Cooling question?

[6camaro9]

I usually dont post alot on here I learn more by just reading but I have a little concern with my car and I thougt with all the knowledge on this site somebody could help. This winter I made a few changes to my 400 sbc and now it is running a little warmer than it has in the past. Installed a set of Dart aluminum heads, added vintage air with a front runner system, did away with mechanical fan and now just running a electric fan with a shroud on a griffen rad. I have the condensor and a trans cooler mounted on the front of the rad. My first question is will the aluminum heads run a little warmer and if so how much warmer. The temp gets up to about 190-200 now sitting in traffic as where it use to run about 170-180. Second question is what is a temp. that is too much for aluminum heads. Thanks for any help or suggestions.

Richard

[Vince@Meanstreets]

Originally Posted by 6camaro9

I usually dont post alot on here I learn more by just reading but I have a little concern with my car and I thougt with all the knowledge on this site somebody could help. This winter I made a few changes to my 400 sbc and now it is running a little warmer than it has in the past. Installed a set of Dart aluminum heads, added vintage air with a front runner system, did away with mechanical fan and now just running a electric fan with a shroud on a griffen rad. I have the condensor and a trans cooler mounted on the front of the rad. My first question is will the aluminum heads run a little warmer and if so how much warmer. The temp gets up to about 190-200 now sitting in traffic as where it use to run about 170-180. Second question is what is a temp. that is too much for aluminum heads. Thanks for any help or suggestions.

Richard

Hi Richard,

Due to head swap, It could, depending on compression and if you had moved the timing.

At what temperatures are your fans cycling and how are they switched? Could be a simple thing as lowering the turn on time.
What temperature is your t stat rated? 180* would be a good temp.

You have AC so there is more in front of the rad adding to temp.

Much like engine performance, the cooling system must be tuned also.

[malibu795]

also an electric fan will not pull near the air(cfm) a mechanical fan with of same size will....

i'd check the on/off switch for the fan(s) and have it set right about the t-stat range..also make sure the fans come on when AC is running as well

i'd make sure the fan is big enough.. wire the fan to constant ON.
if it cannot keep temps within 10* of t-stat rating, ideally 1808 t stat=180-190 ECT by the t-stat, need a bigger fan(s) if it can.. adjust your on/off thremo switch for the fan.

also where if your ECT probe and your thermo switch probe for the fan switch at?
also how clean is the fins of bugs/dirt that would restrict air flow?

as for max temp limit... alot depends on gasket durability, coolant system pressure(high pressure higher boiling temp).. a 21# system can be ran hotter than a 16# system without over heating...

with that said... i wouldnt start to get worried till i am above 240* not that i am reccomend running that hot.. i prefer 180-200 range.

side note.. my 08 duramax has aluminum heads.. GM wont derate the engine till 250* and darn near shuts it down at 255* ECT via tuning.

[JKnight]

Did you have the steam holes drilled in the new cylinder heads?

400 SBC blocks require the heads to have steam holes, the location of which is identified by using the head gasket as a template.

[6camaro9]

Thanks for the quick replies. first i did drill the stem holes, I knew the 400 was notorius for overheating so i made sure they were drilled. Vince I had not considered the compression it did go up to approximatley 10.1 from about 9.1 so that is a good point. The t stat is 160 I believe and the fan kicks on at 175 controlled by a ron francis relay. The fan pulls about 2500cfm acording to the company. I have also considered putting in a close out panel from header panel to rad. support. So far it has not went over 210 so I have not been two alarmed. Thanks for all the help and anymore suggestions will help

Richard

[WSSix]

Given the changes you made, your temps sound perfectly reasonable and nothing to be worried about. I'd double check the gauge just to be certain too by using an infrared temp gun or separate temp gauge located at the upper radiator hose. Is the car cooling off quickly once you start moving again? Does it get to a steady temp and stay there? The engine temp should not continuously climb. It should stabilize.

[AMSOILGUY]

Motor oil plays an important part in cooling our engines as well. If water temps are rising so are oil temps. Consider a premium synthetic if your not using one already. Enjoy the benefits of those new heads.

[malibu795]

Originally Posted by AMSOILGUY

Motor oil plays an important part in cooling our engines as well. If water temps are rising so are oil temps. Consider a premium synthetic if your not using one already. Enjoy the benefits of those new heads.

Or an oil cooler.. Not to steal you thunder boss..
Oil is usually 20-30* hotter than coolant

[6camaro9]

Appreciate all of the help I'm going to try a few things that you guys have suggested and a few things that i have seen on another thread on here.