Aluminum head question - The 1947 - Present Chevrolet & GMC Truck Message Board Network

ratrod67 · 10-29-2003, 08:33 AM

Is there a difference in operating temperatures between cast iron heads and aluminum? I rebuilt a 454 for a 70 Monte Carlo and it's running about 210 compared to the 190 before the rebuild. I also installed a BeCool radiator, electric fans, Edelbrock water pump and March pullies. Everything seems to be fine just a difference in temp. I called and talked to March and asked about the pullies because the crank pully is a smaller diameter than the stock one and I was wondering if the coolant was passing through the system faster than the radiator could cool it down. They told me that the aluminun heads will run hotter than cast and that was probably the reason for the temp increase. Any truth to this?

ratrod67 · 10-29-2003, 08:41 AM

pic

**breeh** · 10-29-2003, 08:50 AM

There are some other variables to consider. Did you raise compression? How much time have you run the new motor?

JimKshortstep4x4 · 10-29-2003, 10:28 AM

A couple of questions that I have are:

Did you have to change the sensor?

How are the electric fans controlled, temp switch?

If you put a smaller drive pulley on the crank then, the accessories would run slower.

Jim

ratrod67 · 10-29-2003, 10:55 AM

Thanks for the replies. The compression is 10.5:1. There is about 3 1/2 hours on the new motor. The first fan is controlled by a switch and the second comes on when the temp gets to 180 degrees. When running and staning still the motor will climb to 230 or more pretty fast and even with the fans and an additional fan as shown in the pic it will not go below 210 degrees. The other fan is an industrial blower and blows like a dang hurricane. We've done a compression and leakdown test and everything seems to be ok. Just gets really hot. Also we just had water in the radiator. No coolant.

REPO1 · 10-29-2003, 11:06 AM

Try the easy stuff first. Maybe install another new 160 degree thermostat and see what happens.

miket · 10-29-2003, 11:52 AM

When my ZZ502 was installed it ran about the same temp as the original iron headed small block, however, I used a BeCool module that included the same parts you listed as well the aluminum water pump. Only one sensor was used to trigger the fans and it was 180 however the thermostat was a 190...kinda dumb. So I replaced the thermostat with a 160 and the fans hardly ever kick on unless I am sitting in traffic. The motor has roughly 500 miles on it but is 9.6-1.

Nice monte by the way....

low 84 · 10-29-2003, 12:24 PM

like someone said, the smaller crank pulley underdrives your accesories, so your water pump is now spinning slower than with a stock sized pulley. so at idle your not getting alot of coolant flow. i have billet march pully's also and i was concerned when i noticed the crank pulley was much smaller than stock. but i havne't had any problems yet.

**breeh** · 10-29-2003, 01:34 PM

I 'd put some more time on the motor if it only has 3 hours. It is still wearing itself together and that extra friction causes them to run a little warmer for a period of time. If time doesn't help then move on to some other possibilities. I assume that you bumped up compression since you are at 10.5:1. This could also cause you to be running a bit warmer.

tom hand · 10-29-2003, 05:21 PM

Horsepower=Heat The more horsepower you have the more heat you have to deal with. You will never get that combo to run 180 idleing on a warm day. Most hopped up big blocks I've ever delt with like to run 210-220. That is not overheating. My advice would be to dump the electric fans and and put a real fan on that monster.

Tx Firefighter · 10-29-2003, 06:28 PM

Aluminum absorbs heat much easier than iron. The heads are now absorbing more heat from the combustion chamber than before. The coolant is seeing more heat as a result.

My Mustang increased 10 degrees in temp when I installed Edelbrock aluminum heads. Absolutely no other changes. Never had a problem, just had to get used to seeing the guage read higher.

**breeh** · 10-29-2003, 06:49 PM

Aluminum also dissipates heat much faster. Everything else being equal, compared to an iron head, aluminum heads run cooler. This is why you can usually get away with running a point higher on compression without getting detonation.

Tx Firefighter, were the combustion chambers smaller on the Edelbrocks. I know that they are on the BBC's - thus, increasing compression ratio and increasing heat.

*rage'nrat638* · 10-29-2003, 07:11 PM

don't run that thing to lean....LEAN = HOT....
ALSO USE A MSD DIST..
PUT IN THE WEIGHT SWING OUT LIMITERS AND GET MORE BOTTOM END TIMING===
THIS WILL GIVE YOU COOLER EXHAUST TEMP.....
BETTER FIGURE OUT WHATS UP...

ENGINE WILL RUN HOTTER W/HOOD ON

also better get a trans cooler on the return line to the trans....

what size carb. u got...should be 850 cfm

tom hand · 10-29-2003, 08:11 PM

Quote:

Originally posted by breeh
Aluminum also dissipates heat much faster. Everything else being equal, compared to an iron head, aluminum heads run cooler. This is why you can usually get away with running a point higher on compression without getting detonation.

Yes you can run more compression with aluminum heads, but it because the combustion chamber is cooler because the aluminum absorbs the heat quicker...this would make the actual coolant tempature hotter

ratrod67 · 10-29-2003, 08:25 PM

Thanks for all the help!! Here's a little more info. I'm running a 160 thermostat. I have a complete MSD ignition system. We've played with the timing and haven't noticed any changes in temp. It's running a 825 cfm Mighty Demon. It has a seperate tranny cooler and dosent run through the radiator.
I knew it would run a little hotter since the motor isn't anywhere near stock anymore but I didn't expect about 40 degrees hotter.

*rage'nrat638* · 10-29-2003, 08:34 PM

put those swing out limiters in...
what range plugs u running

10-29-2003, 08:33 AM	#1
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	Aluminum head question Is there a difference in operating temperatures between cast iron heads and aluminum? I rebuilt a 454 for a 70 Monte Carlo and it's running about 210 compared to the 190 before the rebuild. I also installed a BeCool radiator, electric fans, Edelbrock water pump and March pullies. Everything seems to be fine just a difference in temp. I called and talked to March and asked about the pullies because the crank pully is a smaller diameter than the stock one and I was wondering if the coolant was passing through the system faster than the radiator could cool it down. They told me that the aluminun heads will run hotter than cast and that was probably the reason for the temp increase. Any truth to this?

10-29-2003, 08:41 AM	#2
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	pic Attached Images

10-29-2003, 08:50 AM	#3
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	There are some other variables to consider. Did you raise compression? How much time have you run the new motor? __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

10-29-2003, 10:55 AM	#5
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	Thanks for the replies. The compression is 10.5:1. There is about 3 1/2 hours on the new motor. The first fan is controlled by a switch and the second comes on when the temp gets to 180 degrees. When running and staning still the motor will climb to 230 or more pretty fast and even with the fans and an additional fan as shown in the pic it will not go below 210 degrees. The other fan is an industrial blower and blows like a dang hurricane. We've done a compression and leakdown test and everything seems to be ok. Just gets really hot. Also we just had water in the radiator. No coolant. Attached Images

10-29-2003, 11:06 AM	#6
REPO1 Shortbox wanna-be. Join Date: Mar 2002 Location: Fort St.John, British Columbia, Canada Posts: 773	Try the easy stuff first. Maybe install another new 160 degree thermostat and see what happens. __________________ 1970 Chevy C20 Custom Camper 402BB Turbo 400 trans. (Slowly becoming a '70 shortbox 1/2 ton) '71 Camaro SS 402/T400 resto '97 Z28 (11.41@127MPH)

10-29-2003, 10:28 AM	#4
JimKshortstep4x4 Senior Member Join Date: Jul 2001 Location: Muskegon,MI,USA Posts: 6,026	A couple of questions that I have are: Did you have to change the sensor? How are the electric fans controlled, temp switch? If you put a smaller drive pulley on the crank then, the accessories would run slower. Jim

10-29-2003, 11:52 AM	#7
miket Registered User Join Date: Jan 2003 Location: Seattle WA Posts: 1,466	When my ZZ502 was installed it ran about the same temp as the original iron headed small block, however, I used a BeCool module that included the same parts you listed as well the aluminum water pump. Only one sensor was used to trigger the fans and it was 180 however the thermostat was a 190...kinda dumb. So I replaced the thermostat with a 160 and the fans hardly ever kick on unless I am sitting in traffic. The motor has roughly 500 miles on it but is 9.6-1. Nice monte by the way.... __________________ FocuzTech Performance Evergreen Protective Coatings Gatorhyde...the best kept secret in spray in bed lining & protection

10-29-2003, 12:24 PM	#8
low 84 Registered User Join Date: Jan 2002 Location: Houston, TX Posts: 2,144	like someone said, the smaller crank pulley underdrives your accesories, so your water pump is now spinning slower than with a stock sized pulley. so at idle your not getting alot of coolant flow. i have billet march pully's also and i was concerned when i noticed the crank pulley was much smaller than stock. but i havne't had any problems yet. __________________ '51 F100, backhalf with a narrowed 9 and coil overs, 18.5" mickeys, monte front clip, +400" sbc in the works '05 1500 Crew Cab RIP '84 swb 5/7 drop, solid cammed 408 w/ fully ported dart heads, th350 w/ 10 inch hughes, 12 bolt w/ 3.73 richmonds and a locker '80 swb 4x4 in progress: 7" lift, 350 th350/np205, d44 and 1.5" ORD tie rod, 14BFF w/discs , armored diff covers, 40" MTR's

10-29-2003, 01:34 PM	#9
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	I 'd put some more time on the motor if it only has 3 hours. It is still wearing itself together and that extra friction causes them to run a little warmer for a period of time. If time doesn't help then move on to some other possibilities. I assume that you bumped up compression since you are at 10.5:1. This could also cause you to be running a bit warmer. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women"

10-29-2003, 05:21 PM	#10
tom hand CCRider Join Date: Feb 2000 Location: Olive Branch,MS,USA Posts: 2,232	Horsepower=Heat The more horsepower you have the more heat you have to deal with. You will never get that combo to run 180 idleing on a warm day. Most hopped up big blocks I've ever delt with like to run 210-220. That is not overheating. My advice would be to dump the electric fans and and put a real fan on that monster. __________________ 72 GMC Sierra SWB almost finished---- 84 Softail Olive Branch MS

10-29-2003, 06:28 PM	#11
Tx Firefighter Watch out for your cornhole ! Join Date: Jun 2003 Location: Azle, Texas Posts: 14,162	Aluminum absorbs heat much easier than iron. The heads are now absorbing more heat from the combustion chamber than before. The coolant is seeing more heat as a result. My Mustang increased 10 degrees in temp when I installed Edelbrock aluminum heads. Absolutely no other changes. Never had a problem, just had to get used to seeing the guage read higher. __________________ I'm on the Instagram- @Gearhead_Kevin

10-29-2003, 06:49 PM	#12
breeh Recovering 67-72 Addict Join Date: Oct 2000 Location: North Bend, WA Posts: 1,788	Aluminum also dissipates heat much faster. Everything else being equal, compared to an iron head, aluminum heads run cooler. This is why you can usually get away with running a point higher on compression without getting detonation. Tx Firefighter, were the combustion chambers smaller on the Edelbrocks. I know that they are on the BBC's - thus, increasing compression ratio and increasing heat. __________________ 68 Short Fleet 4x4; 427; BTO Level 3 700R4; NP205; Dana 60 front and rear; 4" lift with 35's; Disc brakes; AGR variable ratio steering; factory bucket seats; factory tach and tilt. "Friends call me cruzer cuz I like fast cars and fast women" Last edited by breeh; 10-29-2003 at 06:52 PM.

10-29-2003, 07:11 PM	#13
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	don't run that thing to lean....LEAN = HOT.... ALSO USE A MSD DIST.. PUT IN THE WEIGHT SWING OUT LIMITERS AND GET MORE BOTTOM END TIMING=== THIS WILL GIVE YOU COOLER EXHAUST TEMP..... BETTER FIGURE OUT WHATS UP... ENGINE WILL RUN HOTTER W/HOOD ON also better get a trans cooler on the return line to the trans.... what size carb. u got...should be 850 cfm Last edited by rage'nrat638; 10-29-2003 at 07:24 PM.

10-29-2003, 08:25 PM	#15
ratrod67 Registered User Join Date: Sep 2002 Location: DFW Texas Posts: 2,270	Thanks for all the help!! Here's a little more info. I'm running a 160 thermostat. I have a complete MSD ignition system. We've played with the timing and haven't noticed any changes in temp. It's running a 825 cfm Mighty Demon. It has a seperate tranny cooler and dosent run through the radiator. I knew it would run a little hotter since the motor isn't anywhere near stock anymore but I didn't expect about 40 degrees hotter.

10-29-2003, 08:34 PM	#16
rage'nrat638 Account Suspended Join Date: Mar 2003 Location: THE FALL GUY CHICAGO IL Posts: 5,883	put those swing out limiters in... what range plugs u running



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