. No surprises thankfully!
A few days ago on Saturday, I attended a Fall cruise with the local mopar group, which included some beauties (I'll post some pics of these if you wish). Well the temperature was over 90F and I thought I was in for some trouble! I almost cancelled but gave it a shot. Turns out I was the only one of the group that was affected by the scorching heat. Yeah, I know 90F is nothing like you south western guys are living with, but it is nasty for up here!

Car is/was running fine and the temperature gauge generally sits in the middle and drifts upward until the stat opens and it usually falls back to the middle. This has been consistent since I started driving it in August. I do not have aftermarket gauges yet, but seems normal for it with the 180 stat.
Driving along the open roads was fine as the outside temperatures started to rise. As we pulled into the first town, some light traffic slowed things down for a few minutes and the temperature started to rise on the gauge a bit, but nothing alarming. The engine however, was now stumbling a bit and eventually stalled in the parking lot for our first stop. Started easily to park though.
We left but the car had not cooled enough and I noticed it stumbling as I waited in line at the stop sign. It hesitated as I turned but got moving. The temperature gauge showed slightly higher than normal but was dropping as I drove at about 50 mph. First stop sign, waited about 30 seconds for my turn and stalled. Started but was sputtering a bit. I continued to drive for a bit until I slowed to stop at the side of the road where it stalled. It would start if I floored it, but would sputter when I put it into gear. It even started to diesel when I turned it off. Temperature gauge was a bit higher than normal, so I figured I had heat soak going on and vapour lock?
I managed to get it into the shade to let it cool, even though it did not boil-over or overheat. Once it cooled and started up again, one of the mechanics with us, adjusted the idle screws a bit which seemed to help the rest of the journey.

Yesterday, I ran the motor in the shop (which was about 85F) and the heat that was coming off of the rad/fan was incredible. Even with the hood open, I could not touch any metal parts on the engine like the coil or chrome covers, etc., without getting burnt. Even my chrome timing light became so hot that I had to wrap it with a rag. The temperature gauge was again slightly higher than normal and was not overheating. I assume the rad is doing its job to cool the motor, but I'm wondering if the engine is just running too hot.
I have a few questions:

How does the timing affect the engine temperature?

Could exhaust manifolds be too restrictive for certain cam designs and cause excess engine heat, besides the heat they climb too?

While a shroud should help with temperatures in traffic, can it make any difference with engine compartment temperatures?

Here's the engine specs and some analysis info.

 

[Glenwood]

Engine 413:
bore 4.25", stock stroke with Ohio H-beam rods, CP flat top pistons with valve recess
906 heads, with stock valves, new guides and gasket match porting, stamped rockers and Comp 911 springs. Did not cc heads but estimate compression to be around 9.4
Lunati 60303 hyd cam:
Basic Operating RPM Range:1,800-6,200
Intake Duration at 050 inch Lift:226
Exhaust Duration at 050 inch Lift:234
Duration at 050 inch Lift:226 int./234 exh.
Advertised Intake Duration:268
Advertised Exhaust Duration:276
Advertised Duration:268 int./276 exh.
Intake Valve Lift with Factory Rocker Arm Ratio:0.494 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio:0.513 in.
Valve Lift with Factory Rocker Arm Ratio:0.494 int./0.513 exh.
Lobe Separation (degrees):110

Melling HV oil pump
Summit Iron HV water pump
OER Alum Rad with two 1" tubes
7 blade fan
HP Manifolds
Edelbrock PErformer 440 intake, no crossover
Edelbrock 750 with 1/2" phenoilc spacer
Carter fuel pump
orange box and stock distributor. Timing was set at 12-13 BTC. The mech adv is stamped 9* and vac adv seems to bump it up by 10*.

5/16 Fuel line was installed at the rear and a sock added when I first had an issue a few months ago.

 

[moparnation74]

Carb and timing.....would be the two focus areas....Sounds like too much timing....

Carb...throttle blades could be too far open at idle...or idle needs adjusting

bad gas.....low octane

 

[Glenwood]

I relocated the fuel line yesterday, thinking the heat is too much at the firewall. My feet while driving on Saturday were roasting, even with the insulated mat and carpet.

 

[moparnation74]

I relocated the fuel line yesterday, thinking the heat is too much at the firewall. My feet while driving on Saturday were roasting, even with the insulated mat and carpet.

View attachment 518757 View attachment 518758 View attachment 518759

The heat your experiencing is not normal at all for a big block in these cars...

I do think you have simple fixes to correct it....

 

[Glenwood]

I made sure that the gas I've been putting in it is non-E, according to the pumps at 93 octane.

Pulled the plugs and they look rich to me.

Also did a compression test. I think that looks good.

 

[Glenwood]

Here's the rad & fan.

 

[Glenwood]

I tried backing off the timing to 10, 7 and then 5 btc, but the engine would stumble when throttling the carb a bit. I also went higher to about 20*, which ran ok and brought the total timing to about 30* with the vac advance left disconnected and plugged off. Once I add the vac adv, the timing would climb to over 40 at a few thousand rpm. I thought the vac advance wasn't used once the rpms climb?

 

[Glenwood]

The heat your experiencing is not normal at all for a big block in these cars...

I do think you have simple fixes to correct it....

I've never felt that much heat thrown from a rad. It was like that during the cam break-in, but I thought that was normal. At the time, I could barely adjust the idle screw as it was burning my hand. Doesn't seem much better now.

 

[moparnation74]

The key factors here are Heat, stumbles and stalls, Dieseling and hard start when hot....

Timing and carb....

Keep in mind you do not have a stock cam it is not unusual to have non stock timing ranges....bigger cams like bigger initial timing...So more initial timing but your overall around 36

What do you have with he vacuum disconnected....you may just have to run on mechanical only...

 

[1967coronet440]

Hard to tell but looking at the plugs you may be running rich, also like moparnation said timing could need adjustment.

 

[Glenwood]

The key factors here are Heat, stumbles and stalls, Dieseling and hard start when hot....

Timing and carb....

Keep in mind you do not have a stock cam it is not unusual to have non stock timing ranges....bigger cams like bigger initial timing...So more initial timing but your overall around 36

What do you have with he vacuum disconnected....you may just have to run on mechanical only...

How is the vacuum advance supposed to behave? This one appears to be adjustable, so maybe I can turn it down some.

 

[moparnation74]

Do you see fluid movement in the radiator from cold start?

How is the vacuum advance supposed to behave? This one appears to be adjustable, so maybe I can turn it down some.

you can stick an allen head wrench in it to adjust it....it will advance the timing at without it you retard the timing...it allows a little more spark at idle to burn the lean mixture

Some cam you cant run/time better without VA....Some you can

 

[Glenwood]

Do you see fluid movement in the radiator from cold start?

you can stick an allen head wrench in it to adjust it....it will advance the timing at without it you retard the timing...it allows a little more spark at idle to burn the lean mixture

Some cam you can run/time better without VA....Some you can

I didn't look at the rad coolant this time, but I know that it does not flow until the stat opened when I checked before. I also tested the stat before installing. I use an overflow/recovery bottle, and the fluid rises and falls in there as I would expect.
It is like the engine is heating up a lot, then the rad throws a ton of that heat as it cools the motor, which seems normal but very intense amount.
I did spot checks with a thermal IR gun. The manifolds climb to about 6-700F, the motor seems to be between 195-230F at various spots depending where I'm aiming.

 

[Mike67]

X2 on everything said but that fan distance without a shroud is a killer....Im betting that is most of your problem at low speed and in traffic.
There's not enough negative pressure across the whole area of your radiator to cool it effectively. You can take a small strip of a paper towel and hold it in front of the radiator and see if it gets sucked to it. I'm betting anywhere outside of the circumference of the fan is getting no flow...JM.02

 

[moparnation74]

I didn't look at the rad coolant this time, but I know that it does not flow until the stat opened when I checked before. I also tested the stat before installing. I use an overflow/recovery bottle, and the fluid rises and falls in there as I would expect.
It is like the engine is heating up a lot, then the rad throws a ton of that heat as it cools the motor, which seems normal but very intense amount.
I did spot checks with a thermal IR gun. The manifolds climb to about 6-700F, the motor seems to be between 195-230F at various spots depending where I'm aiming.

I have to say it again I would focus on carb and timing first.....

Come to think of it I had the same problem with a car I had and it was the carb...190-200...230 is up there but you do have a cam and ethanol burns at what?.....hence timing may need some adjustment. We have hotter days here in Texas and it is not uncommon to slam the pedal to the floor from a warm start but yours stalls out and sputters.....back to the carb....

 

[Glenwood]

X2 on everything said but that fan distance without a shroud is a killer....Im betting that is most of your problem at low speed and in traffic.
There's not enough negative pressure across the whole area of your radiator to cool it effectively. You can take a small strip of a paper towel and hold it in front of the radiator and see if it gets sucked to it. I'm betting anywhere outside of the circumference of the fan is getting no flow...JM.02

I thought that the ideal distance for the fan was about 3/4" without a shroud. I know a shroud will help to cool better, but wouldn't that throw even more heat at the engine? I haven't had overheating or related issues until we hit 90F. I also haven't driven it much more than 20-30 minutes at a time on the hwy until Saturday.

 

[Glenwood]

I have to say it again I would focus on carb and timing first.....

Come to think of it I had the same problem with a car I had and it was the carb...190-200...230 is up there but you do have a cam and ethanol burns at what?.....hence timing may need some adjustment. We have hotter days here in Texas and it is not uncommon to slam the pedal to the floor from a warm start but yours stalls out and sputters.....back to the carb....

I agree with you regarding the timing and carb focus. I was wondering what the effect of timing has on engine heat and what other factors come into play, such as cam specs, manifolds, etc. I can only imagine how much heat is trapped under the hood in 90F+ weather while idle. This is likely what is causing the sputtering, etc. This is the only time it has happened since putting a spacer and sock on it. The temperature has been fairly mild this summer however.

 

[oldbee]

You need a shroud definitely, ur running a direct drive fan & not channeling the air correctly. Total timing oughta be 34-38* range revved up w/vac advance unhooked. Forgot the t-stat ur using, if u said, nothing higher than 180*. Do u have the hood-radiator rubber seal that seals on the rad.support? That helps too.

 

[moparnation74]

I thought that the ideal distance for the fan was about 3/4" without a shroud. I know a shroud will help to cool better, but wouldn't that throw even more heat at the engine? I haven't had overheating or related issues until we hit 90F. I also haven't driven it much more than 20-30 minutes at a time on the hwy until Saturday.

It is the fluid your cooling and shroud allows the fan to pull air from the whole perimeter....without it you pull he circumference of the fan....That area not pulled equates to a decent percentage of fluid not cooled